Thread: Mystery Hot Stalling

Hey guys and girls. I will start off by saying that if anyone can help me out with this, my GTP and I will be eternally grateful!

Vehicle: 02 GTP, 110K miles, only engine "mods" are zzp headers (w/egr), Autolite 104's, drilled 180 deg T-stat

Problem: Vehicle stalls when hot(outside temp greater than 75 and running for more than 20-30 minutes), but this is not consistent somedays its blazing and its fine. The two situations where it stalls are accelerating from a stop or when cruising down the highway (foot off accelerator). When it stalls while accelerating from a stop it struggles to stay on then just drops. In contrast, when it stalls while cruising, it does so quickly and quietly; I usually don't notice until I tap the brakes or gas again (very scary). After the stall it will usually not start, it cranks great, but will not start, or if it does it dies in seconds. It will start just fine after about 10 minutes, but I only have a few more minutes of drive time (depends on how long I waited and outside temperature, anywhere from 2 to 20 minutes).

Roadside Diagnostics: After stalling, I have checked the shrader valve on the fuel rail and it sprays fuel promptly, so I do not think this is a fuel issue (unless the injectors are the failure point). I have unplugged the MAF and attempted restart, did not work. Scanned for codes, nothing there. One thing I have not been able to do is check spark (never have someone to crank while I look).

Diagnostics/Parts Throwing: In summer 2012, when it first happened, I changed the Idle Air Control Valve. No change. Then, Crankshaft Position Sensor. No stalls for remainder of summer however I did not drive much and temperatures were mild when I did. Summer 2013, it stalled again but this time it threw a MAF code, changed the MAF and everything was fine for a week, then stalled. Next, I changed the Ignition Control Module with a new one from Cardone. No change. Finally, I did the camshaft sensor and things were fine for until late summer early fall where it stalled on a 77 degree day. Switched cars until winter. Here I am getting into summer 2014 and I dont want to drive the thing until I get this solved.

Starting college I was okay with throwing parts, now I realize how bad of an idea that is due to adding more variables. Recently, I have done multimeter diagnostics on the MAF, coils and injectors, I just have not had time to do the the Crank, Cam, and Ignition Control Module. Furthermore I need to rerun all these tests on a very hot day. Thoughts? Ideas?

Thanks a ton!

Additional Information: I forgot to mention that the EGR also threw a code in the fall and tested bad so I replaced it, code cleared on its own. Also, regardless of temperature, the car seems to have very long shifts, and when coasting to a stop from greater than 30 mph the engine rpm "breathes" between 800 and 1200 (this is inconsistent, comes/goes)

Anybody? You guys are my last hope! At this point I am getting ready to off the thing, or drop the engine into a fiero

Hey guys thanks for the responses! The new crank sensor has been on the car for about two years now, so unless the new one went bad I do not think thats it. Plus when it dies at a stop light the tach doesn't drop off, instead the engine struggles to stay alive (tach bouncing between 400 and 1500) and then it dies.

As for the fuel pump I forgot to say that I changed that in June 2012. I bought a venturi style pump from Zack at Moar performance. I did have to pull a venturi canister from the junkyard when doing so. However, fuel pressure tests show all the numbers I am expecting, around 45 PSI with engine on and 49 PSI with the ignition switched to on (engine off). When I changed the pump, I also changed the filter too. As for fuel treatments I have tried heavy doses of lucas but I will be honest I do not think it had much of an effect, if any.

I dont want to throw bad ideas out there, but do you guys think this could have anything to do with the Pressure Control Solenoid in the trans. I know they tend to go readily on these cars and given the crappy shifts I get I am thinking possibly trans related issue. Although I do not think a PCS could cause stalls (please correct me if I am wrong!)

Originally Posted by Scottydoggs

checked for vac leaks yet? spray some carb cleaner at the lines and sensors. if the idle jumps up thats the leak area. spray the TB gasket area and lines off it too.

I definitely need to do more of this. I recall doing so before I parked the car but I mainly checked the lines and fittings. Good idea to check around the TB (and LIM). I went out yesterday and checked under the hood now that it has been sitting for a while and I have got a puddle of oil/coolant in the crevices under the TB. I am assuming the coolant is from the LIM and the oil is from the valve covers.

Originally Posted by Scottydoggs

lim gasket time. my one out side lim bolt used to cry when the engine was hot lol looked like a tear running from it.

you can also try moving the vac lines while spraying them, sometimes you hit a bump they bounce and the crack opens and the vac leak can show its face.

I did try wiggling as many of the connections as I could reach. I think I need to either replace or put clamps on the lines running near the boost bypass valve and pcv. There is definite room for improvement!

Originally Posted by Slick2500

This is the firs thing that comes to my mind http://www.grandprixforums.net/threa...rmittent-start!

This is amazing! I am really impressed with the amount of detail in this writeup. I am going to borrow some the ideas in here and attempt to make a remote ICM as well as trigger that fans at startup. If I achieve something simple and effective I will have to take pictures and maybe do a writeup of my own! I will report back if this solves the issue, of course I need it to get above 75 outside!

Thanks for all the help guys! Really.

One day I will get around to replacing all these 12 year old lines haha. I ordered the materials to go ahead with the ICM standoff. I am back at school so the earliest I can report back on results will be this weekend. I am hoping for the best.

I agree that post was loaded with info!