pr8head Posted November 8, 2009 Share Posted November 8, 2009 I messed with the untouchable throttle postion screw on my Loyales spfi . I have a Haynes manual which doesn't tell how to set the idle on the spfi. My alternator is a lil on the weak side and at 800 rpm it can't keep up with fans, radio, lights, etc. So I wanted to bump the idle up to 1000 rpm. I adjusted the (wrong) screw and I was idling at 1000 and for about 3 days it worked like a charm. BUT now it idles at 2000 and it revs up the 2500 if you just touch the gas pedal and slowly settles back to 2000. I have tired to reset the screw but I can't find the sweet spot. I have cleaned the IAC and my idle adjustment screw. I have tested all the sensors on the throttle system and they all work (at least according to my Haynes manual ). I have checked for vacuum leaks and just put a new fuel filter. If I unplug the IAC it will kick down to normal idle and runs fine if warm but wont restart if IAC is left unplugged. I have tired to set the idle with the IAC unplugged but it doesn't really seem to change much and if backed out very far the engine stumbles when revved. How can I get my car to forgive me? Help me Obi Wan you are my only hope! PHins UP!!! ~~^~~ Tim Link to comment Share on other sites More sharing options...
dhise Posted November 8, 2009 Share Posted November 8, 2009 (edited) You'll have to search but I do remember a thread where the procedure for setting the screw that you're not supposed to mess with was described. edit: here's the thread http://www.ultimatesubaru.org/forum/showthread.php?t=80073&highlight=spfi+stop+screw Edited November 8, 2009 by dhise Link to comment Share on other sites More sharing options...
pr8head Posted November 8, 2009 Author Share Posted November 8, 2009 Thank You INFINITY!!!!!!! I'm headin out to try it now PHins UP!!! ~~^~~ Tim Link to comment Share on other sites More sharing options...
WoodsWagon Posted November 9, 2009 Share Posted November 9, 2009 I'm not sure if the spfi ECU's have an A/C on input, but many fuel injection systems do. When the A/C compressor is commanded on, it signals the ECU to up the idle a couple hundred RPMs. You could wire a switch to that input so that you could up the idle speed when needed. Link to comment Share on other sites More sharing options...
markjw Posted November 9, 2009 Share Posted November 9, 2009 I messed with that screw a while back. And, regretted it. I had all the bad idle issues your talking about and I could never quite get it set right. I did actually get it really close to where it was tolerable,but,of course,I messed with it again,and made it worse. Very worse. It's only function,as far as I know,is to keep the throttle plate from sticking in the intake bore. If the throttle plate goes to a flat,90 degree horizontal position,and is allowed to cool,like your car sits overnight,then you come out to start your car in the morning,the plate will be siezed in the boar. The set screw is designed to keep the plate a couple degrees off horizontal so it doesn't do that. The plate can become so seized in the boar that it will actually destroy your throttle cable as your pumping on the gas pedel wondering why the heck the gas pedal feels weird. I know 'cause this is what finally happend to me before I "fixed" the problem. In the end,I went to the wrecking yard and found a throttle body that hadn't been messed with. You can tell a good one 'cause it will have dried white paint on the set screw that hasn't been disturbed. Thats what worked for me,anyway. Life is back to normal now. But,it was quite a horrible experience. Link to comment Share on other sites More sharing options...
pr8head Posted November 9, 2009 Author Share Posted November 9, 2009 91Loyale "I'm not sure if the spfi ECU's have an A/C on input, but many fuel injection systems do." I have gutted the A/C and removed the fuse. My car has so little power I figured with the A/C turn on it would start going backwards . markjw "In the end,I went to the wrecking yard and found a throttle body that hadn't been messed with." I'm REALLY starting to like this idea! dhise http://www.ultimatesubaru.org/forum/...pfi+stop+screw The link was very helpful. I did as it says and it is better but still very fast idle. It won't kick down to 800 any more. I have reset the TPS where it was at the high side of the 1.5* and at the low side with no difference. If I unplug TPS idle falls to normal. I have tried putting washers as spacers in the IAC and it makes no difference in the idle. I have turn the idle screw from bottomed out to about 3 turns out with no change in rpms. The only thing my idle screw does is make the engine stumble if turned out to far. It is makin me head hurt. PHins UP!!! ~~^~~ Tim Link to comment Share on other sites More sharing options...
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