Engine Missing

[tomtom72]

Originally Posted by c4zr1

Here are the codes I think I got when I did the A B pin cross
Code #34: Manifold Absolute Pressure Sensor Circuit Low - High Vacuum.
Code #42: Electronic Spark Timing (EST) Circuit.
Code #44: Left Oxygen Sensor Circuit Lean.
Code #54: Fuel Pump Circuit (Low Voltage)
Here are the codes I think I got when I did the A G pin cross
1. C12 9. H72

Where do I go from here?

Hi, I thought I would try to share some thoughts.

1. the EST code could be from a PROM ( MEMCAL ) not seated fully. You swapped chips & it might be worth a look. Unless some one disconned the DIS box connector and going back on they had it upside down. That will bend a pin on the box and give a 42...ask me how I know that one!

2. MAP low volts/high vac. Take a look and see if the MAP hose has oil in it, even the MAP itself can get oil into it and if it does it will simulate high engine vacuum. Our motors pass a bit of oil vapor from the PCV system into the plenum and then it can get into the MAP hose and sensor. Also, the MAP hose can get soft and collapse under engine vacuum and give the same code.

I would, after checking the MAP & hose and the PROM seating, disconnect the battery for a minute or two to clear the codes and start her up and see what there is to be seen. Not trying to be a wise guy. It's just sometimes multiple codes throw me for a loop till I remember to start with the lowest number code. Stupid Q: do you have a FSM? FWIW, two tools that I rely upon with this car are my scanner & software pkg and my FSM. Best money I spent besides Marc's chip!

A senior member ( Jerry, our VP ) told us when you get multiple codes that don't seem to be related start with the lowest number code for the diagnostic procedure.


Tom