Folks-
I have what we'll call a 1989 Chevy K1500 with TBI 5.7L V8, 700R4 automatic transmission (because it's actually in an 89 S10, but I digress..)
ECM is a 1227747, running factory code. Definition file for Tunerpro was EagleMark's $42-1227747-V5.2
I am experiencing high idle (around 12-1300 RPM), stumbling at speed, and although I do have a good bit of torque it still feels like it's down on power.
I datalogged a recent drive, and have the following observations:
-TPS Volt is way out of range- 0.14V at idle, and IIRC about .4 volts at heavy throttle
-IAC counts may be out of range as well- I'm still learning this stuff
-Temp seems fine, at 194deg at speed and 199 at idle (ambient temp was about 75)
-Vacuum is ranging from about 19 at idle, to an indicated -6 on heavy throttle. I believe I saw somewhere that a negative indication before the integer actually indicates positive pressure.
-I messed around under the hood looking for a vacuum leak, finding none. I did find the vacuum reservoir had a hose that had dropped onto a manifold and melted in two. Can not find where that is supposed to go, however. I haven't found any vacuum hoses "adrift" in the engine bay. Only thing that has a loose hose is the cruise control servo and the trans vent. This bears further investigation, that reservoir used to go somewhere, I need to find it. However, given that I have 19 inches of vac at idle I'm thinking it can't be much of a leak.
-While chasing down the above with engine off, I had my hands pretty much on everything. Afterwards, I cranked and it was idling at about 800RPM. I applied the throttle and let go, and idle would not go below 1100. I almost wonder if this is indicative of a throttle cable with too much stiction- it's 30 years old, maybe it just needs to be replaced like the TV cable on the trans was?
-I pulled codes. 22, 32, 33, and 45. I see that as:
22- TPS Signal low (um, duh, knew that! :) )
32-MAP sensor signal open or EGR Error (I have the EGR vac port capped off both at the TBI and the solenoid)
33- MAP Sensor Signal error (signal high indicating low vacuum)
45- OX sensor error (rich indication)
The Injectors, fuel pressure regulator, and associated gaskets are brand new. The O2 sensor is brand new. The TPS is likely near 30 years old. The MAP sensor is not known to fail, typically.
Being that the TPS is most suspect and demonstrably bad, I plan on replacing it first. The other problems may be cascading false positives from that (and the fact the EGR is capped off)
I have a log file, will attach it to this thread for inspection.
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