04 5.3 intermediate miss and stumble at low rpm

redneckgames · September 13, 2020

Our 04 suburban just recently developed a miss and stumble that is stumping me. 5.3 flex fuel. At about 1800 rpm you can fill a slight miss. Just a bit of a hesitation is all and it is not constant. But sometimes it will start a bad stutter to where it feels like the motor has dropped 2 or more cylinders. It will last a couple of seconds. Most of the time it will recover if you let off or give it more pedal.
yesterday it done it with my wife to the point it killed the motor. But she was able to start it right back and it drove fine. My dad drove it yesterday while I was watching live data in my cheaper scan tool to see if anything obvious showed up. But I couldn’t tell. In 30 minutes of driving it only done the stutter once but he said he could fill a miss at other times.
only engine code that is showing is the knock sensor bank 2. It has came and gone for a couple of months. I bought the stuff for it but haven’t took time to put them in. From what I have read it shouldn’t cause the problem I’m having.

Any ideas? If these were cable driven I would suspect a problem spot in the tps. I guess that could still be the problem. Is there an easy way to test the drive by wire throttle body?

Any other suggestions?

Edited September 13, 2020 by redneckgames

redneckgames · September 13, 2020

And Now it is dead and won’t fire up. Any suggestions on where to start would be nice.

CamGTP · September 14, 2020

Do you still have spark??

If not it could be the crank sensor.

redneckgames · September 14, 2020

Not certain yet. It’s sitting at my dads garage right now. Crank sensor was on my list to check.

figured might want to double check fuel pressure first since it is easy. Then crank sensor then throttle body. Was thinking that maybe tps failed that’s why the 1800 rpm original issue.

If you try to start it now it shakes and stumbles like the motor doesn’t know where it is. So maybe crank sensor is the culprit....

redneckgames · September 15, 2020

Crank sensor fixed it

redneckgames · September 16, 2020

Well it half fixed it

fired up and drives now. But still has a stumble and no codes. Going to go ahead and put a cam sensor in it and do knock sensors at the same time.

redneckgames · September 21, 2020

Well knock sensor and cam sensor wasn’t too bad of a job. It sure needed the knock sensors and I’m sure cam sensor is a lot easier with intake off

still has the miss. Maybe it’s just a coil going bad. Only does it after it warms up and under load.

CamGTP · September 21, 2020

A live data scan tool will be needed to monitor all cylinders, this way you can track where the misfire is.

redneckgames · September 21, 2020

Well.....

shut off again. I was behind it this time. My wife was driving. Looked like exhaust went rich. Guess I’ll try throttle body next. Thinking that first time we thought it was fixed was only because we unhooked the battery to put crank sensor in. Maybe that causes the tps to reset. So what we thought was crank sensor was really just the computer resetting.

oh well. We will see