Villager/Quest Knock Sensor

mlangali

Hello guys... I have a 99 Mercury Villager, and I read hundreds of posts about the knock sensor codes, but still could not get an answer to my question. Basically, my check engine light is on and I am getting error codes for a bad knock sebsor. The van is fine when its started, but within minutes you can feel intermittent puffs of exhaust at the tail pipe. I verified that all the spark plugs and injectors are good. The Hayes manual says that you can check the knock sensor by finding the KS sub-harness next to the intake manifold, but the manual only shows diagrams of the KS harness for models up to 1998. When I looked next to the manifold, there is a rectangular harness with several (about 40) wires going in one side and out the other. I am not sure if I am supposed to test the KS using the white white wire in that harness. Also, would I pierce the back end of the harness with a multipeter probe, or undo the harness, and connect to one of the ends?

Do you think it's worth spending the $500 to have it replaced?

Thanks a ton!!

efitzgerald

Wow.... I remember the first time I took my villager into the pool ! LOL, sounds like you need a plumber ! sorry i couldnt be any help...

stever

My '99 Quest service manual shows that it's a white wire going into terminal #64. It should read 2.5V DC at idle speed. A low or high voltage from the KC will be sent to the ECM and the book says to check either the harness connectors (for open or shorted circuit) or the knock sensor itself.

There's another test about disconnecting the EMC harness connector, finding terminal 64 and checking the resistance between it and ground, and look for a 500-620 KΩ on your ohmmeter.

I'll see if I can find my scanner and post the manual pages on my CarSpace page.

Steve, Host
SUVs and Speed Shop

sickandtired

I have a 1999 Villager w/200k miles. A great vehicle other than starting to loose power going up hills. I just changed fuel filters seems to help some. When accelerating slowly from a stop the van tends to lurch. I was told to check the catalytic converter. There appears to be the usual amount of exhaust. Any Suggestions?

stever

Maybe these scans from my Quest manual will work for your Villager:

Album: 1999 Quest repair info

Steve, Host
SUVs and Speed Shop

trikmc

Hi

1999 villager estate w/ 75K miles. recent major svc incl fuel filter, belts, battery, and air filters.
Our check engine light is on. It came on intermittantly then stayed on. Opened gas cap and it went gurgle gurgle gurgle and the light went out.
It came back on yesterday (all the same tank of gas) and the
local service station checked the codes this am.

They want 750 to replace the knock sensor.

Should be get a 2nd opinion? Maybe a nissan/merc dealer?

thanks

k

mke039

Wow, you could have been reading my mind with your question. I have done EXACTLY the same things you have done with my 99 Nissan Quest (they are the same vechicle).
Our problems started when we had the engine changed out after the timing belt broke and trashed the original.
I bought an OBD II computer to read the error codes and got knock sensor P0325 which will NOT trip the check engine light, and the occasional cylinder misfire P0360 which will.
I looked at the manual to see how to change out the sensor, and found that it is a joke. You have to basicly take apart the top of your engine. To have a shop do it is tremendously expensive due to the man hours involved....Still..I would do it if I knew it would solve the problem. My understanding is that it probably won"t. Knock sensors themselves are very simple devices, basicly a microphone that hears the sounds of detonation, and then sends a small voltage to the ECM and retards the timing...
Many things can 'set off' the knock sensor, and by the number of posts on this subject it is likely that we all have good sensors, and bad whatevers...
I went to 4door.com and paid an expert 20 dollars for the information that some kind soul posted here by scanning the Manual...Thanks for that.
I am going to trouble shoot the sensor circuit and see if the resistance and voltages are OK. I will tell you how this comes out.
I will NOT replace the sensor, due to the high cost, until I know for sure that it is bad. As I have said, I suspect it is something else.

stever

Our problems started when we had the engine changed out after the timing belt broke and trashed the original.

