88 chevy 2500 tbi 350/5ml60
I've been chasing this issue for a little while, the truck will start and die as soon as it turns over. stays running if you give her some throttle but will die as soon as she tries to idle.sounds fine when you rev with no load. misses and runs like crap taking off. unplug the map,she runs beautifully. running rich that way but no issues and has 18 in of vacuum at the map port. if i plug in the map while running she'll die right away and it looks almost as if the injectors get cut off right before she dies . I've tested the injectors, coolant temp sensor, tps, map, iac, egr solenoid,egr and passages, o2, fuel relay, and oil pressure switch which all test out fine. fuel pump was weak so i replaced it and the filter, and rebuilt the throttle body because of a leaky regulator. replaced the distributor because of a failed coil pickup and replaced plugs and wires too.
The previous owner replaced the original motor with another and swears he didn't change the ecm out. it has the 1227747 ecm and i've not taken it out to check which prom is in it. jumping the terminals to read codes, it gives me the map codes and rich code. i've hooked up my cheap scan tool (innova 3120d) and it reads these codes:
42-EST circuit open or shorted
33-MAP voltage high
32-MAP voltage low
31-park/nuetral switch
55-ECM fault
54-fuel pump circuit fault/fuel relay
52-calibration package chip/ oil pressure sensor low voltage
43-esc circuit low voltage
descriptions are according to the scan tool. I've reset the codes and they go away jumping the terminals but the codes still read through the scan tool whether the mil is on or off.
Is there anything else i should look into before blaming the ECM/PROM?
should i check to see if the correct PROM is in?
Any thoughts and advice wouldbe great.
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