92 Lesabre running rough

[3echo9]

Hey all..I could use a little help with diagnosis.

The car is running very rough as if not all cylinders are firing. Even at idle. It will seem to smooth out after the car sits running for awhile. Not getting any SES indications.

Details: 150k miles, changed plugs and wires, fuel pump replaced this summer. Unplugged MAF after warmed up and car stahls and will not start unless plugged back in.

Other strange items..noticing strong exhaust fumes if that means anything.

Thanks for any help.

[danielsatur]

Bad Plastic, rubber, seals, causing unmetered air leaks.
Suspect - air leaks on Intakes, EGR, and PCV systems.
It's worth the money to have a smoke test done for vacuum leaks.

[3echo9]

No doubt a good idea. Are there any DIY options to the smoke test? If not, do you know what one should run at a shop?

[Jrs3800]

Check the lines at the top of the throttle body, if they are rotted replace them and see if the car still acts up...

[big white bufflo]

did you make sure the firing order was correct and the gap on the plugs were correct

[3echo9]

Originally Posted by big white bufflo

did you make sure the firing order was correct and the gap on the plugs were correct

Ya', that was the first thing I checked. It wouldn't be out of the question to have switched a couple of wires.

The car runs OK when it's cold. It's just when it warms up does it start this bogged down-no power-feels like I'm running on 3 cylinders thing.

Some of the vacuum lines on top of the engine look to be cracking so I'll replace them and see if that helps.

[HotZ28]

What kind of ignition system do you have, Magnovox with integrated coils, or Delco with three individual coils sitting on top? (Delco with optional MSD coils shown below)

[3echo9]

Originally Posted by HotZ28

What kind of ignition system do you have, Magnovox with integrated coils, or Delco with three individual coils sitting on top? (Delco with optional MSD coils shown below)

Based on the graphic I have the Delco.

[HotZ28]

You need to check the spark on each cylinder with a spark tester (similar to the ones shown below) supplied by K-D Tools # 2756 or Lisle # 58050. Both of these tools are relatively inexpensive and will help you diagnose the condition of coils. If that checks OK, look for a cracked plug insulator, or wire terminal not fully seated. Once you have all the ignition components verified for proper operation, then we can move on to fuel system checks.

[3echo9]

OK here's an update.

I got the ingition tester and a day off. To start, the day was too cold for the car to repeat the problem but after driving for an hour it warmed up enough to start acting up.

I pulled all of the plugs and tested each. The second bank gave no spark.

Ahaa, right? Just replace the coil. Did that and nothing...no spark.

Any ideas why there would be no power to that coil? Should I try swapping a spots with the other coils?

Thanks..

[Jrs3800]

So when this happens you have no spark on the rear bank? Cylinders 2,4 and 6?

[3echo9]

OK end of story..

I took the control modual to Advance Auto and Autozone. Funny thing, Autozone said the control mod was OK. I had two different AA's test it and both called it bad.

I swapped it out and all is good.

Good call on the spark tester. I just wish I had eliminated the coils before buying one. I ended up buying a coil I didn't need.

[3echo9]

Originally Posted by Jrs3800

So when this happens you have no spark on the rear bank? Cylinders 2,4 and 6?

Sorry Jrs, you must have been posting at the same time I was.

I had no spark from the middle coil pack. I can't remember which cylinders they link to but that was were the problem started and it ended up with a bad control mod.

[Jrs3800]

I am glad you got it fixed.. The next thing I was going to tell you to do was to swap out the ICM from your GP onto the Buick as a test..

Funny thing is that I gave my friend an ICM a few hours ago as he was having trouble with a 96 LeSabre..

Good to hear its back to normal

[HotZ28]

Originally Posted by 3echo9

OK end of story..

I took the control modual to Advance Auto and Autozone. Funny thing, Autozone said the control mod was OK. I had two different AA's test it and both called it bad.

I swapped it out and all is good.

Good call on the spark tester. I just wish I had eliminated the coils before buying one. I ended up buying a coil I didn't need.

Thanks for the feedback and I know you are pleased with the results. It's not uncommon for AZ to misdiagnose ICM's! It may be that it's the equipment they use, or the person using it was not properly trained. At least you have a spare coil! If you ever have a similar problem, rather than depend on diagnosis from the box parts store; I will share with you a little “shop secret” that we use to see if the ICM module, or the crankshaft sensor circuit are functioning properly. Connect a halogen headlamp to the spade terminals that mate the ICM module to the coils. (A headlamp is recommended because it puts more of a load on the module than a test lamp.) If the headlamp flashes when the engine is turned over the ICM module and crankshaft position sensor circuit pass the test. (Be sure to test all three) BTW, if you only dropped one or two cylinders, you know from the beginning that the crank sensor is doing it's job.