Acceleration problem.

[Badge68]

I have been having issues with my 1999 Pontiac Grand Am where I go to accelerate, and the car feels like it’s bogging down, the rpms don’t shoot up. It takes a few seconds for it to actually get going. It has been a recurring issue and has started to become more frequent. It even happens when I enter onto the freeway, it’ll seem to bog down a little bit. Shift sensor was changed recently. Don’t have any service lights popping up in the dash. Any recommendations would be greatly appreciated. Thank you. 

[Last Indian]

1 hour ago, Badge68 said:

I have been having issues with my 1999 Pontiac Grand Am where I go to accelerate, and the car feels like it’s bogging down, the rpms don’t shoot up. It takes a few seconds for it to actually get going. It has been a recurring issue and has started to become more frequent. It even happens when I enter onto the freeway, it’ll seem to bog down a little bit. Shift sensor was changed recently. Don’t have any service lights popping up in the dash. Any recommendations would be greatly appreciated. Thank you. 

Most likely you need to clean both the IAC & the MAF sensors, but in the case of the IAC you need to clean the bore that it goes into as well. Also you should, since you’re already there, clean the bore of the throttle body & throttle plate.

[Badge68]

Would you recommend a spray or any other alternative to clean it out and flush anything out? There’s also a oil residue left in the throttle body as well. Haven’t been able to pin point where that’s coming from. 

[Last Indian]

50 minutes ago, Badge68 said:

Would you recommend a spray or any other alternative to clean it out and flush anything out? There’s also a oil residue left in the throttle body as well. Haven’t been able to pin point where that’s coming from. 

Get yourself a spray can of Gumout! Take the IAC out, disconnect it from the wire harness. Depending on how Carboned up the plunger is, either put it in a container and spray enough Gumout in the container to let it soak then using a small soft bristled brush, gently clean it or spray the Gumout on to a rag and clean the plunger that way. Next take a rag and spray the Gumout on the rag using a finger that fits the bore of the IAC bore, clean the bore of the built up carbon. You can also spray Gumout into the hole. Likewise take the MAF sensor out and spray it down while using a small soft bristled brush to clean it. 

Next opening the throttle plate, take a Gumout soaked rag and clean the bore of the throttle body as well as the throttle plate and it’s edges.

Note: you should wear nitrile groves and eye protection!

The oily residue is just that! This is from intake valves being open. Whenever you shut the engine off there are some intake valves opened In varying volume. Since the engine is hot the unburnt residual mixture of gas/ oil that are vaporized roll back into the plenum. This vapor deposits on plenum walls/floor etc. this is what creates the carbon deposits. When the throttle body & plate get carboned up to much a portion of that vapor makes it past the throttle plate and deposits in the boot! It doesn’t turn to the carbon deposit in the boot because the temperatures in the boot are to cool to crack the back of the molecules to create a carbon chain, but they do in the plenum and throttle body. 

You should use a good pea fuel injector cleaner at least every 2 or 3 tank fulls.

Edited February 20, 2019 by Last Indian

[Badge68]

So I cleaned off the throttle body and attaching parts. I just replaced the spark plugs and it’s still having the same issue. The idle control valve still had some carbon built up on it. The car still feels like it bogs down when I go to accelerate, and the rpms don’t go above 2000 when I do try to accelerate.