Hi Guys
Have a problem where my ecu wont go into diagnostics mode with engine running. It will allow key off codes. Car idle rises slightly as if it wants to start fault code process but no led flashes.
Have recently done mpfi conversion using auto ecu. . Fault code 67 with engine off (car in gear or air con switched on) will this fault cause the car to not enter diagnostics mode?
Done the resisor trick and ecu is showing 4 volts (in park).I have had it in code mode after the conversion but wont anymore. the air con compresser is not installed and wondering if an unplugged air con wire could upset things a bit.
cheers

Yeah, that fault will prevent diag mode.

You sure the thing is in Park, maybe try setting it to neutral?

When it went into diag mode previously, did it have the compressor hooked up?

Its the ECU that turns the compressor on and off, so the dash switch (which is hopefully set to off) will trigger something in the ECU which in turn triggers the compressor. So I cant see how not having the compressor installed will cause a problem.

Although, it might be part of its internal checks to see if that wire goes to ground. Those ECU's check resistances in everything.

well its got me stuffed, ecu seeing 4 volts (Park) even tried changing resistor to show 3 volts (neutral) reset ecu for an hour, still giving code 67. Tried connecting air con compresser back up as well. Time to shell out for a manual ecu i think
any other ideas? stuffed ecu?, Im still getting a guts full of air or fuel intermittently ( maybe spark issue) after changing gears as well, coughs and jerks briefly, checked every sensor and replaced all hoses. Maybe look at the coil??

all sorted now, did the resistor trick on a 3.9 auto ecu on a recent mpfi conversion, causing lots of problems as these autos only have a PRN switch. Removed resistors and made sure the clutch neutral switch was working and now have no problems. Misread info as its the 4 litre ecu's that require the resistor trick not the 3.9's.