Runs great until warm, then acts like its possessed!!!

[tkrolo01]

My 93 240sx has somewhere around 100k on it.

I have had issues in the past with response and running rich, but most have been fairly easy issues to fix, until now.

My car has been having a hard time starting lately; cranking longer than normal, not always idling after the first start. After the start, it seems to run alright until it warms up, then the "ghost" shows itself. Too much gas, and the car won't rev past 3500-4000rpms, with an internal backfire here and there. It will rev past 4000 if I massage the throttle slowly. It will stumble, cough, backfire, and die accelerating from a stop unless I give it a lot of gas before releasing the clutch. Trying to start the car while it is still warm has also become a problem - crank, crank, crank, and nothing. The last time it died, I had to crank it three times for 10 seconds each time, and then hold the pedal down to keep it from dying.

I've checked maf, timing, fuel pump, everything I can think of. The only code I'm getting is for the o2 sensor which I've changed twice and am sure that it is ok. Also, the car runs like new at times, with great response all rpms, but only when cold, and that becoming less and less frequent.

Read a post on another board with similar problems that the ecu was the problem, but I wanted a trained opinion before I drop a couple hundred on an ecu and the problem remain.

Thanks in advance.travis

[tkrolo01]

anybody?

[EstoMax]

coolant temp sensor stuck closed ? is it overheating a bit maybe or tryin to overheat?

i would replace the coolant temp sensor tho

max

[navysnail]

dont replace the ecu, as that is probobly not the problem. first check your CTS (search will turn up the values of it, ive mentioned them before) and also your injectors, see if the system holds pressure after you turn off the pump.

[tkrolo01]

I understand those could contribute to the problems, but what doesn't make sense is that after initial startup (after being off several hours) it runs fine at all rpms.

But twenty minutes later, it is backfiring internally, cutting out at all speeds, and dies during takeoff unless you ride the clutch.

It doesn't try to overheat at all, stays below half way point on gauge.

I will try out your suggestion, but am not very optimistic.

[tkrolo01]

Replaced cts yesterday, still has same problems. The problems are diminished somewhat, but still remain.

ARGGHH

[NISTECH]

take a look at your distributor cap. if its made in italy chuck it and get a nissan cap. your problem sounds very charicteristic of that. you also mentioned your getting an o2 code evan after replacing it??? if your ecm is seeing a constant 0.00volts from the sensor it may be trying to compensate but the no start wouldnt be as a result of the o2 as it doesnt look at that for at least 1 min after startup

[s13sr20chris]

I understand those could contribute to the problems, but what doesn't make sense is that after initial startup (after being off several hours) it runs fine at all rpms.

But twenty minutes later, it is backfiring internally, cutting out at all speeds, and dies during takeoff unless you ride the clutch.

It doesn't try to overheat at all, stays below half way point on gauge.

I will try out your suggestion, but am not very optimistic.

you would be suprised how many components only fail when hot. try getting her to act up and then dumping water on the suspect component(carefull not to short anything). if she perks up you found your prob. yes i am a dealer tech and i do very ghetto stuff like that in order to cut my diag time.

[NISTECH]

damit chris your giving away the tricks of the trade!!!!

[s13sr20chris]

oops, i swear i do a complete 1.0 flat rate basic inspection/diag/engine overhaul before i break out the ghetto trick shortcuts.