GMC takes long to idle Normal?
Question:
—–BEGIN PGP SIGNED MESSAGE—– Hash: SHA1 Anyone have recommendations; I have a 89 GMC 350. The truck runs great, only after it’s warm. Takes at least 5-10 minutes. If I only wait 2 minutes, the engine idles way too high, I can feel it on the brakes and sounds loud. I tried to get a tune up in hopes of this condition gone, but it’s still there. Don’t understand…. Any ideas Ron —–BEGIN PGP SIGNATURE—– Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPAglWMw5z0pvhH5qEQJkUwCgxlFK7tpuA3ju1Z0kInTaRfPtsB4AoLcK Vt8ItT49LjT0zmk9ErmjifJ8 =Ln05 —–END PGP SIGNATURE—–
Response:
Two items comes to mind, in no particular order: First, the IAC (Idle Air Control) valve is either worn and not seating completely or has dirt build up on the valve seat or pintle allowing air to pass even when valve is closed, which will raise your idle. Either remove and clean the IAC or replace the unit ($50-60). It is screwed into the back of the throttle body and has a wiring connector attatched to the end. Simple 15 minute job requiring only the removal of the air cleaner to gain access to the IAC and an open-end wrench to remove and replace the unit. Be sure to swab inside where the valve goes to remove any dirt from the seat inside the throttle body before replacing the unit. Second, the gasket under the throttle body may have a crack in it allowing air to enter on the intake manifold side of the TBI. Very common problem with the older 350’s which was corrected by using a fiber based gasket in the later units. Fairly easy 45 minute job (or longer is extensive cleaning of the old gasket is required), but requires unbolting and lifting the TBI from the intake manifold. New gasket costs only $5-7. Good luck – Jonathan — Acta Non Verba – Deeds Not Words Jonathan Race, Lieutenant EMS Supervisor, EMS-7 A-Shift Orange County (FL) Fire-Rescue Department
– Hide quoted text — Show quoted text -> —–BEGIN PGP SIGNED MESSAGE—– > Hash: SHA1 > Anyone have recommendations; > I have a 89 GMC 350. The truck runs great, only after it’s warm. > Takes at least 5-10 minutes. If I only wait 2 minutes, the engine > idles way too high, I can feel it on the brakes and sounds loud. > I tried to get a tune up in hopes of this condition gone, but it’s > still there. Don’t understand…. > Any ideas > Ron > —–BEGIN PGP SIGNATURE—– > Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> > iQA/AwUBPAglWMw5z0pvhH5qEQJkUwCgxlFK7tpuA3ju1Z0kInTaRfPtsB4AoLcK > Vt8ItT49LjT0zmk9ErmjifJ8 > =Ln05 > —–END PGP SIGNATURE—–
Response:
I would check TBI Base plate gasket , they like to leak air and cause a Hi Idle
—–BEGIN PGP SIGNED MESSAGE—– Hash: SHA1 Anyone have recommendations; I have a 89 GMC 350. The truck runs great, only after it’s warm. Takes at least 5-10 minutes. If I only wait 2 minutes, the engine idles way too high, I can feel it on the brakes and sounds loud. I tried to get a tune up in hopes of this condition gone, but it’s still there. Don’t understand…. Any ideas Ron —–BEGIN PGP SIGNATURE—– Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPAglWMw5z0pvhH5qEQJkUwCgxlFK7tpuA3ju1Z0kInTaRfPtsB4AoLcK Vt8ItT49LjT0zmk9ErmjifJ8 =Ln05 —–END PGP SIGNATURE—–