These are supposed to be non-interference engines; can you detail what happened and the mileage when your belt broke? Maybe we should move this to a timing belt discussion?

thanks,

Steve, Host
SUVs and Speed Shop

trikmc

So, i went to get the van after deciding that the local shop was in over its head and the light is out and the van drives fine. Ive got to make a trip to the airport this eve
so i'll burn up some gas and see what happens.
(and as an aside, the local service station crew charges us $73 for 'diagnostics and resetting codes)

Guess we'll not be going back THERE in any hurry.

mlangali

Hello guys...

From all the advise I have gotten, after extensive research, I have decided that it's a better idea not to change the knock sensor. Along with the 500+ cost, you could have problems later on such as coolant leaks and overall engine issues since it is a pretty major surgery to the engine.

Instead switch to premium gas, and have the codes erased. Also , make sure that all your injectors and plugs are good. You may just have a misfire due to a bad injector.

Since the sole purpose of the knock sensor is to help the engine deal with low octane gas causing premature detonation, you may be able to get around the issue by using premium gas.

hope this helps...

And thanks to all of you...I didn't know any of this stuff a few weeks ago.

Good luck...

evanna

I have a 1995 Villager. My radiator fan burned up causing some of the wires to melt. A new (after market) fan has been installed but since the repair, none of my power windows work. The work was done by a friend and we're both baffled.
There was a previous post about this exact problem and he never received a response. I'm a rural mail carrier and I have to have working windows. Any help would be greatly appreciated! :lemon:

evanna

#2069 of 2519 95 quest. Radiator fan and power windows stopped working by meshhomelife Sep 22, 2005 (7:26 pm)
Bookmark | E-mail Msg
The radiator fan blew a fuse and melted through the lead wires. When I stopped the car because it was getting hot, I couldnt roll up the windows. I replaced the fuse for the power windows but they still wont roll up. They dont seem to be connected in any way to the radiator fan motor. Do they possibly share a ground wire? The fan motor is shot. It costs 116 dollars from autozone. The dealer wants 340$. Does anyone think that these two problems are connected? The fuse for the windows did not blow, so i doubt that it has anything to do with the motor. The passenger side and driver side wont roll up. Does anyone know anything about this? The radiator fan looks easy, but does anyone know how to fix the windows?

Claires

Hi, evanna,

That post doesn't seem to have gotten any answers. You can try searching the posts here by typing words like "radiator fan", "windows", or "fuse" in the search box at the top of the group here: NIssan Quest.

If you don't see a discussion here that fits your question, feel free to start a new discussion by clicking the "Add a Discussion" link in the group here: NIssan Quest

sarinaz

Anyone have any luck here. just bought a 2000 Villager, runs great, but does lack power uphill. I have watched all the posts and am at the crossroads of doing this myself. Thanks!

trikmc

Hi,

We had a similar issue. Local shop wanted $700 to replace the knock sensor. I said no. Meanwhile, the check engine light came and went (mostly my blushing bride drives this car). I got behind the wheel the other day and it felt and sounded like it was not firing on all cylinders.
I checked the leads coming off the distributor and some of them were decidedly loose. They are a circular cylinder receptacle with a slightly smaller cylinder for the plug. I spread the plug a tiny bit with needle nose pliers and the connection became better and the check engine light went out and the engine seems to be firing on all cylinders.
$700 indeed!
Happy Holidays

sarinaz

Many Thanks. I have replaced cap, rotor, wires, plugs. I bought a code reader and it pops an occasional P0325, but no check engine light. I really don't believe the ks is bad itself. Thanks!

dtopp

I've spent some money trying to fix an odd problem with our Villager. We're not sure if the problem is fixed, simply because the problem doesn't seem to make sense to any of the mechanics who have worked on the car. I'm hoping someone here can shed some wisdom.

Here's the situation: Family road trip along I-70. I'm getting warm and notice that the blower fan is not working. Naively, I think to myself that "it's probably a fuse; I'll check when we stop for gas." About 10 miles further down the road, I hear a "clunk" as if the cruise control had suddenly disengaged and the car starts to slow down.

