Backfiring, sputtering, hard starting, after warmup?! HELP!

[tkrolo01]

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Ok, I've got a 93 240sx se coupe with around 100k miles. Been messing with stumbling and backfiring for a couple of months and near my wits end. In its current state, it will start and run beautifully for 10-15 minutes, until it gets warmed up. After that, its like it isn't the same car. From a stop, you have to ride the clutch a give it extra fuel or it will stumble and die. After you get going you have to continue to baby it by easy onto the gas or it stumbles and backfires, at times, violently. It seems to idle fine and run fine once you get to operating speed as long as you don't have to touch the gas. I've replaced the fuel pump, filter, alternator, cts, tps, and adjusted the timing, but nothing helps. If you try to start it before it cools down completely, it takes several extended cranks to get it to fire. I just bought a set of injectors hoping that this is my problem, but any other suggestions would be GREATLY appreciated. Thanks in advance.__________________

[InsanityInc]

Well, there's a few potential problems.

1) You said you replaced your TPS.. did you adjust it correctly after replacing it? That is, by VOLTAGE, not resistance.

2) Could have a leaking injector, or a screwy MAF.

[tkrolo01]

I actually replaced the tps prior to these problems and it was running fine. I have replaced it on two occasions (probably more than necessary) with no problems resulting from it. My belief(hope) is that the injectors are not spraying a good pattern and fuel is pooling rather than being burnt. I am getting the smell of fuel from the exhaust but normal coloration. At times, there is fluid from the exhaust.

[InsanityInc]

well, the first thing to do is make sure your TPS is in good adjustment. It's a huge part of your engine management system.

[JNM240]

Please check your coolant temp sensor. If it is bad, it will tell the ECU that the engine is cold, even after it has warmed up, dumping fuel, making you run rich, backfire, stall, and be extremely hard to start once warm.

[rsmithdrift]

Check your codes. It's easier than you'd think. lol.

If you're too lazy to do that, IMO it's the MAF for sure.

My MAF on the z had a bad connection and would run fine untill it warmed up, then it would stumble, stall, miss, not idle and worst of all, if you gave it gas when it wanted to die it would make it die quicker. (Yes all those feelings go through your head when that happens)