Cleaning the Throttle Body?

[jwbouch]

This is in reference to my 2004 Grand Prix with the 3800 series III. This issue with stalling on start up seems to be pretty typical of the vehicle.

I've been reading anything I can find on my Grand Prix starting issues, and I have read many other people who have had this issue and they say to clean the throttle body, because of the sensitivity to build up by the "drive by wire" throttle system. Anyone ever hear of this, or have any good ideas on how to go about cleaning the throttle body? I haven't had the time to check into anything else yet, such as testing the pressure in the fuel system, because I don't have a tool to do that with. Plus, I don't know nearly as much as I would like to! I am going to try to figure this problem out this week/weekend, because it is getting annoying! Thanks for the input.

[fightingbee]

My method of cleaning the TB on my 2.2L Saturn once was to have an assistant floor the gas pedal with the key on, engine off, opening the throttle plate all the way. I then just wiped it all down with some spray TB cleaner and a clean shop rag.

[jwbouch]

My method of cleaning the TB on my 2.2L Saturn once was to have an assistant floor the gas pedal with the key on, engine off, opening the throttle plate all the way. I then just wiped it all down with some spray TB cleaner and a clean shop rag.

Thanks for the advice! This is my project for tomorrow. With a throttle by wire system, would someone actually have to hold the gas pedal down? Or would it not really matter, since it isn't a mechanical system? I generally make my brother help me work on my car, but he lives in Ohio, and I"m in Jersey. He is the mechanically inclined one in the family!

[SAmadei]

I haven't had issues with the TB on the 2004 Grand Prix, but its supercharged.

On my '99 Bonne, I did have issues, to the point where the the butterfly would get sticky. I cleaned it from the outside, but it got sticky again. I took the TB off, and it turned out the goo was on the inside, from the PVC. At that point, I totally cleaned it with TB spray and it was fine up to the point that I redid my upper intake and at that point I put a hogged out TB on the car.

As for the starting problem, are you getting any codes?

[PurdueGuy]

On many cars it's a piece of cake to remove the throttlebody completely and clean it thoroughly, giving you much longer intervals between cleanings. It can also help things like idle air control valves not get gummed up (again, depending on the throttlebody design.)

[jwbouch]

I haven't had issues with the TB on the 2004 Grand Prix, but its supercharged.

On my '99 Bonne, I did have issues, to the point where the the butterfly would get sticky. I cleaned it from the outside, but it got sticky again. I took the TB off, and it turned out the goo was on the inside, from the PVC. At that point, I totally cleaned it with TB spray and it was fine up to the point that I redid my upper intake and at that point I put a hogged out TB on the car.

As for the starting problem, are you getting any codes?

I have no indicator lights on on the dash board. I would assume this means no codes were thrown?

[PurdueGuy]

I have no indicator lights on on the dash board. I would assume this means no codes were thrown?

As long as you don't have any bulbs out, no dash "check engine" or other "service" lights = no codes.

[jwbouch]

Well, that job wasn't very difficult at all. Now I just have to see if that solves the problem. I have my fingers crossed!

[trinacriabob]

Just now, trinacriabob said:

Is there a way to view the other side of the throttle body from the air cleaner assembly that leads into it?  It is in the closed position.  I teethed on carburetors and you could very easily move the "butterflies."  What you do here to get the valve to open without pulling that area apart to look at the other side?  On my last car, it did not require service.  I put in fuel injector / fuel system cleaner per the recommended frequencies on the bottle and also changed the air cleaner more often than I should.  I'm guessing that drive-by-wire changes the game when compared to the same engine as it was built in the '90s.

There are some interesting YouTubes on TB cleaning ... and also specific to GM vehicles.

 

Edited September 24, 2018 by trinacriabob

[Drew Dowdell]

Seafoam

[trinacriabob]

3 hours ago, Drew Dowdell said:

Seafoam

The branded fuel system cleaner via the gas tank or one of their products for the TB and aimed right at it?

[Drew Dowdell]

Depends on how bad and where the gunk is. Honestly just running top tier fuel for a few tanks would probably be enough.

[G. David Felt]

You can buy CRC or Gumout throttle body cleaner and then with the engine off, manually open full wide the butterfly, spray everything and you will see the carbon wash away and then start the auto and let it get blown out. It will run rough but then should smooth out. You can also as Drew stated run top tier gas or get one of the many cleaners you add to the tank and then fill up.

On my daughters 1999 Durango with 5.9L V8 I used Gumout and sprayed heavily to clean the throttle body and intake. started it and let it run to smooth and then while running finished using the can into the throttle body and let it naturally just clean everything out. I then did an oil change as the carbon also gets trapped in the oil but it was time for one. 

Over all that plus the other normal 30,000 mile tune up stuff and the Durango pures like a kitten.

Good Luck,

[trinacriabob]

I was doing more reading on cleaning the throttle body.  With my last car, I never had it done and it went over a quarter of a million miles. 

Here's what I learned.  The contaminants in the oil can travel upward and cause the soot in the throttle body.  My oil has always gotten changed while it is still a bright enough gold color.  I never let it get dirty.  To that, I add the Techron every 5,000 miles.  On the other end, as physically laid out, I change the air filter every 10,000 miles.  I'm guessing that's why I haven't noticed changes in drivability on my current and last car.  They say that your throttle body will tell you it may not be operating correctly through a "check engine" light that's tied to it or something near it (the MAF sensor), by engine hesitation, by poor mileage, or by a rougher than usual idle. 

I sure would like to know how the oil and/or the combustion process release by products upward so they would gunk up your throttle body flap.