91 ZR1 Correct Idle Speed
09-24-2016, 03:54 PM
#1
Intermediate
Thread Starter
91 ZR1 Correct Idle Speed
What would be a correct idle speed for this Car? Stock and only Mods are headers and true dual straight exhausts. And K&N Filter setup to pull more cold air in from the bottom of the front end dam. Thanks in advance for your help!
09-24-2016, 07:37 PM
#3
Using the C68 control panel you could compare the TACH to what the ECM sees using the various parameters of the C68 control. This thread explains how to check various parameters using the C68 control.
https://www.corvetteforum.com/forums...post1577429729
If you have the FSM this information would be found very early in the 1C1 section, likely 1C1-1 thru 1C-5 or so.
09-25-2016, 02:02 AM
#4
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Welcome, About 750 warmed up, If the chip has been changed it may be set different. What WVZR-1 is referring to is, if I remember correctly there were 3 revisions in 91 proms. You would have to look at the prom to get the numbers here is a link on how to.
http://www.zr1specialist.com/HAT%20W...librations.pdf
http://www.zr1specialist.com/HAT%20W...librations.htm
http://www.zr1specialist.com/HAT%20W...librations.pdf
http://www.zr1specialist.com/HAT%20W...librations.htm
09-26-2016, 09:13 PM
#5
Instructor
When I got my '91 I thought I had a high idle. I used the A/C computer to check and the tach was off reading about 400 rpm high at idle. I found a thread on how to repair the tach by fixing the bad resistance in the tachometer for the C4 cars. While the ZR-1 is in a lot of ways unique, it is also susceptible to common C4 problems. I have a lot of them on my car and am sorting through them one at a time. I've fixed the ride control, stereo, LCD display UV damage and a lot of little things so far thanks to this site. I'm adjusting the tach now and then I will finally have my dash all back together. Next up is the fuel level sender. After that I will be doing the door panel droop repairs so commonly documented here too. Then I need to rebuild the PCV system on my LT5 which is unique to our cars.
Anyway, good luck, and don't be surprised to find out it's the tach and not your idle. In any case, you need to check it too.
Anyway, good luck, and don't be surprised to find out it's the tach and not your idle. In any case, you need to check it too.