Engine stalls after running fine... NEED SOME HELP

[RegDunlop]

usually stalls after it was running fine for a while, it will start right up again with NO problem. When it stalls while I am driving I immediately put it in neutral and coast out of the flow of traffic ( which is sometimes hard as the power steering loses power).

I also have a CEL, that sometimes will go out after stalling, and I need to wait for it to come back on before I dare drive again or it will definitely stall ( in other words if the CEL light is NOT on I KNOW it will stall again).

When in park and I rev the engine it starts to stutter (lopes I think is the word) at higher RPMs ( not sure- car has no RPM gauge) , then when I release the gas pedal it returns to WELL below normal idling RPM's sometimes to the point of just nearly stalling out then regaining idle RPMs and sometimes it stalls out.

It is a GM 3800 series 1.

I cleaned the throttle body and MAF sensor ( using MAF sensor cleaner) , I changed the fuel and air filters ( both were changed a few months ago), I recently changed the plugs but NOT the wires. I changed out the vacuum lines yesterday, as some of them appeared to be falling apart.

The fuel pump sounds strong when I put the key in and turn to 2nd position w/o starting the engine, so I don't think it is a bad fuel pump.

I am thinking it is a TPS, IAC or coil pack or wires?

I am leaning against cam/crank shaft as that problem often does not trip a CEL?

Is it possible the fuel filter, even though only a few months old, is clogged? Are there bad brands of fuel filters that could cause this?

Any other ideas?

I haven't been able to get the code read for the CEL as it is the older OBD 1 or 1.5 and nobody will read it on the cheap or free.

Thanks

 

[Chris142]

Isnt obd1 the type that can be read with a paper clip stuck into the connector?

 

[crazyoildude]

hearing that the engine stalls and the cel light goes off and wont start unless it is on again sounds like maybe it could be the computer.. Or something in the wiring we had a gm here that ran great almost all the time except it would do exactly what you say and it turned out to be the computer..next time it happens try the "tap" test have someone tap on the computer and see if that changes things if not try to unplug it for 1 minute and plug it back in if that cures it a couple of times its the computer
What year and car and is the engine original?

 

[RegDunlop]

Car is a 1995 bick lsabre and it is original engine.

 

[JimPghPA]

Could be an electrical system problem, such as a bad connection to the battery, or a bad battery. Could even be something wrong with the charging system.

These modern engines require a lot of electrical power. If the alternator does not supply enough for even a brief amount of time, then it must come from the battery. If the battery and its connections are not up to it, the computer will not be able to maintain proper voltage to keep running, and it will not be able to tell when to generate the spark to run the engine.

One way to check that the battery and connections are good is to turn on the head lights and then blow the horn. Even if this looks good before you run it, I would do the same check again right after it stalled.

The fact that the CEL light drops out, is a hint that it could be some kind of electrical problem.

If you have any way to look at the voltage when it is running you might be able to see if it gets too low.

BTW, Advance Auto Parts will read the code for free, but the readers they use are not the best.

 

[RegDunlop]

Thanks JimPa but auatozone pepboys etc can NOT read the older codes only OBD 2

 

[ltslimjim]

Originally Posted By: RegDunlop
Thanks JimPa but auatozone pepboys etc can NOT read the older codes only OBD 2


Look through the manual about using the 'short' at the test connector from your ECU. Find where the test connector(should be 2 pins only) wire is located and read up in the manual of how to read the codes.

At least, I hope this is possible for you.

 

[RegDunlop]

thanks jim nothing in the buick manual or haynes manual about this...just says to get the codes read

 

[chad8]

some possibles
pulling codes first:

I'm told that you can pull codes on a 1995, one of three ways

1) early 95's are usually a 12 pin configuration located under the steering wheel inside the car, if so you can stick a paperclip in holes A and B which when looking straight(from drivers position) at the 12 hole pin is the top right one and the next to top right.

