throttle body return spring question

[tigmaned]

my vette likes to take a while when slowing down for a light to ilde down the the 700rpm range. i'll let off the gas it drops to say 1000rpm, i touch my brake pedal hold it and drops to say between 800 & 900rpm. then after sitting a little while she'll finally go down to 600 700 rpm range and settle in. am i worried about nothing here, or could the T/B return spring be going bad?

 

[Moonunit 451]

Let's assume that your TPS is good and adjusted properly as well as having good sensors, tune ect. Have you cleaned the TB? Is the linkage shaft without excessive slop?

I have had a similar problem, had the TB rebuilt and no cure. The problem you describe is so irritating I finally added an additional spring to have the TB return to idle properly. No problems now, and it didn't take much spring.

 

[tigmaned]

moon
yeah when i first got my vette i removed the t/B and cleaned it, the iac too, don't think i really checked the shaft for slop? i will now. another spring huh?
Thanks

 

[Moonunit 451]

I should have mentioned I didn't have the problem with the stock TB or when I put the stock TB back on.

I have the problem with the 58mm TB. Can't account for it, but the spring works. I drilled a couple small holes and tried a few different length and strength springs till I came up with the right solution.

 

[tigmaned]

moon
man you got a monster under you hood!! very cool.

 

[regalniz]

i had the same problem after i put a 52mm tb. damn thing would just wouldnt come down from 1100 rpms. so i threw on a tighter return spring and all is well. however it will be harder to depress the gas pedal now.

 

[tigmaned]

i may try the same thing soon.
thanks

 

[blacktiger69]

hey guys! i have right now just the same problems on my 86 red corvette with my NEW 58 BBK TB.Do you realy think that the spring will work out?i realy hope,cause i also did a lot of resetings and always the same problem..i seatle my TB and TB position sensor to 600-700 RPM and after i did a few miles again and agin the same problem....may iddle stays at 1100-1200 RPM...this is very not pleasant situation!do you think that i have to clean that original black coating in the trottle?in manual for instalation is written that i have to leave this coating on!!what do you think?
thanks a lot for all answers!if you want to write me in private my email is themindmachine@gmail.com
thanks guys!

 

[tigmaned]

BT69
not sure you wrote that right? you set the TPs at 600-700 rpm?? my 86 with automatic you set the IAC at 400rpm so that may be diff if you have stick or auto trans? and you set the TPS at .054 volts.
ED

 

[Moonunit 451]

LOOK, you guys think I like that spring? But I tried everything else I could think of, and looked to others with my setup as well. It deosn't happen to everyone, don't know why.

It ain't purty, and I'd rather not have it, but it works and it's not a huge change in accelerater pressure involved.

Welcome to blacktiger69

 

[vetteboy86]

Like moon said, I would go with whatever works. I too plan on going to a larger TB, so I have made note of this thread.

Good luck everyone

 

[rrubel]

FWIW, I have the same problem with the SR (like Moon's), a 52mm TB, and the STOCK chip. Using a custom one, though, it doesn't happen as often or as badly (ie, drops to 900 then falls to 700).
[RICHR]

 

[Moonunit 451]

Believe me, I don't have a stock chip. But I have more dyno time ahead with a great tuner TJ, and if it's chip problem, we'll figure it out. And I will get into the 11's when the time comes. I'm in no hurry

 

[Hrtbeat1]

it's not a huge change in accelerater pressure involved.

Maybe there just isn't enough Lead in the right lower extremity. You are right TJ does know his stuff (I'm sure we are talking about the same guy,) he's given me some little hints/tips so maybe here's one in return you could pass along. I tweaked the requested idle vs coolant temp just a bit and it helped some and there was another field ... something to do with vaccuum, can't remember exactally.

 

[blacktiger69]

tigmaned ...i have an automtic transmission!
and this big problems with this new BBK 58 TB!
i set my trottle body sensor at .054 and iddle at 700-800..but when i do few miles it will return to iddle at 1100-1200!
is possible that is something wrong with iddle motor, which is situated under the TB?
tnaks

 

[rrubel]

Isn't the IAC supposed to push the TB open just a bit to keep idle up? Maybe the bigger TBs are letting in a touch more air than the ECU is expecting, causing the higher idles.

Of course, that doesn't address Tigmaned's problem... unless his IAC is messed up.
[RICHR]