Really Bad Idle
 

Just purchased a 1995 Mustang with the 3.8L as a project car.

The car has a brutal idle ... the car will choke down to about 600rpm and burp back up to 1100rpm and drop all over again. Also, when I put it in gear (auto tranny) the car will sometimes stall. :confused:

Is this something I could fix myself? And if it is ... What are the steps in following the proper procedure?

I had a similar issue when I needed a new IAC (Idle Air Control) Valve.

I thought it could of been something to do with the IAC or Throttle.

How much is a new IAC? Would it be more reasonable to try and clean the original first before purchasing a new one?

Before assuming it is a IAC, have you taken off the throttle body or any of the plumbing before the throttle body...?

You have a MAF in your intake and if your getting "UNMETERED-AIR" your car will run like a BAG! this is something else you should look into.

Having the smallest leak even between your throttle body and intake is unmetered air, so have a look even with propane "un-lite"

Thanks, I'll look into that. I'm going outside later to do a few things with the car and I'll tell you if that's what's causing the idle problems.

try and clean the iac first mine did something similer and after i cleaned it it was fine

MIL on?(money light) :LOL:

I took apart the air cleaner box (I've yet to find out where it is drawing air from, that's another mystery) and there was alot of preventing air flow so I cleaned everything out. The air filter itself wasn't too bad. I put everything back on and started it up .. After quick fire, and a quick idle adjustment, the car was running MUCH better, and it's not stalling anymore when put into gear. But it still sounds like there is the odd misfire. I think I might swap it out for a cold-air intake to save myself some headaches. As for the IAC, to my surprise it was as clean as a whistle.

Would a computer re-programmer help with the rest of the issue? I've seen a few but never really looked into it.

Take your MAF (Mass air flow) sensor out and spray it with brake clean, and/or electrical spray. you can get both from your nearest CTC.
But always remember to never touch the diode it self, only handle it by the housing, and do do try and rub it with a Q-Tip or anything else.

Good luck,

try to O2 sensor as well my stang ran like a bag of poor,idle,missfiring replaced that and everything was solved

idle air sensor?

Idle Air Control Valve (IAC)

yeah. if you look at the throttle body underneath where all the piping is, you'll notice another passage between the plate and the intake. also, there is something resembling a stopper at the neck of this extra "pipe". the computer takes all the numbers like ECT (engine coolant temp) and all that stuff and decides if the motor needs more air to run better or to warm up faster (more air + more fuel= you get the idea)... and depending on how much air the ECM decides the motor needs, it can open the stopper minimally, or all the way, and everywhere in between.

how does the car act after it is at normal operating temps? (ECT on the dash shows "normal"...that'd be midway.. duh)