Car won't go into PE mode?
10-20-2008, 07:42 AM
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Car won't go into PE mode? Hey everyone,
So this weekend I installed LT's and dumps on my car and I had a buddy scan the car with HPtuners. After doing a couple pulls, we realized that the car wasn't going into PE mode under WOT. The car appeared to be staying in CL and trying to achieve a 14.7 AF ratio. We also saw that under WOT the O2 sensors stopped pulsing and stayed a constant 25-40 mV, and not the 800 mV or so that they should have been at. Also, the injector duty cycle only hit about 55%. Also, around 2,500 RPM the car would lean out real bad, and the car would stumble. The car did this when I first bought it, but I cleaned the MAF and that seemed to fix the problem.
The car as a lid, Pacesetter LTs, and TSP Duals and that is it.
I have attached the scan and my tune. The tune is pretty much a stock tune with EGR, AIR, and secondary O2s turned off. A few other small things have been changed, torque management, cooling fan temps, etc. but nothing that should affect PE mode.
I don't really know anything about tuning, so I wasn't wondering if someone could look over the scan and see if anything would be causing the car to stay in CL.
So this weekend I installed LT's and dumps on my car and I had a buddy scan the car with HPtuners. After doing a couple pulls, we realized that the car wasn't going into PE mode under WOT. The car appeared to be staying in CL and trying to achieve a 14.7 AF ratio. We also saw that under WOT the O2 sensors stopped pulsing and stayed a constant 25-40 mV, and not the 800 mV or so that they should have been at. Also, the injector duty cycle only hit about 55%. Also, around 2,500 RPM the car would lean out real bad, and the car would stumble. The car did this when I first bought it, but I cleaned the MAF and that seemed to fix the problem.
The car as a lid, Pacesetter LTs, and TSP Duals and that is it.
I have attached the scan and my tune. The tune is pretty much a stock tune with EGR, AIR, and secondary O2s turned off. A few other small things have been changed, torque management, cooling fan temps, etc. but nothing that should affect PE mode.
I don't really know anything about tuning, so I wasn't wondering if someone could look over the scan and see if anything would be causing the car to stay in CL.
10-20-2008, 11:35 AM
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I would say from the log you have is that it IS in power enrichment. Without logging the "Commanded AFR", a WBO2, or any status bits I can' say for sure, but it appears that your fuel trims lock out during 100% throttle. I'd say the reason your performance is poor and the O2 mV stay at 25-40 mV is because you are THAT LEAN. My first thought would be a fuel flow problem. Pump or filter. Check those before trying to tune it out.
10-20-2008, 12:02 PM
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I would say from the log you have is that it IS in power enrichment. Without logging the "Commanded AFR", a WBO2, or any status bits I can' say for sure, but it appears that your fuel trims lock out during 100% throttle. I'd say the reason your performance is poor and the O2 mV stay at 25-40 mV is because you are THAT LEAN. My first thought would be a fuel flow problem. Pump or filter. Check those before trying to tune it out.
10-20-2008, 12:49 PM
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Possibly a bad/damaged MAF sensor. Friend of mine had the same problem recently. Find a donor car to borrow a MAF from and see if it performs any better.
10-20-2008, 01:08 PM
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A fuel pressure gauge that you can read at WOT, would be a good
thing. I cobbled a sender and Autometer gauge onto my cheapo
Actron dial-gauge (AutoZone) so I can read with the hood closed.
Any filter, pump or wiring limitation will show up at the rail. It it is
hanging tough (less than a couple PSI drop from idle to WOT) then
you look at the airflow side.
A WOT miss can also whack NBO2 and WBO2 readings. But you'd
expect to see this only on the bank with the problem (unless it's
a global firing / fueling problem).
thing. I cobbled a sender and Autometer gauge onto my cheapo
Actron dial-gauge (AutoZone) so I can read with the hood closed.
Any filter, pump or wiring limitation will show up at the rail. It it is
hanging tough (less than a couple PSI drop from idle to WOT) then
you look at the airflow side.
A WOT miss can also whack NBO2 and WBO2 readings. But you'd
expect to see this only on the bank with the problem (unless it's
a global firing / fueling problem).
10-20-2008, 02:18 PM
#6
First thing I would do is log the pe mode status bit & commanded afr PID so you can determine if its actually commanding your vehicle into pe mode & the lower afr. If not there are several things that would cause this, most of them surrounding your throttle blade body 
