I have a little of an off miss that I can't find right now.

It usually happens most before the engine has warmed up completely, and is most noticeable during acceleration from a stop.

I can feel it best while going through second gear, and then third gear, which is where most of the accelerating occurs.

It isn't really that bad, but is a tad on the aggrevating side at times, especially when it starts on some of the hill climbs around here, there have been times when I've had to go a gear lower than usual because of it missing.

So far, I've changed the spark plugs, plug wires, distributor cap (twice, broke an ear off one), rotor button and PCV valve. It had a new fuel pump put in it back before Christmas time, with a new filter then. I just crossed 100,000 miles on it recently, so I figured the tune up stuff would help it out some, but it barely made a difference at all.

Other things I've tried are running a bottle of injector cleaner through it that came from the Chevrolet dealership. I cleaned the MAF sensor, but it really wasn't all that dirty to start with, helped some but not much.

Right now I'm at a loss, and could use a couple new ideas. Hope someone can help.

 

does you ses light come on?

 

It could be weak ignition or mixture is too lean. Using the shotgun method, the next replacement would be the ignition coil and electronic ignition. The coil's insulation could leaky.
A scan tool would be useful here, if you can get one, and an ignition scope would tell you if the ignition is failing during accelerations, but those are special test equipment.

 

No light at all. I often wish it would come on because then it would be something to point me in the right direction.


In reply to the other post, I do have a scan tool, sort of. I have a thing that plugs in to my laptop, and I can read all the same things as a scan tool from there. Shows how all the sensors are reading and such. So far I haven't noticed a lean condition on it from the O2 sensors yet. It could be something faulty with the ignition, but I wouldn't know where to start with it.

I should also mention that it isn't a constant miss, it happens at random times. In between times it will run great, could even be days.

Since it's raining here today, I was reminded to that it is worse when it rains. I've already went through all the plugs on it, thinking maybe one was getting wet, found no water in any of them, and sealed with di-electric grease when I put them back together.

That's leading me to think it's something electrical, but I'm still unclear as to what it could be. The coil may be somewhere to start.

 

I had this same problem with my Bravada when I bought it. Doing a full tune up helped a lot, but it would still feel like it would miss slightly & randomly at times. Often worse when it was wet outside. Since I have been driving it as my main vehicle for the past few months, it has gotten to the point where I can't tell if it is still happening.

I am fairly confident in saying that it is gone now. One thing that I know helped was a can of Iso-Heat every other tank full for about a month. I believe my problem was water in the gas tank.

Maybe try a can or two of Iso-Heat the next time you fill up and try to run it close to empty before filling up again with another can of Iso-Heat. Give that a whirl and see how things go.

 

I'll try it. I hadn't given much thought to it, but its easy to get condensation with this winter we've had around here.

 

does it still miss?

 

It's not as bad as it used to be, but still happens from time to time. We have been having nicer weather here lately. I was thinking maybe the warmer air temperatures have helped it out some. It still seems to do it most when it rains, or actually the day after it rains, like something has gotten damp or something.

I am wondering now if this has something to do with the fast idle problem I was having yesterday. I was thinking maybe air was getting in somewhere behind the MAF, and that was causing it somehow, but all the connections are good and tight, and the gaskets don't seem to be leaking.

I actually just got done running the scan program I have on my laptop here. It basically just does all the same operations as a scan tool would, since that's what the program is. It show's how the computer in the vehicle is reading all the sensors. It appears as thought everything is reading normal, nothing out of the ordinary, no codes or anything. Of course it is running fine so far today so that could have been expected.

I just don't know.