Hi fellas, first off I want to say thank you to all the contributors to this forum, you guys have taught me so much over the last 4-5 years.
I have a customer that has a 2011 CTS-V and we are trying to figure out some intermittent hot start issues. I would appreciate any input as I feel like I have exhausted every avenue that my knowledge will allow. The car was built and tuned by a very reputable shop (I know this means absolutely nothing), but figured it may be valuable info to some. The car will crank and idle fine every time when cold, as the car idles for 15-20 minutes, the engine gets heat soaked and will not start.
Mod List:
- Ported Blower
- Ported Snout
- Flex Fuel Kit
- Upper Pulley
- 127lb 1200cc Fuel Injector Connection Injectors
The car has 100% stock returnless fuel system, aside from the injectors. The issues that we are experiencing seem to be very IAT dependent and seem to be more prominent on gasoline over E-85. I have noticed that there are a few IAT injector tables, but I'm trying to avoid messing with any injector tables that could possibly throw the whole tune off as the customer just needs the car fixed to get it sold - at least until I can rule out all possible mechanical issues. Customer says that he did not have this issue last summer, so this leads me to believe that there is something going on with the hardware.
I found a vacuum leak at the injector o-rings, so I replaced all of them and the leak has been mitigated. Car is still having hot start issues, but fuel trims are much better. Fuel pressure is a consistent 58psi at idle.
Are these injectors too large for the returnless fuel system? My theory is that the extremely hot fuel rail is building up too much pressure in the rail and the injectors will not open with that much head pressure. The fuel pressure will rise to around 70 with the engine off key on and seems to be boiling within the rail when I relieve pressure. I personally have used 80lb injectors on other CTSV's and they had plenty of fuel on e85 with similar modifications.
Any input would be greatly appreciated.
Tune file Harry Gunner 11 CTSV Base.hpt