98 LeSabre dies randomly and is pissing me off

Car just dies randomly. The engine runs like a top in the driveway. Fire it up, let it idle all day long. Give the throttle a few good raps, no problems. Put it in gear and it dies. If it doesn't die immediately, then it will die as you come to a stop (sometimes). It has also died just cruising down the road at speed. Right now it is running like a champ.

Stuff I've done so far:

Replaced fuel pump

Replaced crank position sensor

Unplugged MAF, no difference, still dies

Cleaned idle air control valve. Unplugging it doesn't seem to make a difference (which should NOT work, right?)

Cleaned EGR valve. Unplugging it makes no difference

Fuel pressure regulator seems fine, no diaphragm leaks

Ignition module under the coils has been replaced TWICE

Shaken/jiggled every major wiring loom

Shook/jiggled the crap out of the ignition key while it was running, no change

Tried two different keys (stupid PATS), no difference

When you start it up there is a sucking sound that comes from the intake which lasts about 20 seconds, then goes away. It spent some time at the local mechanic, but even they couldn't figure it out. And even better there are no codes. And sometimes it will start right back up, other times it is DRT for an hour. It pisses me off when the tow truck driver backs it off the trucks and pulls it right into the service bay like nothing ever happened.

I told the owner that these cars are usually great until crap starts going wrong that isn't easily fixed. I think we have hit that point and they need to start looking for another car.

Throttle position sensor?

my wife used to have a 1998 olds 88, and it does the same thing. Never figured it out. It did it infrequently though (about 1 time every 3-4 hours of driving), and we just pop it in neutral, and restart, and continue driving. I do remember that the issue only ever happened with zero throttle input (coming to a stop, coasting, idling around a parking lot, etc). And it would always restart no problem.

Come to think of it, I did replace the intake manifold gasket, and the intake was full of oil in little pockets that wouldn't drain naturally into the cylinders. I don't remember having the problem after that. Her grandmother still drives the car today and I don't think she complains of random cutouts either.

Maybe the leaky gasket let the mani fill up with oil, and every once in a while some oil gets slurped up and since the computer isn't expecting it the car dies?

Also, my dad's 96 taurus did this for a long time. Turned out it was the fuel pump fuse or relay being intermittent (or corrosion thereabouts). Common problem I guess.

Iac valve?

In reply to gearheadmb: I had an issue with a '94 bonneville dying like this. turned out it was a loose ground bus under the driver's seat.

It sounds like the IAC is starting to fail. Usually you hope they just quit, but sometimes they keep trying to work.

As for the sucking sound at cold startup, they all do that, its normal (but I wish they didn't do it). My Bonneville did it and it was more noticeable after I removed the baffles inside the airbox. I've noticed it on other GM vehicles too.

My '95 LeSabre had similar issues. Chased it for over a year. Replaced a bunch of stuff like you did. Finally replaced the ECM and the problem was solved. Just before the ECM was replaced, it showed all kinds of stupid codes - including stuff we replaced. Before that though it was very frustrating because we didn't get codes.

Don't some GMs have a problem with the torque convertor staying locked up, or locking up when its not supposed to?

81cpcamaro wrote: It sounds like the IAC is starting to fail. Usually you hope they just quit, but sometimes they keep trying to work. As for the sucking sound at cold startup, they all do that, its normal (but I wish they didn't do it). My Bonneville did it and it was more noticeable after I removed the baffles inside the airbox. I've noticed it on other GM vehicles too.

I am wondering about the IAC. I cleaned it and idle passage in the throttle body. I don't understand how the car will run with the IAC unplugged! I may do a PaP run for a used ECM.

I hate to spend so much time on this car. I told the owner (my in-laws) to just get another car, but they think it will be cheaper to fix this one. This is the same car I found for them two years ago with explicit warning that it would last them for...two years. It was supposed to be a temporary solution.

HappyAndy wrote: Don't some GMs have a problem with the torque convertor staying locked up, or locking up when its not supposed to?

I refuse to touch the transmission on this car. If that needs work then the car is totaled in my mind.

I've seen IACs do some weird stuff, probably when you unplugged it, it was already open some so it kept running. I agree on the trans, if it goes, the car goes. Too many of these cars out there for cheap to put money into the transmission.

Also, on the MAF sensor, mine randomly cut out when it was going out, but it did it quite often. I would try another one to see if that helps. Mine did at least show the MAF code when it went bad. New it was about $140ish if I remember right.

My SVX used to do the exact same thing. Eventually solved it when I did the timing belt - both cylinder banks were retarded by a tooth.

slefain wrote:

HappyAndy wrote: Don't some GMs have a problem with the torque convertor staying locked up, or locking up when its not supposed to?

I refuse to touch the transmission on this car. If that needs work then the car is totaled in my mind.

Geez. To answer the other question first, yes and no. The problem is the screen on the solenoid is filled with junk. The solenoid applies like normal, but because the solenoid is filled up with crap it can't exhaust off the fluid in the converter and the clutch stays "locked" on. Because it's on, it stalls out the engine. The start settles the crap back out so it all works again until the clutch has to engage again. Wash rinse repeat. Now the converter itself isn't fallible as they can still fail because the whole pump drive isnt as robust as it could be. But then again I would expect other problems.

To fix the the TCC, all you have to do is drop the drivers side of the subframe, pull the side cover, and replace the solenoid. Refill with the old and now strained fluid. You'll be out maybe one full day if you like beer and I mean really like beer.