TB Cleaning

Yesterday I replaced the air filter, so I pulled the accordian tube off the TB to check how dirty it was while I was at it. The butterfly plate looked ok on the outside, but I could see that it was pretty gummy inside when I turned it open. I would have bought some TB cleaner and cleaned it out, but on the TB under the accordian tube there is a warning label that says don't clean it. I can't remember the exact words, but it says something like "Caution: Do not clean throttle body. There is a special coating that can be damaged by chemical cleaners". What do you recommend?
1998 Contour, 2.5L Duratec, ATX.
-Simon

I think I would save the intake manifold cleaning for when you have time to pull the UIM & LIM off the car & do it right via intake overhaul in the FAQ. If you're not prepared for it at this time, here is what I would suggest:

The TB cleaning that most do here involves the relatively simple task of removing the 4 bolts around the TB, and pulling both it & the gasket off. Behind the gasket, on the UIM, you will find the EGR passages that typically need cleaning out.

Once that is done, perform an intake cleaning via the intake vac method. It does help some, though obviously not as effective as a full overhaul.

The special coating is mainly to help the TB to stay clean. If you do clean it regularly, I wouldn't worry about the coating, as you will be cleaning it anyway. Just my .02.

Use an old toothbrush with a cleaner that says it is intended for teflon coated throttle bodies. There is no need to remove the throttle body from the car. Pay special attention to the black ring that builds up behind the throttle plate.

The teflon coating is intended to keep from needing to pay for cleaning during the warranty period. It does slow down the gunky build up, but it doeswn't eliminate it. Clean it and you will be surprised at how much better it runs, especially at light and part throttle acceleration.

Is there a how-to for this anywhere? The car is due for an emmissions test, so I'd like to do it beforehand.

I don't know that anyone has ever pinned it or added it to a FAQ but I've posted about it many times.

I'll go over it again for your benefit. Some believe that you must remove the throttle body to clean it properly. I don't. Doing it as I do will get it cleaned as well or at least nearly as well. So some will insist on removing the throttle body to clean it and that is certainly a way to do a thorough job, but I would not unless you need it off anyway either to clean the EGR passages behind it or for access to replace the IMRC.

To clean on the car, gather your materials. A screwdriver to remove the air inlet tube at the throttle body. Throttle body cleaner, preferably a spray that says that it is safe for teflon coated throttle bodies. An old used soft toothbrush. A soft rag, preferrably 100% cotton. A paper towel is acceptable, but harsher. An assistant to step on the gas pedal to hold the throttle plate open when needed during cleaning. You can probably figure out how to do it without an assistant, but it's easier with one.

Remove the air inlet tube for access to the throttle body. Have your assistant hold the throttle open. Spray the throttle bore with cleaner. Don't leave it soaking more than a half a minute or so as prolonged exposure to the teflon is possibly harmful. Use the toothbrush and GENTLY scrub the throttle bore and then both sides of the throttle plate. If needed, wipe the worst of the junk out with a soft rag. When cleaning, pay special attention to the black carbon ring on the throttle bore that is just inside of where the throttle plate closes.

Part of the cleaning should be done with the throttle plate partually closed or closed as well as wide open to make sure you have acces to everything. When the throttle plate is wide open, scrub the bottom side that is not accessable when it is closed. The toothbrush will allow you to also catch the edge of the throttle plate at the throttle shaft where it meets the bore.

When finished, either do one last blast with the cleaner to flush any junk away or wipe it with the soft rag, or both. The stuff that goes into the engine won't harm anything.

Reinstall the air inlet tube and anything else that was disturbed for access. Start the engine. You may need to hold the throttle slightly open or even fully open to clear the cleaner out of the cylinders so the engine will fire up. The engine may run rough for a moment as it blows the cleaner out as well.

At this point, you are basically done. If the throttle body was extremely dirty, you may need to clean the IAC (idle air control valve) and go through adaptive strategy.

The IAC can sometimes be cleaned in place by removing the tube to it and shooting cleaner into the IAC with the engine running. You will probably need to hold the throttle open a bit to keep the engine from stalling. If it is really bad, it may be best to remove it for cleaning.

Adaptive strategy is getting the computer to relearn now that the throttle body no longer restricts airflow or no longer holds the hard stop slightly open. Talk to 100 technicians and you will get 100 different ideas on how to perform adaptive strategy. At minimum, dump the computer adaptive strategy memory and then gently drive the car for about five minutes.

Here is a bit more detailed way to do it. Start with a warmed up engine. Shut off the engine. Remove the fuses that keep the adaptive strategy alive. On the 98 and older cars it is fuses 4 and 11 in the fuse panel under the hood near the battery. Disconnicting the battery is OK but you will also loose your radio station and clock settings. Disrupt the power to the computer for about 5 minutes.

When you restore the power to the computer, start the engine with the AC and any electrical loads off and hold the engine speed at about 2000 RPM for at least 30 seconds. With the engine speed up, turn on the AC and hold the engine speed for an additional 30 seconds. Allow the engine to return to normal idle, turn off the AC and hold the idle for 30 seconds, then turn on the AC for at least 30 seconds of additional ideling. Now drive the car for 5 to 10 minutes avoiding heavy acceleration.

Enjoy.

While you have it apart use some brake cleaner on a reg to clean the lim passages and butterflys.

Big Jim said:

I don't know that anyone has ever pinned it or added it to a FAQ but I've posted about it many times.

Click to expand...

Extracted, posted, and pinned. thank you.

So I've done the cleaning, and I've noticed a huge difference in gas mileage. Before doing the work, I was getting approx 18 mpg. After doing the TB cleaning, PCV valve replacement, air filter replacement and injector cleaner in the tank, I got 23 mpg on the last tank. I also just had the emissions test done yesterday, and it passed no problem (emmissions of HC, CO and NO very close to 0).

I'll try doing the UIM/LIM cleaning sometime over the next couple months when I have a bit more time, see if that makes for a further improvement.

One last thing... with the injector cleaner. I've never done it before, and I bought the car used 2 years ago. Would it be benificial to add injector cleaner a couple more times now, or is one shot probably as good as it gets?

Thanks Big Jim for the how-to... It made things much easier.

With the improvement you have seen, the injectors are probably clean. Go ahead and do a second treatment if you like, but it may not make much difference. You should do it about every 10,000 to 15,000 miles or maybe once a year as maintenance.