I press the gas pedal with the intention of getting back up to highway speed, but I get no response from the gas pedal. I do *not* get the high pitch whine of an engine revving in neutral. It simply does not respond.

The car continues to slow down, but the needle on the speedometer slowly rises (70 mph is about 1 o'clock on the speedometer -- the needle slowly "fell" to the maximum speed, at about the 5 o'clock position on the dial).

I gradually coast to a stop and shut everything down. After muttering a few words and eye balling the distance to the closest exit, I decide to try to start it up again.

It starts like a charm; and, everything works. The blower fan is blowing. The car responds to the gas pedal and moves forward.

I then drove the vehicle to the next town (about 45 miles) and consulted with a couple of mechanics. After carefully explaining to me that we were chasing a ghost, they recommended that we replace the speed sensor.

We did replace the speed sensor. And at this point, we've driven the car another 1000 miles or so without incident.

But I no longer have confidence in the car. I'm not sure that we really fixed the problem. What do you all think?

Thanks,
Dave

nicsun

Hello. I have a 99 Nissan Quest with a few issues. The speedo use to bounce all over the place and now it is not working (along with odometer and cruise control). The check engine light is on and the obdII codes come up as speed sensor and knock sensor. As well the o/d light flashes at start up for a few seconds. I have seen many others with the same problem on this and other forums, however I have not come across what the problem is, or the solution. Just wondering if anyone has come across this as well. Thanks

flight205

I have issue with my engine. two codes came out P1447 and P0325. I quess the knock sensor isn't the problem, because it detects that there is an engine issue. When i drive the car on cruise controle the would pull back and surge forward. Feels really weird. Cannot figure out what is going on. And this last week i noticed that when the engine is working on parking it goes from 1000-1500-2000 rpm without me doing anything like pressing the gas pedal. Can you help me figure this out.

warfalini

I am dealing with the same issue on a 1994 villager. The speed sensor is bad, but mine is seized in the casing. I hope you don't have this problem! I am really struggling to get it out. I am looking for advise on this also. I have been fighting it for 5 hours and making no progress.

ddgiant

I have noticed several peoples post on this now and I was wondering if any one actually has tried to replace there knock sensor. The reason I am asking, after looking at my engine, and the Hanes manual, and the images that have been posted on Steves carspace page, I think that it can easily be replaced with out pulling the intake manifolds (the main cost in the replacement)

If I am looking at all of the photos correctly, this sensor is located between the top 3 spark plugs, and the lower 3 spark plugs. I am not sure if there was a change in the model just before the 1999 model or not, thus causing the manuals to be incorrect on what is req'd to change it out.

Also I have found a web site that does sell the knock sensor, but it is showing 2 different ones, the first matches the one in Steves post, the other one matches the one that I think I am seeing in my van.

http://replacement.car-stuff.com/parts/carstuff/wizard.jsp?year=1999&make=MR&model=VILL--008&category=F&part=Knock Sensor&returnurl=null&dp=true&showdc=true#top

Thanks for any advise any one has.

stever

You might find some more info online using one of the links in the Online Repair Manuals. Try your local reference librarian to see if you can get access to Alldata or the EBSCO one.

I don't know the build date of my Quest off-hand; maybe that's the difference in the parts though since the first one refers to a 9/1998 and up model?

