Wierdest issue. Experts please give some input. (Super Rich, then not)

[OBEEWON]

Drove to work friday, car drove fine. Parked it, worked, came back 9 hours later and start it. Its running super rich, black smoke rough idle, wideband reading off chart rich. Like so rich if I move it it floods out and I have to unplug the injectors to restart. So I think its a boost leak. I checked the couplers and all vac lines. Nothing. Get fed up and leave it in the parking lot till Saturday night.

I go back Saturday night to check the intercooler piping for leaks. But first I start it to try and limp it to some light. Hmm its running fine. Wha?? I didnt do anything. It fixed itself. Why? without my permission. I have my theory on this but I would like to hear expert opinions or first to second hand expirience.

Oh yeah this happened twice before that I can recall. First time was at a drift event, ran rich for like 30-40 sec. then went back to normal. The second time I had went to the UK for a month and came back and it was doing the same. I took apart my intercooler and checked for leaks, didnt find any, put it back and it was fine.

[SleepR 240sx]

Weird...possible that your MAF is reading way more air than is coming in and the fuel system is compensating. Why it would do it randomly I'm not sure. Maybe try cleaning your MAF and see if it helps. What it really really sounds like though is a big vacuum leak. If you don't have one go to autozone and you can rent a vacuum gauge, see if it's where it should be. More info on your motor would be of use. Hope I helped.

[Tenchuu]

ethanol gas? that shit is in 1/2 the gas stations around me and it fucks with my car unmerciful.

[Sileighty_85]

Check your wiring somthing rubbing & shorting out, look at the harness that wraps around the #4 injector

[OBEEWON]

Im 99% sure its not: MAFS, injectors etc. I cant reproduce the problem. I suspected the ECT and unplugged it while the car was running and it didnt change much, but if I turn the car off with it unplugged the engine floods. Can the ECT cause the car to run super de duper rich like hotpipe of the turbo rich?

[Chrischeezer]

was it misfiring?
pull the plugs... read em..

[lok]

check the ecu for codes.

the ecu might have gone bad also.

i once drove from oklahoma to texas for a drift event trouble free and then pull up the line for the event and the car started running real rich and missing bad.

switched out mafs with a few people and tried the normal stuff then switched ecu and everything was fine. plugged mine back in and then it worked for the rest of the day and started messing up on the way back.

had to keep unplugging it and plugging it back in the whole way home.

opened it up and there were a few bad spots on the ecu.

bought another one and have been trouble free for a few years.

[OBEEWON]

It supposedly is a new ECU, but not sure. A shop fried my last one tuning. In order to try a new one I would have to transfer my ROM.

So ECT wouldnt cause super de duper richness? I have 850cc's so I was thinking if it was the ecu it wouldnt even run??

How can I know the ECU went bad? There isnt a code for that is there?

[steve shadows]

WHOA WHAT?

you have 850 cc injectors with a rom tune for 850 cc injectors? RIGHT?