The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Help, High idle problem TBI, how the heck do you get it down.

**A1971Blazer** · 01-04-2018, 08:20 PM

check all the vacuum lines for cracking...high idle is usually a vacuum leak....
also as someone stated check the coolant temp sensor AND the connector....
but usually if either one is bad you will get a rich condition in addition to a high idle...if the pcm sees a cold engine condition it will dump in extra fuel....
also check the IAC for proper operation....this controls the amount of air going in at idle...
and check the TPS voltage at idle...you may need to tweak it a little.

read here...http://www.gmtuners.com/tech/TPS_IAC.htm

01-04-2018, 08:20 PM	#5
A1971Blazer Senior Member Join Date: Nov 2013 Location: East Tennessee Posts: 2,107	Re: Help, High idle problem TBI, how the heck do you get it down. check all the vacuum lines for cracking...high idle is usually a vacuum leak.... also as someone stated check the coolant temp sensor AND the connector.... but usually if either one is bad you will get a rich condition in addition to a high idle...if the pcm sees a cold engine condition it will dump in extra fuel.... also check the IAC for proper operation....this controls the amount of air going in at idle... and check the TPS voltage at idle...you may need to tweak it a little. read here...http://www.gmtuners.com/tech/TPS_IAC.htm __________________ 1967 C10 Step side 1968 C10 Step side 1970 Chevrolet K/5 Blazer 1972 Chevrolet K/5 Blazer .............