Steve, visiting host

svess6652

We have a 1995 Villager and are having some of the same problems. Paid 60 to have the codes read and the said O2 Sencor and Knock sencor. We replaced them as well as the fuel pump,fuel filter, Plugs, plug wires, dist. Cap and we still have the same problem loss of power going up hill, and it boggs down when you first start off. the computer only reads o2 and knock sencor problems. Please help I am running out of money and no one knows what to do? :sick:

efitzgerald

Hi you may wanna check the ground wire to the onboard computer. I had this same problem with my 98 villager with 269000 kms. Iv paid to have changed cap/rotor, plugs/wires, coil, fuel filter catalitic convertor , still nothing worked. Took it to the ford dealer who changed the o2 sensor, still nothing, then a knock sensor, still nothing, then they got me a rental while they called the ford hotline, they found a loose ground wire on the computer, works great now.. Simptoms were ran good while cold, once it warmed up the engine sputtered/misfired and the rpm gauge would dance no power going uphill, terrible engine performance, hope this helps.

donnad1

Hi... I posted this under electrical, but I was looking under this thread and noticed others with speedo, etc. problems, so I decided to copy it to here.

Hello. My problem/question is.... after I drive for a few miles, my speedometer, which is digital, registers the correct mph and then drops and jumps around to 0, 4, 0, 1, 3, etc. and the check engine light goes on and off intermittently.

I haven't checked to see if the cruise goes out yet.

There's a gas mileage indicator on the left side that will show, mpg, average mpg, miles left in tank, temperature, etc. and that will then read 7.7 mpg.... 0 mpg. Anyhow, the numbers go all haywire. The outside temp is okay.

When I turn the vehicle off, start it up again, it's okay and registers correctly for a few miles and the indicator on the left shows the numbers correctly and is racking up the average mpg. Then it wacks out again.

After I turn it off and put the key in the accessory position, nothing lights up.

Is this all electrical, or can it be from a bad tranny sensor?

This all happened when I left it at a Ford dealers on consignment. AND OF COURSE they are not responsible. I picked it up, started to drive it home, and the above happened.

HELP, please. Thank you.

tester1

Hi, any advice on when 99 Mercury villager timing belt needs to be changed?

stever

I have a '99 Quest which is supposed to be a twin of yours. 105,000 miles is the recommended interval for my Quest (link). Ford says 100,000, for your Villager. Everything I've read around here says it's a non-interference engine on this era Villager/Quest so I haven't changed mine yet at 119,000 miles.

dgeese

Hello all,

I have a 1997 Villager with 130K on it. The van has been running fine until two days ago. I went out to start it and it spits, sputters, backfires and dies.

Let me explain more. I turn the ignition key on and can here the fuel pump run for around 5 seconds (normal). I start the engine and it idles perfectly for about 5 to 8 seconds. It then starts to die off. Pressing the gas pedal only causes it to rev slightly and then it starts to spit and sputter and backfire and dies. If I start it and hold the gas pedal down it will rev up and then the rpms just drop off no matter how far I hold the pedal down.

My brother-in-law-to-be came over and we pulled the knock sensor code by way of the flashing check engine code. (The check engine light never came on before this happened) After getting a Haynes book and following the testing procedure of tapping on the manifold and testing voltage change, it seems to be working but I cannot get and Ohm reading on it???? :mad:

I have replaced the spark plug, distrib cap and rotor to no avail. Fuel pump replaced less than a year ago. :confuse: I also checked the Power Transistor (as the Haynes Book calls it)following the diagrams they provided. I calls for continuity between terminal A and B and no continuity between A and C. Well, I get no continuity between A and B or A and C but I get continuity between A and C. :P

I hope this is not a boring read but I want to give as much information as I know.

Can anyone lead me in any direction????

graham66

D geese,
Did you ever figure this one out.
I have a 95 murcury villager with a similar problem.
The van runs great for 15-20 minutes, then when it is warm has no power, barely runs.....
The problem started after I needed to jupstart the van, and then replace the battery.
I have verified the following
FUel pump and delivery is good.
Checked the Spark at each plug,,,, all good, even when its running bad.( Still can be a timing problem.)
Eliminated the catalytic converter,
Thought the TPS was faulting took it off measured all of that, all checks ok, but on the van the voltage measurements don't match the Haynes book. So this might get replaced.
and I am measuring the Power Transistor.
I get the opposite results of what the Hayes manual says too.
Positive terminal of Ohm meter to A and negative terminal of meter to Pin B I get an open circuit.
Attach the negative probe to to teminal A and the positive terminal to C and I get a reading....
Reverse the leads on last test and I do not get a reading, So i think there is some type of diode, that is in there that makes a difference in what terminal you probe with your meter neg or pos.

