Dead 99 Lesabre

[mrbear3800]

Perhaps some of you can help me here....

My wife's 99 Lesabre crapped out on her this morning. She started the car for the first time today and went to church, about a 2 mile drive. Ran fine. After church, it started fine. As she attempted to drive through the parking lot, it started bucking and missing. Then is stalled.

She started it again and the only way it would keep running was to keep her foot on the gas. And even doing that, it ran crappy and kept stalling so she gave up and called her mother to pick her up.

After I got out of work, I took a look at it. Got it started and it felt/sounded like it was not running on all cylinders. Black/brown smoke was accompanied by a nasty unburnt gas smell and it kept stalling.

We had it towed to my parents house. I managed to keep it running long enough to get it somewhat warmed up. After awhile, it started to idle on its own but it was very erratic and was missing and shaking like crazy. Cranking the RPM's up to 3 grand would smooth it out and it would begin to run on all cylinders for the most part. Also, I peeked under the car and of course, the convertor was glowing red. At this point, it started to run real bad and I could not keep it going anymore so I shut it off. Didn't want to cook the convertor.

The plugs and wires are one month old. I also checked the coils with an ohm meter and they checked out fine. I attempted to have the ignition module tested at the parts store but the counter person said she didn't have the right connector.

I filled the tank the night before and thought bad gas could be the culprit. But it was driven a good 15-20 miles that day after filling it, with no problems. Also, the plastic upper intake plenum had an internal coolant passage rupture a little over a year ago and was replaced(sound kinda familiar?..lol..). When this occured, it exhibited similar symptoms, although this time, the cooolant level is still full and not all sucked out the tail pipe.

I'm stumped. Any trouble shooting guidance would help. Thanks!

[fordinator]

find the fuel regulator, its right on the fuel rail on the drivers side, pull the vacuum line and see if its blowing gas off into the vacuum lines. but a glowing red converter isn't a good sign. they will take allot of unburned fuel before they will glow, my guess is the brown smoke is coming from the converter.

[mrbear3800]

I'll give that a try. Also, if compatible, I'm going to swap the whole coil pack/ICM module from my mother's 03 Lesabre and see what happens. At least then , I can eliminate that as a possibility.

[starshooter10]

sounds like too much fuel is going in...

[Bangster]

hung injector or faulty fuel regulator.

[mrbear3800]

Well, no luck with the coil pack/ICM module. Put the one from my parent's leasabre on and it ran the same. So...

Is there a way to check the FP regulator? Rather not replace it if its not bad...

[mrbear3800]

UPDATE:

I checked the fuel pressure with a gauge. All was within spec. I checked the FP regulator for fuel on the vaccuum side. Bone dry.

I then pulled the plugs out. ALL six plugs are pitch black. They all look the same, no variation between them. They reek of gas. They (and the plug wires) are only 1 month old.

It will run but barely and its not drivable. When it was idling on all cylinders briefly, it was fluctuating rapidly(engine speed racing up and down). The coolant level is still the same. I'm not seeing any evidence of coolant consumption. No white smoke out the tail pipe. Its just getting too much fuel. If I rev it up high enough, it will run on all cylinders and smooth out temporarily.

I filled the tank about 20 miles before this started. Could it be the gas? I would think it would have manifested itself before hitting 20 miles, though.

Whats next?? Crank or cam sensor??

[Paul229]

I'm thinking an electrical problem of sorts. My Rodeo was exhibiting identical symptoms. It was diagnosed as a faulty ECM at first. It was replaced with a junkyard piece and all was well for a while. The symptoms appeared again and it was traced to two exposed wires in the wiring harness. My mechanic is pretty sure that the short is what killed the ECM from before. Just something to check.

[BamaWildcat]

Replace all the coil packs.

[mrbear3800]

Replace all the coil packs.

Already tried that. I used the coil pack/ignition module from my mother's 03 Lesabre. Didn't help.

