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YOUR RESEARCHQuick Cure for a lumpy or erratic idle!
Reported or suspected cause
heat and humidity in the midwest
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Read evidence and context
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Reported cause · Original poster
Part of the issue was the heat and humidity in the midwest, but the main reason was that I put the top on was that the car was much more quieter, and the aerodynamics were better, hence better gas mileage.
Leading evidence: 'heat and humidity in the midwest' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'heat and humidity in the midwest' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Clean ...i've never seen a new one look' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
My thought would be, if there is, how would you be able to clean the TB?
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Suggestion
OE...you must drive your car indoors...that thing is so clean...I've never seen a new one look that good.
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Suggestion · Original poster
You will know when you are done because the surfaces that you are cleaning are polished, and easy to see if there is stuff left on them.
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Suggestion
Personally I would not just spray into the TB without removing it for cleaning first.
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heat and humidity in the midwest
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
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Reported fixes
Read evidence and context
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1
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Reported cause · Original poster
Part of the issue was the heat and humidity in the midwest, but the main reason was that I put the top on was that the car was much more quieter, and the aerodynamics were better, hence better gas mileage.
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25 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T003124Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
One of the problems that I see with many 996/986/997/987 owners complaining about is a lumpy or erratic idle and sometimes sluggish acceleration.
I have a quick cure for this problem. In fact, this cure will work for any car that has a throttle body.
The issue is that over time a sludgy gunk will build up in the throttle body where the throttle butterfly opens and closes. This gunk will eventually change the airflow characteristics of the gap between the butterfly and the throttlebody which will cause the erratic idle. In addition, this gunk can cause the butterfly the stick as it opens which will effect acceleration.
The car's DME will compensate for this buildup over time, but if it gets too thick, then the "Throttle Adaption" will reach its limit, and will throw a code. Many times people think that it is the MAF that is bad, when it is just a dirty throttle body.
Notice that the butterfly valve is slightly cracked open. This is for the idle airflow, and that crack can get clogged because of the gunk buildup.
The solution is to remove the air cleaner box for access to the throttle body, and simply clean the throttle body with spray carburetor cleaner.
Open the butterfly valve with your hand, and wipe out all of the gunk on the backside of the valve, and the inside of the throttle body. You will see a dark brown ring inside the throttle body. This is the buildup you want to remove.
Take a rag, wet it with carburetor cleaner, and wipe out the gunk. Be sure to get the edge and the back side of the butterfly valve as well. You will know when you are done because the surfaces that you are cleaning are polished, and easy to see if there is stuff left on them.
Here is a picture of what your throttle body should look like after it is cleaned. Notice how the inside shines.
Don't worry if you spray too much in the engine, when you fire the engine up, all of that stuff will burn off in the combustion chamber.
Where does the gunk come from? It is residue from the crankcase vent opening that is right there behind the butterfly. The reason it is there is because there is high vacuum there that will suck the crankcase oil vapors back into the combustion process of the car. Over time oil solids will accumulate there and will form a sticky lip around the opening.
This cleaning should be part of your 30,000 mile maintenance as a minimum. However if you have never had your throttle body cleaned, try doing this weekend. You will be amazed at how much better your car runs.
Thanks for the compliment but actually:
I just finished a 5200 mile road trip with the car. California to Dayton Ohio and back in 8 days. And unfortunately, I drove for 60 miles through the wildest thunderstorm I have been in for a while. Here I am about to go into the belly of the storm on I70 east 80 miles east of Denver. The car is now like a dirty dog, and will need a through going over tomorrow as this is Pebble Beach weekend.
The car rolled over 60K miles on the trip, so I did the 60K maintenance on it today. That is how I discovered how bad the throttle body was, and decided to clean it.
But despite this dirty throttle body, the car returned an average MPG of 29.4 for the trip at an average speed of 70 mph. (I think it was more like the mean!). Absolutely no problems were encountered on the trip.
By fluke I did a modified orang cap mod last night and while the air box was off I wiped the TB clean. On reassembly I felt the car ran smoother - chalked it up to the orange cap mod (although I knew this could not be true) but now I realize I probably just did the service you specified. huh!
I followed everything until the process with the "key and the ignition at the end"....do I have to do this with a 2002 Cab...to reconfigure the throttle body settings?
hmm... I remember reading somewhere that there is a coating on the inside of the TB or intake ? that carb cleaner will remove and cause other types of problems.....
No.
Just a flash of memory that I remember reading somewhere.. that there is an internal coating TB or Intake ? not sure.... that can be damaged by harsh cleaners. Intake finish is critical to combustion chamber flow.
Personally I would not just spray into the TB without removing it for cleaning first. YMMV
Great tip! thanks.
Just curious, as a Cab driver myself, I have taken a few short trips of less than a thousand miles in my car with the top down and loved the experience.
It looks like you had the top on, did the unusually hot weather out west have anything to do with that?
Agree. That's why I think the way OE suggested is best. Wet a cloth FIRST and clean instead of spraying the entire TB down with the cleaner then clean.
We cleaned the TB when we put in the RSS Plenum on my car; it was indeed dirty and my idle is now so much smoother
Tja, part of my Plenum placebo is now gone - thanks!
Part of the issue was the heat and humidity in the midwest, but the main reason was that I put the top on was that the car was much more quieter, and the aerodynamics were better, hence better gas mileage.
Rachel (Area 51) NV at the Lil Alien Inn
Greetings. I'm just about to clean the throttle body of my 06 Carrera S, 997 3.8! A technician told me the butterfly cannot be opened by hand (will damage it), only electronically with the key and accelerator pedal. In the primary explanation, above, we're advised to do it by hand. Which method is correct? Or, is the 997 different from the 996 TB?
Thanks!
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