So I took in my car to have some suspension work done along with the front brakes and an oil change.

I pick up the car and notice rough acceleration in any gear including park. I was wondering if they may have loosened a mount but the mechanic said no. I'm taking it in for them to go over it and make sure nothing is wrong.


My dad says it could be the spark plugs. Car has original spark plugs and it has over 92,000 miles.

Any ideas where to look?

First thing I would so is check plugs AND wires.

Look for any vacuum hoses around the oil fill or oil filter. They could have been damaged or loosened, causing poor performance. Check your brake booster, too. It has a large vacuum hose.

So I took in my car to have some suspension work done along with the front brakes and an oil change.

I pick up the car and notice rough acceleration in any gear including park. I was wondering if they may have loosened a mount but the mechanic said no. I'm taking it in for them to go over it and make sure nothing is wrong.

If it wasn't doing it when you took it in, it's probably safe to assume that something bad happened at the shop. In case the shop is unwilling/unable to remedy the situation, "rough acceleration" isn't much to go on. Sometimes the motor runs a little rough after the battery is disconnected until the PCM adapts.

What was the nature of the "suspension work" and care to elaborate on the symptoms? Are there any warning lights on the instrument cluster while the engine is running?

The suspension work done was they replaced the front struts and rear shocks. Also replaced the passanger side ball joint and control arm, along with the replacement of the front brake pads and an oil change.

There's no indication of a problem in the cluster. I did notice that the exhaust smells a odd. I had my dad take a smell and he says that's what it smells like when the engine isn't burning all the gas.

I noticed that the PCV valve was dirty so I replaced that along with the grommet.

It sounds like there's unburned fuel getting dumped out the exhaust, but the CEL isn't lit? Do what Silver LTZ (http://www.chevymalibuforum.com/forums/member.php?u=3430) and DrivenDaily (http://www.chevymalibuforum.com/forums/member.php?u=4189) suggested but, after that, you run the risk of damaging something expensive while guessing and throwing parts at the problem.. The thing is, the powertrain electronics got really sophisticated starting with 2004. If you don't have access to a decent OBD scanner, I'd recommend taking it to a shop (this particular shop probably can't be trusted).

I went to Autozone and asked them to check for codes, but they said they wouldn't be able to tell me anything unless the CEL was lit. Is that correct?

I assume there would be codes being sent out all the time but the CEL wouldn't lit up until certain codes showed up.

I may just bite the bullet and take it to the dealer.

I don't know what they use and thus I can't really comment. However, I was referring more to being able to sanity-check various sensor inputs with a decent scanner. A simple code reader wouldn't support that.

Ah...I see.

I'll just have the dealer check it out.

So I decided to let the guys who originally did the work take a look at the car. They called back and said they found a high amount of carbon in the throttle body. From the quick research I did it sounds feasible.

Would that be a possiblity for the rough acceleration?

I'm beginning to realize that I'm not quite sure what you mean by "rough acceleration." You didn't answer but if this anomaly existed prior to them working on the vehicle, then it would be plausible. If not, you really need to get a second opinion.

By rough acceleration I mean that the engine vibrates a little too much than normal when hitting the gas.

Also read that the strange smell I was smelling could be carbon being burned up.

But they cleaned the throttle body at no charge, we'll see how it goes. They also said that there's some carbon build up on the plugs.

If problem still occurs then I'm taking it to the dealer.

I just wanted to give these guys the benefit of the doubt as my dad highly recommended them.

It seems that carbon on the throttle body was the problem. Works like a champ now!!

Congrats.:) The cynical in me finds the whole episode just a little odd, though.:( Thanks for the update.

You might try getting some electronic contact cleaner and cleaning the MAF sensor too. That might be the reason the plugs are coated in carbon because it's not detecting how much air is coming in properly so it's defaulting rich. I've had the butterfly on the throttle body coated in goop - mostly from the pcv line. I put a 1/4" inline compressor filter on that line to stop oil from going into the throttle body there.

Cleaning the throttle body is a good thing. I cleaned mine at 85,000 miles and my mileage went up.

I took the TB off the car and cleaned it with throttle body cleaner. Took about 1/2 hour to do it and reconnect everything.

What are you using for an air filter? Over-oiled K&N filters really cause the TB to get crude buildup.