Strange Cutting-Out Problem On The 'Pree

[1990 Lumina Euro Coupe]

Can anyone give some direction to me about what to look for for this strange problem?

 

My 1991 Grand Prix 3.1 MPFI has began to cut out. It seems to want to keep running, but it jumps and hesitates when it is driven for a few minutes.

 

Although not all at once, this is what has been done to it so far:

 

• 
   
  
• A new fuel pump
   
  
• A new fuel filter
   
  
• A new fuel pressure regulator
   
  
• Idle relearn procedure that I just did a few minutes ago.

 

The fuel pump and filter are less than a year old, and I put the pressure regulator on it a couple of weeks ago because you could not even touch the throttle or it would die. That actually solved the problem, but now it has began to cut out at random unpredictable times. I took it out for a drive just now to see if the relearn helped any, and I was afraid I was going to end up on the side of the road. I acts like it does not want to go dead, but that it does not want to move when you depress the throttle, either. It wants to jump violently, especially at low rpms. When I drove it into the driveway and put it in gear, it smoothed out and didn't hesitate when I applied the throttle. I was like

 

Now I'm like

 

What else should I explore to find out what the problem is? I am not getting any lights on telling me that anything is wrong. It would save me alot of time if I were to be pointed in the right direction.

 

Thanks in advance from a current owner of 3 W's. I love them in spite of them being persnickity at times.

[1990lumina]

Well my Lumina has done that.. but the idle relearn worked after a while..maybe bad gas to..or coils?

[joberlee]

TPS? does it only do it at idle or does it do it all the time?

[1990 Lumina Euro Coupe]

TPS? does it only do it at idle or does it do it all the time?

 

When I drove it into the driveway and put it in gear, it smoothed out and didn't hesitate when I applied the throttle.

 

It wants to idle, it's when you depress the throttle. TPS is a possibility. Is the jumping a sign of TPS? The "Service Engine Soon" light has not come on yet.

[joberlee]

You could have a "dead spot" in the TPS. That would cause it to not know where the throttle is at that point and it will assume that it is closed.

[1990 Lumina Euro Coupe]

You could have a "dead spot" in the TPS. That would cause it to not know where the throttle is at that point and it will assume that it is closed.

 

I'll check into that, Thanks!

[Andrew]

if the TPS idea doesnt work, have your injectors tested for their resistence. my Z had similiar but worse probs, having 3 bad injectors pushing way too much resistence. i had really sparratic cutouts, many times killing it. so you may only have 1 bad injector.

im not sure if all your injectors are accessible without removing anything, i know i had to pull off my plenum to get to my rear 3. if yours are all accessible, drive it to a mechanic and he can test all your injectors pretty quick for pretty cheap.

[sonyman87]

Another possible theory.. your ignition wires are going bad or your coilpacks are weak. when you apply throttle your preasure in the combustion chambers goes up creating more resistance making it harder for the electricity to jump threw your plugs. If you havent already maybe condiser replaceing or repairing your sparkplug gaps

[1990 Lumina Euro Coupe]

Another possible theory.. your ignition wires are going bad or your coilpacks are weak. when you apply throttle your preasure in the combustion chambers goes up creating more resistance making it harder for the electricity to jump threw your plugs. If you havent already maybe condiser replaceing or repairing your sparkplug gaps

 

That is one of the things that I am leaning towards. I am thinking about seeing if I can have my coilpacks checked, because now it is not wanting to run at any throttle. It has gotten worse today, and it is progressive. It is backfiring through the fuel injection, which leads me to believe that it may not be getting enough spark.

 

Are the coilpacks one piece or are they a unit? I know that there are two wires going to each pack. So each fires two cylinders.

 

Thanks for the help so far.

[joberlee]

Jumped timing?

[1990 Lumina Euro Coupe]

Jumped timing?

 

That's what I am afraid of. Take a look in the service manual at what it takes to replace the timing chain on a 3.1

 

It requires removing the inner fender well just for a start.

 

The backfiring gave me the idea that it may have.

 

*Sigh* I guess I'ts going to be a fun next week.

 

Thank you for staying on top of things, and thanks to everyone who has been helping.

 

If anyone else has any suggestions, I'm open for them too.

[joberlee]

I suppose it COULD be a bad cam/crank sensor. I don't remember which these engines use.

 

I would start by changing the plugs and maybe cleaning the intake and throttle body. Check for any loose connections under the hood. It sounds like you are getting fuel, so it's probably a spark issue or computer issue. Have you checked to see if the ECM is not f'ed up? I had that happen on an 89' regal with a 2.8. Had all kinds of wierd problems; speedometer was wrong, random service light codes, stalling, etc.

[1990 Lumina Euro Coupe]

I suppose it COULD be a bad cam/crank sensor. I don't remember which these engines use.

 

I would start by changing the plugs and maybe cleaning the intake and throttle body. Check for any loose connections under the hood. It sounds like you are getting fuel, so it's probably a spark issue or computer issue. Have you checked to see if the ECM is not f'ed up? I had that happen on an 89' regal with a 2.8. Had all kinds of wierd problems; speedometer was wrong, random service light codes, stalling, etc.

 

I can tell that you know what you are talking about. A mechanic that I kind of know just told me today to check the cam and/or crank sensors. He said that is what he would do before tearing into it to replace the timing chain. Even he called it a "Job" and he has been a mechanic since the 1970's.

 

He said that is another place that reads time, and if they are malfunctioning, it can give the same symptoms as being out of time.

