94 idle too low

evan · June 5, 2006

I have a 94 suburban 155000 miles runs great but with the a/c running idle only about 400, can I adjust it ?? I looked around the tbi could not find a adjustment screw

snoman · June 5, 2006

I have a 94 suburban 155000 miles runs great but with the a/c running idle only about 400, can I adjust it ?? I looked around the tbi could not find a adjustment screw

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Try replacing the ICVv (Idle Control Valve) There is also a adjustment for the minimum opening of the throttle plates.

redvett · June 5, 2006

If it was idleing OK before dont touch the min. idle screw. Check out the IAC counts with a scanner should be 15-30 and go up when A/C is turned on and compresser is running. There may be a electrical problem and min. air wont fix it. Clean the IAC and port but do not get solvent on outside connector or outer surfaces.

snoman · June 5, 2006

If it was idleing OK before dont touch the min. idle screw. Check out the IAC counts with a scanner should be 15-30 and go up when A/C is turned on and compresser is running. There may be a electrical problem and min. air wont fix it. Clean the IAC and port but do not get solvent on outside connector or outer surfaces.

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Actually I had to readjust my minimum setting once because the throttle plates and IAC would not let in enough air above 12000 feet for a noraml idles. After I tweaked it years ago it worked there and at sea level too.

Shocker · June 6, 2006

Where does it idle with the AC off?

As I recall, my old 97 suburban would idle at about 400.

evan · June 6, 2006

Where does it idle with the AC off?
As I recall, my old 97 suburban would idle at about 400.

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right around 400 with the A/C on, my 6liter 04 idles around 600 as all the other chevys I have own it idles about 750 in park no a/c but when I put it in drive with the ac on it drops about 300 rpm`s seems low. when in park with ac on it ldles about 700 just drops about 300 when it goes in drive

snoman · June 6, 2006

Where does it idle with the AC off?
As I recall, my old 97 suburban would idle at about 400.

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right around 400 with the A/C on, my 6liter 04 idles around 600 as all the other chevys I have own it idles about 750 in park no a/c but when I put it in drive with the ac on it drops about 300 rpm`s seems low. when in park with ac on it ldles about 700 just drops about 300 when it goes in drive

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Not a 5.7, My 2000 5.7 idles at about 500 to 550 A/C on or off in gear.

evan · June 8, 2006

REPLACED THE IAC, IT FAST IDLES THEN SETTLES DOWN AROUND 600 IN PARK , WITH AC ON STILL AROUND 375RPM GOING TO RUN SOME LUCAS FUEL INJECTOR CLEANER TOMAROW WE HAVE A 1200 MILE TRIP BACK HOME ..

redvett · June 8, 2006

I would say you are not getting an A/C signal to the ECM. You need to have someone with a scanner read the IAC counts and see if the A/C is being enabled when turned on. Injector cleaner isnt going to fix an electrical problem.

snoman · June 8, 2006

I would say you are not getting an A/C signal to the ECM. You need to have someone with a scanner read the IAC counts and see if the A/C is being enabled when turned on. Injector cleaner isnt going to fix an electrical problem.

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I would agree with this. When AC is switched on (compressor engages) it sends a signal to ECM to step idle up.