i have a 94 z28 that is bone stock, engine wise. im just wondering what the normal idle speed should be b/c mine seems a bit high. once it has warmed up and settles, it stays at 1000 rpm and never falls below that. is this normal? if not, what can i do to rectify the situation?

thanks,

Mike.

 

Don't forget the tach is probably off some. Mine on a cold start sits at 1500 for a bit, settles to 1000, then 800 when warm, then 600 in drive when warm. The stock tach is off a few hundred rpms, the only way to get a for sure reading is a different tach or a computer scanner.

 

my car does the same sits at 1000 the whole time idleing

 

The stock PCM settings for a fully warmed up engine:

M6: 800rpm

A4: 650rpm in neutral; 550rpm in gear

 

fred, is there anything i can do to get it down to the proper idle speed?

 

check for air leaks on the intake

 

The best thing to do would be to put a scanner on it.

First, check the RPM reading on the scanner.... that will eliminate the inaccuracy of the stock tach. Mine always showed 900rpm on the tach, and 800rpm on the scanner.

Then check the IAC "counts".... should be in the range of 20-40 counts. If the IAC counts are low, it could indicate the engine is getting air from another source, like a vacuum leak.

 

thanks for the reply.. i have ordered a aldl cable to do the scanning via my laptop and will try and track down the things you suggested.

 

Once you get a cable, you can download a free trial version of tunercat. Buy the Lt1 definition file for $20, then read your pcm file. And see where it's set at. And adjust if needed