 

I will also check to see if the computer is fubared.

 

I just love cars today, where electrical can mimick mechanical. I remember the words that a former co-worker of mine told me when I purchased my first dubya. (My 1989 Oldsmobile Cutlass Supreme SL. I purchased it in 1993.)

 

His father had owned a garage, and he helped him in his off time. I had complained about how frustrating it was to work on third generation F-Bodies because everything was so tight.

 

I'll never forget he said: "You've never known frustration until you've worked on a W-Body."

 

Like I said, I love dubyas, or I would not own three. They are solid cars. That is why I fix them instead of just selling them and purchasing another car.

 

I cleaned the throttle body when I put the fuel pressure regulator on. Now the plugs and wires are a possibility. I'll change those first. Then I'll move on to the coil packs, and also at the same time I'll check the computer for codes. I'll get it straight, it will just take some time.

 

Thanks for all the help so far.

 

If anyone has any other ideas, I'm open for suggestions.

[joberlee]

When my ECM went bad it would still show codes and act like it was working, but it wasn't. Luckily, all 3 off the Ws you have listed in your signature have exactly the same ECM.

 

Off topic, but funny, when i went ot buy an ECM for the 89 regal I had we looked up what other vehicles used that computer. 88-9? W-body with 2.8 and 3.1 v6 and the Corvette ZR1! Go Figure

[1990 Lumina Euro Coupe]

When my ECM went bad it would still show codes and act like it was working, but it wasn't. Luckily, all 3 off the Ws you have listed in your signature have exactly the same ECM.

 

Off topic, but funny, when i went ot buy an ECM for the 89 regal I had we looked up what other vehicles used that computer. 88-9? W-body with 2.8 and 3.1 v6 and the Corvette ZR1! Go Figure

 

That's a good suggestion. Today I'll pull the ECM out of the Lumina and install it in the 'Pree. They both have the 3.1 just in case the Cutty's PROM is a little different. I know that the service numbers are the same on both ECM's, so any differences would be in the PROM's.

 

On a side note also. I have a pretty good story myself.

 

In 1999, I turned a bearing on the Cutty. I was trying to decide if I were going to build it, or put a crate motor in.

 

I called a local auto parts store and asked them how much a 2.8 for a 1989 Cutlass would be. The guy at the store told me that they did not put 2.8's in 1989 Cuttys.

 

Here is the conversation:

 

Me: "I've had this car since it was four years old, I doubt it had any engine change."

 

Him: "It had to have had one. 2.8's were not avalible in 1989.

 

Me:"I'm looking at one, plus the owners manual list it as one of two engine options, and I have an 1989 Oldsmobile FACTORY service manual that I just picked up and it tells the dealers how to rebuild and work on a 2.8. Why would Oldsmobile not know what engines went in their own cars?"

 

Him: "I don't care what they say. My computer says 3.1's only."

 

Me: "Perhaps when you get your head out of your arse, you will realize that your computer is wrong" *CLICK*

 

Yup that actually happened. That was one of the deciding factors in my decision to rebuild as opposed to replace.

 

Stay with me, I'll post an update this evening or tommorrow.

[1990 Lumina Euro Coupe]

Okay, I have a question about the ECM's in these cars.

 

I am trying to remove the ECM on the pree and am wondering if you have to remove those 4 small bolts and the two T-10 Torx screws that are attatched to the plastic piece that the car side of the harness clips to.

 

Also can you remove that plastic cover that covers the harness where it clips to the ECM? It seems to want to come off, but is being a pain.

 

Let me illustrate to be clear:

 

 

 

BOLT BOLT

_______________________________

T-10 -both ends

 

___________ECM__________________

BOLT BOLT

 

____________________________________________

CARS ECM WIRING HARNESS

 

CLIP CLIP CLIP CLIP

_____________________________________________

 

 

There is a black cover over the clips with spaces so that you can see them. Can this cover be removed? The wires and clips would then be totally exposed.

 

I've torn my hands up messing with this. Has anyone replaced an ECM? If so how did you do it?

[joberlee]

The ECM, IIRC, has the 4 big connectors and is held down by a couple of stud and nut things. Kind of look like the peice that GM used on their radios for a long time. Snaps into a cut out area, hard to describe. The computer is weather sealed. Is there anyway you can send me a pic of that area. My car is unfornuately not in front of me at the moment.

[joberlee]

The ECM, IIRC, has the 4 big connectors and is held down by a couple of stud and nut things. Kind of look like the peice that GM used on their radios for a long time. Snaps into a cut out area, hard to describe. The computer is weather sealed. Is there anyway you can send me a pic of that area. My car is unfornuately not in front of me at the moment.

[joberlee]

The ECM, IIRC, has the 4 big connectors and is held down by a couple of stud and nut things. Kind of look like the peice that GM used on their radios for a long time. Snaps into a cut out area, hard to describe. The computer is weather sealed. Is there anyway you can send me a pic of that area. My car is unfornuately not in front of me at the moment.

[1990 Lumina Euro Coupe]

The ECM, IIRC, has the 4 big connectors and is held down by a couple of stud and nut things. Kind of look like the peice that GM used on their radios for a long time. Snaps into a cut out area, hard to describe. The computer is weather sealed. Is there anyway you can send me a pic of that area. My car is unfornuately not in front of me at the moment.

 

Sorry for the delay. My Mother was admitted to the hospital with Pancreitus.

 

Since you are the only one still responding:

 

You have a PM.