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Make sure it doesn't rub on the balancer when you reinstall. After 93, from what I've read, the CPS is not adjustable in any way. I haven't done one, but I've kept reading about them because my 98 has 193,000 miles and I've expected it to give problems, but it hasn't. Runs so well I can't get rid of it.
The other thing it could be is your ISC under the coil packs. Check the wire connector on it for a good connection.
An anecdotal test for CPS is to pour cold water on it when it won't start after a hot soak sit. See if that speeds up the cool down and resulting improvment in the magnetic field so it can trigger the ISC.
Also, take off a plug wire and put in a spare spark plug from anything, lay the plug on engine metal, and have someone crank while you watch for spark. That will tell you if you spark and it might be fuel. If you get no spark, then you know you're in the right area in the ignition system.
But if it were mine, I'd start with the CPS with your repetitive symptoms. Lots of people have fought various other parts and replaced by guessing only to end up with the CPS.
2014 Malibu 2LT, 2015 Cruze 2LT,
I like the idea of testing a few things while the no-start condition is happening---testing both for spark and for fuel pressure.
link title
This shows the coil and module on the engine (#89)
link title
This link shows the crankshaft balancer (#53) and the crankshaft position sensor (#58).
link title
Puller for the harmonic balancer on crankshaft from Autozone. I do NOT believe this is in their loaner tools--you'd have to ask the local store.
http://www.autozone.com/autozone/accessories/OEM-Heavy-duty-harmonic-balancer-pu- ller-set/_/N-26b8?itemIdentifier=532440&_requestid=3077447
2014 Malibu 2LT, 2015 Cruze 2LT,
As for "testing for fuel", you (the owner) might pull a spark plug to see if there's fuel on it---if so, that pretty much tells you that the issue is ignition related.
For others reading this, your description seemed very consistent that it would shut down after hot. Then had to cool for restart. As Mr. Shiftright suggested, there may be other causes. But because this one gave one type of symptom, I felt the CPS was a good start.
The fuel pumps that I've read about aren't as consistent in their symptoms posted by folks on H-body forums I frequent. The ISC, spark control unit under the coils, also is not consistent in most symptoms.
This particular car did have the Magnavox coils which are a unit rather than 3 coils like later 3800's. These can give problems, but not consistent as a cutoff.
Diagnosis is key.
2014 Malibu 2LT, 2015 Cruze 2LT,
You are saying it will not start. Is that it will not crank or that it will crank but won't fire up and run normally?
If it won't crank, do you have more than one key? Try the other key to see if the security system likes that key.
If it cranks and won't start, does the exhaust smell like gasoline? Hold the accelerator to the floor while cranking to clear flooding. Then pull of the vacuum tube on the FPR (fuel pressure regulator) and see if you smell raw gasoline in the tube. If the car does start, pull off the tube and see if gasoline comes out the opening of the FPR after 2 minutes of idling or more? There should be none.
If it cranks and it won't start, take off one of the front spark plug wires and lay it against metal. Have someone crank the car. The spark should jump the 1/4 inch gap with a blue spark. If there's no spark, then you have narrowed down your problem to a bad spark control module (ignition control module under the three coils) or the crankshaft position sensor (CPS) which is one thing that triggers the spark.
Is there full fuel pressure? Weak fuel pump? Or a badly plugged fuel filter? One test would be to spray ether or carburetor cleaner into the throttle body as someone cranks. You must take off the rubber tube leading up to it from the air filter assembly.
Another thing is the MAF. The test is to take off the leads to the MAF and see if the car starts.
If it runs really badly, it could be spark plug wires (test by spraying water with a bit of salt in it over the wires while car's running to see if you get sparking). Or it could be the EGR, and that can be tested by tapping on it with something heavy like the end of a screwdriver to make sure the opening is closed off by the plunger.
http://www.greatautohelp.com/sensor-location/3800.html
2014 Malibu 2LT, 2015 Cruze 2LT,
If it stalls, you can try throwing cold water on the crankshaft position sensor to cool it. That sometimes speeds the restart.
The other possiblility with an electrical shut off like that is the spark control module connections or the module itself under the coils.
To test for the crank or spark control, remove one of the spark plug wires on the front and lay it on engine metal. With someone cranking the car, there should be spark to ground. No spark means you're not getting that.
2014 Malibu 2LT, 2015 Cruze 2LT,
What year is your car?
So, you need to test the injectors to see if they are firing. People say you can use the two leads of a 194 bulb and put those into the connector for an injector while cranking and you should be able to see the very short flash as the 12 volt pulse hits. Or use a voltmeter.