Since my measurements did not match the Hayes book, I was pretty sure that this power transitor was failing. So I plan on getting a new one. But when I see that you question the Haynes book. I wonder if it is even bad.
I guess when I get it I will carefully measure the new one and compare it to the old..... The Hayes book might not be correct??
I saw another dicussion around grounding of the PCM....
May try that this weekend.

efitzgerald

Hi Graham666. Let me try to help you out. I have a 98 mer villager. I have spent thousands trying to fix this very same problem. Have a reputable mechanic or friend with automitive skills pull out your distuber. You will probably find.... Debri build up on your photo eye sensor on your distibutor. Just clean it up well and re-insert. And give it a good drive and see if that helps. Also remove your battey and replace your negative battey cable as it sits on the cable underneath and corossion builds up on it giving your cable "High Resistance". Hope this helps. E

graham66

E
Thanks for the response, I think this is my last effort to fix this problem.
I do most of my own mechanical work and was not afraid to look into the insides of this distributor, I may not have dug deep enough, because the insides of what I saw were very clean, I got as deep as seeing the timing wheel with the 360 slots in it and wiped it with a tissue. a very small amount of black came off but not a lot of stuff. the screws on the sensor looked like they were filled in with epoxy, so I left them alone. . As I mentioned in my previous note. There are no codes being stored in the computer. I suspected the Ignition module because my resistance measurements did not match the Haynes book reference. The book is wrong.or I am interpreting it incorrectly. I have all of the measurements written down from the new module if anyone needs a reference.. where they mention there should be open circuit, it is not and where you should have conductivity, it is open... So I went out and bought a new ignition module....Before I put it in I did the same exact resistance measurement on the new module. The new module measured very close to the old one, I put it in anyway and restarted the van...It runs great until the engine compartment reaches operating temperature.
I had a small can of freeze spray and began to spray individual modules to try to isolate this problem. Well I ran out of spray. So I was getting pretty frustrated and grabbed the garden hose..Now I do not recommend spraying a hot engine with a garden hose, I did manage to trickle cold water over individual parts. Luckily I started right at the distributor. I already had new wires, rotor and Cap, so I was not to worried about getting water on them. I removed the plastic dust cover from the distributor, While the van was running, trickled cold water, very slowly over the distibutor and kept teting the throttle, When warm it would idle ok but would not run smoothly over 2000 rpm..I cooled the distributor until I could feel that the aluminum base was cold to the touch. When in that state the van runs perfectly. I allowed it to warm up again and verified this at least 6 times.
So in a round about way I think I have determined that this distributor needs replacing. I just ordered an brand new one from a company on EBAY for $105, I will repost all of this in another posting if this solves the problem.
I am glad others have shared their experiences on these forums. I have learned a lot about this van. My regular mechanic did not have the scan tools and told me he did not want to work on it. I I think if I get this running I have saved a lot of money. If this new distributor solves it I will have less than $150 and about 20-40 hours invested.
I will let everyone know how I make out once I get the new part Thanks for your interest.

efitzgerald

The symptoms your discribing is the exact same thing my van was doing. I have 275,000 kms on it. I have spent thousands from incompentant automotive techs from Canadian Wheel to fixorrepairdaily dealer. I have changed cap/rotor, wires/plugs and throttle body clean and injector flush, new coil, new catalitic convertor before i took it to foundonroaddead dealer who put on a new o2 sensor, finally they said lets do a diagonstic which found a knock sensor fault, 600 dollars later they had to call the f- hotline who told them to check for faulty grounds on ecm which seemed to work for a while. Took it back again and they said it was High Resistance on neg battery cable. Well after changing that it still wasnt right. Had to have it towed to a Nissan dealer (which i should have done in the first place) they said it was the distributor and it was just filth build up on it. They said it may happen again but i may get another year or two out of it. My symptoms were.... started up fine after reaching operating temperatures it started to buck and sputter/misfire with loss of power, rpm gauge would dance. Been one expensive lesson. hope this helps.

