New to VE engines and servicing. Had gradually increasing engine stumbling issue when accelerating/under strain. Now, even the slightest strain causes it to stumble...like it's running out of gas almost. Does better in higher rpms, doing worse in high gear, lower rpms going down highway...especially under strain like starting and going up a hill or trying to accelerate.

I have tested front 3 injectors, all 6 coil packs, MAF, temp sensor, Fuel pressure, and fuel pump. All tested fine. The Power transistor tested bad based on Chilton, but I swapped in another one I had and it tested the same and made NO difference. I checked ECU, but Chilton doesn't tell how on a VE. I used the method for checking VG ecu, but it didn't produce the Check Phases like the VG. The best I seemed to get from the ecu (again based on VG codes) was 55 which is no malfunction and 34 which is knock sensor. Would the knock sensor contribute to this problem of loss of power/stumbling? Any help appreciated. I even one at a time unplugged the coil packs and the problem got worse after each one. Help!

 

Check your private messages.

 

I am going to call a bad coil or two on this one...I had the same experience from my ve a few weeks ago...It would run fine sitting in the driveway,but misfire going down the road...It wasn't a complete misfire either,kinda half misfiring if you know what i mean...ended up being a bad coil. Are any of your coils cracked??

I could come down there and give you a hand if you want...I am only about a hour away...

 

You could jumper the knock sensor easily with a 470K ohm 1/4 watt resistor, and road test to find out. How many miles on the engine? Is this an auto transmission vehicle? If auto did you run the transmission diags? If you rev the engine in nuetral (no load) is there a stumble?

 

It sounds to me like a bad coil pack or two.

The coils will test out fine and still be bad. That's because you aren't testing them under load.

When you put a load on them (accelerating) they fail. Actually, it only takes one bad one to cause this to occur.

I had a bad coil pack and that's exactly what happened to me. I bought a set of used ones from a wrecked car that was running fine. I just replaced one at a time, then jumped on the freeway and accelerated hard on the on ramp until I found out which one was faulty. It turned out to be the passenger side rear one.

There might be other possibilities, but this is most likely. When I was trying to figure out my problem, I read in a few places where a bad cam position sensor would cause similar symptoms. That was not the case in mine, however.

 

Check the ECU dash fuse

 

How would a blown ecu fuse cause a misfire???

If the fuse is bad,the car just wouldn't start....

 

Not so....not only will it start, but it will run.

The car runs in a "default" mode, very sluggish, better at high RPM, VTC's clack loudly, despite grounding, bad idle, tendancy to stall.....

http://forums.maxima.org/showthread.php?t=441419
http://forums.maxima.org/showthread.php?t=441635


It may not be the problem HERE, but what he is experiencing sounds just like symptoms I was having.

 

Hmmph? I just went out and tried this and it wouldn't hardy idle[about200rpm] and all the dash warning lights[airbag,batt,etc] stayed on,even when revved up...But it ran..

Thanks for the ecu 101..

 

I concur with the guys saying coil packs. Mine did exactly the same thing and it was coil packs. Just like you took your foot off the gas, right?

 

Coil packs especially if its a stick

 

It is a stick. You can hear/feel it stumble in neutral when given throttle. May be more than one. I checked them and observed no crack in any of them. Will inspect more closely. It truly just feels like it's running out of gas...or drowning if that idea helps.

MyGreenMax: Where can you meet? Sunday is really good for me as I'm going to Rainbow and Ramps Festival this Saturday at Cherokee Fair Grounds out of state. But you tell me what your schedule is like as you are helping ME out! I would love some aid in diagnosing or allowing me to swap out your coil packs to check. I can pick some up locally if that's the problem or get off a fellow orger.

Pervis: Thanks for the help! Got the message. Great man! Great man!

 

Inspecting coil packs won't help you. It's the crap inside that goes out. Mine had a bad rear coil pack that looked brand new.

It could still be something else. These cars are so damn finicky.

 

You gots pm.