So I noticed my '90 K1500 5.7L was idling rough in closed loop a couple weeks ago. Hooked up the scanner today and see that at warm idle, my IAC was dropping to 7-13 whereas I recall it generally stays around 30-40 at warm idle (been a little while since I've scanned this truck). In closed loop my Integrator was also down to 118 when it was rough running, so I assumed I had a fuel issue. Fuel trims pop back to 128 +/-2 above 700 RPM. I checked out the injectors and see decent spray patterns with no detectable drips. I do have some seepage around the injector hold-down (see pic below), so could this small leak be enough to impact the A/F ratio at idle, but at cruise its just in the noise? Its been 35k since a tune-up, so I'll add a TBI rebuild kit to the list. Unfortunately I wont have time to work on this thing until 2020, but I do have an hour or so a day to check sensors/scan data. Open to corrections/suggestions/thoughts in the meantime.
Things I've checked:
Checked base timing and its right at 0
Secondary ignition: 2-4-6-8 are running consistently 2 kV higher than the driver bank on Spark and Power KV which, I think, reinforces my leak assumption since The O2 sensor only reads off 1-3-5-7. Could more fuel be getting to the passenger bank and the ECM cant detect/correct for it leading to higher KV?
I do see the IAC indexing in/out with throttle snaps, and there is some crud down in the corner across from the pintle (another sign its time for a rebuild)
Fuel Pressure: Havent checked, but I now have an excuse to install that schrader valve at the TBI which I purchased a few months ago.
https://imgur.com/vFCOLC6
Things I've checked:
Checked base timing and its right at 0
Secondary ignition: 2-4-6-8 are running consistently 2 kV higher than the driver bank on Spark and Power KV which, I think, reinforces my leak assumption since The O2 sensor only reads off 1-3-5-7. Could more fuel be getting to the passenger bank and the ECM cant detect/correct for it leading to higher KV?
I do see the IAC indexing in/out with throttle snaps, and there is some crud down in the corner across from the pintle (another sign its time for a rebuild)
Fuel Pressure: Havent checked, but I now have an excuse to install that schrader valve at the TBI which I purchased a few months ago.
https://imgur.com/vFCOLC6
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