cool, got the '86 IROC running, but the idle is like 2000rpm and it stumbles alot, almost like it has a huge vacuum leak..

things i've done:
<ul>[*]i changed all of the vacuum lines, no change in how it runs..[*]it doesn't throw codes[*]revs up fine, but very very fast... wants to hit redline almost instantly![*]timing is set at 6 BTDC with the EST disconnected[*]clearing the ECM makes no change in how it runs[*]all sensors are hooked up[*]EGR's vacuum line is good[*]all soft vacuum lines have been changed..[/list]
SO, i'm thinking it could be TPS or IAC... what would the TPS or IAC make the car run like if they were out of spec? i thought IAC affected how high the car idles...

my DAd cleaned the TB with carb cleaner while the motor was apart, could that have screwed up the TPS or IAC? no sensors on the TB were removed during the cleaning..

thanks! the car is a 305tpi btw..

thanks again,
Colin

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Webmaster: www.IROC-Z.org

 

add: i cleaned the IAC and it dropped the rpm by 500 but it still idles at over 1400rpm, holds it, but won't idle down..

ideas?

Thanks!

 

Colin,

Is the CTS working/connected? The engien target idle speed will be prett high until the ECM sees an increase in coolant temperature.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

hey thanks for replying Vader..

the CTS is connected and works... i got a CTS error when i initially started it but after clearing the ECM and running it around the block it still doesn't show up..

i'm thinking that it may still be fairly advanced as I set the timing when i first started the engine, with the EST disconnected..

that might be the problem, gonna take it out for a quick spin and set the timing when it's warm and see what happens...

right now it's at 4 BTDC with a cold engine and no EST...

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Webmaster: www.IROC-Z.org

 

Do you hear any vacuum leaks? When I put a cam in my old car (85 T/A 305TPI) I didn't have the cold start valve seated properly. It did the same thing as what you are describing. Man did that throw me a curve ball. I was still pretty new to the TPI system and it took me a WHILE to figure it out.

Just and idea...... Good luck!

Laterzzzzzzzzzzzzzzzzz

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone and AFPR, TB bypass, AirFoil, !AIR, !A/C, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"

 

A bad IAC would actually make the car run REAL LOW RPMs and probably die a few times on you!! I found this out one time when I hooked my IAC up and the connector wasn't seated properly! You might check the TPS setting but I don't know if that's going to affect it or not! My 305 Tpi engine has over 200,000 miles on it and always idles above 2000 RPMs while idling in PARK! When it's in gear, it idles just fine at about 650-700 RPMs! I don't know what's wrong with mine either... I just kinda deal with the annoyance of it idling high in park since it idles just right in gear! If your problem is similar to mine and you figure out what's wrong, plz let me know because I'm curious myself!!

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1986 Trans AM
305 TPI
Well over 200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear (2.77's....oh joy) :P
Completely Stock
Current Project: upgrade to a 355 TPI, 6" rods, 9.5:1 Compression, Stock TPI ported, 24#/hr LTI injectors, Hedman Shorty Headers, SBC Stock Casting heads pocket ported, Comp Cams XE262-14 TPI Cam, Ed Wright Fast Chip, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Box, proform hot coil!!