Throttle Body Deposits?

It's a problem in the 03 Vortec 4.2 from what I've read. I'll have to clean mine this spring weather permitting as it is a little sluggish @ 60k miles.

The tach has nothing the do with the throttle body.

they are trying to sell you a very profitable "cleaning". I seriously doubt a dirtly TB would cause that much sticking of the throttle, HIGHLY unlikely.

a sticking pedal usually is cable or pedal related. could be cruise related too I guess. That car is most likely injected with injectors at each cylinder so an injector cleaning wont do crap either.

did it only stick once? Does it do it every morning?

Eiter way unless you have money to burn I would pass on the injector cleaning at 50k. He probably tells everyone they need that service. ($commision$)

What about a stepper motor?

Oh, there is a recall on 03/04 chevy pickups with bad clusters I wonder if the Impala has a similar problem....

I'm going to guess since "stepper motor was used" in the wording that the

04 Impala 3800 throttle is fly by wire like my 03 4.2 Vortec. This would eliminate any "sticky pedal/cable" problem and pretty much isolate it to either the stepper or deposits inside the TB.

On google groups try alt.autos.gm for cars. Throttle deposits can cause a sticking throttle plate, typically when cold and the deposits are gummy. If you have the aptitude, a $4.99 can of carb cleaner and a shop towel will save you about a $124 bucks. Remove the air inlet snorkel and open the throttle plate, spray liberally the back side of the plate, and the bore, wipe with rag and done. The only hitch is if the mass airflow sensor is mounted right on the throttle body, then it would need removed. I don't know why you would notice a severe drop in mpg, that don't make sense. If the tach jumps erattically, I would agree with the cluster issue. The dealer should have a scan tool that can perform output tests which would include a gauge sweep test on the ipc. That can be one way to diagnose it, other than a shot from the hip. Gerald

Get a can of carb cleaner and do the job yourself. Also it would not hurt to put in some fuel system cleaner to get to the parts in the fuel system. My vehicle has a sensor on the pedal, there is no cable or arm going to the throttle body. The throttle body has the receiver for the pedal position. For fuel system cleaner use Techroline, as it has more of the actual chemical that cleans your fuel injection system than any other cleaner out there.

Jon NW Chicago burbs

I used to clean the throttle body on my '95 Yukon once a year. It looked like new when done using a can of spray carb cleaner. Never had any problems with that truck or engine. Can't say that about any of the newer Vortec engines...... :-( They have more power for sure, but they also have issues.

On google groups try alt.autos.gm for cars. Throttle deposits can cause a sticking throttle plate, typically when cold and the deposits are gummy. If you have the aptitude, a $4.99 can of carb cleaner and a shop towel will save you about a $124 bucks. Remove the air inlet snorkel and open the throttle plate, spray liberally the back side of the plate, and the bore, wipe with rag and done. The only hitch is if the mass airflow sensor is mounted right on the throttle body, then it would need removed. I don't know why you would notice a severe drop in mpg, that don't make sense. If the tach jumps erattically, I would agree with the cluster issue. The dealer should have a scan tool that can perform output tests which would include a gauge sweep test on the ipc. That can be one way to diagnose it, other than a shot from the hip. Gerald

Yes but.....Why would the pedal be hard to push????? I've never worked on a "fly by wire" system, doesn't that mean there isn't a cable to stick? he said the *pedal* was stuck. Heck, it coulda been the floor mat too.

He may have referring to feeling like the pedal was stuck as a lag in engine response. I've noticed this on my 03, 4.2L and that's why I took it that way. The stepper would be mounted directly on the TB (assumptiuon).

Although I haven't looked I would assume that the end of the pedal is fitted with some kind of potentiometer or an LED or HAL device to transmit the pedal motion to the ECU. It would be possible for the pedal to bind somehow but the stuck pedal issue to me is a lag in the engine when the pedal was pressed.

My 4.2L Vortec i6 had a pretty good lag in it after I replaced the battery. I think I spiked the ECU when I was reattaching the - cable and touched it to the battery pad and the alarm went off :) Naturally I jumped and the connection sparked. After that when I ran the air or defrost the compressor would kick in and kill the engine (at idle) or idle up and down until it died. The ECU wasn't adjusting the idle quick enough to make up for the additional load the compressor put on the motor. Someone lurking here chimed in with "clean the TB" but after a couple days the ECU being a "learning" ECU relearned when I had wiped out (another assumption) when I spiked it. Now it idles ok and I will clean the TB this spring when it warms up, don't have a heated garage and there looks like a lot of junk I have to remove to get to the TB. I might even price out a new stepper and slap that in just because I'm there. Also need a new serp belt at 61k it's a little squeaky.

xposted to alt.autos.gm - that will get you some more answers...

Don't drive 120MPH? :P

Service writers typically don't know very much about cars. You say "sticky throttle", they try to sell you a throttle body cleaning service. A work order is printed and handed to a mechanic who performs a throttle body cleaning service.

Will it fix the problem? Maybe. Probably not. But they still got your money.

(I can't take credit for this - read it on a post somewhere else.)

When they do that, take the work order and cross out "Perform throttle body cleaning service". Write in "Fix sticky gas pedal". When they're done, test drive the car. If the pedal is still sticky, don't pay.

They should have the expertise and equipment to diagnose those problems accurately without making you take a gamble. If course, they deserve to get paid for that.