My Blazer wants to go fast…whenever it chooses. The idle will bump up to 2500-3500 whenever it wants. The local shop put it on the magic computer and the tech said the computer is sending a command to the idle air controller to boost it up but he said there are so many inputs to the computer it could be any of them. 4 hours and he gave up.
Additional info
-putting in clutch and pressing brake just hard enough to light up brake lights but not slow car will bring idle back to normal after 2 seconds.
-It’s really fun on the ice!!!
-Air on or off no difference.
-Does when cold or hot engine (temp runs just under middle of scale when warm)
-Seems to have started when they replaced the radiator
-Cold outside air temp may make it a little more common but it does when 100 degrees too.
-Cleaned throttle body and replaced idle air controller twice, no help.
-Think Blazer down deep wishes it was a Ferrari.
Me again…forgot to say
Blazer is 1999 V6 4.3 Liter 5 Speed
When it revs will sometimes stay at high RPM or will fluctuate between 2500 and 3500, up and down, back and forth. Not consistent.
Thanks!