Honda Civic GX Engine Questions

gxuser · January 2006

One of the fuel injectors (#4) on my 2000 GX broke this week at 73k miles. Check engine light flashed and engine ran rough. The last injector (#3) failure was just over a year ago. It is now covered under emission warranty but the warranty is going away soon @80k. Parts and labor cost is expensive - around $800 each at dealer if no warranty. Wonder if this high failure rate is caused by Honda's manufacturing defect or caused by other components or the gas.

I have kept up the maintenance and even changed gas filter a few months ago. Anyone else has injector failing before? Any suggestions to avoid another injector failure?

jerrylippmann · December 2005

I've had a 00 Civic 5 1/2 years now, and my kids have driven the heck out of it, 115K mi, and never more than half a tank away from a refueling station. Luckily, there are several in the Phoeix area on our normal travel routes. I'm a competent mechanic, and have done all of the routine maintenance on the car myself.
In the past few months, it has developed a stumbling idle. No troubles with injectors (good thing, they're $550 each!), changed the dist cap, rotor, plugs at 100K mi, so I don't think it is ignition. Out of frustration, I took it to a dealer for service, they have one guy who works on GX. He spent one hour (which cost me $100) to tell me that since it had Bosch Platimum plugs instead of the original NGK, that it would require a full tune-up for $450 before he could diagnose the problem. Precisely why I avoid dealer service. Anyway, I'm confident the plugs are not the problem, but still looking. Anyone have info about fuel filter problems limiting gas flow? I've seen in this forum some discussion about both high pressure and low pressure filters, anyone know whether the 00 has both?, and where they are?

Thanks in advance,
Jerry

thatdeonguy · December 2005

Jerry:
Thanks for all the high mileage GX info.
I just had the dealer change the high & low pressure CNG filters @ 49,000 miles on my 2001. $352.00
I was told that Honda will not sell the 2001 & newer a&b cng filters to owners.
It's a GX dealer approved service item for installation only.
I don't know about the CNG filters on your 2000 gx.

I was glad to have the CVT transmission fluid replaced.
It has made a nice difference in the ride of the car.

Next week I start driving my GX from OC to Big Bear once a week for the next six weeks. 200+ miles round trip from sea level to 7,000 ft and back.
I hope I can make it all the way on a full PHILL fill.
It should be very interesting putting snow chains on a GX. :surprise:
I'll keep you all advised
Deon

jerrylippmann · December 2005

Deon,
you're right about the dealer not wanting to sell the CNG Fuel filter. They don't outright refuse, but to have them replace it costs $132 (Part + 1 hr labor), and to purchase the parts is $849. I am strongly leaning towards having the dealer do the replacement (duh!).

Good luck in your weekly runs to Big Bear. I'd rarely get 200 mi range, you must have larger tank(s).
All the best,
Jerry

lakewood90712 · December 2005

Get a OBD2 code reader , the type that can scan in real time,( because the misfire may not be bad enough to store in the computer) and find the cyl. that is misfiring. Don't think it's the fuel filters. Spark plug wires ?, tiny cracks in the coil ?, may be valve clearance too tight. Stick with oem honda parts. Several honda dealers sell on the internet at deep discounts.

John

fbaldwin · December 2005

The Honda Service Manual GX Supplement provides simple instructions for replacing and or servicing the fuel filters. The Maintenance schedules indicate that filter B (low Pressure) should be replaced every 10,000 miles and filter A (high pressure) should only be inspected including drain every 10,000 miles. Both schedules (severe and regular) specify the same procedure.

Replacing the low pressure filter is similar to replacing an oil filter. The first step is to relieve the fuel pressure between the engine and the manual shut-off valve.

I hope this does not become a dealer scam to sell both filters every 10,000 miles when the schedule indicates only an inspection of the high pressure filter every 10,000 miles.

The factory service manuals can be purchased from Helm. The web site is www.helminc.com

thatdeonguy · December 2005

Hey fbaldwin:
I love this forum, you guys are the best.
I have been looking everywhere for the Honda Service Manual GX Supplement. Thanks for the info, I just ordered one.

