I tested the good, I thought, LOL, working jeep with the Snap-on MT-2500 and it started and ran in open loop (I had pulled the O2 sensor heater power relay to keep in open loop at first), and it ran with the LTFT and STFT both rock solid at 128. No doubt in open loop it uses the tables, thus both park at 128 open loop???
In closed loop the STFT moved up over 128 at times when I reved the rig. LTFT was solid at 128.
It took about 10 minutes to reach closed loop with the O2 sensor heater power relay removed, while mine went closed loop at idle in 2-3 seconds with the relays removed, so my exhaust on the problem rig is hot, so some cylinders must be real rich (open loop rich mode) and some lean (HOT) on mine heating that O2 sensor up so fast???
In closed loop the good rig read RICH for low voltage, but I discovered that the scanner RICH/LEAN message is locked in an old data state when the rig is in open loop. That is what threw me, in part. Its a red herring.
In open loop the good rig voltage was low, so low voltage is a rich state. In closed loop it read rich at low voltage and lean at high voltage and switched very quickly which confirmed that low voltage is rich.
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I disconnected the battery on my problem rig, and still got the same test results as before. No changes, very low STFT, like 30 +/- 20 at idle in Open-closed????, arg my notes don't say which loop, and read 128 on both fuel trims in open loop at 1500 RPM, but it seemed to run smoother, but still has a problem, stumble miss, just not as bad and happens at higher rpms today. Still goes to about 1.0 Volts open loop after a miss from reving or higher rpms, and takes a while at idle to get back to closed loop. I need to confirm if the low STFT is in open or closed loop at idle again since I cleared the memory.
At 1500 RPM O2 data was down to 1.3 Volts, rich, open loop and the STFT went to 128??? WTF??? I guess the Fuel trims are now both going to 128 in open loop after clearing the memory from disconnecting the battery.
If that is the case then at idle in open loop the STFT should be 128 also, and then in closed loop at idle the STFT going way down. But if STFT is going down so far to keep it in closed loop, it must be response to the problem I chasing down!!! Ah HA!!!!
So Renix does store sensor and performance optimization data as I have been saying for 8 years!!! Just no know way to retrieve it yet.
TPS passed all the tests. All the sensors on both rigs tested the same, all working good in spec.
