[Gmecm] 93 CHEVY g20 VAN

[WopOnTour]

Here's some things to check:
- First remove, clean and reinstall the main ECM/PCM ground connection.
- Replace engine oil if significantly fuel contaminated 
- General engine condition/state of tune can affect MAP sensor. Check engine vacuum vacuum at idle should be 18-22 " HG if much lower MAP sensor will assume this is load and delivers more (unnecessary) fuel. Vacuum leaks, bad TB gasket etc etc
- Check fuel pressure should be 9-13 psi while the pump is running 
- Make sure injectors are properly spraying without a lot of "slobber" by using a timing light to observe the spray pattern.
- Make sure correct injectors PN#s 
- Check O2 voltage with a scan tool, a circuit fault  may be being influencing the O2 input resulting in the PCM thinking you are lean. Confirm voltage is approx 450mV at IGN ON. Even partial continuity to ground in the O2 sensor circuit will pull that voltage lower.
- Check vapor canister purge system.Can disconnect purge line from TB temporarily to quick check.
- Check ECT (coolant temp) on scan tool for accuracy. (Showing significantly colder than actual engine temp can cause rich)
- Check for a stable RPM value on a scan tool. EMI induced interference in the IGN REF wiring between the DIST and PCM will cause erratic RPM readout and additional (unnecessary) injection pulses

HTH
WopOnTour


 
  ----- Original Message ----- 
  From: michael b 
  To: gmecm at diy-efi.org 
  Sent: Friday, December 30, 2005 11:22 AM
  Subject: [Gmecm] 93 CHEVY g20 VAN


  93 CHEVY G20 VAN 5.0L  RUNS TOO RICH, I REPLACED PLUGS, CAP,ROTOR,WIRES, O2 SENSOR,THROTLE BODY GASCKET,MAP SENSOR, I EVEN CUT THE CAT OUT TO SEE IF WAS CLOGGED ALOT OF PARTS AND HAD THE CODES CHECKED ( NO FAULT CODES FOUND) BLACK SMOKE , RUNS ROUGH, STALLS. ANY HINTS?


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