Speaking of Dealer scams, my Dealer informed me that they recommend removing the CNG tank @ 40,000 miles to inspect and check for leaks. For only $550.00!
I know that before I bought the car it had a warranty service to repair a gas leak. And since I don't smell gas I think I'll hold off on that dealer recommendation.

I did ask the dealer to print out all the warranty repairs Honda had in it's computer for my VIN.

I bought the car just after the warranty expired. I have most of the original work orders from the previous buyer but it was nice to double check what had been serviced before I bought the car.

Thanks Again!
Deon

jerrylippmann · December 2005

The service of filters must indeed be a scam. When I asked the service adviser about it, at first they said no, we have never had to change a filter. Then they looked at the maintenance schedule and remarked: oh yes, it does say change every 30K miles. I had it changed, in an unsuccessful problem solving attempt, and the service tech said it looke fine. By the way, he is the only CNG tech at this dealer; they have sold hundreds of these, and this was the first filter he changed.

He again attributed my rough idle to non-OEM parts (I guess Bosch doesn't know how to make Platinum plugs, or automotive spark plug wires). When I was ready to take the plunge and buy the Honda parts, the guy at the parts counter had seen the rough idle problem in the past, and knew it had been fixed by changing the distrubutor base plate. This is the main housing which carries the spindle, and the dist cam sensor. He didn't know whether it was bearing wear causing spindle wobble, sensor position, or sensor failure, but he was pretty sure it would work.

HE WAS RIGHT! $225 USD later, my rough idle was gone. This was great info from a guy who does not diagnose car trouble, but observed what worked to solve this problem in the past. He also agreed with me that Honda parts makers don't have any proprietary pixie dust to make their parts work better than other equivalent parts from alternate suppliers.

All the best,
Jerry

fbaldwin · January 2006

The 2005 GX, registered and normally operated, in California, Connecticut, Massachusetts, Maine, new York and Vermont has a warranty for 150,000 or 15 years for listed emission parts including fuel injectors (labor included). All other states (Federal) the injectors are covered for 36,000 or 3 years.

The eight year 80,000 mile warranty covers only the Engine Control Module Module (computer)for the 2005 Federal warranty.

I do not know what the 2000 warranty covers but It may be worthwhile obtaining a copy of the emissions warranty.

The staff at the dealer may need to be reminded about the warranty.

fbaldwin · January 2006

The GX has two filters. Filter B (low pressure) looks like an oil filter and can be purchased for $120.75 at the dealer. The maintenance schedule indicates to replace it every 10,000 miles! Kind of expensive.

There was no restriction on over-the-counter sales. But the parts guy had a lot of trouble finding the part in the catalog. I needed to show him the diagram in the Honda Service Supplement. It appears that the dealer staff may not have the best training or expierence.

Changing this filter requires specific understanding of the GX fuel system and IS NOT simple as changing an oil filter.

freedml · February 2006

if it's a close call, open an account with San Bernardino and fill before/after the trip 'up the hill'

Michael

yip_choi · March 2006

Hi ,

I am new to this message board, so please bear with me.
I just purchased a Civic GX from Ebay and received it a month ago. It
is a 1998 Honda Civic GX model with only 18k on it. However, after I
drove for a week, the engine light is on. It does not have any
noticable problem except sometimes the rpm is rough when stop. First,
I brought it to a local mechanics who called himself as "Honda
Specialist". He claimed it needs a major tune up (with valve
adjustment) for $500. If the light is still on, then it needs to
replace the ECM (The computer) which costs over $800. I told him to
do the minor tune up but not the valve adjustment which I believe it
has nothing to do with the engine light on and valve should not be
adjusted after 100k (not 18k). After minor tune up and he cleared the
engine light code, it runs fine for a week and then the light is on again.
Does any of you have the engine light on experience and the car is
driving totally fine? What is the finding?
Is there any relationship between the engine light and valve adjustment?
On the other hand, I did smell some natural gas inside the vehicle
after parking overnight or days. Is it normal?
If I want to bring it to Honda dealer, does it requires for CNG
technicians?

