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Throttle Body Warning!


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21 replies to this topic

#1 qjoshh

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Posted 09 December 2005 - 01:17 PM

A warning to all those considering working on or even CLEANING their throttle bodies:
As noted in a previous thread, I recently cleaned the throttle body on my 1998 Subaru Outback... the Subaru dealership recommended this as a part of their 150,000 mile service, but I was unwilling to pay $500 for the entire package, so I opted to do as much of it as possible myself. Having previously cleaned the throttle body on my 1990 Dodge Dakota with good results, I simply bought the can of cleaner, exposed the throttle body, and cleaned away. The car began idling at 2500rpm after that. I checked all hoses and any other trouble spots that I (or anyone else) could think of; with no signs of improving after a week, I saw no option but to take it to the dealership. $150 later, the mechanic tells me not to tamper with the throttle body because it is "factory set", and that it took him two hours to recalibrate it.
How can this be? Is the throttle body THAT intricate on these models? Now I'm gunshy... what other seemingly routine procedures should I beware of performing?

#2 frag

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Posted 09 December 2005 - 01:39 PM

You did'nt say which car you have.
For my part i recently cleaned the throttle body and IAC with no ill effects at all. I replaced the electrical part of the IAC as close as I could to the initial settings and had no idle problems.

#3 qjoshh

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Posted 09 December 2005 - 01:46 PM

You did'nt say which car you have.
For my part i recently cleaned the throttle body and IAC with no ill effects at all. I replaced the electrical part of the IAC as close as I could to the initial settings and had no idle problems.

Tell me more about "replacing the IAC as close as you can to the initial settings". On my model (again, 1998 Subaru Outback 2.5) it looks as if this would have to be done electronically. How did you do that?

#4 frag

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Posted 09 December 2005 - 01:54 PM

The electrical (magnetic) part is held to the mechanical part (lower part)on my 96 Legacy 2.2L by two screws going thru elongated holes in the top part(for factory adjustement). I just marked the place of the top part relative to the lower one and replaced accordingly.
So I was speaking only of a mechanical setting not of an electrical or electronical one.
Hope I'm clear.

#5 Legacy777

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Posted 09 December 2005 - 02:11 PM

The throttle body issues I ran into were because of a sealant/coating they put on the inside of the throttle body. If your throttle body had something similar, then yes cleaning that off will throw off the calibration.

#6 beezer

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Posted 09 December 2005 - 09:55 PM

OK I'm a little confused here.

What actually gets out of whack when you clean the TB. I've read about the coating on the TB, and that shouldn't be taken off. Why then would Subaru recommend TB cleaning? What has to be recalibrated? the TPS?, the idle screw?, the butterfly thing?my head?(a given there)

Thanks,
Beezer

#7 Scoobaroo

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Posted 10 December 2005 - 08:04 AM

With the rubber air intake boot removed, manually open the throttle butterfly and feel the area around where the butterfly comes to rest for a small ridge of gunk. If there is a small ridge of gunk, manually rub it away with a rag wrapped around your finger until it's gone. Using spray cleaners is a bad idea. They can wick themselves into the Throttle Position Sensor, the IAC motor and dissolve the internal throttle body coating.

DO NOT mess around with the screws. They are factory preset. Cleaning the ridge of carbon away should restore the throttle body to proper operation. Dealerships love to hype up throttle body cleaning. They charge $100+ for 5 minutes worth of work.:-\

#8 DerFahrer

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Posted 10 December 2005 - 10:55 AM

Scoobaroo, you do NOT want to wipe away that gunk!!! That is the sealant that Josh was talking about in his thread. I presume it seals the throttle plate when shut. If you clean that away, logic would suggest that too much air would make it through the throttle body at idle, and that would make your idle raise significantly.

I can tell you as well that the throttle body (and in my opinion, the IAC valve also) are set to certain specifications from the factory and are non-serviceable. Do not try to clean, adjust, or disassemble them in any way. If you do, you will have all kinds of problems and end up having to replace them anyway.

I have replaced both the throttle body and IAC valve on my Legacy because I tampered with them both when I was a stupid little kid. Now that they're both good, un-tampered-with units, I have no problems.

