dadasracecar
Member
So Lou at cp-e and I tried an experiment to cure the winter fuel cut. Basically it's temperature and load related. On my car I documented the temperatures, boost levels, and gears that I could induce fuel cut. The only way the car knows what temp it is is through the MAF and the IAT. Lou decided to focus on the IAT. We pulled the IAT plug out of the MAF connector and tapped the wire with a potentiometer. We could then read the IAT using a scan tool. I did several runs in 4th at WOT with the boost set at 18 psi and my tune. All runs were done in 4th to minimize variables. The ambient temp was around 48 deg F for the 64-77 deg runs. The ambient temp was ~37 for the 80 and 82 deg F runs. The following is a list of IATs and the approximate rpm where FC occurred:
64 4400
71 4700
75 4950
77-8 5050
80 5150
82-4 5300 - very infrequent
Using the dashhawk or another scan tool that can read real time parameters, you can easily dial the temp you want. The issue with dialing it to high is that the car will pull timing. We tried at 100 degrees and it was pulling a lot of timing.
Also, as has been discussed, the air density changes with temperature and setting an IAT of 40-50 degrees higher should alter any fuel calculations performed by the ecu. I was scared of this and have been watching my afr in closed loop very carefully. It seems the car places priority on the wideband O2 sensor as my afr is always very near stoich (14.5-8) at idle and closed loop even with the iat set at 84 deg.
The document below describes what is to be done. It instructs you to cut the IAT wire and solder it to a potentiometer. You don't necessarily need to cut it if you're handy at pulling the plug from the maf housing. Just be careful not to eff up the housing. I pulled the plug out and used a scotch lock on the wire. THis makes it easy to disconnect the potentiometer and push the plug back in the housing when it warms back up and a fuel cut fix isn't necessary.
Finally, I get a cel about every 10th time I start the car. It's a IAT circuit out of range or something like that. If I turn the ignition to on, wait a second or two, and then start the car it seems to happen less frequently. I clear it with the Dashhawk.
For all you cp-e haters, don't say they never did anything for ya...
View attachment 122769
64 4400
71 4700
75 4950
77-8 5050
80 5150
82-4 5300 - very infrequent
Using the dashhawk or another scan tool that can read real time parameters, you can easily dial the temp you want. The issue with dialing it to high is that the car will pull timing. We tried at 100 degrees and it was pulling a lot of timing.
Also, as has been discussed, the air density changes with temperature and setting an IAT of 40-50 degrees higher should alter any fuel calculations performed by the ecu. I was scared of this and have been watching my afr in closed loop very carefully. It seems the car places priority on the wideband O2 sensor as my afr is always very near stoich (14.5-8) at idle and closed loop even with the iat set at 84 deg.
The document below describes what is to be done. It instructs you to cut the IAT wire and solder it to a potentiometer. You don't necessarily need to cut it if you're handy at pulling the plug from the maf housing. Just be careful not to eff up the housing. I pulled the plug out and used a scotch lock on the wire. THis makes it easy to disconnect the potentiometer and push the plug back in the housing when it warms back up and a fuel cut fix isn't necessary.
Finally, I get a cel about every 10th time I start the car. It's a IAT circuit out of range or something like that. If I turn the ignition to on, wait a second or two, and then start the car it seems to happen less frequently. I clear it with the Dashhawk.
For all you cp-e haters, don't say they never did anything for ya...
View attachment 122769
