What causes "throttle gunk" ?
 

My friend has a 2002 Jaguar. It has spent most of its life in the shop under warranty. She said she knew it was bad when the loaner car guy noticed when she changed her hair style. The engine light has been on so much it has about burned out the bulb. Anyway, the latest saga is that her "throttle box" is "gunked up" (this is all according to the dealer). They claim that because she has been running 89 octane instead of 91 octane, this has caused it to gunk up. Now this sounds like the biggest load of BS I have heard. I don't see what octane could possibly have to do with it. As far as I know, the only stuff going through the throttle besides air is EGR gasses. Can anyone clear this up?

Mike

If I had to guess I would say it's mostly caused by particles in the air that get past the filter. That and maybe water too. ever drive in the rain??
Ok maybe not water per say but water vapor in the air entering the chamber.

Then there's always bad gas or gas that's sat for too long.

Danny

At the risk of getting flammed here, could she run a few cans of gas additive to clean it out?:1blank:

My guess would be the crankcase vent and/or vapors reversing when the engine is shut off. This is common in any vehicle but shouldn't be excessive. The dealer is full of it if he's claiming it has to do with octane. Pick up some throttle body cleaner and give it a wash.

Clearly the dealer can't clear this up without another serious infusion of cash. Assuming you are accurately relating the dealer's diagnosis and stated probable cause, I think the dealer knows a sucker when he sees one. Try another Jag dealer, or even better, another make of automobile. A friend of mine had an X-Type that was an exquisite POS, practically living at the dealership while waiting for parts from Bulgaria.

I second that! Jags are Junk! I had a late 80's XJ6 or whatever you call it. What a piece of garbage! Everything fell apart, nothing worked, I've seen better switches on a childs toy. And don't even get me started on the wood! YUCK!

What was wrong with the wood? Sorry, i knew you specifically requested not to start you up.

The antiknock sensors would just dial back the timing a bit if she ran 87. Dealer is FOS.

It's 1/8 inch laminate that desinigrates in the sun. Looks absolutely horrible. Mercedes knows how to build wood interior parts.

? The Mercedes wood has the same plastic coating that cracks in the sun.

My indy in Staten Island had a sign in front of his shop, he listed most foreign cars, German and Japanese allike except on the bottom of his board, he wrote, I don't do no Jaguars. :)

Not nearly as bad........ All of mine look great with the exception of 2 or 3 hairline cracks in the 300E center console wood, and that's just the clearcoat. You see, the problem is the thickness of the wood. Jag went as cheap as possible.

Hm I see. I'll always have a soft spot for the 70's XJ6's even though the quality is supposed to be pretty crappy..especially compared to MB.

Yep its throttle body and it is just carbon buildup. Jeeps are well known for this problem and when I took mine in they just pulled it off and sprayed it with brake cleaner and put it back on and it was fine. Charged $90 which I thought was very reasonable.

Well the dealer was able to clean it. Only cost 300.00 !! I think maybe they brought in a lawyer to do the actual work... I told her to run to the emissions test place before it throws another code!

Mike