#9 frag

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Posted 10 December 2005 - 11:23 AM

Scoobaroo, you do NOT want to wipe away that gunk!!! That is the sealant that Josh was talking about in his thread. I presume it seals the throttle plate when shut. If you clean that away, logic would suggest that too much air would make it through the throttle body at idle, and that would make your idle raise significantly.

I can tell you as well that the throttle body (and in my opinion, the IAC valve also) are set to certain specifications from the factory and are non-serviceable. Do not try to clean, adjust, or disassemble them in any way. If you do, you will have all kinds of problems and end up having to replace them anyway.

I have replaced both the throttle body and IAC valve on my Legacy because I tampered with them both when I was a stupid little kid. Now that they're both good, un-tampered-with units, I have no problems.


Well, there must be a god for «stupid little kids» cause I cleaned both the throttle body and IAC (after removing it from the throttle body and after separating it in two parts) with no problems. I dont remember his sig, but someone (nice guy who gave me a hand when I was doing this) from Hawaï did the same with similar results. But maybe it's not the kind of maintenance anybody should tackle.

#10 blitz

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Posted 10 December 2005 - 11:44 AM

All I can say is some of you need to be more careful or something.

I've made it a point to clean my T/B with T/B cleaner and a toothbrush every summer as a part of normal maintenance, guess what? No problems.

When I bought my '00 Impreza used, it had a re-occurring CEL. After replacing the PCV valve, cleaning the T/B with T/B cleaner and a toothbrush, removing the IAC valve and cleaning it with T/B cleaner and a toothbrush, guess what? No more CEL light ...and no "problems" either.

I didn't spray cleaner at, onto, or in anything that had rubber or electronics. My intense discipline and flawless work ethic allowed me to keep the the solvent spray confined to the areas that required crud removal.

Notice that I didn't tamper with the factory set adjustments? All I did was remove the accumulated crud that wasn't there when it was new (yes I did look at the T/B when my '02 was new, so I DO know what it looked like ...it was clean & shiny metal, not black & sooty).

Under WOT, reverse crankcase fumes (oil mist, blowby, etc.) are re-directed through the T/B. As a result, all the byproducts of bullshyte tend to condense out of the vapors and form solids on the T/B blade and the T/B bore. It needs to be cleaned.

You folks with EGR valves need to clean that system too, it gets gunked up as well.

#11 Legacy777

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Posted 10 December 2005 - 11:48 AM

My specific issue was due to an oddity on the earlier throttle bodies. They had a bypass screw/needle valve that let you adjust how much air went by the throttle plate.

They stopped doing this, and therefore removing the sealant isn't as "critical"....but personally, I won't screw with it.

#12 frag

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Posted 10 December 2005 - 11:52 AM

Is it possible to think that the idle problem some have had after cleaning the crud where the butterfly meets the throttle body is maybe due to the fact that it was not completely removed. The butterfly would then not be able to close tight all aorund.
Just a thought.

#13 blitz

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Posted 10 December 2005 - 01:15 PM

Is it possible to think that the idle problem some have had after cleaning the crud where the butterfly meets the throttle body is maybe due to the fact that it was not completely removed. The butterfly would then not be able to close tight all aorund.
Just a thought.

Without a doubt that's one possibility in many. Other possibilities: questionable (too harsh) cleaning products, getting the cleaner & dirt into the IAC motor, messing with the DO NOT TOUCH adjustments, not putting stuff back together exactly as it came apart.

The throttle needs to be dealt with carefully for the same exact reasons that it needs to be kept clean in the first place: It's a precision assembly.

Accumulated gunk and hack cleaning jobs both will cause it not work like it's supposed to.

#14 Scoobaroo

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Posted 11 December 2005 - 10:09 AM

Scoobaroo, you do NOT want to wipe away that gunk!!! That is the sealant that Josh was talking about in his thread. I presume it seals the throttle plate when shut.


I'm talking about the little ridge of carbon that builds up over time where the throttle butterfly seats, not the coating on the aluminum itself. This carbon deposit will affect the minimum air rate somewhat.

