1996 GTP - another stalling thread.

[96GTP]

Here's the background on this one.

I've been having a little problem since last summer. But it just got big. When the car was warm, it wouldn't start on the first try. Cold starts, it was fine, even sub zero temps. But if I drove it, parked it for less than say 2 hours, and tried starting it again, it would take 2 or 3 tries to start. It would fire, rev to around 3k real quick, then die. The 2nd try usually it would stay running.

Then it got bad.

Apparently my transmission fluid cooler was plugged, building up pressure in the lines, and causing the line that runs by the radiator to blow off, draining all my fluid when driving. That happened 7 times. The first 6 I was luckily going downhill, put it in neutral and coasted to where there was a good place to pull over. The last time, I was in the city and it was snowing (parking ban). So I drove across the city to some relatives' house so I could leave my car. I know, I would've been better off paying a parking ticket.

The torque converter was making a nasty whine noise from being dry. Reconnected the lines, filled it up with fluid and that went away. The car shifted fine. But on the way home, every time I let off the gas it would stall. Had numerous people (mechanics too) say that the torque converter was burnt out and it was like I was trying to stop a standard without using the clutch. Seemed right.

Went out and bought a new transmission, 32k on it. About $1000 installed.

The night I picked it up, the guy that did the work said it was fine. Got 2 blocks down the street from his house and it stalled. Every light after that, it would stall. Finally about halfway home it straightened out and was fine.

After that, it would always stall in one of two places on my way to school (22 mile trip one way, and would always stall in the exact same spots, about 20 miles into the trip). But those were the only two places it would ever stall. I could drive a different route for 100 miles and it'd be fine. But every day I knew exactly where it would stall on the way to school, it was really weird. It would also stall whenever I put it in park.

Then one day I was leaving school headed to work, and it wouldn't stay running AT ALL. Every time the RPMs dropped under 2000 it would stall. It wouldn't start unless I held my foot on the gas. It'd fire, rev real quick to around 3k, then die. So I kept it in 3rd and took the highway straight to the dealership so the RPMs would stay up enough so it wouldn't stall.

Paid $90 for the dealership to diagnose it. They told me the lower intake gaskets (which I just did last year) and MAF sensor were bad. Told me it would cost more to fix than the car was worth (blow me, right?) Got the parts, did the work. No change.

Since then I went to clubgp to ask about it. Tried everything they suggested, no change. So they sent me here. Here's the thread on clubgp:

http://www.clubgp.com/newforum/tm.asp?m=5240730&p=1&mpage=1&tmode=1&smode=1&key=&language=

Also here's a video of how it runs. There's nobody in the car. Had my dad start it and I got the camera out.

http://www.youtube.com/watch?v=yd0ZyAf0a_U

And here's a list of everything I've replaced:
Transmission (and torque converter obviously)
All gaskets from the oil distribution area (below the lower intake manifold) up.
Lower intake manifold
Coolant Temperature sensor
MAF sensor
Fuel pressure regulator
IAC valve
Throttle Positioning Sensor

Also, it runs the same with the plug on the TCC solenoid plugged in or disconnected.

Keep the ideas coming, and I'll keep sinking money into it...

[RedZMonte]

any codes? anyone near you have a scanner (dhp, hpt)... if the intake gasket was leaking, shooting some carb cleaner will make it stumble/rev... but usually its bad when cold not hot... metal expands with heat and seals the leak... i wonder if a bad ground or faulty ign module would cause what you are seeing check all grounds.. make sure they are clean and tight

good luck

[96GTP]

any codes? anyone near you have a scanner (dhp, hpt)... if the intake gasket was leaking, shooting some carb cleaner will make it stumble/rev... but usually its bad when cold not hot... metal expands with heat and seals the leak... i wonder if a bad ground or faulty ign module would cause what you are seeing check all grounds.. make sure they are clean and tight

good luck

Check engine codes for the O2 Sensor and air pump. They've been there for years. Have to fix it this year though, the state just changed their inspection system, so clearing the codes a block away from the garage won't work anymore.

What is DHP and HPT? According to the dealership, there's no scanner that'll read more than DTC codes on this car.

I have a spare set of coils and a spare ignitoin control module I can try, but it's not acting like a misfire.

[RedZMonte]

DHP/HPT are scan programs/tuning programs that will scan the 1996+ OBDII GM systems... DHP and HPT can read any sensor that the ECU reads... it can give you more information and you can save the scan file and have other guys read it to see if there is anything funny happening..


O2 Sensor Code? what code exactly (what is the Number)? bad O2 sensor can most definatly cause a stall... As can a bad ign modual (no fire rather then a miss fire).. Im just throwing out ideas with the IGN modual... I wouldnt think the AIR pump would cause a problem... but you never know...

