idle - ZR-1 Net Registry Forums

icarus-54 · 07-15-2013

Hi guys,recently bought zr-1 #361,and have a problem with the idle taking too long to come down.It takes sometimes over a minute to return to 750.It seems to come down in stages which makes me think its the iac.These cars are a totally different animal to me as I come from the sy/ty world.I don't believe its a vacuum leak as it does come back but its a real pita to drive. If anyone has any ideas,I would be most grateful.
thanks,Jack

It is the IAC and its doing what its supposed to do, at least based on the stock calibration for the 90. It can be changed and the rpm decline sped up. However, the LT-5 wants to stall and if the Throttle Follower reacts to quickly, it will do that. Modded motors are more susceptible to this. But before doing any cal changes, make certain everything is nominal mechanically. IAC and port should be clean. Make sure throttle plates are also clean. Check TPSv at idle. Should be > .53v but < .57v.
BTW, its an SD motor so many of the Sy/Ty stuff applies. I learned using an 84 Xfire. Much applicable when it comes to tuning.

07-15-2013	#1
icarus-54 Join Date: Jul 2013 Location: Mt.Bethel Pa. Posts: 72	idle Hi guys,recently bought zr-1 #361,and have a problem with the idle taking too long to come down.It takes sometimes over a minute to return to 750.It seems to come down in stages which makes me think its the iac.These cars are a totally different animal to me as I come from the sy/ty world.I don't believe its a vacuum leak as it does come back but its a real pita to drive. If anyone has any ideas,I would be most grateful. thanks,Jack It is the IAC and its doing what its supposed to do, at least based on the stock calibration for the 90. It can be changed and the rpm decline sped up. However, the LT-5 wants to stall and if the Throttle Follower reacts to quickly, it will do that. Modded motors are more susceptible to this. But before doing any cal changes, make certain everything is nominal mechanically. IAC and port should be clean. Make sure throttle plates are also clean. Check TPSv at idle. Should be > .53v but < .57v. BTW, its an SD motor so many of the Sy/Ty stuff applies. I learned using an 84 Xfire. Much applicable when it comes to tuning. Last edited by XfireZ51; 07-15-2013 at 03:54 PM.