Stay away form spray cleaners. Just wipe the inside of the body clean with a dry cloth. It's not really a big deal. Dealers SAY that it's a big deal so that they can charge you a hundred bucks to do it.:-\

#15 MDW25gt

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Posted 11 December 2005 - 08:08 PM

I cleaned my 90 leg 2.2 anytimes as well as my current 99 2.5 with spray gumout. Pop the boot off the throttle opening/inlet slightly and with engine running spray away. Need to blip the throttle to keep the engine running. I have had no problems. Noticable difference when finnished.

#16 Cougar

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Posted 11 December 2005 - 09:18 PM

I think using WD-40 to clean with would do a good job and not cause any trouble to other things. It would be interesting to know what this coating that has been talked about, is for, inside the TB.

#17 NOMAD327

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Posted 12 December 2005 - 06:40 AM

The 99 factory service manual talks about cleaning the 2.5 IAC valve using either GM top end engine cleaner or another spray solvent which I forget, but was probably Subaru dealer provided. It involved using a fast idle and injecting through the inlet tube. The 2.2 has a different arrangement and was to be cleaned in the traditional way. The high idle is necessary, because the motor will not run slow with the tube disconnected. I disassembled the throttle body and the IAC valve and cleaned them manually on my car with no problems, but the IAC valve is hard to access on the 2.5 and has some small scary parts that have to be handled correctly. The GM top end engine cleaner is good stuff but $10 a can.

#18 fishy

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Posted 12 December 2005 - 08:28 AM

The 99 factory service manual talks about cleaning the 2.5 IAC valve using either GM top end engine cleaner or another spray solvent which I forget, but was probably Subaru dealer provided. It involved using a fast idle and injecting through the inlet tube. The 2.2 has a different arrangement and was to be cleaned in the traditional way. The high idle is necessary, because the motor will not run slow with the tube disconnected. I disassembled the throttle body and the IAC valve and cleaned them manually on my car with no problems, but the IAC valve is hard to access on the 2.5 and has some small scary parts that have to be handled correctly. The GM top end engine cleaner is good stuff but $10 a can.


Was the other stuff "Seafoam"? That gets a LOT of discussion over at honda-tech. Apparently it's very close to GM top engine cleaner and is for the same purpose. It seems to be quite popular.

#19 trxeslr66

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Posted 12 December 2005 - 09:35 AM

My car stalled one time from the idle dipping low, so my mechanic "cleaned" the throttle body. Ever since, I have had a cel p1507 Idle control valve coming up. I replaced the Idle control valve and still have the low idle and CEL. I have tried 100 things except for messing with the TB. Any ideas? I really need help?

#20 cidion

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Posted 12 December 2005 - 09:54 AM

. . .unwilling to pay $500 . . .but to take it to the dealership. $150 later, the mechanic tells me not to tamper with the throttle body because it is "factory set", and that it took him two hours to recalibrate it.


Sounds like you saved $350!

=)

#21 NOMAD327

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Posted 12 December 2005 - 10:21 AM

The two referenced choices were part number 1050002 GM Top Engine Cleaner, or part number X66-A AC Delco Carburetor Tune-Up Conditioner. The Seafoam product would probably do at least as well, as long as it was O2 sensor safe.



Per manual: Cleaning applies to 2500cc engine only at least on 99 model year. 1, start motor and warm up until radiator fan operates. 2, hold throttle valve to maintain engine speed 2000 RPM. 3, Disconnect air by-pass hose from air intake duct. 4, slowly pour one 16 oz. can of cleaner into bypass air hole. 5, leave the engine running for five minutes, allowing white smoke to come out from muffler until the cleaner is used up. 6, stop the engine. 7, Release the throttle valve. 8, Reconnect the air by-pass hose to the air intake duct. 9, check the duty ratio of the IAC solenoid using Subaru Select Monitor. (should be 25 to 40%)

#22 Legacy777

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Posted 12 December 2005 - 01:49 PM

Seafoam is O2 sensor safe.....and is an extremely good product/cleaner.




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