2) 16 pin configuration is a paperclip in the 4 and 5th hole to get the flash codes

3) 16pin requiring the same code II as a 1996 car or later would require, this would be a late model 95 and the code II along with the computer brain should be under the hood.

all 3 of these scenarios are only possible on the 95's and once you figure out which one is yours the codes are easy to read, you will receive series of flashes from your check engine light the first series is the first number the second series of flashes is the second number.....ie 6 flashes then 4 flashes, would be error code 64

Next:


Get some CRC Lectra contact cleaner and spray it into the connectors for the MAP sensor, Throttle control sensor and the Idle control sensor. This may solve the problem. The check engine light might not come on and the car will no longer stall.
My other real thought is the MAF sensor. Or the IAC may be sticking. Both of these are on the throttle body and can be removed. The MAF can be cleaned but the little wire is fragile. Use CRC contact cleaners that are for intake cleaning, such as CRC on the shelf at stores.

 

[demarpaint]

Sounds like something electrical. It could be a bad ground, a poor or dirty connection inside a plug or harness, a loose or bad wire going to a sensor. I'd start looking at all grounds and conncections for corrosion, etc. Run the engine and shake wires and connections, get a volt meter test connections and sensors. It can be a time consuming PITA to find, turst me!

 

[sciphi]

I'd bet the engine computer (PCM) is shot. It's a known flaw on the 1994-1995 H-bodies, of which the LeSabre is one.

You need a scanner capable of reading the OBDI on your car. The paper clip trick won't work.

 

[nwjones18]

Make sure the car isn't OBD-II. My dad's 1995 lesabre is. I thought it started in 96, but his car is definetly a 1995 and is OBD-2.

 

[RegDunlop]

Thanks I'll try the paperclip idea.

The car is 100 percent NOT OBD 2.

I'll clean as many contacts and grounds as I can find

Then I'll bring to the mechanic if I can't figure it out.

 

[Trav]

I ran into this on a Gen 1 3800 a few years ago,it was a bad connection at the ignition control module.
I had someone crank it while i lightly tugged on the wires and as soon as i touched the connector at the ICM it fired right up.
The ground wire pin connector was loose on the pin.

Not saying this is the problem but its worth looking at.

 

[SteveSRT8]

I've seen those same ignition modules work great until they get a little hot.

Then they die. Cool it down and they run again.

 

[meep]

same with jeep. simulate test. car cold. heat ecu for 10 with hair drier. try to start.

 

[willix]

I'd be looking at the fuel system.

 

[RegDunlop]

Thanks willix

I did the fuel filter about 6 months ago...any reason to do it again?

The fuel pump is in the tank so thats beyond my capabilities

What other parts of fuel system can I check?

 

[JimPghPA]

Some GM cars have an anti-theft system in the ignition switch. If this acts up you have to replace some parts and also get the resistance of some parts to match up. People spend hundreds and even over a thousand dollars trying to get these systems to work reliable, and still have problems with them. Some have had this problem for years.

There are two other fixes for this anti-theft system when they act up. There is a way to cut and splice in a resistor. The resistor must be chosen to match the unit. I do not know the details of where this is done.

The other fix is easier to do and very reliable, more expensive than a simple resistor instillation, but much lower in cost and much more reliable than swaping ignition and anti-theft components. You get the anti-theft bypass box that is normally installed when you put a remote start system in the vehicle. Some of these bypass boxes still require you to adjust them by choosing what resistor you install with them, but at least these bypass boxes tell you how to wire it in. This fix works every time if the anti-theft system is the problem.

-------------------------------------------------------------------------

There is one thing you should check first. The computers for most GM engines have a removable chip that has the program the computer runs. Some speed shops sell an upgrade chip that you can swap into this location. The existing original chip can come loose in the socket. If this is the case, it can become intermittent. All you have to do is remove the cover for the computer to access the chip and press it into the socket. My 1985 Olds 88 had that chip come loose about 10 years ago, and after it was pressed back in, it has not caused the problem again. Before and while you do this, you would be wise to attach a ground wire to your wrist to insure you do not zap the computer with static.

 

[JimPghPA]

Originally Posted By: RegDunlop
Thanks willix

I did the fuel filter about 6 months ago...any reason to do it again?

The fuel pump is in the tank so thats beyond my capabilities

What other parts of fuel system can I check?


Fuel filters should be good for over 30K miles.