Item Posts    Sort Order

1993 vette high idle (1500rpm's)

I love my Chevy Chevette!
Posts: 1
Joined: 11/10
Posted: 11/03/10 10:26 AM

can't seem to get idle to go down.idle conrtol valve replaced, egr replaced. new plug wires and distributor. any ideas?  

Post Reply
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 11/03/10 11:51 AM

to really know whats going on..... you are going to need a scan tool...

look at the coolant temp sensor reading... 210F to 240F warmed up..

look at the Throttle position sensor voltage..    0.5 to 0.98 volts.

look at the idle air counts...     20 to 50...

has anybody messed with the throttle body idle speed screw..

can you with the engine off.. use a hand and open the throttle part way.. see if the throttle shaft has any wear...  this is only noticeable when operated by hand.. and the throttle is part way open..

got any vacuum leaks...  from the power brake booster hose???  from the PCV...    from the various vacuum hoses...

i have run into problems with some mechanics that only change things when the check engine light is on.. they don't diagnose things..

print this chart...


take it with you if you don't have a scan tool...

have the tech write down the scan tool data on the proper line...  

there are more lines on this chart than your car will display...

so start with the first data stream in the scan tool.. write it on the proper line...    when you get to the last line of data... then you can compare it to what the chart says it should be...  

Post Reply
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 11/03/10 11:58 AM

warning.. a lot of the current crop of consumer scan tools does not display live data on these systems...

you are going to need somebody with almost any serious professional scantool

snap on MT2500...

otc monitor 2000, monitor 4000, 4000E  OTC genisys..

there are a few actron CP9110 scan tools floating around with a gm cartridge and cable..     these can be found on the craigs list also...

i just called SPX corp.. who make autoxray.. OTC and actron    they said the OTC 3499N is the current one to buy that will display live data on both obd2 and OBD1 systems...  not cheep.. but not as expensive at a professional version...   most places sell them for under 500 bucks..  sorry... the first scan tool i bought was 1400 bucks...  

Post Reply