graham66

Your comments here make me feel pretty good that the replacement distributor is going to fix the problem, The van is going to end up being my kids vehicle.. it does have over 100,000 miles on it but form other owners I see that these engines will run until the body rusts out.
I should be getting the new distributor next week. If this does solve the problem, I will post a very detailed description of all of the steps I took to determine and fix this problem. Hopefully our comments here can save the next person a lot of trouble. I did read another forum that warned me of going to a FORD dealership... Nissan dealership was strongly suggested. If I get away with these repairs only costing me $150 I will be real happy since I see what this could have cost me.
If this does not fix the problem, you will see may 95 Mercury Villager :lemon: parts for sale....Including a new distributor and ignition module.
If this solves my problem all I have left is to replace the 2 rear brake lines... and the kid has a real cool 7 passenger family van to call his own.
I will let you know as soon as I get the new parts installed. Thanks for sharing the infomation

graham66

E, I finally got the new "Rebuilt" distributor, and that solved all of my problems. I found a company on EBAY that sells this rebuild for $105.... with no core charge.
I will write up a detailed description of what I did and how I verified the bad distributor, by cooling it with water. I also want to point out that there may be a mistake in the Haynes Manual around the resistance measurement of the ignition module.
I will get all of my facts straight and post it in a new thread.
Thanks for participating in this forum.... all of this information led me to a much cheaper fix.

genejock24

My CEL has been on for the past 6 months. Immediately after having the timing belt/water pump replaced the CEL came on. The codes returned were for the knock sensor and O2 sensor. I had the knock sensor and both front and rear O2 sensors replaced; the light came back on. Now the code that comes up is P1148 and an online search tells me this a "Closed Loop", but I can't find any more information than that.

Any explanation of what this means (and what it is going to set me back) would be greatly appreciated.

Thanks

efitzgerald

Pull off your distibutor. And clean off the photo sensor on the distribor and re-install. Then disconnect the battery cables for half an hour and clean them and re-attach. See if this clears your mysterious codes. hope this helps.

efitzgerald

I have read something from AUTO TAP about this "closed loop". It says that it is a sensor problem. A coolant temp sensor is used when the vehicle first starts up until it gets warm then the 02 sensor (Oxygen) takes over adjusting the fuel/air mixture, this is called a closed loop . Perhaps it may be the coolant temp sensor? hope this helps.

efitzgerald

I realize this is an old message, but was it dirt debri on your photo eyes on the distributor? I had this very same problem.

efitzgerald

Any Mercury villager owners pass the 300,000 km landmark ?

needs123

help please new batt./starter is OK how do u get to the alt.thanks

graham66

Before I would change out the alternator, Get the van running and check the charge voltage out of the alternator. If it is 13-14 volts, the alternator is good.
Double check all of the connections at the battery and starter make sure they are clean and tight.
Don't rule out a faulty new battery, I just helped a friend with a similar problem, he was going to change out the starter.... ended up his new battery, about a week old had a bad cell and would not keep a charge. If you have access to a different battery its worth a try to swap it out.
If this is going dead over night, check to make sure there are no lights staying on, I had a glove box light that would draw a battery dead in 1 day.....

