Heinri_k Posted January 13 Share Posted January 13 Last week I cleaned my throttle body and installed a new IAC and upstream O2 in my 89 4.0. After installing everything worked great and my idle was a perfect 700 rpm. Driving the truck around and it warmed up I noticed my idle would go to 1200-1500 when warmed up. I drove the truck for probably about a 5 days like this and made a 180 mile round trip during this time period with no issues besides the high idle. I dug around on the forums and found that most likely I had a leak on my manifold that was causing this warmed up idle increase. Sure enough, the back bolt was loose and the bottom nut in the back was missing entirely. No big deal, I tightened the bolt and threw a new nut on the bottom and hand tightened them just to see if they would fix the issue and I would retorque everything if it was. I go to start the truck and it’s totally acting up. It barely idles at about 100rpm before misfiring, burping and eventually choking out after a few seconds. When it’s doing this, no amount of opening up the throttle will have any effect. Additionally after I turn it off it stinks of gas. Now I have undone the nut and bolt tightening as well as unhooking the IAC plug to see if either of these fix the issue. No dice. My vacuum lines have all been double checked and we’re completely replaced in May by myself. I have also tried clearing the computer by unplugging the battery and grounding the truck out. Since making this post I have re-tightened the nut and bolt thinking they’re probably not the reason for this and it’s either probably the IAC being faulty or possibly a massive coincidence of the distributor crapping the bed. I’m thinking I’m going to remove the IAC completely and see if I can get an idle at all, but otherwise I’m at the point where I might have to just process of elimination the thing. To me I’m getting the idea it’s either an issue involving lack of air or lack of timing. But I would love and appreciate any insight given. the video I added (if it posts) is what I’m dealing with when it turns over. IMG_1274.MOV Quote Link to comment Share on other sites More sharing options...
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