I had a buddy drop by with his 07 3500HD CCLB Dually last night. He wanted help correcting his speedometer after installing bigger tires. We did the speedo correction using EFI live and took the truck on a test drive. The speedo read accurately and ran just fine. We parked the truck on the driveway and let it idle while we were inside the garage doing something else.
After it idled for 30 minutes my buddy hopped into his truck and went to pull away when I heard it surge and die shortly after he put it into gear. It re-starts but won't idle smoothly for more than 10 seconds at the very most then goes into a bad surge and dies. It does this regardless of if it is in gear or not.
It spews grey smoke out the exhaust while it is surging but seems clear when it does idle smoothly. It appears to be unburnt fuel. There is zero throttle control. Touching the throttle it doesn't even try to rev up.
I returned the tune back to the stock one I'd downloaded and saved on my computer just before adjusting the speedo. I even tried downloading another tune from a tune depot and it behaved the same. The truck had an SCT tuner on it. We returned it to stock before we modified the tune for speedometer correction.
All the sensors are reading correctly. Fuel rail pressure is around 48mPa and matches the desired pressure. Balance rates look fine for the little while they run. The APP sensors are both good, MAP reads atmospheric and changes when the engine runs. IAT and CTS are both reading good. The MAF reads when the truck tries to run.
The truck had crappy batteries in it so I swapped a good set in and found no change. I replaced the fuel filter and verified that the tank isn't building suction.
There are no DTCs at all. I'm at a bit of a loss. This happened suddenly and without any warning. Buddy claims this happened once before and that the truck came back to life after being towed and has been perfect since.
The oil is clean. The cooling system had a vaccum on it with a collapsed upper rad hose but I think that is due to the rad cap being no good. I don't believe it has a bad head gasket.
Any ideas?
After it idled for 30 minutes my buddy hopped into his truck and went to pull away when I heard it surge and die shortly after he put it into gear. It re-starts but won't idle smoothly for more than 10 seconds at the very most then goes into a bad surge and dies. It does this regardless of if it is in gear or not.
It spews grey smoke out the exhaust while it is surging but seems clear when it does idle smoothly. It appears to be unburnt fuel. There is zero throttle control. Touching the throttle it doesn't even try to rev up.
I returned the tune back to the stock one I'd downloaded and saved on my computer just before adjusting the speedo. I even tried downloading another tune from a tune depot and it behaved the same. The truck had an SCT tuner on it. We returned it to stock before we modified the tune for speedometer correction.
All the sensors are reading correctly. Fuel rail pressure is around 48mPa and matches the desired pressure. Balance rates look fine for the little while they run. The APP sensors are both good, MAP reads atmospheric and changes when the engine runs. IAT and CTS are both reading good. The MAF reads when the truck tries to run.
The truck had crappy batteries in it so I swapped a good set in and found no change. I replaced the fuel filter and verified that the tank isn't building suction.
There are no DTCs at all. I'm at a bit of a loss. This happened suddenly and without any warning. Buddy claims this happened once before and that the truck came back to life after being towed and has been perfect since.
The oil is clean. The cooling system had a vaccum on it with a collapsed upper rad hose but I think that is due to the rad cap being no good. I don't believe it has a bad head gasket.
Any ideas?
