Sputter when stopping. Not TB, not fuel filter, not air filter, not coils...so??

[DevGau614]

Hey everyone!

My 02 trailblazer is doing the same "sputter when coming to a stop" thing. you see in the title all the things I have already recently had replaced. She's got 238k miles, second engine, rebuilt transmission, and a yanked 4wd fuse because the damn thing couldnt be figured out and I was done spending money on this problem (who knew it would be such an easy fix?).

Anyway, I noticed the car was just not acting right. When I would come to a stop, the ipms would drop anywhere from a little under 600 to almost 300. My wife states the car also sputters when she accelerates (but I've never been able to replicate the issue at acceleration). Additionally, if I turn on the AC, the rps drop and the idle gets worse. If Im at a dead stop and I turn the wheel, the rps really drop. I'd be willing to bet if I threw on the AC and cranked that wheel, I could probably make it stall completely.

Last year, I had some of the coils fail on me, and blow out my cat (or so my mechanic says). So I swapped out all 6 coils, replaced my o2 sensor, and the cat. Since then, it's just never been the same. I cleaned the TB and that seemed to make it worse (another trip to the mechanic- aparently, he says, you cannot just take it off and clean it beacuse its so electrically tuned that it ruined the internal electrical components).

So I thought to myself, "self, maybe it's just not getting enough air. You ought to clean the air filter- That's not an electrical component!" So I yanked the K&N air filter and cleaned that with the K&N Recharge kit. That was needed- but didnt fix the issue.

I have no clue what the deal! Anyone have any suggestions?

 

[Midnyteryder196]

when you took the tb off to clean it.. did you disconnect the battery? or pull pcm fuses 10&28? to reset the pcm? Contrary to what your "mechanic" says.. it is considered a part of the maintenance procedure to clean the tb at least once a year... especially using an oiled air filter. there are numerous threads on the stalling while ac on.. usually always a dirty throttle body..

Also what brand of 02 sensor did you use? for some reason these motors only like oem delco sensors. when you did coils, did you also do spark plugs? Delco 41-103 plugs are what are recommended also..

edit: I guess actually first things first.. any check engine light? if so what are the codes? that will help us to diagnose a lot more.

 

[MAY03LT]

aparently, he says, you cannot just take it off and clean it beacuse its so electrically tuned that it ruined the internal electrical components).

That is possible IF someone sprays the cleaner directly into the t-body like some of those youtards do. Spraying the cleaner on a rag/toothbrush is safe. Either that or I just got lucky hundreds of times lol.

Sorry to pick one line out of your post but midnight axed all the questions that I would have.

 

[Mounce]

Mechanic sounds incompetent towards our platform. I've taken off and cleaned my TB twice and it hasn't ruined it. Symptoms of rough idle with AC on and while turning the wheel is pretty much textbook examples of a dirty TB...if it wasn't taken off then the backside is likely CAKED in sludge. Make sure you reset the PCM as mentioned above when it gets cleaned properly.

Good luck, we'll help where we can.

 

[Sparky]

Cleaning the TB without resetting the computer can actually make it seem worse, as the computer has learned how to operate with a gummy throttle body.

 

[DevGau614]

My mechanic actually replaced my TB. Originally, I removed it myself and cleaned it thoroughly, and put it back on. As he tells it, the electrical on the Trailblazer is SUPER sensitive and while I did remove the fuses, I may not have left them out long enough. Either way, I have a new TB in there now.

No check engine light... yet.

I dont know if he replaced the plugs when he replaced the coils... but I do know I replaced the plugs a few years back.

I cant say what kind of o2 sensor was used- the mechanic did that as well.

I think a new mechanic may be needed soon. For someone who claims to be an off-site mechanic for Chevy, he sure was unable to fix my 4wd- but thats another story.

 

[Mounce]

Yeah new mechanic, pronto.

TB's aren't cheap and yours was replaced for no reason.

When trying to reset the PCM, normally anywhere around 30 minutes does it. You're supposed to start it up and let it idle a while without touching the gas, too..not sure the specifications for that.

 

[Chucky1322]

this might sound dumb but i have had this happen to me so...., these engines are notorious for leaking oil in the plug well. If your mechanic is as good as you say he is then he probably didn't drain that oil when he didn't change the plugs. This oil will get deep and into the coil. Not sure of the impact but I know mine ran like crap when I found this issue.

 

[Mark20]

You can get throttle body cleaner which is supposed to be safe for the electronics in TB's. I went that route since I didn't have any carb cleaner on hand. Others have reported using card cleaner and had no problems. Most if not all of the problems you state do sound like dirty throttle body related. You can pull the fuses or disconnect the battery (my preferred way since the negative post is quicker to find) and clean the TB. By the time you disassemble, clean and reassemble you'll eat up at least 30 minutes.