Please advise.
Thanks in advance

William

lakewood90712 · March 2006

A "too tight " valve was causing misfire at idle and sometimes triggered the check engine light at 22,000 mi on my 01. The dealer adjusted it , no charge.
As to a "Minor tune up" ,nothing to tune up. Spark plugs on these last 80,000-100,000 miles easy .I would stay away from that shop.
Bad ecm computer ?, don't think so.
This vehicle may still be under the federal emissions warranty , or if it is a california car , the california emissions warranty.
As to the gas smell , you prob. have a very small leak in one of the fittings at the tank in the trunk.

FBALDWIN is a frequent poster on this board and knows all the emission warranty info.

If you are in so. cal , or the bay area, you have a choice of several dealers with cert. gx tech's.

fbaldwin · March 2006

Your GX has has a computer standard called ON BOARD DIAGNOSTIC II (OBD II). The computer frequently runs tests (monitors)to verify that the computer is working properly. If any of the computer sensors are producing data that is not in specifications which would cause the emissions to exceed 1.5 the Federal Test Procedure. The "check engine" light is turned to on.

It is very rare for the computer (ECM or PCM)to fail! It is well protected from damage. The computer sensors or wiring are more likely to fail because of the environment they operate. A trained technician will have a computer "scanner" that can read any stored codes and the data that is produced by the sensors. This would only be the first step in diagnosing any problem with the OBDII system. A specific trouble code will direct the mechanic to a problem area for further diagnoses.

In the late 60's and 70's technicians performed a "tune up" which included replacing the spark plugs, points and other parts that frequently failed. The carburetor idle mixture was adjusted. Most of the time the performance of the engine improved. The term "tune up" does not apply any longer. You will never see "tune up" in the maintence book.

Any technician with training with OBDII or preferably with ASE A6, A8 and L1 certifications should be able to properly diagnose your engine problem.

The fuel system should only be repaired my a technician that has reviewed the Honda GX service supplement.

2gxowner · March 2006

I just had our '03 fixed for a 'check engine' light that kept turning on then going off. They found that there was arcing between the spark plug coil and the spark plug in two of the cylinders. They said that under cold start up, this arcing can occur and cause a miss fire and turn on the light. The light would come on when starting in the morning which made sense. We did not tell them when it would come on. The dealer also said that hosing or pressure washing your engine could cause this by getting moisture into the spark plug area. Easy thing to look at for you.

nostrom0 · April 2006

You should change the low-pressure fuel-filter every 10,000 miles. It's fairly easy to do yourself if you're competent at changing your own oil. I bought the part from Majestic Honda for $85.
But this item is very important, not a dealer scam. It prevents contaminants from getting into your engine. There is variation in the quality and content of CNG Fuel obtained at filling stations.
Don't skip this maintenance.
The high-pressure fuel filter is another story. That does not need to be changed until much higher mileage.

gotgasgx · April 2006

Can you help with some simple steps to changing the filter? Do you notice any mpg improvment after the change?

Thanks.

fbaldwin · April 2006

The Honda Service Manual GX Supplement provides simple instructions for replacing and or servicing the fuel filters. The Maintenance schedules indicate that filter B (low Pressure) should be replaced every 10,000 miles and filter A (high pressure) should only be inspected including drain every 10,000 miles. Both schedules (severe and regular) specify the same procedure.

Replacing the low pressure filter is similar to replacing an oil filter. The first step is to relieve the fuel pressure between the engine and the manual shut-off valve. This should only be done after reading and understanding the GX manual.

I hope this does not become a dealer scam to sell both filters every 10,000 miles when the schedule indicates only an inspection of the high pressure filter every 10,000 miles. Frequently new car dealers make their own maintenance schedules which include more service and parts (and more profit)than the Honda schedule.

The factory service manuals can be purchased from Helm. The

yip_choi · April 2006

Hi All,

Thank you very for all of your help. My mechanics finally fixed the problem. After he changed cap & rotor and spark plugs wires, the problem is gone. In addition, he did a tune up.

