997.2 engine suddenly died at stoplight
09-24-2019, 11:33 AM
#61
Are you all running high flow air filters from BMC or K&N? Once or twice my engine has stalled at the lights, or on a hard stop (in which the revs drop quickly) and my indy tells me that I have excess air flow. which is odd as I have had the filters in there for quite a while...
09-24-2019, 11:44 AM
#62
RL Community Team
Rennlist Member
Rennlist Member
This is such a random occurrence that I don't think we'll ever solve this one. Someone would have to be monitoring live values for fuel trims or MAF readings when their car actually did this so we could get some info from what the DME was doing, like did it make the mixture really rich or really lean right before the stall? Did it see weird MAF values, etc, etc, etc, With it happening and then all the cars restarting and running just fine afterwards, we can't even pull any good data right after it happens. Weird for sure - solvable, pretty unlikely IMO
09-26-2019, 08:49 PM
#63
Instructor
Consider the type of gas. I have been having an issue with vapor lock in an air cooled motor with carbs. I use nothing but premium shell gas. I recently learned that gas that is blended with ethanol has a lower boiling point and is therefore more susceptible to vapor lock. It's hard finding ethanol free fuel in the Midwest, but I have made the switch and it seems to have helped.
09-26-2019, 10:45 PM
#64
RL Community Team
Rennlist Member
Rennlist Member
Consider the type of gas. I have been having an issue with vapor lock in an air cooled motor with carbs. I use nothing but premium shell gas. I recently learned that gas that is blended with ethanol has a lower boiling point and is therefore more susceptible to vapor lock. It's hard finding ethanol free fuel in the Midwest, but I have made the switch and it seems to have helped.
Is the fuel lump for your carbs at the front of the car bear the tank or the rear of the car in the engine compartment? If the latter, get a fuel pump relocation kit that moves the pump to the front. The fuel pump can't pump vapor and the heat from the road rising up to the fuel lines turns it to vapor baletween the tank and a rear pump, whereas if the pump is at the front with the tank it will pump the liquid, which will push the liquid and vapor to the carbs, where it will still atomize and run the motor.
If the pump is already at the front, you've done all you can do except look for non-ethanol gas like you mentioned.
10-09-2020, 03:19 PM
#65
Cruisin'
Join Date: Jun 2020
Location: Washington
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I have this problem, or something REALLY similar. 2005 997S with the VF engineering supercharger, and Fabtech full exhaust with high flow cats. Car runs fine, but occasionally will just die, or hunt and then die, at idle only, and if I can keep it running, (it will fire right back up, but not necessarily idle) it drives fine. I've replaced the MAF, and I've replaced the throttle body, I've smoke checked for vacuum / boost leaks, and nothing seems to fix it.
If anyone ever figured this out that would be amazing.
If anyone ever figured this out that would be amazing.