the flyin' scotsman

Not likely..........it controls the ignition system although disconnecting the batt will reset both brains.

Mrmerlin

Hi Just a thought try doing a vacuum test on your heating/AC control unit, disconnect the vacuum line that goes to the control unit pull a vacuum if it is leaking you will see it , and also plug the line that goes to the HVAC if you do find a leak.
See if that changes anything.
I just replaced all of my HVAC diaprahms, 4 of them, two of them ,the bigger ones were toast, the hardest one to replace was the outside air /inside air diaphram, Good luck, Stan

John Speake

Hi Kevin,
No, EZK will not cause this effect. If Temp sensor 2 (engine water temp sensor) goes open or short, then the LH ECU recognises this fault and defaults to the fuelling it would give at normal engine water temp. It would not cause the over richness your car has.

You have eliminated the O2 sensor. The remaining possibilites are

1) Fuel pressure too high - unlikely, unless PO changed this to compensate for a dodgy MAF. Do you know if the FPR was changed for a non standard one ?

2) LH ECU on it way out, as already suggeted. Sometimes they can aprtially fail where they "think" the WOT switch is closed, even when it isn't. This gives fuel enrichment across all settings.

LH ECU can also partially fail where it fails to recognise the throttle closed switch. Then the car won't idle properly. Also, idle control circuits are in the LH, these also fail frequently

Regards