Ivan Posted July 27, 2006 Share Posted July 27, 2006 Have a 1991 V8 3.5 EFI discovery. The problem I am having (and have been for some time) is that I can't seem to get the tickover revs correct. It tends to tickover at about 1100 rpm instead of 7-800 rpm. I have adjusted the allen bolt on top of the plenum (idle air valve ?) which has brought it down some but not enough. The screw has now been turned fully clockwise (I think) which did drop the tickover revs but not enough to bring iot down to the 7-800 rpm it should be. Sometimes just after starting it will settle to about 750 rpm but as soon as I use thethrotle it goes up again. Any clues ? TIA Ivan Quote Link to comment Share on other sites More sharing options...
MogLite Posted July 27, 2006 Share Posted July 27, 2006 Sticky throttle cable/linkage Poor return spring on the linkage ? Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted July 27, 2006 Share Posted July 27, 2006 Provided that you have no air leaks on the inlet side, then it looks like the IAC is probably gummed up and sticking. As it’s a 91 I am assuming it will be a hot wire ………. The IAC (Idle Air Control) is a stepper motor on the rear of the plenum ………. Remove it and carefully give it a clean …… but don’t be too rough as they are expensive …….. usually a good clean will do the trick. However, as I said before……… check for air leaks on the vacuum side as often a small split in a pipe will give the same symptoms Ian Quote Link to comment Share on other sites More sharing options...
Ivan Posted July 27, 2006 Author Share Posted July 27, 2006 Thanks for the info guys. I'll check for leaks and give the tsepper motor a clean. Cheers Ivan Quote Link to comment Share on other sites More sharing options...
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