If you do have to get to the alternator, I think My 95 was located behind a plastic cover behind the passenger front tire. from underneath.
You will have to jack it up, put it on Jack stands, maybe remove the passenger tire then take the plastic cover off, From what I remember its not to bad to get to once you get under there.

billburns

I have a 93 Villager with 384,954 KM on it 239,145 miles it runs and rides very well!

stever

Sweet - did you ever have exhaust manifold bolt issues? My '99 is idling along at 121,000 miles.

efitzgerald

Cool- my 98 is closing in on 300,000 kms. Runs well but has the usual maintenace issues, ball joints, motor mounts, tie rods , daytime running light issues and so forth.

smilingsandy

I have a 95 Villager and when it rains......water collects somewhere behind the passenger front floorboard/dash...and you can hear it slosh back and forth when in-town driving.....also..when turning left and stepping on the brakes water will come gushing inside the floor!!! Any help?????

ckent724

I have a 1996 Mercury Villager, and I thought I had a knock sensor issue, but now I am not certain. I have three codes present, P0136 Downstream O2 sensor or circuit fault, P0325 Knock sensor and or circuit fault, and P0400 EGR insufficient flow detected. I have pulled the knock sensor sub-harness and have checked volts at the connection. I have 3.28 constant and when I hammer on the intake the volts don't change at all. not even .01. I have checked the EGR by putting my fingers on the diaphram and moving the throttle up over 2000rpm and I cannot for the life of me feel any movement. I pulled the upper vacuum hose on the EGR and checked for any vacuum and I cannot feel a thing. I haven't voyaged down to the O2 but I am wondering if it is possible that my Knock sensor is the issue and has caused my other problems. I have had this light on for a while now and the times I have had it read and cleared (for NYS inspections) that was the only code present. The last time I had it read was about 6 months ago and it was the Knock and EGR codes. Today when I read it I had all three. Any suggestionsthat someone may have would be great!!!! I have the ability to change the Knock sensor myself and I can get it from a Parts store up here for like 115$ but the labor involved is the main reason why I am hesitating. Thanks to anyone that can give me an Idea. Oh I have NO driveability problems whatsoever!!!!!!

efitzgerald

Before you do that may i suggest checking your distributor. I spent the money changing my knock sensor, as well as 3, thousand dollars for other things too. My 98 vehicle was bucking and sputtering when warm , ford changed my knock sensor and made no differance. I towed it to the nissan dealer, did a diagnostic and took off the distributor and cleaned off the photo sensor on it, works great now and no codes. hope this helps.

graham66

How does the Van run when cold and then hot..... I had some problems that would only effect the perfomance when the van was up to running temperature.
I had no codes being set on the computer.. My problem ended up being the distributor. I got a rebuilt one from Ebay, a company out in california for $100. I had replied to other forums that detailed all of the trouble shooting I did in hopes of saving someone else some money...
Let me know, and I can repost the entire thing.

ckent724

The van runs very well, no driveability issues, when its cold or hot. I think I may have found my problem though. I talked to a friend of mine who recently started working at a Lin/Merc dealer and he passed the issue on to some of the guys in the shop and one tech send 90% percent of the time it is the BPT hose. It will in the beginning throw a Knock code due to backpressure in the emission system, Then as the hose corrodes more the Egr code will come on, then after a period of time of running rich it will post the O2 code. He usually doesn't see the O2 code though. Apparantly what happens is that hose goes from the EGR to the EGR BPT (Backpressure Transducer Control) It will begin to leak causing it to run rich, then causing it to detonate, the Knock sensor reads the detonation and flips the CEL. After complete breakdown of the hose the EGR BPT cannot perform and it will cause the EGR to not function. The BPT hose is a small 90 degree 1/4inch vacuum hose (On my 96). It connects on the bottom of the EGR BPT then connects to a 1/4 inch steel line. That steel line maybe 6 inches long then connects the the EGR. I picked up that hose at a parts store in the "HELP" section. Replaced my old hose (Which was rotted out and not even connected to the EGR BPT ) cleared my codes and to date 90 miles later, no CEL! It has also stopped running rich!!! As for the knock sensor, It is measuring 3.00 volts. When I tap on the intake it will jump up to 3.20 or more. I almost think that the knock sensor was at its maximum range that is why I wouldn't see any flucuation previously. I couldn't even see the hose at all until this guy told me where to look. Once I felt around under the EGR BPT i felt that it had corroded off. Thank God!!!!!! Hopefully this is it.... and it only cost me 3$!!!!!!!!!!!!!!!! Thank You for replying I really appreciate your time and input!!!!!!!!!!

