99 GTP sputters, dies, idles odd. Only when warm.

[Mr. Cynical]

Howdy!

Here's the situation:

1999 GTP. 128k miles. Daily Driver. Never had an engine problem at all...till now.

I'm in Illinois. The problem started after a long drive on a cold night. There was no building-up of problems; it was just there all of a sudden.

When I start the car cold, it runs fine. Once it warms up, it starts to sputter when accelerating, and very occasionally when at speed. If I sit at a stop light, it sometimes attempts to die out, surges and lurches. I can see the tach drop, and swing back up. When cold, it seems to idle a little fast, when warm, it drops.

I have had to keep left foot on the brake while holding the RPMs at about 1200-1500 to keep it from happening. Of course, this warms it up more, so the problem exacerbates.

I had coils, plugs, and wires changed about four months ago. I just had the fuel filter changed to check and see if that was the problem, but no dice. I've gone through a couple of cycles of filling the tank as well, hoping to eliminate bad gas as a cause.

There has been NO SES light at all.

About a week ago, I left it running in the driveway to warm up. It ran just fine for a while, then warmed up and died. Lights were still on, radio was just running away, but the motor just died with no real protest; it just quit.

Any ideas? I've so far been suggested that the coils could be bad, and have read about a fuel resistor, and mass air flow sensor.

Your Pal,

Mr. C

[tblake]

When it died, did any indicator bulbs light up? "TCS OFF" by chance?

Have you tried disconnecting the MAF sensor to see if it runs better with the MAF disconnected?

[richtazz]

I'm with Tim on unlugging the MAF and see if it runs better. A failing MAF will not always trip a CEL, and will cause your symptoms.

As Tim was alluding to with the trac-off/TCS off question, if the tach drops to zero and the trac-off light illuminates just prior to stalling, that could indicate a bad CKPS.

[Mr. Cynical]

Morning!

As I recall, when it died, there were no lights illuminated aside from standard stuff. I'll try disconnecting the MAF sensor as soon as it's feasible; I'm looking out the window at about a foot of snow that magically appeared overnight

[Mr. Cynical]

Quick Follow-up:

After brushing about 18 inches of snow off my car, I decided to wait a few more days before driving it. Will post results when the weather at least improves a touch!

[Mr. Cynical]

Update:

It's been mighty cold. -17f last night.

I have not yet disconnected the MAF sensor, but plan to do that in the morning during some driving around. It's been a busy, busy week. What I have found, though, is that if as soon as I start it, I crank the heat and fan all the way up, it drives smooth the entire trip. If it hasn't, however, had sufficient cold soak time, it does do some sputtering until I drive it far enough to freeze it back down.

New Development: Hit a pothole on the way to the office the other day. ABS and Traction lights illuminated, and stayed on. As soon as I parked, I restarted the car, and they went off. Since then, at some random point in my drive, they both come on. Usually when I hit a bump. Coming into my neighborhood tonight, I slammed the brakes just to see, and it didn't seem like the ABS was working.

If it ain't one thing, it's another

[discnik]

I am curious what your fuel trims are reading after warm-up. If they are running in the positive I would suspect the ,"Engine Coolant Temp." sensor.

[Mr. Cynical]

Update Part Two : Component Booglaloo

Back in the saddle again. Today, I fired it up to head to the office, and, as usual, it ran fine until I had to stop for gas. On restart, it sputtered on and off all the way to the office.

When I left, about an hour later, it was TERRIBLE. Surging, trying to die, sputtering at speed. I got it home and went looking for the MAF sensor, since I figured it was plenty warm enough to check.

I was helped with locating it by this website:
AutoZone's repair guide, as it had a pretty picture to check. I'm glad I did; the first attempt would have removed the Inlet Air Temp sensor. Durrrr.

Anyway, with the MAF sensor cable removed, I fired it up again, with no problem. I did note that the Service Engine Soon light was most definitely illuminated now. I took it for a short drive around the neighborhood, and did not sputter or surge one single time.

When I parked, I did note that the idle rpms seemed to wobble a bit. Nothing extreme, just definitely noticeable while watching the guage.

Stay tuned for Update 3 : Components of a Lesser Cost

[tblake]

You found your problem. Make sure your replacement is a delco brand (dealer price 325.00)

ZZP used to offer GM replacement MAF sensors for 129.99, but a lot of us opt for their ported throttle bodys for 199.99 instead simply due to the fact that the new t-body's include the TPS, MAF, and IAC.

Just make sure you swap over the inlet screen if you get a new t-body. I did not, and I had some TCC indecision issues untill I got a screen back in there.

[ISmellRubber]

I have chased the exact "Ghost" you are right now.....It was on a buick 3.8 SC, 1993. One of the things that does go out,but not often is the CP sensor located right under the belt tensioner passenger side of engine. I have an old school collage instructor watch me for a day and a half as i ran this one down. The car starts, then gets to operating temp and just dies! after $13.00 the replacment of this sensor is what the problem was. He said it is a common failure for the 3.8 that just does not get picked off unless you know it. Your problem sound exactly like this, that and it is a very cheap easy fix unplug the harnes to it move the belt off and 2x10mm nuts hold it on the block.

[BNaylor]

Originally Posted by ISmellRubber

I have chased the exact "Ghost" you are right now.....It was on a buick 3.8 SC, 1993. One of the things that does go out,but not often is the CP sensor located right under the belt tensioner passenger side of engine. I have an old school collage instructor watch me for a day and a half as i ran this one down. The car starts, then gets to operating temp and just dies! after $13.00 the replacment of this sensor is what the problem was. He said it is a common failure for the 3.8 that just does not get picked off unless you know it. Your problem sound exactly like this, that and it is a very cheap easy fix unplug the harnes to it move the belt off and 2x10mm nuts hold it on the block.

If you review the prior posts the issue in this thread appeared to be the MAF sensor not the crank position sensor. Although it is a common failure item your suggestion has some merit but with error. To properly replace the crank position sensor on a SII 3800 engine circa '95 and up it is not a simple job like removing the drive belt. The crankshaft harmonic balancer and pulley must be removed using the proper bolts and tool.

[CrazyHorst]

I think Rockauto has a NIB AC Delco MAF sensor for around $220 + ship last I checked.