I am very tired of my car giving me the same problem. After it runs for about 30 min or so, all of a sudden it starts tu run like crap. I have tried many options:New distributor,changed the ignition module twice,O2 sensor also new,ignition coil,cap and rotor. And it still gives me the same problem. Sometimes if gives me a code for the O2 sensor,and it also gave a code for the EST, so I changed it twice. Still the same. Would somebody guide me in the right direction. Any input is greatly appreciated.

 

possible ECM issue

have u traced all your wires also?

very intresting though, im defintely subscribing to this thread. good luck with it though

 

Is it TPI? Have you put a gauge on the fuel pressure 30 minutes in?

 

I have not traced wires, Not sure what to look for. And I have a brand new Walbro pump in it. I have checked the fuel pressure with a gauge and I get around 37 to 39 PSI, but I have not checked the pressure when it starts to run bad. It usually happens when I get home from work and is around Midnight, so at that point I dont want to mess with it. But now is making me think, so I will have to put the gauge to the rail. It is a TPI with a MAP sensor.

 

How can I know if the ECM is going or gone bad, if is not giving me any codes for it????

 

You can get a used one for $20-40 on ebay, may be worth a shot. Does it feel like it's building up an unusual amount of heat? Is the fuel pump heating up from use? Try topping off your tank- the gas will cool the pump.

 

Well, I have tried topping the fuel tank, but it did not make a difference. I will try the ECM in the morning. Also Ill try a new set of wire while Im at it.

 

I changed the spark plug wires, and still no change. I have not had a chance to swap ECMs. I will try it . But before it will take about 30 to 40 minutes for the car to run like crap, now it takes about 10 minutes before it runs bad. It still keeps giving me a O2 sensor code. Im ready to shoot that damn sensor

 

do you have voltage to the O2 sensor?

 

I'd start with that fuel pressure first. Which code are you getting for the O2?

 

The code for the O2 sensor is 13. As far as voltage, I have not checked the voltage on it. I ll assume to check the connector and to a ground with a multimeter. Like I mentioned before, It ll take about 30 to 40 minutes to fail, now it only takes about 10 minutes to start running bad.

 

the ECM doesnt read the O2 sensor signals until the car enters closed loop (when the car is warmed up)...which could be the reason why its running bad a certain time after startup. does the car smell like its running lean or rich? what exactly do you mean by "running bad"?

 

I would say the car is running rich. After I get off the car, I can smell gas. By running bad, I mean the engine runs rough, like the timing is off. I have check the timing with the ECM connector off, and the timins is @ 6 deg. I have an old scan tool, and it reads the car being on open loop all the time, even after the car has reached operating temperature. I turned the car on this afternoon to come to work, and it only took a minute for the car to run rough at any speed, I hooked up the scanner and it gave the code 13 and 43 for the EST. With work and school, I had not had a chance to try a different ECM,I dont have to work tomorrow, so I have to do it tonite or tomorrow. Do you guys think it could be a wiring problem or an ECM problem?. I appreciate your help. THanks

 

Does your car have a knock sensor? IIRC Code 43 can be triggered by the knock counts being too high. Try unplugging the sensor and see if the problem goes away.

Check this thread out - sounds like a similar problem to yours.
https://www.thirdgen.org/forums/tech...t=knock+sensor

 

My car does have a knock sensor. I ll disconnect it and see what happens. And thanks for the thread.

 

Well today finally I had the time to work on the car. First I swapped the ECM with a different one, disconnected the knock sensor, checked the fuel pressure. Did all this and still no difference was noted. I appreciate all your help, maybe some one had the same problem and can BAIL ME OUT!

 

I think I got the key to your problem, i would check, see if your car is going into Closed Loop beings the o2 sensor is getting a code, i believe your car maybe be staying in open loop, which it would make your car run like crap after you car is running hot. the ECM wouldnt know your car is warm because it is staying in open loop. This seem to be your problem to me. Btw did you clear the code after putting in the new o2 sensor? The o2 sensor will effect the way your car runs if it is staying open loop... Hope this solves your problem...

 

THanks for the info, I will reset the ECM ans see what happens.