Eriko5000 Posted March 25, 2022 Share Posted March 25, 2022 So yesterday I pulled my throttle body off to clean it. The thing was filthy (Like, maybe has never been cleaned in its 30+ years of existence filthy). Cleaned the throttle body and and got it put all back together, test drive the truck and it's idling at like 2,500 RPM's. Checked everything and the butterfly valve is cracked open in its resting position. So I've found the screw that I need to adjust to get it to close tighter. A little hex screw.. With the Hex head inside this hole.. I can't get it to budge.. I'm hitting it with PB blaster, WD-40, and it won't move. How do I break it free? Without breaking any hex wrenches? Can I grab the threaded part, sticking out with Vice Grips? That would probably wreck the whole thing. Also, could there be another cause of the crazy high idle? Anything I need to look out for? Link to comment Share on other sites More sharing options...
Ωhm Posted March 25, 2022 Share Posted March 25, 2022 You might not have to move it all. Do this first: http://cruiser54.com/?p=94 Link to comment Share on other sites More sharing options...
jdog Posted March 25, 2022 Share Posted March 25, 2022 http://cruiser54.com/?p=94 http://cruiser54.com/?p=54 Also did you clean the iac, replace the gasket, check for vacuum leaks? Link to comment Share on other sites More sharing options...
Eriko5000 Posted March 25, 2022 Author Share Posted March 25, 2022 20 minutes ago, jdog said: http://cruiser54.com/?p=94 http://cruiser54.com/?p=54 Also did you clean the iac, replace the gasket, check for vacuum leaks? I cleaned the IAC and was able to reuse the gasket. Checking for vacuum leaks if my next step before I kill myself trying to adjust that screw. I read where car computers will typically take a bit of time to correct and adjust the idle air levels. Is an '89 Comanche too old for the onboard computer to do that itself?? Link to comment Share on other sites More sharing options...
Eriko5000 Posted March 25, 2022 Author Share Posted March 25, 2022 I did see somebody talking about the IAC, that when installed you may have a high idle, that driving the car at normal temps and over 40 MPH for a few minutes would allow the ECU/computer to reset the IAC so it controls the air like it's supposed to. Could that be my issue? Link to comment Share on other sites More sharing options...
rokinn Posted March 25, 2022 Share Posted March 25, 2022 I was having similar issues. After replacing a failed MAP sensor my idle was still running about 1250 or so. I had previously adjusted the butterfly to the .003 recommendations with a flat feeler gauge. Decided to close it down to almost imperceptively open. Brought the idle down to about 1000. Decided it was time to do Cruisers tip 31 map hose conversion. That made a big difference. Now fluctuates between 750 and 950 or so depending on engine temp and running time. Next will be to replace the broken rear lower stud on the exhaust/intake manifold. Once I'm convinced winter is over. Good luck to you! Link to comment Share on other sites More sharing options...
Eriko5000 Posted March 25, 2022 Author Share Posted March 25, 2022 35 minutes ago, rokinn said: I was having similar issues. After replacing a failed MAP sensor my idle was still running about 1250 or so. I had previously adjusted the butterfly to the .003 recommendations with a flat feeler gauge. Decided to close it down to almost imperceptively open. Brought the idle down to about 1000. Decided it was time to do Cruisers tip 31 map hose conversion. That made a big difference. Now fluctuates between 750 and 950 or so depending on engine temp and running time. Next will be to replace the broken rear lower stud on the exhaust/intake manifold. Once I'm convinced winter is over. Good luck to you! As I was trying to figure out how to adjust the butterfly position via that screw, I noticed in a picture I had taken of it that the arm that sits against that screw looked a bit bent, holding the butterfly in a slightly more open position. I took some pliers and bent it back straight a little bit, and now the truck is idling at about 1,200-1,500 RPM's. Way better than 2,500 RPM's! There's still some room to bend it straighter, so I'm hoping that'll help me get it down the rest of the way to 700-900 RPM's at idle. Link to comment Share on other sites More sharing options...
Ωhm Posted March 25, 2022 Share Posted March 25, 2022 3 hours ago, Eriko5000 said: I did see somebody talking about the IAC, that when installed you may have a high idle, that driving the car at normal temps and over 40 MPH for a few minutes would allow the ECU/computer to reset the IAC so it controls the air like it's supposed to. Could that be my issue? There is a relearn procedure for when the battery is disconnected. Have you disconnected your battery recently? 88 FSM Computer Relearn Procedures.pdf The 3 thou is a calibrated air leak setting. This allows the pintle on the IAC to be in such a position for idle air bypass control. That is too say, a good place for the pintle to move in or out of the air bypass chamber. Also this setting will prevent throttle plate freeze up/lockup during extreme cold temperatures. Link to comment Share on other sites More sharing options...
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