Just performed the ever-famous cluster swap with a salvaged donor truck so I can finally have a tachometer. How cheap of Ford not to just have it as standard equipment, especially on manual trannys. Anyhow...

My idle after normal engine warm-up is barely under 1000. Its slightly hard to tell because of the fat needle and the relatively small size of the gauge. I'd say probably 950 at the lowest. The truck is a '92; oldest vehicle I've owned. This will be an ignorant comparison to make, but my mustang idles at like 650-700. What gives? Is this about average for my engine (300) and year? If not, any suggestions as to why its high, or how I can go about fixing it?

 

While 700-800 would be ideal, my truck likes to hover around 1000.

 

my '89 hovers around 700-800 i had intake gasket problems and when i fixed it i had to adjust my idle. im not saying thats where its supposed to be set at thats just where i have mine set. it runs just fine.

 

Is it an Auto or Manual trans? An automatic's idle speed is adjusted with the vehicle in gear. If your truck is an automatic trans, start it up, put it in gear and see what the idle speed is then. Most likely, it'll be around 800 and will increase slightly when in neutral, this is normal. If it's a manual trans then it should idle around 700 -800, keep in mind the factory tach is not the most accurate gauge in the world, none of the factory gauges are for that matter. They give more of an estimate than an actual reading. That's why I'm putting all AutoMeter gauges in my truck, I'd like to know EXACTLY what my truck is doing....

 

Manual trans...

Well sounds like everyone hovers around the range that mine is in, I was just curious. I know the factory gauges are more of an estimation (hahaha) and the needle is so fat my actual range could be anywhere between like 8000-9500.

Thanks guys

 

If you want 700 rpm at idle, with the engine at norm. op. temp., with the truck idleing, have someone disconnect the IAC while you have your foot on the accelerator. The engine will start to stall. With the accelerator, keep the idle at 700 RPM. It will fight at first, but settle in after about 45 secs. Maintain Idle at 700 rpm for 2 full mins. after that, then shut off the engine, plug the IAC back in & after waiting 1 minute, restart. Let Idle for 2 mins.,shut off 1 min. Restart and w/ foot on brake, put in gear & let idle for 2 mins. shut off 1 min. For Manual trans during that 2 mins., create an engine load by having accessories on for the 2 mins.. A/C & fan, headlights ect. then shut off 1 min. Your resetting the IAC range. Usually just disconnecting the Battery for 5 mins., which clears & causes the KAM to rebuild will do it. If not, re-ranging the IAC will! 800 -1000 rpm is too high! My 302 idles at 650-675 rpm. These procedures assume you have good Vac system integrity & no currently active codes!!!

 

Excellent guide, thank you. I do have active codes however, so I'll have to wait until I get all of those cleared out and repaired before I'll be able to perform this.

 

When you do get rid of the codes, go ahead & clear the KAM first. What codes do you have left? If the ECU locks out a sensor for continually being out of range, that's the easiest way to get rid of the code sometimes, after the problem has been rectified. This is when a sensor still reports out of range even after it's been replaced.

 

x2........