However, I was told not to use aftermarket parts because the ECM of Honda Civic from year 1998 to 2000 are so sensitive. Any aftermarket parts might trigger the ECM to lit the engine light. I am glad that the first problem is solved.
However, I am looking for the way to find if there is gas leaking because I can smell some natural gas when I first open the door after parking overnight.
In addition, I don't have refueling system (Phill) at home, so I go to PG&E (3000psi) or Pinnacle (3600psi) to refuel. How many mileage it can run with a full tank? The empty tank light will lit when it reaches 150 miles. I believe the tank is 8.5 gallon, but we cannot fill up all with fast-fill such as in PG&E or Pinnacle. With 30 to 34 mpg, what is the maximum mileage I can drive?
Can anyone give me some hint what are the extra maintenance has to do for this CNG NGV car? Thanks in advance.

lakewood90712 · April 2006

The capacity of the tank is 8 gge , but that is under laboratory conditions @ 70 deg. f. to completely empty.

Real world useable is about 5.5 @3000 , 6.5 @ 3600. The owners with a phil at home get more range than stated above because of the slow fillup.

150 - 175 miles with a 3000# fast filup is about correct.

I have gone 50 miles with the low fuel indicator on many ,many times ,but I ran out once , had to be towed .

Keep in mind ,the fuel gauge is a temperature compensated pressure gauge , not a level gauge.

How much is PG&E ? Last time I was up north ,2003 , they were 97 cents

yip_choi · April 2006

Thanks for your reply.
I was told my 98 civic has a bigger tank (8.5 gge) than 01 to 04 model. Well, I guess the 0.5gge does not make big difference.
On the other hand, I always refuel at Pinnacle with 3600psi. Again, the low fuel indicator always lit up around 150 miles. As you mentioned, you have gone 50 more miles with the low fuel indicator, does it mean I can drive about 200 miles?
Can you explain more about the fuel gauge is a temperature compensated pressure gauge, not a level gauge? do you mean I should not trust the fuel gauge because it also depends on temperature.
PG&E charge $1.86 per gallon. You can refer to this link:
http://www.pge.com/nots/rates/tariffs/GRF.SHTML
Thanks!!!

lakewood90712 · April 2006

As to tank size , look at the label on the tank. If it says 100 liter water capacity , it is a 8gge @ 3600. Honda had some pre production brochures in 1997 that had estimated specifications.

The low fuel warning is calibrated for about 50 miles , but I try to avoid driving more than 20 after activation.

The 01-05 with the cvt does use approx 10% less fuel per mile.

The "Gauge" . The gas sold to us is 88-90% methane , the rest is propane, co2 , nitrogen ,water , and misc. contaminants. Gas law dictates a given quantity of gas will occupy a certain space at a certain pressure and temperature. Raise the temperature and keep the space constant , and the pressure will rise , but you have the same quantity of gas.

Your honda senses pressure and temperature and its computer makes calculations for the properties of natural gas to give you an approximate amount of fuel left. Actually pretty simple.

Time to get off my soapbox now.

nostrom0 · April 2006

Correct. The slower the fill, the less pressure created by thermodynamic expansion and more pressure created by actual natural gas.
Similarly, cooler ambient temperatures create less pressure for the same weight of CNG, allowing for a larger fill at the same pressure.

fbaldwin · April 2006

I think the Phill unit compensates for temperature. I am not sure but it fills to a lower pressure at lower temperatures. This may be why the Phill owners manual indicates that the car and the unit need to be in the same environment so the temp is the same.

The fuel gauge is temperature and pressure compensated.

fbaldwin · May 2006

The GX has two fuel filters one is changed every 10,000 miles the other is replaced every 30,000 miles.

Filter "B" (the one that is to be replaced every 10K) cost $122.45, carry out, at a Monrovia dealership! This filter looks like an oil filter and it installed near the engine.

Filter "A" is replaced every 30K and serviced every 10K it cost $51.72, carry out.

