My truck has piss poor mileage right now (<15mpg) and is gutless as ever. I'm having a hard time getting the truck up to 55 mph at even the slightest of inclines. I can offer more metrics for lack of power but lets just say that even for the 22re, this is bad. CEL comes on intermittently while driving. i thought it was just the O2 sensor relocation problem (see below) but it turns out it's more than that. I got error codes 2, 5, 6, and 8.



Briefest history I can, happy to offer more if it can be relevant:

Just installed a new engine 400 miles ago (with harness and ECU), but these problems are persisting from before the swap. I think the ECU I have in the truck is '86 or before, because it's throwing single digit codes, although I have the diagnostic connector on my harness ('87 and up I believe?). Because the problems were there before the swap I think this helps me to narrow it down to peripherals?
I have an LCE header which required moving the O2 sensor down the exhaust pipe. I thought the O2 sensor code was being thrown because of the lack of heat issue, so I just installed a 4-wire O2 sensor with a heater (via a relay off the IGN fuse) and I am still having problems.
3 of my codes have to do with the AFM, so I checked the resistance of the unit according to the FSM and everything checked out in spec. I still need to check the operation/resistance of the measuring plate, planning on pulling the AFM open and doing that tonight.
I have good connectivity for the O2 sensor form the connector back to the ECU, although I haven't been able to measure the voltage yet.
The truck seems to be running really rich (black soot at tail pipe and on O2 sensor, smell gas in the exhaust), obviously this would kill efficiency, would it also kill power?
The injectors were just professionally cleaned and re-furbished with this re-build.
As stated, these problems seem to have persisted across two different ECUs (the engine I had in the truck was out of an '85, so I used that ECU previously)

What am I missing that is glaring me in the face? Where should I look for resolving the No engine revolution sensor to ECU code?

 

I'm assuming you're getting "stored" codes (as your CEL is intermittent). Just to avoid chasing dem Wild Gooses, you should reset the ECM (pull the EFI/MFI fuse for about 30 seconds), then drive around for about 3 miles (enough to reset the learned fuel trim and settle the codes). Then re-check for codes.

 

Great advice Scope. I pulled the EFI, put it back in and checked to make sure I got "normal" operation.

Just took it for a 15 mile or so, 20 minute test drive to make sure I got it up to temp and help it at high RPMs for a while. I only saw the CEL come on once, and when I got back, I only have code 5.

So I guess this starts me diagnosing the O2 sensor even more? I'm having a heck of a time understanding the O2 sensor flow chart in the FSM, but it sure seems like all roads lead to "replace the O2 sensor or the ECU" I've done both independently and still have issues which makes me suspect the wiring between the O2 and the ECU? Or the "ceramic coating" on the flange from the LCE header is not making contact to ground?

 

So as with most things, turns out this one was my fault. When I installed the header over a year ago, I apparently got some of the wire shielding from the O2 sensor harness wrapped into the heat shrink with the signal wire. I've been shorting out my O2 sensor for over a year!


So, now that I've fixed that problem, the truck is having a harder time finding the idle (was set right at 850, now it seems to jump between 500 and 950?) , and sort of feels like it is missing a bit? How long does it take for the ECU to relearn the A/F ratio once the O2 sensor starts working again?