Cold start RICH mixture

[digger]

could be a overall fuel issue that the O2 sensor is masking once it comes online (i.e. o2 only helps when warm/hot).

if everything checks out i would test another ECU as its relatively simple/cheap

how did it drive before the rebuild?

[snaponbob]

Good thoughts. Will do.

[snaponbob]

Weeeeeeellllllllllllll !!!!!!!!!!!!!!!!!!! So after looking at the data stream on my SnapOn scanner, I found that the TPS was NOT indicating Throttle Closed at idle. Addressed THAT, and presto. Just the "normal" M20 cold start rich. But, starting properly, idling properly, and so on.

[digger]

interesting that the TPS didnt show symptoms when hot/warm.....

[snaponbob]

Once it warmed up, it was still (smelling) rich. FIRST time I had to deal with this sort of thing .... and I have dealt with a few !! Anyway, I think I need to replace the TPS, because at this point I do not trust it. Certainly it needs adjustment as there seems to be an off idle hesitation. Plenty of time, so no worries.

[snaponbob]

interesting that the TPS didnt show symptoms when hot/warm.....

Probably because the computer was in closed loop and the O2 takes over.