I hope the aftermarket offers fuel filters for the GX soon to reduce the service cost.

jankowski · February 2007

I have just purchased a 2007 Civic GX and after about 30 miles the engine has started to make a noise like one of the valve or tapits is out of adjustment. i took it to the dealer, and they said that all the GXs make this noise becuase the magnet in the injector is larger. Has anyone else ever heard of this, and do any of your cars sound like a clock when you drive it?

Thanks,

joe

dejapooh · February 2007

My 2007 Civic sounds like a regular car to me.

bank1avp · February 2007

Thats normal for a GX it's the injectors you here,(ticking noise right) some are louder than others, The ECO system I have in my Suburban sounds like a diesel when running on CNG and quite as on mouse on gasoline.

Murphy

jankowski · February 2007

Thanks guys.

joe

fbaldwin · February 2007

You could listen to another GX. My 2005 is quiet but it simply makes normal engine noise. Did you get an estimate sheet from the dealer when you left your car for inspection stating your complaint? When you picked up your car, you should have received a final estimate indicating your complaint and the technician's inspection results. The documentation could be helpful in the future.

Depending on you state your future warranty rights could be limited if you do not have any documentation of a problem.

My local dealer has was very generous with the only warranty issue that I had with my car. And they gave me a ride to my office.

hondagxsales · March 2007

Just curious about your Suburban sounding like a deisel. Is it because of compression issues. The GX is 12.5:1 because of the 130 octane. A lower compression could make the Bi Fuel motor rattle if compression was left at say 9:1, as it was set up at the factory for gasoline.

bank1avp · March 2007

The ECO system CNG injectors have always been loud. Not sure why. Very simular to the factory GFI Ford setup but without the noise.

adea · May 2007

yip_choi wrote: "The gas sold to us is 88-90% methane , the rest is propane, co2 , nitrogen ,water , and misc. contaminants."
I just saw this so I need to reply. It really depends on WHERE you get your cng. When I first started using methane in '97 (had my '90 Toyota Celica GTS converted), I purchased it from FLEETSTAR at about $1.05/gge in AZ which was 99.9% pure methane made from LNG right at the site. It was the cleanest/purest you could get and my car ran great! (CleanEnergy bought them out and I still don't know how clean CE's is [does anyone know?]). Then I moved, so I had to use Trillium for a year and when I went to get my car emission tested, it FLUNKED :sick: on cng (HC), but passed on gasoline! A cng expert told me that it was the OIL used in the pumps that got in the lines and tank. When I bought my '00 GX I went to APS Electric here (they opened it to the public) and they told me that theirs was also 99.9% pure methane, and once again, it ran great! I just changed the fuel filter (only one high pressure in rear) at 118K miles, it didn't look that bad actually.

So I would love to know the purity % for Trillium and CleanEnergy. Thanks.
adea

adea · June 2007

Just wanted to let all of you know that I just received my ScanGauge II. (free one day delivery!) I already diagnosed the check engine light on our other car and cleared the code, which put out the light. It took just a few seconds. (You can move it from car to car with no problems.) With the Honda Supplemental Manual, it has all the codes, so I'm planning on saving a lot of money diagnosing it myself. It looks like a great gauge! It is a tripper, OBD II scanner, and has a lot of gauges. It is made right here in AZ and has a one year parts and labor warranty. To have an accurate mpg readout, you have to calibrate it with a few fillups...with more making it more accurate.
adea

ignis_fatuus · October 2007

Okay, I just bricked my civic GX. I closed the manual valve and ran the line "dry" by idling the engine until it stalled. I was diagnosing a fuel gauge peculiarity. After I reopened the valve the fuel gauge stayed at empty with the empty light blinking. The car refuses to turn over, and it won't even come out of park with the ignition on. Is there an excess flow valve I might have tripped with the transient surge into the empty line? How do I reset it? I think I located where it lives: behind the rear seat inside a rubber boot. Anyone with any ideas to reset, or must I tow to the dealership?

ignis_fatuus · October 2007

Update: I had an epiphany last night that I should try cycling the power. So after disconnecting and reconnecting the battery, all is well. Hmmm...

