: Some unanswered throttle body cleaning questions

03-06-05, 01:05 AM
After parsing the forums about the throttle body cleaning procedures, I am left with some questions.

1: My throttle body was extremely bad, black, and covered with a thick layer of carbon buildup, After cleaning twice, I feel that cleaning the rest of the black carbon from the whole inside of the intake manifold must be a better way to go.

I failed to disconnect the battery terminal after either cleaning, I found today that I should have done that to complete the job basically. I drove the car 3000 miles in a week to miami from TN after the 2 cleanings. It ran much better. However i feel that the TPS computer adjustment offset or whatever that was not done will now improve the gas mileage once again and lower the idle on cold start. I will reclean the throttle body again and perform the reset.

I did not clean the "fuel pressure regulator" or the "egr valve" With my engine having 103k miles I bet I should perform these easy tasks as well. My sticking gas pedal and loping engine was fixed in the original 2 cleanings which took place 2 weeks apart to prepare for that taxing trip. I just know that I could have and need to do more.

The spark plugs are new Autolite double platinum * the right ones, *the Bosh plats performed horribly. The wires are new Belden and the air filter is new.

So what of the extremely dirty inside of the intake manifold past the throttle body internally?

I had a MotorVac service performed by some trusted honda specialists previously and so when I later saw the incredibally dirty throttle body and intake I was of course stunned.

03-06-05, 10:14 AM
Cleaning of the throttle body is actually relatively easy if you have the right tools. First you disassemble the air intake and remove it from the throttle body. You will want a quality throttle body cleaner. I recomend 3M throttle body cleaner because you spray the can upside down and it removes really good without being too harsh. Force the throttle wide open some how, using a broom stick on the gas pedal or something on that order to keep the butterfly wide open. Spray the cleaner in and scrub it with a toothbrush. Then wipe it out with a lint free rag to get the heavy deposits out. Just keep repeating that till it is totally clear. Remember to get the pivot points and the back side of the butterfly. Then go and run car at normal driving speeds for approx 5-10 min. It will run rough and shoot white smoke till all the cleaner is burnt but after that smooth running. :coolgleam

03-06-05, 04:57 PM
Or you could just use carb cleaner (some people swear by Sea Foam) and an old toothbrush or rag. That's how I've always done it. Either way, you want to clean out the bore and the circumference of the blade as well as the back side of the blade. It can be a very messy job. Black stuff gets all over the place.

There will be a small amount of stuff accumulated in the intake. It's normal and probably not causing you any problems or impacting performance in any way. The throttle body bore and blade need to be cleaned. Do that properly, disconnect the battery for 30 seconds and reconnect it, then drive it and forget about it unless you have some other symptoms. If there is still a problem of some sort, post it here and one of the experts will probably be able to tell you what to do about it.

Good luck...

03-06-05, 10:59 PM
Forget about cleaning the inside of the intake. It will always be sooty due to the EGR introduction into the plenum of the intake near the throttle body. It doesn't hurt anything and is going to get carboned up again quickly so why bother...?? The throttle body bore and blade needs to be cleaned periodically to keep the airflow around the perimeter of the blade (when the throttle is closed at idle) consistent. This just affects the freedom of movement of the blade (the stickyness you felt when the blade catches on the buildup) and the idle speed control gain rates. Squeeky clean isn't needed as the system can compensate for some build up...just, at some point, the builup is so great the idle speed control cannot compensate and stalling or near stalling and surging starts to happen. Just a general cleanup and you are fine. The battery disconnect just resets the idle learn and TPS learn values to the "clean throttle body" default values. It is not going to affect the fuel economy or driveability...just the idle speed control gains for the first few miles until the system starts to re-learn due to the clean throttle body.

The inside of all port fuel injected engine intake manifolds get very sooty from the EGR....just a byproduct of a dry intake. When intakes had a lot of fuel sluicing thru them (like with carburetors and throttle body injection) the manifolds were constantly cleaned by the gasoline pouring thru them. With the port fuel injectors at the ports the intake does not see any cleaning solvent...i.e..gasoline...so they do get sooty from the EGR. It doesn't hurt a thing and is pointless to clean out. There are money making scams that show you all the "dirt" that they clean from inside the intake...LOL...forget about them.

The fuel pressure regulator is not something that needs cleaning. It can be inspected for fuel leaking internally past the vacuum diaphragm..but it is not something that is recommended to be cleaned. With the engine idling just pull the vacuum line off the FPR and watch the vacuum nipple on the FPR for several minutes for any sign of fuel seeping out. There should be none. Do NOT put any sort of cleaner or carb spray into the vacuum port to "clean" the FPR least it be ruined.

The EGR valve is fine. If it starts to stick a code will set. Then take the valve off and clean the shaft. Until then, drive it. It is self diagnosing and the code is very robust at detecting a sticking valve and it will set the code. Leave it alone until you have a problem with it. It is not something that leaves you stranded or anything.

03-08-05, 11:28 PM
Thanks, That answered my questions bbob.