Have you replaced the fuel filter recently? have you put a Fuel pressure gauge on it when it dies? my fuel pump would run fine cold but when it got hot it would stall... let sit for a while and once it cools down it would fire right up... put a gauge on it and i saw it drop when the engine would stall. replaced the pump and it was good to go. I would get a pressure gauge on there and see what it reads when it dies.. kinda sounds like what happened when my pump was failing... Very random no consistant time between stalls.

S

[walterdude]

For what it may be worth, the second time my FPR went it did similar things. Would fire right up when cold and run normally. Turn it off and try to start when warm,, forget it!! Let it sit a few hours and it would fire fine again... I agree that a pressure test is a good idea... Also you say you did LIM, UIM and FPR,,, perhaps the vacuum line for the FPR got pinched somewhere??
NEW parts don't always mean GOOD parts, trust me on this!!
Good luck,,,
Tom...

[96GTP]

For what it may be worth, the second time my FPR went it did similar things. Would fire right up when cold and run normally. Turn it off and try to start when warm,, forget it!! Let it sit a few hours and it would fire fine again... I agree that a pressure test is a good idea... Also you say you did LIM, UIM and FPR,,, perhaps the vacuum line for the FPR got pinched somewhere??
NEW parts don't always mean GOOD parts, trust me on this!!
Good luck,,,
Tom...

Well, I knew the FPR was bad last time because there was fuel in the vaccuum line (meaning it was getting dumped into my air intake). There's no more fuel there now.

Would a pressure test help? To my knowledge, the fuel pressure from the pump is constant, and the FPR controls how much gets past. Am I right? If I know that the FPR is good, then there's no point in bothering with checking fuel pressure is there?

The vaccuum lines all look fine. I have a friend with a smog machine to test for vaccuum leaks but he's never around. Is there a way I can do this myself? The carb cleaner method doesn't work cuz the idle is so erratic, you can't tell if it's picking up on its own or because of the carb cleaner.

[pocket-rocket]

Checking fuel pressure will tell you if the pump is keeping up with the engines fuel consumption. If your pump is failing or the filter is clogged, the ECM is still going to expect to see a certain fuel pressure depending on what the MAP is telling the ECM the engine vacuum is. If the engine isn't getting the fuel pressure the ECM is expecting, it won't run right because it will be running really lean when fuel pressure drops out.

[96GTP]

Checking fuel pressure will tell you if the pump is keeping up with the engines fuel consumption. If your pump is failing or the filter is clogged, the ECM is still going to expect to see a certain fuel pressure depending on what the MAP is telling the ECM the engine vacuum is. If the engine isn't getting the fuel pressure the ECM is expecting, it won't run right because it will be running really lean when fuel pressure drops out.

Again, correct me if I'm wrong. But if the fuel pump is weak/filter is clogged, I shoudln't be experiencing problems idling, I should be having problems under load. Right? The car runs great with my foot on the gas.

[RedZMonte]

if its not getting enough fuel at idle you will choke... Low RPM's=Low fuel pressure (vac controled by the FPR)... As well as a cloged fuel filter will not let enough volume threw, may still have the right pressure but not enough volume... You rev up, you gain fuel pressure as well as the injectors are dumping more fuel at higher RPM's.. new filter and test it with a gauge is easy way to see if that is your problem. ~$5 for the filter and if you don't have a gauge they are also cheap.

S

[pocket-rocket]

With my experience troubleshooting engines, fuel pressure and volume can be everything. It can't hurt to rule it out, and narrows the possibilities of what's causing the problem.

[96GTP]

With my experience troubleshooting engines, fuel pressure and volume can be everything. It can't hurt to rule it out, and narrows the possibilities of what's causing the problem.

We might've found it.

My brother said to disconnect the sensor on the EGR valve and see if it works. I guess my dad tried it yesterday when I was at work, he said it ran fine for 20-30 minutes before it ran out of gas. It hasn't been able to stay running long enough to make it to the gas station lol

Bad news is RockAuto lists EGRs for it for between $100 and $200... don't really wanna pay that much but I guess I have to. Funny, it takes the same EGR as a couple Jaguar models, no wonder its so expensive lol. Hate to be a cheapskate but maybe I'll just grab a couple from the junkyard for like $10, I wanna get it running before the end of the month (inspection runs out) but my daily driver comes first and that needs a new power window motor and a sensor for the heater fan.

[RedZMonte]

if it truely is your egr then pull your EGR off, clean it with carb cleaner, get all the gunk out of it, same on the intake manfiold, replace gaskets and see if it works properly. Check a junk yard for one if you don't want to spend alot of $$. most guys clean the EGR and have no problems after. I think the EGR is the same one on the 3800's and other GM V6's but don't quote me on that.
S

[pocket-rocket]

Yeah, a 96 is a linear EGR, so it's found on tons of other GM's, even trucks.

[96GTP]

No luck. Replaced the EGR valve. Found a vaccuum leak and fixed it. Seafoamed the intake. Still doing the same thing.

[RedZMonte]

Did you ever check fuel pressure?