giorgi · January 2008

My check engine came on and my engine runs rough at idle. I did a complete tune up and I changed the coil. Check the code and it came up as cylinder 1 misfire. I took it into the dealer, gonna see what happens. Anybody had this problem on thier GX's? Mine is a 99.
Thanks,
Anthony

giorgi · January 2008

Well I heard back from the dealer and they said that I needed a new set of injectors. They are very expensive. They wanted 500 for each injector. I told them I would get the injectors myself. Started looking online and found a place in Arizona that will rebuild them for 17 dollars each. I told them it was for a natural gas vehicle and he said they would do it. Yes!!!!!!!
Here's the website if your interested:
http://www.accurateis.com/index.php

jmonk · February 2008

Had the same symptoms with trouble codes (misfire) on all four cylinders. Brought it to my local mechanic and had to replace all four ignition coils. They had cracked with signs of heat scorching. Just over $50 a piece. It's a 2001 and only 58K miles. I'm hoping there is nothing else that caused this.

lakewood90712 · February 2008

It IS very common for the coils to go bad , even at that mileage. Should be covered under the federal 8 yr /80,000 mile or calif. 15 yr/150,000 mile emmisions warranty on a SULEV rated car. The 01 gx is SULEV. Call honda customer service , I think you will be getting some money back. The coil towers go deep into the head, and really cook from all the heat.

jmonk · February 2008

Thanks very much for the heads-up on the warranty. I'll contact honda to check on reimbursement.

One week later I'm noticing a random misfire and some performance problems on freeway acceleration. Hope it's not an injector problem. With 60K coming up, it's time to have a thorough maintenance check.

jmonk · February 2008

Many Kar Karma kudos are due you. I've contacted Honda CS and so far they say they will reimburse for this work. Thanks so much.

epnfrn · February 2008

ok -- i'm at 30k on my 06, and have decided to replace both low and high pressure filters. i've read here and there that neither filter change is all that advanced for a decent home garage mechanic. i feel that i've also read that no-one but a trained CNG specialist should do them. if YOU have actually done one of these, i would like to get the exact protocol from you, as well as any suggestions/advice. if you have only 'heard' something about something ... please don't reply, as i've also 'heard' the same something (probably). based on what comes back, i'll either attempt it, or take it in to the shop.

thank you very much,
brian (epi)

dejapooh · February 2008

I would love to observe someone changing the filters.

rojak · March 2008

I'm curious if anyone knows there the warranty in CA for 150K mi / 15 years is documented? The only documentation I can find states 7yrs / 70K for CA, and for some parts its 8yrs / 80K. Although... I'm looking at this for my 1998 Civic GX...

I have a similar misfire on Cylindar 1 problem, and it is seeming to be the injector for cylindar 1 being locked in the open position...

lakewood90712 · March 2008

The CA SULEV emmisions designation was not even on the books until late 2000, so none of the 98 - 99 and few of the generation 6 California 2000 models have the 15yr/150k emmisions warranty.

The CA SULEV rating is available to the manufacturer who wishes to make the vehicle qualify , and wishes to warranty for that long. It is not a mandatory rating.

The generation 7 (01-05) and generation 8 (06 and later ) sold in those states do , and will be on the emmisions sticker under the hood.

The rating is also only for the GX first sold in CA and I think MA, and NY. If you take it to other states, the federal warranty applies.

On the fuel injectors, You could call Honda Customer Service and tell them a sad story and how much you love Honda products..... They may split the cost , like Honda pays for the part and you pay for the labor. Remember they have to listen to people complain ALL DAY EVERY DAY , and do not have to do this ,so be polite when you call !

If that does not work out , internet Honda parts dealers like Bernardi, Majestic, or hondapatrscheap.com will sell them for about $350 each. 30% off list price. I have purchased from all 3 .

lakewood90712 · March 2008

Brian.
I have changed both on my generation 7 (01-05). The high pressure one is the same on all years to present. other than having to fabricate a tool to properly re-torque the housing cover to factory spec ( 30 ft lb) , it was no harder than changing spark plugs. 20 minute job, including r and r of the tank brace/filter cover.

