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Sticking throttle cable
04-07-2007, 09:29 PM
Throttle is sticking when I try to ease on the gas. It only does this when the car is running, doesn't stick at all when it's off. It has a BBK 58mm throttle body. I've been told that BBK's were known for sticking. Looked at BBK web site and their tech question section said this was known as "vacuum lock". They suggested using the Idle set screw to prop open the throttle blades a tiny bit more. I tried it and it helped but the idle is so high it's ridiculous. Anyone have other ideas?
04-07-2007, 11:38 PM
Suggestions? Do you still have the stock 48mm TB?
04-08-2007, 08:04 AM
There's not much you can do about the sticking throttle unless you are interested in doing some machiening on it yourself. BBK's quality control on their throttle bodies is crap. And the suggestion that you use the minimum air adjustment screw to "fix" it goes to show that they really don't know what they are doing.
What is happening is that the throttle blades are binding in their bores due to machineing tolerances not being strict enough and would require removal of the throttle body and with the minimum air screw properly set, shine a bright light in from the back and look at where the blades are contacting the bores. Mark them at the contact points. Mark them for which bore thay are sitting in and which edge faces the top of the bore. Then remove the blades and using a jeweler's file, carefully file down the contact areas. Be advised that you could end up going too far and ruin a throttle blade or two. If you go this route, file a little, reinstall the blades and recheck them, remove file some more..etc. Keep doing this until you have them free in their bores. Then reinstall the blades with locktite on the screws. Also, the ends of the screws may be steaked. This is where they peen the end of he screw where it protrudes out the back side of the throttle shaft. To remove the screws you'll need to grind them down on the back side with a dremmel until they can be removed without them shearing off.
Since you bought this car with all of these things on it I would bet that the TPI doesn't even need the 58mm TB and whoever put it on didn't machine the plenum to make it useful.
04-08-2007, 09:31 AM
No, I don't have the stock throttle body.
I will check the clearances of the blades and make sure there is no binding.
05-03-2007, 02:16 PM
Pulled the throttle body off this past weekend. Cleaned all the gunk built up around the blades then looked through it and could see where it was binding. Took the blades off and made an arbor to center them on. Then spun them in the drill press and polished the edges down and gave them a nice rounded edge. After lots of trial fitting they now have a tiny, even gap all the way around. Just got back from a test drive and throttle is very smooth. Now working on getting the timing and idle set correctly.
Thanks for all the help,
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