My father was with me in my IROC the other week and he thought it idled a little too fast in park, said it shouldn't drop that much when I put it in gear because the park/neutral switch should tell the ECM to accommodate the extra load on the engine. Lo and behold, both of our s-trucks only idle about 50-100RPM lower in gear than in park (both autos), so I started to worry. My IROC idles at 900-1000 in park and around 650RPM in gear. Is this normal, or should I adjust the P/N switch or replace it? Thanks guys.

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, Accel coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

Jethro,

950 in PARK or NEUTRAL is about right if the IAC is working correctly.

The S-10 trucks probably have the 24202310 torque converter, which has a stall speed rating of 2,025 RPM (so the little truck can be used as a truck to pull more weight). This higher slip will cause less loading on the engine when idling in DRIVE, so the free-speed in NEUTRAL will be much closer to the idle speed in DRIVE. If you trade converters with him, his engine will have to be adjusted to a higher idle air setting in DRIVE and you will get much better launches.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Thanks a bunch, Vader. I just get a little nervous (or maybe obsessive) sometimes!