The low pressure filter on the 01-05 is a spin -on , exact same size as the oil filter , but it's red and has a thicker shell and different seal. NOT interchangable with an oil filter.

On the 06 and later , I think the low pressure filter is an element in a housing. Never seen or done that one.

The last time I changed filters , they were VERY clean and prob. did not need to be changed.

Any southern california member of cngchat.com can borrow the tool from me , no charge. send a pm on that forum . Also can e-mail photos and info from the gx service supplement.

J.L.

epnfrn · March 2008

JL -- thanks for the reply -- i'm pretty handy in the garage, so with the description you've described (and other bits and pieces I've heard) I think this should be an easy job. I'll order a couple filters and check it out. I may email you when it comes time, should I see any major issues before I start.

Thanks
Brian

freedml · June 2008

It's ALMOST as simple as changing an oil filter.

Close the CNG shut-off valve (every GX driver should know where this is, behind the left rear wheel). Let the car idle until it shuts off by itself.

Here's the tricky part. Find a 2' long oil filter wrench.

Unscrew the old oil filter and put the new one on. Open the valve, check for leaks, and start 'er up.

jc_auto · March 2009

Giorgi - did you send your injector to Accurate Injector to have it serviced? What was the result?

qb79 · January 2010

I am new to this forum so bare with me, this may be a long post. I have read through the majority of the Honda Civic GX (CNG) threads since I own a 1998 Honda Civic GX and am having some troubles with it. Awhile back the check engine light came and it was idling roughly and would sometimes hesitate upon acceleration (as if some cylinders were misfiring). The problem seemed to be exaggerated in cold weather. So I took it to the local Autozone to have them hook up their computer to see what the computer said the problem was. It was reading multiple misfires and catalytic converter. So in effort to remedy the problem I replaced all spark plugs, wires, distributor cap, and rotor. However, that did not solve the problem.

I also adjusted the value clearance since a few mechanics thought that may have been this issue but that didn't fix the problem either.

So I settle for the last resort, I took it to the honda dealership CNG mechanic. He diagnosed that I need to replace all four injectors (550.00 ea), new fuel filter, and catalytic converter. He quoted me a total of something over 3000.00, which I had a hard time swallowing. So I paid for the diagnostic and to have them replace the fuel filter but I held off on the injectors and catalytic convert since I figured I could get them cheaper online.

I found a site that refurbishes CNG injectors (Rockauto.com) and sent my injectors in. They claimed they were able to refurbish 2 of the four. So I bought two new ones from Autozone. The injectors from Autozone look exactly like the originals and were only 167.00 a piece with shipping. Has anyone had luck with CNG injectors from Autozone? I am a bit suspicious of them since they are half the price of the other cheapest online injectors I could find.

Once I had all four injectors (2 refurbs and 2 new from AZ) I installed all four but the check engine light came on again and it still idled a bit rough and hesitated upon acceleration at times. I was able to drive it around town fine but it just wasn't running up to par.

So I researched about troubleshooting faulty catalytic converters and found out that engine sputters, hesitation or unequal power may result from a bad catalytic converter. Also, I noticed at times on the freeway the car acted as if it had a govenor on it and this was one of the symptoms of a bad cata converter. After reading about these symptoms I was certain that was my problem. So I decided to remove the catalytic converter to see if I could determine whether or not it was bad. Upon removal I could clearly see that the insides were not intact; therefore, I performed a little surgery to help determine if blockage caused by the broken internals of the catalytic converter was causing the car problem. I completely removed the internals and reinstalled the catalytic converter but the check engine light is back on and the engine sputters (misfires) and hesitates upon acceleration still.

Any ideas as to what the problem may be? Is it possible that some piece from inside the catalytic converter could have fallen out and causing blockage farther down the exhaust pipe? Could the lack of internals result in mis-representative O2 reading from the two sensors on the catalytic converter, thus resulting in sputtering and hesitation upon acceleration? I am all out of ideas. Any suggestion would be helpful. Thanks and sorry for the lengthy post.

Honda Civic GX Engine Questions

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