From what I read, if you have no pulse to the injectors that can be related to the crankshaft position sensor as well. Or there is a fuse, according to this article, on the passenger side A pillar below the dash where there are relays and a few fuses. There is a 10 amp fuse on that inside board on my 98 for the injectors power. The injectors are fired by grounding through the PCM. I've been assuming your car is a 92-99 model. If you have a 94-95, the PCMs occasionally have more problems than other years, but those often involve rough running or barely running.
Here's a long 5 page discussion of a problem that might include diagnotic steps that will help you. Good luck with this one.
2014 Malibu 2LT, 2015 Cruze 2LT,
But since the car runs with ether, you're doing the right kind of troubleshooting.
If you have a voltmeter try testing for a pulse when the PCM grounds each injector while cranking. Did you read the link I put in the prevous post? Is your injector fuse okay providing power? Note that you have a 94 with the higher failure rate on PCMs.
BTW, did you disconnect the MAF sensor to see if the car would run with it off putting the car back in a different mode? MAF sensors get replaced because they are easy to blame. I've never had to do one on 4 cars that have had one even with high mileage. I read more about problems with replacement brands in Bonneville and leSabre discussions. AND disconnecting it and the car working in a limp mode does not mean the MAF is bad. It's only a diagnostic step. A longtime shade tree mechanic up the road from me worked on another neighbor's Monte Carlo, 95, and symptoms of running rough and occasionally dying. Disconnected MAF, ran. Replaced. Still had problem. Disconnected MAP. Ran. Replaced. Still had problem. Took to transmission buddy who knows diagnostics and had engine tools, and it turned out to be something else. But they had put hundreds into the MAF and MAP sensor on the 24-valve engine.
2014 Malibu 2LT, 2015 Cruze 2LT,
It's under the air intake or inside the air intake in the engine compartment.
Or it's against the passenger side of the A-pillar inside the car under the dash.
Without rereading all your posts, remember if the crankshaft position sensor is not sending certain pulses, there will be no spark and no injector pulses.
I'm beyond my troubleshooting ability here, so I may not be able to be of help. But are you getting spark on a plug when you lay the wire against metal on the engine or you lay an old spark plug with the plug wire attached against metal, do you get the spark across the gap?
When you say your car runs if you use ether, that would indicate it's getting at least a weak spark.
I gave you one test for pulses to an injector using a 194 bulb wires plugged into the injector lead.
I forget what year your car is now... aaah, 1994.
The problem with just replacing parts, is you can spend up a lot of money with guessing. And it requires a test device to really see what's not happening that is giving you the problem.
Does someone you know have a 94 where you can switch the PCM to see if yours is the trouble?
2014 Malibu 2LT, 2015 Cruze 2LT,
http://townhall-talk.edmunds.com/WebX/.f277491
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When the PCM senses the engine starting to crank, all injectors are fired in unison one time to put some fuel into the intakes to be ready for the first firing cycle.
This is getting beyond my ability level. I think it needs some circuit checking and probably needs a TECH II scanner that dealers use and some shops have equivalents for.
2014 Malibu 2LT, 2015 Cruze 2LT,
I have a 1991 Buick LaSabre with 76k miles. The car turns on just fine, it drives just fine, but when the car becomes idle, as in I stop at a red light or stop sign, the engine just cuts off. I took it to an autoshop and they told me it was the Idle Air Control Valve so I got it replaced. Drove it down the street and it stalled again. The mechanic did a power check on the valve and says there's some electrical issues short circuiting the valve. They put the old valve back in and I took it to another auto shop because they don't deal with electrical issues. The second auto shop told me just by looking at the engine that it seems like there's a vacuum leak but didn't know where. I called the first auto shop and they didn't believe that it was a vacuum leak. Has anyone else had this issue or may know what the issue is? I'm not that savvy with cars.
The engine doesn't cut off every time when I'm idle. When it doesn't cut off, it sounds like the car is struggling to stay running, like you can hear the engine drop then go back to normal. I have changed the oil, refilled the coolant, and changed the car battery. My next step is to get the car tuned up because it has been a while. Another thing I noticed is that my temp light would flicker whenever I have the AC on.. I don't know if they're related or not. At first I thought the car was overheating but it doesn't seem like it since my radiator fan is working and its taking the coolant. Anywho, does anyone have any ideas or suggestions?
Bobby
The autoshop is doesn't know what to do. They put all their test equipment on the engine and everything checks out fine. They said something is causing the car to produce rich air, or something like that. Basically the car's air is too rich and causes it to stall. Note this only happens when the car is HOT. When it is cold, it runs just fine. They tried swapping out the CPU and the ignition module and that did not help. Frankly, they have no idea and its driving them nuts and its driving me nuts too.
Has anyone had similar issues or have any suggestions? Would replacing the crank sensor work out?
The leak can also be some other tubes such as the rubber tube from the carbon canister to the vent valve which closes so the vacuum can be drawn OR the vent valve itself may not be closing. That would set a different code.
