I went to get an oil change today. (I know... too lazy to do it myself. Was under a time constraint) The mechanic asked for me to come into the garage and pulled off the air filter setup. He stuck his fingers in the throttle body and came out with finger cover with black sooty grime. He tells me that I'll need to have my fuel injectors cleaned. I just had them cleaned in July. How the hell did all this dirt get in there?!?

Another thing, the mechanic pulled out the dipstick for the tranny fluid. He says it smells like burnt crayons. I smelt it, but I don't know what burnt crayons smells like so I had to agree. He tells me that in two weeks it'll turn to acid and eat away at my transmission parts. (yeah, right) After I paid the guy for the oil change and head home. I checked my car personally. The transmission fluid is still pink. That means it's still okay right? I normally know these kinda things, but this mechanic really screwed with my head leaving me with doubts.

In short, my questions are: Is my tranny okay since the fluid is still pink? What the hell is the black sooty grime doing in the throttle body/plenum? How the heck did they get thru the K&N filters? And is it normal? Is there a way to get rid of it? Please let me know.

Thanks for you time.

Humvee

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1989 IROC-Z Convertible
305 TPI automatic
White with black top
Mods:
None to date... Working on it!!!
My webpage: http://mindspring.com/~humvee

 

How long since the tranny fluid was changed? If it smells burnt, it's probably time for it to be changed.

That funk in the plenum is normal. Get some throttle body cleaner and hose the hole can inside there...stop every now and then for it to drain out the front of the tb. There are some air passages in the tb that that junk can also clog up and cause idle problems. If you know how, pull the IAC motor and hose down the housing for it w/ some cleaner too. I think I read somewhere that it was condensed gasoline/combustion fumes.



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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

 

Hummer,

I can't answer your transmission question with any certainty, since I can't see/smell the oil. However, if the transmission oil hasn't been changed in the past 15-20,000 miles, it's probably a good idea unless your transmission has over 100,000 miles and is already starting to slip. While the pan is off the transmission, install a drain plug to make draining the oil a lot easier next time.
Regarding the injectors, the varnish in the intake plenum behind the throttle body is completely normal.

I removed, machined, and completely cleaned a TPI plenum a few years ago. The very next season I had to remove it again for access to the injectors, and it already had the buildup. I did some further porting and matching while the injectors were out, and less than three months later the freshly exposed aluminum had a coating of brown varnish and dirt.

First, this is normal. No air filter can remove all dust and dirt particles. The idea of the filter is to remove all particles above a critical size that can cause damage.

Second, this has absolutely no bearing on the condition of the injectors. "Perfect" injectors in a "perfect" engine will experience the same plenum buildup.

Third, this layer of varnish is not a detriment to intake flow unless it is about a half-inch thick. Cleaning it off is fruitless, since it will appear agin in a few thousand miles of operation. It would be like washing the inside of the muffler to keep the carbon "under control".

Fourth, if the "mechanic" proposes cleaning your fuel injectors, how exactly was that going to be done? Unless he/she was planning to send them to a specialist for thorough cleaning and flow testing, you might be wasting your money. If they were cleaned a few months ago, I would seriously doubt that they needed service again unless you didn't change the fuel filter and flush the lines before installing the clean set. Even if you didn't, I would suspect they are serviceable.

Frankly, a mechanic at a ten-minute oil change store probably has less experience with injection systems than you should be confortable with. If the engine runs acceptably without any symptoms of poor injection, forget about cleaning the injectors or plenum - you're wasting your time in either case. You might want to ask the mechanic if the injector problem was diagnosed by the fuel pressure leakdown method, pulse-width monitoring and exhaust gas analysis, or the "proctologist" method (sticking the finger in the hole). I'll bet he just drops it after that.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

This bothers me..."He tells me that I'll need to have my fuel injectors cleaned"

Due to the throttle body being dirty??...Its TPI!!! With the injectors being downstream from the inlet, how does the mechanic think that the injectors have anything to do with the inlet??.

I think Vader is right on this one...I would stay away from the "mechanic" that told me that.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

[This message has been edited by Engineboy (edited December 06, 2000).]

 

I thought you get the soot in the plenum because of the EGR passages that empty into it. The dirty exhaust coats the inside of the plenum.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Thanks guys! It gives me a peace of mind to know that the black varnish is normal. As for the tranny fluid, I guess I'll change it. I thought as long as the fluid is clear pink, it's fine. Definatly do not want to make expensive mistakes!

Thanks again.

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1989 IROC-Z Convertible
305 TPI automatic
White with black top
Mods:
None to date... Working on it!!!
My webpage: http://mindspring.com/~humvee