graham66

Hey this is good information.
I think it is worth time time to check this hose just as a preventative maintenance.

mccallisterfam

I am posting this in case it could help someone else. We have a '95 Villager with 153K miles. It has been running very well. We had to get it inspected for our (new) state registration. My husband powerwashed under the hood. Yes, he got it very clean, and we passed.
But the next day, the check engine light started coming on. It only came on when I came to a stop or slowed down (let off the accelerator, downshifting) or, as time progressed, climbed a hill.
Our first guess was that something was still wet from the washing. Everyone told us to just drive it, that it would dry off with time and use. At first, it seemed as if it was improving. But in a matter of 3 or 4 days, it had progressively gotten worse. It idled evenly (wasn't missing), started up just fine, and shut off fine too. But once I started driving it, all bets were off. At the height of the trouble, once it was in gear, as I drove down the road, it basically would jump forward over and over as I limped down the road. It would shift very badly, if at all. This came across as the tachometer racing upwards when I gave it gas. Then it would jump or slam into the next gear. I could manage by VERY SLOWLY giving it gas, but it still would either not shift at all or balk and then jump forward repeatedly. When my husband was driving behind us as we (FINALLY!) drove it to our mechanic, he said as it shot forward, smoke would come out of the tailpipe. I couldn't get it up over 45 mph without even greater shaking and balking.
Our mechanic went over every part. We ruled out cap, wires, plugs (no missing), distributor photosensor, EGR, BPT, etc. He ran the codes on it and first got a knock sensor reading. He kept getting that error code. We began to research that sensor malfunction and were not happy with what we found. We knew that since it would be expensive to replace what might not turn out to be the solution, we had to keep looking. This might be the end of our family van. But as it turned out, the knock sensor wasn't malfunctioning, it was screaming that there was another problem.
One thing our mechanic did was check the computer for shorts. In doing this, he unplugged it. When he hooked it up again, he ran codes again. THIS time, the TPS sensor problem code appeared.
Exasperated, I contacted Nissan. I needed to know what we were dealing with. A very experienced tech said that the knock sensor itself will not cause the check engine light to come on. He said that all our symptoms could be explained by the malfunction of our TPS sensor, including the weird fact that when the engine was warm and in Park, it would idle low (normal) and then idle higher (like a cold carburetor from the old vehicles we used to own) for no reason. It never did that before all this. Evidently, the TPS allows the engine and transmission to talk with each other and the computer. He very patiently explained everything, and it all made sense.
When the TPS code first came up, our mechanic unhooked the lead to the TPS and drove it, trying to rule it out (like he had done with the other parts in question). When it STILL didn't run right, he thought it wasn't the answer. But our handy dandy Nissan tech said it was and to replace the entire wiring harness and sensor. We went ahead and had our mechanic put in a new TPS ($45 at parts store) and our mechanic discovered that there are actually TWO leads from that sensor. Since he had only disconnected one, that was why the problem didn't disappear when he thought he had completely disconnected it.
So now our van actually runs better than it did even before my husband washed the engine (we now know how to do it better).
Looking back, I can tell that this sensor, which somehow tragically failed when it was washed, wasn't working up to par for at least the past 6 months. It shifts SO smoothly now. It shifted OK before but had an annoying bump as it went from 1st to 2nd and 2nd to 3rd. Now, it's smooth all around. We didn't need to replace the wiring harness, but would if it gives us more trouble down the road. I wonder how many people have their transmission serviced or replaced when they only need a new sensor. Hope this helps.