ignition problems

[tkrolo]

I have a 93 240sx SE coupe with approximately 100k. It is throwing codes 21, 33, and 43.

For the past few months, I have noticed hesitation, surging, and very poor mileage. Performance wise, at times it would run like a champ (mostly on damp cool mornings) and others very sluggish.

The problem initially felt as if you were lightly applying the brake when coasting. It would also have a slight hesitation during all acceleration.

I took it to a Nissan mechanic and was told he could not find anything except that the wires were bleeding through.

I put the new wires and coil on the car the next week, and it ran beautifully for 3 or 4 days. When I began to feel the engine hesitating again, I decided to try to adjust the tps and the timing. While loosening the tps bolts, one of them broke off at the threads. I went ahead and screwed the remaining bolt in thinking it would be ok. While taking it out for the test drive following my tinkering, the car began to miss badly. Periodically, it would simply stall out as if it was flooded and then take off once the excess fuel was burnt off. After returning and pulling codes again, the tps popped up.

Realizing that I may have put the potentiometer in a bind by attaching it with only one screw, I bought another tps. Put it in Saturday night. SAME PROBLEM!!!! At times it sounds like a volkswagon during acceleration.

I have an oxygen sensor on order along with a new ignition module hoping that I may remove any other problem that could multiply. I have noticed that most of the error falls between 2000 and 3800 rpms. It also has a smell of fuel at the times in question and at shutoff. I did check the egr and it seems to be operating correctly. Another note; when I replaced the tps and tried to adjust the idle, I couldn't get the car to idle with the intake removed at all. Before it would idle but wouldn't rev past 2000. I plan to check the voltage on several sensors tonight and tomorrow in hopes of finding some clues. Sorry for the long post. Any help will be greatly appreciated.

[NISTECH]

start by checking your air flow meter and its imediate harness. it could be droping out.

[tkrolo]

I have wondered about the mafs operating correctly as well but I have it very securely connected.

[NISTECH]

do you know what the codes are? if not they are listed on 240sx.org . i am going from memory here so not sure if its 100% accurate . code 21 is tac to the ecm 33 o2 and 43 tps. you should break out a volt meter and check this stuff especially for the tac signal to the ecm

[tkrolo]

I'm not familiar with tac, but 21 is ignition circuit, 33 is O2, and 43 is the tps. After another few hours of tinkering, I've eliminated the tps from the equation. I also removed the AIV just as a preventative.

Based on my limited experience, I have to lean toward the mafs based on the rpms in which I notice the biggest problem. Coupled with the O2 sensor, I am guessing that could cause a majority of my symptoms.

Thanks for the help so far.

[tkrolo]

Ok, I'm a moron. After working on my car for at least a couple hours every night for a couple weeks, I've found what appears to be the source of my problem. Or at least a large contributor.

I bought some seafoam tonight to put in through the iacv, throttle body, and injectors. When I unhooked the fuel filter, the hoses were being particularly stubborn. I reached down to pull on the hose attached to the fuel line, gave it a tug, and...THE DAMN FUEL HOSE WAS DETERIORATING ON THE BOTTOM SIDE!!!!!

I assumed the smell of fuel at shutdown and at stoplights was the engine not burning the fuel because of an overly rich mixture. But apparently, it was leaking.

Replaced the hose, went for a test drive, and... YEE HAW!!!!

The only thing that needs done now is to perfect the timing and she should be better than new...

Thanks for the help.