ZR-1 Net Registry Forums  

Go Back   ZR-1 Net Registry Forums > C4 ZR-1 > C4 ZR-1 Technical Postings

Reply
 
Thread Tools Display Modes
Old 12-14-2003   #1
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default Idle speed high then slowly comes down.

My 91 zr1 seems to hold a high idle (1200) when cold then drops down to the 700-800s where it should be. as it warms up it slowly goes away. Somewhere I read there is a prom fix for this. How to get it? How much? Or is this a vacuum leak and we should start thinking about a pull of the plenum? Your thoughts!
Anonymous is offline   Reply With Quote
Old 12-14-2003   #2
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

My idle stays at 1000rpm's until I come to a complete stop than it drops to around 700 it’s a little slower to drop with the AC on as far as when its cold that sounds about right.. If you have a vacuum leak, you will hear the pump running with just the key on engine off. It should come on when you first turn the key on than cycle off.. You may hear it cycle about every 60 seconds this is normal. If it runs continually, you have a vacuum leak..
Anonymous is offline   Reply With Quote
Old 12-14-2003   #3
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

so this is normal. wait ac is not on at the time. Gotta check an ac relay as the compressor is not kicking on. fuses are fine and no codes on the console for ac.
Anonymous is offline   Reply With Quote
Old 12-14-2003   #4
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

High idle when you come to a stop and then drops down is usually a PROM update issue on '90 and '91 ZR-1's. See http://www.zr1.net/ZR1_issues.html#2for more info. A new PROM is around $50.(Edited by ZR1Mom at 2:51 pm on Dec. 3, 2002)
Anonymous is offline   Reply With Quote
Old 12-14-2003   #5
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

I checked I have the updated chip...I have noticed after changing to the Flowmaster system the idle stays up at 1000K until I come to a full stop.
Anonymous is offline   Reply With Quote
Old 12-14-2003   #6
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

It also could be dirty throttle body plates or dirty IACvalve.
Anonymous is offline   Reply With Quote
Old 12-14-2003   #7
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

Thanks.. any tips on cleaning.. can't be to dirty only 25K on her..
Anonymous is offline   Reply With Quote
Old 12-14-2003   #8
Anonymous
 
Join Date: Dec 2003
Posts: 491
Default

Take some brake cleaning fluid. Remove the horn on thethrottle body and flip the plate up and look behind it.I'll bet it is pretty dirty.
Anonymous is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:58 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ZR-1 Net Registry 2020