[Chevyguy]

I had a few seperate causes for similar symptoms on my old Lumina. Having to replace the DIS module only to find it was ok was a most horrible thing!! I had the single injector get so clogged that the motor ran like the DIS module had gone into limp mode, Since I already cooked the module several months before I replaced it under warranty. On a 2.5 lumina it's on the firewall side of the motor UNDER the intake which is criminal as the module/coil packs could be mounted anywhere. When it still ran bad afterward I was violently pissed and cursed the entire W body engineering team and this lead to my vow never to have another FWD POS ever again.

Anyhoo enough of that

My problems were probably TBI specific one clogged injector = no run. Another time the car would run PIG RICH when cold to the point I would have to keep the throttle open. Turned out the fuel pressure regulator is mounted on the TBI unit. When cold it would leak from a tear in the diaphram, thus dumping fuel in the motor. Once it went into closed loop it would start running, and eventually the leak stopped.

At the same time I found the intake air temp sensor was bad but in range. It always gave a reading of very cold (high resistance) but never fully shorted. So the motor was always in start up mode and was dumping excess fuel. The multimeter and the resistance/temp table was key to solving this portion of the problem

So grab your multimeter and a good service manual and start going through the diag procedures. It will take some sleuthing to find the problem

[mrbear3800]

Ok...

I started it cold after work today and let it run. It started right up and then ran a little unsteady and rough, then steadied out. It ran for several minutes, then started to surge up and down as it warmed up then finally stalled. Just before it stalled, it began to run very rough and the MIL lamp came on.

I cleared the codes yesterday. So I checked the codes and it said P0101"maf or vaf sensor" or something to that effect. So I unplugged the maf and ran it for about 20 minutes at idle. It kinda fluctuated but it still ran. I even took it for a ride around the block. It only stalled once at a light. Nasty rich exhaust fumes as well.

So I brought it back to the house and took the maf out of my mom's 03 Lesabre(same part number)and tryed it out in mine after clearing the codes and unhooking the battery for a bit. Then I fired it up, ran it for about 15 minutes. Ran nice and smooth, no MIL or fumes. Took it for a 1-2 mile ride, came back to the house and ran it another 10 minutes. No further problems were noted.

Just to make sure, after work tomorrow I'm gonna take the maf from my mom's lesabre again when mine is cold and start it up and drive it again. If it runs fine, then its gotta be it.

[osr1]

Check your old one closely as dirt can simulate a bad sensor. If you can see it, it will have two elements much like a light bulb. If the air filter is poor (or of the oiled type) much dirt will collect on the sensor. With a strong shot of brake clean or being very gentle with a q-tip and alcohol they can be cleaned.
Another common GM style Maf faiure can be simulated by tapping the sensor to see if it changes how it runs. From reading your post it does sound like a misreported measurement of air entering the engine. Last thing, the maf output is only as good as the power/ground into it, so, if it is running rough, scope those two things (power & ground) regardless of GPS (grams per second) and output voltage, the simplest of tools and know how will eliminate the basics. hth.

[mrbear3800]

Check your old one closely as dirt can simulate a bad sensor. If you can see it, it will have two elements much like a light bulb. If the air filter is poor (or of the oiled type) much dirt will collect on the sensor. With a strong shot of brake clean or being very gentle with a q-tip and alcohol they can be cleaned.
Another common GM style Maf faiure can be simulated by tapping the sensor to see if it changes how it runs. From reading your post it does sound like a misreported measurement of air entering the engine. Last thing, the maf output is only as good as the power/ground into it, so, if it is running rough, scope those two things (power & ground) regardless of GPS (grams per second) and output voltage, the simplest of tools and know how will eliminate the basics. hth.

Well, it was the MAF. My mother's 03 Lesabre MAF made it run perfect. Picked up a remanned one from autozone for 137.00. Runs great so far. I changed the oil also as it had become essentially black gasoline from all the excess fuel being dumped into the engine. Oil was only 1000 miles old and it was pure black. All that gas probably scoured any gunk or sludge out of the engine.

I did indeed try cleaning it with electronics cleaner a few days ago.

I checked the voltages and they were within spec. Didn't try the tapping method, though.

Its fixed, though. Thanks for the pointers everyone.