ClarenceT

Ever pull up to a stop sign, put your clutch in, and have your idle shoot up to 1500? 1600? over 2000 as in my case? What is this!!!

Apperantly GM decided it's a good idea NOT to use bearings in the throttle body for the shaft, so the holes wear oval over time, and your throttle plates stick partway open. If this is the case, it's real easy to spot. Pull over when your 'vette is idling like crazy, pop the hood, and look at the gap between the stop screw and the linkage hookup mount. On mine it would stop nearly a quarter inch from where it should be, and my idle was insanely high.

The real fix is e-mail this man (dkoldos@ameritech.net) - he sells remachined TB's with bearings on e-bay that are reportedly quite good. However, untill you do that, you don't have to be stuck with a messed up idle. If it's not too bad, you can try lubricating the shaft. Try some kind of penetrating oil, but make sure it's really a lubricant, instead of a solvent. Then if the stock return spring is still not beefy enough to overcome the tension, you can give it some help.

Make a run to your nearest Home Depot or auto parts store, and buy a stretch spring - then all you do is put one end on the throttle, and the other to something stationary to hellp close the TB blades.

The spring I used was about 2.5 inches long, and rated for 3.5 pounds. One end went on a spiggot at the top of the piece, and the other on the metal plate where the throttle/cruise wires are anchored. Perfect fit, the blades close every time, and the gas pedal is not notieably stiff - in fact, now it's a better balance then before for my feet anyway.
Bellow is a crappy MS Paint rendering of what I did:



SO there you have it. No more "wondering idle" syndrome until I'm ready to get a nice shiney new TB! The spring doesn't look all THAT out of place, and definitely worth every penny of my $1.27! The car now slows down when i lift my foot off the gas as it should, and I don't have to do the "tap dance" at every stoplight to get the idle back down from 2000+ rpm

65Z01

Good job.

I've replaced my stock TB with a 52mm unit a few years ago so should be ok for a while.

I wonder how hard it would be to install a brass bushing into the shaft hole if mine goes and starts to leak air??

runner140*

That might be a record for time and money spent on a mod or correction of the Generals engineering. Congrats.

Unriced

Thats funny, I did the exact same thing but found the feel was
too soft and light.. I just lube it every so often and it's good to go..
Great minds think alike?? Maybe

Bruthish

Hey thanks! I will try that!

ClarenceT

Haha, yeah now in day two, and the vette beahevs every bit like I wanted it too.. For those that havn't experienced this yet, it's a VERY annoying problem. Doesn't make the car undriveable, but takes away half the benefits of driving a stick (like the predictability of the valvetrain drag that'll slow the car down when you lift, etc) Having put the clutch in every time you brake (otherwise the car will keep pulling) and then finding a convinient time to sneak that gas pedal tap in there, gets old FAST haha.. SO I'm happy. I'm still going to track down a re-built TB, but now I can take my time..

Oh and yeah, the feel isn't bad - my heavy foot now has a tinsy bit more resistance so I can "rest" it on the pedal with minimum muscle effort to keep it from pushing the gas any more then I want it to..

gbody5

ClarenceT, I love your art work, esp. the detail like the crossed flags and manifold, sweet!

korvette4u

installing bushing can be done...however you do need special reams for this proceedure...i choose to rebore and rebearing the TB (did it myself)as i bought the milling tools and CNC'ed the throttle plates..my TB operates flawlessly on all three C4....I want to buy old TB cores.. pm me if you have one , two or more ..thanks

VetNutJim

Yes!! Great Vette art!!!

ClarenceT

Haha, thanks! I think I'll e-mail GM so they can hire me as the repair manual artist for the C7!

REDC4CORVETTE

You might also check the IAC and the tps voltage .54 and see if the two are set up right.

ClarenceT

i checked; this is a purely mechanical problem with the plates though - you can watch them stick open with your hood up, and push them back closed with your finger, and the idle comes down to normal

REDC4CORVETTE

My 86 would do the same thing and I installed a spring but checked the IAC and TPS and they were off ,my throttle plates would stick also.
the EGR seems to have a problem from time to time even with the spring and the idle does not always come down.

ClarenceT

Ah, you have other demons then.. I got lucky. My tps measured nearly perfect, and as for the rest, after spring my idle always goes back so I guess it must be ok..

Sucks about the egr, that's a bastard to get to... P&P while you're there meybe? At least you wont have to feel bad about "repairing" - you'll be "upgrading"