Hello everyone. Ever since I swapped out my old 305 for a 350 I've had this terrible idle problem. It seems fine at start up until the car warms up. It will flucuate from 500-100 rpms and stall frquently if I don't keep my foot on the gas. There also is a surge at slower speeds and throughout most of the rpm range. This has been going on for 8 months now. No one seems to be able to figure it out. I've tried pretty much everything(chip, MAP, heated O2, TPS, etc...), but I have a question about my next idea. Could a weak coil cause an eratic idle and slight surging when warmed up? It's an external MSD blaster, about a year old. Any other thoughts?

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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
open 3.73's
2 1/4 stock catback
I love pissing those LS1's off
My Formula

[This message has been edited by Birmass (edited February 21, 2001).]

 

Tried resetting the IAC valve yet ?? You'd be surprised. Also if that doesn't fix it, take it out and clean the pintle and the bore in the throttle body.

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92 Z28 5.7
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Ported stock heads, XR270HR-10 cam, TES headers
Crane AFPR, Flowmaster catback, MSD ignition
#24 SVO injectors, 1LE aluminum driveshaft.

Best ET 13.3@107 mph

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Did that literally 20 or so times over the past eight months. The IAC is brand new. It's a holley 670tbi. I'm tellin ya. This problem is VERY elusive.

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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
open 3.73's
2 1/4 stock catback
I love pissing those LS1's off
My Formula

 

did you check your EGR for correct operation? your problem sounds like EGR..

is the car fine under moderate load but under hard acceleration it's kinda bogging a bit? when your cruising on the freeway you can feel a surging? if so, my guess would be the EGR staying open either too far or open completely...

i had a similar problem with my 86 IROC and after changing the EGR it cleared right up..

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Webmaster: www.IROC-Z.org

 

Sorry, I should have mentioned that I don't have EGR, but the chip is programmed to eliminate it.

Can a weak coil be causing the surging and bad idle?