Rough Idle, Engine cuts off
 

Hey CL, I drive a 92 Sc300 with a 2jz-ge. Also, it has about 106k miles. I bought the car about a month ago and the car seemed to be running great.

Now about a week ago, I was on my way home and after about 5-10 minutes of the car running I felt it tugging a bit so I pulled into a gas station. As I was pulling into the parking spot the car shut off and the check engine light came on. I started it back and it was idling really roughly. I revved the car to about 5000 rpm and it was fine for a few moments until it cut off again. Quickly I realized that the car only shuts off if it's idling. So I drove the car home because my house was only about 1.5 miles away. Everytime I stopped at a light the rpm would drop. It wasn't long til I realized that the car would only shut off or idle strangely when the engine was completely warmed up. However, when I diagnosed the check engine light the code that it gave me was 24 (maf sensor). I got a new maf sensor from a friend with a perfectly good SC and the car continued to give the same problem.

The only other solution we could think of was that the car had a vacuum leak. After changing around 10 feet of vacuum hose, a broken pcv valve and grommet, a broken vacuum switching valve, and a broken egr vacuum modulator the car still gave the problem. Then we tried spraying brake cleaner on some of the engines components to see if we could find any other leaks, but, we found none.

Anyway, the next thing we thought of that could be causing the problem was the ecu. So I got hold of another ecu out of a 92 and tested it out in my car. At first the car sounded like it wanted to cut off but it was struggling to stay on. Never the less it continued to shut off. So I asked a friend with a 93 Sc to see if my computer would run in his car. After hooking up my Ecu in his car and letting it run for 15 minutes (it would usually cut off in my car after about 6 minutes) , the car was still running fine. So I concluded that it wasn't the ecu.

A few other things I've tried include cleaning my idle air sensor and changing my throttle positioning sensor. None of those seemed to work. Since the car only seems to shut off after it warms up I'm now considering that it could be the fuel pump or the spark plugs. But if anyone has had a similar issue or may have a solution, I'm open to suggestions!

Try doing the 12v mod for the fuel pump. Pull the panel behind the drivers seat by pulling the lower and upper back seat. There's a little box there. Take the plug and look for iirc A black/red striped wire and a green/red striped wire. Clip these two from the plug, solder together and heat shrink, or use a quality crimp and heat shrink.

Give that a go.

Are you still getting code 24? Try swapping the maf sensor again and reset the ecu.

I just gave that a try and it seemed to work at first. But after I revved it, the engine hesitated and shut off. I tried it a couple more times and it continued shutting off. Do you think it could be the regulator?

Yea, I'm still getting the code 24, and so far I have tried 3 other different maf sensors off of SC's that run perfectly well. I forgot to mention that after every modification/replacement/fix, I reset the ecu for it to re-calibrate and nothing seems to work.

Check the maf connector and make sure the pins are secure inside it.

Make sure you also get continuity from the sensor plug to the ecu.

I checked all the pins, they are good. I also tested the power wires and they are also good. I think it might be a fuel problem considering the black smoke coming out the exhaust. It's not thick smoke but it's enough to notice. The smell has gotten stronger too. This is getting really annoying :/