1988 Pontiac Grand Am High idle?

1988 PONTIAC GRAND AM

188,000 MILES • 4 CYL • FWD • MANUAL

WITEHOWLR

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My car, on the way to work, just started idling at around 3000 rpms. I've tried multiple things to fix it, but can't figure it out. It's a 1988 Pontiac Grand Am SE with the 2.3L DOHC and a 5 speed. I've tried swapping out the IAT sensor, the MAP sensor, the TPS sensor, and after all that even disconnected the battery, and the car still idles really high. I let it idle for a minute and the SES light came on. I checked it and it gave me a code 36, which isn't in my service manual. I replace some of the vacuum lines, since someone told me it might be a vacuum leak. I replaced many of them that seemed poor condition, even tried plugging off some of the 'accessories' run by it, such as the cruise control and such, but nothing worked. Any other ideas, maybe?

Aug 10, 2008 at 10:45 PM

RASMATAZ

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Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft and a defective idle speed speed control motor/valve stuck in the extended (high idle speed) position/throttle position sensor. Also the throttle plate could be binding in its bore and kinked accelerator cable, coolant temperature sensor might not be operating properly misleading the computer that the engine is still cold and computer throwing fuel at it raising the idle speed.

Aug 11, 2008 at 3:24 AM