Not sure what the "intake valves" are that you mean. But I vote for the crankshaft position sensor. The test is to pour cool water over the sensor which is under the edge of the large pulley low on the engine with the belt around it. If that cools it quicker when your car shuts off, then the $40 part can be replaced by taking off that large pulley--maybe a maximum 1 hour job.
The other could be the Igniton Control Module which is under the 3 coils. It has wires to the end of it. You might wiggle them to see if that improves contact, but they were very well held in place. The module might be getting hot and cutting out.
The real test for the last two is to test a plug wire to see if you're getting spark while the car is cranked when it has just cut off. That requires having a spark plug wire you can pull of and lay on top of the metal to look for spark.
2014 Malibu 2LT, 2015 Cruze 2LT,
2014 Malibu 2LT, 2015 Cruze 2LT,
Does it start flashing for 3 minutes? If so, then you know the computer did not read the right resistance for the chip in the key when it's in the lock cylinder.
Search for VATS (vehicle anti theft system) on the internet and how to bypass it. Use an ohmmeter and measure the resistance of the chip in your key. There are lists of the 15 possible resistances that GM used on the net. Get resistors at Radio Shack in pack to put in series to equal that resistance. Solder them together and then solder the ends onto the wires from the computer instead of the key in the lock.
Be sure to cut the wires high up on the steering column to get extra lead to work with. You are looking for the yellow tube that looks solid until it goes to the connector group up on the firewall by the left foot and instead becomes two tiny white wires that go to the pins in the connector.
Search for some articles and videos. Here's one.
http://www.youtube.com/watch?v=wQPBRD2T85Q
2014 Malibu 2LT, 2015 Cruze 2LT,
When you bought it, what did the mechanic say that you took it to for inspection before purchase? That inspection will tell you likely problems coming ahead for that model.
A prepurchase inspection is really important. You can't trust the used car salesman or lot or curbstone seller to be honest about a vehicle's past and future.
2014 Malibu 2LT, 2015 Cruze 2LT,
And insisting that 2 replacement computers must both be bad when they don't fix a symptom is another problem.
Time to move on to a different mechanic.
Also, I'd look for leaking injectors along with the injectors commanded ON all the time to give too much fuel. That might lead back to the drivers in the computer, but I"m not seeing how the current fellow is coming up with computer as the problem.
And I'd check the indicated temperature from the temperature sensor that the onboard computer uses. If it is telling the engine that the temp is COLD, the computer puts too much fuel in and you would be running rich. My scanner can tell me the temperature--your current or future mechanic should have one capable of that. The temperature gauge in the car may give a different reading from another sensor so the computer's temperature gauge needs to be checked.
My places to start would be too look at the fuel pressure regulator on the fuel line that can leak fuel through its diaphragm and suck that leaked fuel into the intake manifold directly, richening the mixture.
I'd also try starting it without the MAF sensor connected. If it runs then, the Mass Airflow Sensor might be bad.
2014 Malibu 2LT, 2015 Cruze 2LT,
My _guess_ would be crankshaft position sensor_. Usually people have the car stall on them and it won't restart for 10 or more minutes until the engine cools and the sensor is able to operate correctly.
Watch the tachometer when it starts to stumble. The tach should go to zero because of the lost signal to the ignition system. Or it will swing wildly from 0 to 500 or more on the cycles where it's catching an electronic signal.
The position sensor (CPS) is under the edge of the harmonic balancer. That is the lower pulley on the engine with the serpentine belt. It has a couple of wires and is about the size of a thumb under the edge of the harmonic balancer.
Your sensor, I believe, has to be positioned using a gauge for the right air gap. Later ones just fit into a positioning hole.
An anecdotal test is to pour cold water on the sensor which cools it down quicker. The magnetic effect returns and if will start the engine. You might carry a thermos of water with you on a trip or a large cup of ice water.
See if you can locate the CPS on the back side lower of the lowest pulley. Engine off, of course...
Could also be the ISC, ignition spark control, under the 3 coils on the front of the engine top. You could also try cooling it with water; water over the coils and the metal unit under them will not hurt anything.
Good luck.
2014 Malibu 2LT, 2015 Cruze 2LT,
Hi i have a 92 buick lesabre custom 3.8 first of all when starting i have to give it gas to keep it running but only usally for 15-30 secs then its fine also when driving at 55+ it will randomly stutter only a few times and its completely random and usally goes away but check engine light doesnt usally come on while it does this. but i do have a randomly occuring check engine light any idea what this could be? and now it sometimes doesnt want to stay running but starts every time no problem just as soon as i let go of the gas it stalls out until i get it just right or something and it stays running after letting go of gas pedal. just recently replaced plugs and wires and fuel filter ** figured out to make seprate discusing not sure how to delete**