Stalling When Hot
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 139
Likes: 1
From: Alamogordo, NM
Stalling When Hot I know this is a shot in the dark for someone to troubleshoot this online, but here goes...
I have a standalone 2006 GTO LS2/T56 swap with a bone stock tune and factory engine components; no speed parts. After the engine is running at normal temps the engine runs rough for a second and stalls. The mixture smells very rich when this happens. It usually takes up to an hour or two to happen. It usually happens when the engine has been idling for a while or going down the road at a crawl. If I can get the RPM's up fast enough I can usually prolong the eventual stall, all the while while running rough and rich. The engine is not overheating BTW.
I can wait a few minutes and it usually starts and might run for a half hour or more or might quit again in a few minutes.
I feel that it might be heat related, like a sensor that eventually gets too hot and fails. Since it takes a while after the engine is at operating temps, I initially thought of the two components not mounted directly to the engine, the MAF and ECM. After a stall I shot them with a freeze spray, basically 134A, and restarted to see if that would help. Didn't seem to. I even tried to use my heat gun on the MAF to hasten the heat soak process; nothing. The problem is too random. On both units I never saw more than 140 degrees. But because it can usually start within a few minutes, I don't see how a sensor could cool off that fast.
A shop scanned the engine and said everything is running great. (Although I smell what I think is too rich of a mixture all the time.) He never had it stall on him to see what was happening at that instant.
Any ideas?
I have a standalone 2006 GTO LS2/T56 swap with a bone stock tune and factory engine components; no speed parts. After the engine is running at normal temps the engine runs rough for a second and stalls. The mixture smells very rich when this happens. It usually takes up to an hour or two to happen. It usually happens when the engine has been idling for a while or going down the road at a crawl. If I can get the RPM's up fast enough I can usually prolong the eventual stall, all the while while running rough and rich. The engine is not overheating BTW.
I can wait a few minutes and it usually starts and might run for a half hour or more or might quit again in a few minutes.
I feel that it might be heat related, like a sensor that eventually gets too hot and fails. Since it takes a while after the engine is at operating temps, I initially thought of the two components not mounted directly to the engine, the MAF and ECM. After a stall I shot them with a freeze spray, basically 134A, and restarted to see if that would help. Didn't seem to. I even tried to use my heat gun on the MAF to hasten the heat soak process; nothing. The problem is too random. On both units I never saw more than 140 degrees. But because it can usually start within a few minutes, I don't see how a sensor could cool off that fast.
A shop scanned the engine and said everything is running great. (Although I smell what I think is too rich of a mixture all the time.) He never had it stall on him to see what was happening at that instant.
Any ideas?
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 139
Likes: 1
From: Alamogordo, NM
Someone else mentioned this. I'll need to find the resistance values for the temps.
You think I may have contaminated the MAF sensor when I sprayed the K&N filter? I sprayed it in my hand while the MAF was attached.
Thanks!
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 139
Likes: 1
From: Alamogordo, NM
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 139
Likes: 1
From: Alamogordo, NM
Well, it's a no-go on the temp sensor. Died again.
Someone noticed how I had the fuel line clamped to the back of the head. He suggested vapor lock. I suppose vapors could be making to the injectors causing it to die. After it sat for several minutes, I could put my hand on the braided hose. It was definitely hotter at the clamp area. It was even cooler in the area over the header collector, (about 8" above). Earlier, I also shot the hose with an IR thermometer, it read no more than 170-180 degrees. I don't know what the temp needs to be for it to percolate.
I moved the line away from the head and right up against the firewall, about 2-3".
Someone noticed how I had the fuel line clamped to the back of the head. He suggested vapor lock. I suppose vapors could be making to the injectors causing it to die. After it sat for several minutes, I could put my hand on the braided hose. It was definitely hotter at the clamp area. It was even cooler in the area over the header collector, (about 8" above). Earlier, I also shot the hose with an IR thermometer, it read no more than 170-180 degrees. I don't know what the temp needs to be for it to percolate.
I moved the line away from the head and right up against the firewall, about 2-3".
