97 PU idles too fast

Greybeard · Dec 10th, 2005, 05:42 PM

So far, everything is fine - lots of new found power, willingly revs right up (but its still in the breakin mode...) and even the chain doesn't rattle on startup.
BUT.....
Before rebuilding the head and bottom end, this 97 KA24e had no cold/warm idle problems. Since then, right after cold startup it idles around 1500-1700 for about 2-3 minutes then drops to about 1300 and stays that way, all at once returning to 750-800 when it gets completely warmed up. The cold snap hasn't changed anything other than extend warm up time. If I retard the timing about 6*, it slows down to about 1000 but loses a lot of power. Advancing just makes it idle even faster. In the morning its not so bad because there's no traffic and only 1 stop sign in the first 10 miles. At night coming home, it's stop and go for the first 3 - 5 miles. I'm really anal about making clutches last forever (128,000 so far on my 86 Trooper, 100,000+ on my MGB and 8 years of using my farm tractor as a front end loader...) only because I have to change disks in my Mustang every season to stay competitive, and that's more time than anyone ought to have to spend on one's back lying on concrete.... And while this fast idle isn't a big deal for a couple weeks, it is a pain in the butt. The other problem is how quickly it accelerates at a 1500 rpm idle in heavy traffic.

I'm reasonably certain that there aren't any vacuum leaks, and I did a resistance check on the computer coolant temp sensor - it was fine.
Any suggestions?

79kz400 · Dec 10th, 2005, 07:24 PM

Congrats on the rebuild man!

This happened to me to when i cleaned my intake system with seafoam and no one here helped me solve it. First i replaced all my vaccume lines to be sure that wasn't the problem. I finally took off the idle air control valve and cleaned that. Didn't help much. Then i adjusted the idle screw and got the RPM's down around 850 ( Was sticking about 1250 ). Pull up your FSM and goto page EC-27 and there's a picture of the idle adjustment screw.

dvdswanson · Dec 10th, 2005, 09:22 PM

congrats on being moble again. I think you need to look at the 15-1700 problem. on cold starts mine is 12-1300 then drops when warm. I don't think it's you FIC because it drops down to normal when warm. look at EC-72,73 for the basics, sounds like you started some of it but check it all. and make sure your connections for the IAC and TPS are good.

got mud? · Dec 12th, 2005, 11:06 AM

first have you unhooked your battery if not try this cause the computer will have stored the setting for your iac and tps and now that you have a cleaner build (engine) the settings are to high if that doesnt work check your linkage for the choke and f.i.c.d it may need lubed up or just adjusted down sound to me like your f.i.c.d isnt kicking out after warm up good luck