i need to rule some things out here...
up until i replaced the wiring harness, the car ran 14.7 ish and 12.5ish wot above 2500 rpm and 11 ish wot below 2500 rpm.
after the harness replacement, i started getting a P0105 periodically.
a couple weeks later, the wideband started to stay lean, as time went on, the duration that the wideband would display "---" (18+) would get longer and longer, but the performance of the car never changed. The wideband would not show lean right after startup, even if it was a stall and restart with the clutch, (and still does not show lean at startup, though after 2-5 minutes after initial cold startup, and 5-10 seconds after a warm startup, the wideband shows lean again)
About this same time, unbeknown to me, the pin for the purple wire (the GM Schematic calls this the "LOW" wire) on the front 02 sensor, backed out of the connector. it appeared that it was completely backed out, however the scan tool was still reading o2 voltage, and never threw an o2 sensor low input code. Additionally about this time, my cat started heating up, and i found chunks of it in the driveway.
a couple weeks after that the ECM went, it started throwing a crank position sensor code when the crank, sensor, and wiring were tested to be good. i gutted the burned remains out of the cat and reinstalled it hollow. After replacing the ECM with a stock ECM (using my stock injectors), for about 2-3 days, the car ran 14.7 with about 12.5 at WOT. Then the car started running lean again, this time, when its lean, i have noticeable performance loss. (the few times the wideband shows numbers, the car drives normal)
After finding and repairing the bad o2 sensor wire, as well as replacing the o2 sensor, the car still runs lean. As of today, the long term fuel trim was -19.5 before i reset the adaptive values on the ECU (still runs lean after reset)
Now i don't know if the P0105, the running lean, and the performance loss are connected or separate... in addition, the new ECM was out of an automatic, the .430 lift cams are hating the 700 RPM idle... and i get an instant CEL with 4 codes related to the Automatic trans, so i can't get a freeze frame on the P0105. My tuner sent me GM's diagnostic sheets for P0105. I followed it everything checked out, no vacuum leaks, no electrical issues with the MAP or the TPS (the grounds showed ground, the 5v references showed 4.9997 volts, and the signal wires showed voltage in spec with the values on the chart, neither had any sort of short to power, the TPS shows 0% closed, and 100% at WOT, the map showed 100 kPa with engine off, and 10 kPa disconnected with the sensor disconnected. The diag chart stopped with "Replace the MAP Sensor" which didn't fix the problem.. .
again i wonder if the symptoms are related, or separate coincidental things. i wonder if my performance loss could be due to the stock injectors... but wouldn't it be a consistent performance loss, and not random? i wonder if im leaning out due to the cams/pistons/stock tune combo. i don't want to waste my tuner's time, though i think going back to the LSJ injectors and getting my tune back would greatly help me diag any additional issues. Kinda a catch 22.
any suggestions/thoughts/ideas?
makes me think you have a bad ground what are your ltft and stft
see ya!
prior to resetting the adaptive values, the ltft was -19.5 while the stft was 0
Im with the bad ground theory. It has to be something to do with the harness since it was fine before installation. A bad ground does seem like a pretty logical possibility. If its not a ground I would use Brad's junkyard harness idea. All the sensors check out so harness is the only logical thing thats left.
the grounds appear to be good... but i'd like to check the one under the intake manifold better before i make a final determination. a buddy of mine suggested to unplug the IAT, since this would usually cause a rich condition. On my old wiring harness, the wires to the IAT at the connector were pinched and had an intermittent (mostly all the time) fault. with the IAT unplugged, i don't run lean as often, but still do about 70% of the time (from what i would say 95% of the time), i also don't feel the power loss (not to say anything because i need more time to drive on it to figure out if this is the case).
it seems like the wideband reads, stoich-lean-stoich-lean... like i get fuel, so the computer corrects and i lose it, then due to the cold temp the computer thinks its reading from the IAT, it gives more fuel, then the computer corrects and i lose it, etc... at WOT above 2500 RPM, i see about 13.7 (in between a few seconds of 18+) and below 2500 i see about 12.4
so i have a new theory...
im running the fontana gen 1 HO spacer, and its a little off center. Its never given me problems in the past, but what if ive developed a very small intake leak where the mani meets the head. That would explain my high rev between gears, the idle issues, the P0105, the running lean, and the power loss (due to the computer compensating for this...
does my theory hold water???
i plan to remove the manifold and investigate wednesday... i really should slot the holes on the spacer so that the runners line up correctly...
"I followed it everything checked out, no vacuum leaks"
Vacuums leaks can be hard to find, I got one I haven't found for almost a year.
- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
