91 exp idle/coolant problems

[91expy]

91 auto exp eb

It has a very high idle when you start it up and sits around 1500-2000K. I reset the EEC and it went away for a bit, and the problem returned. Today i took off the IAC and cleaned it out i was built up with carbon. When I put it back on it didnt solve the problem, but if i unplug it i can idle @ 600rpm. Also for some strange reason when the truck is running it spit up antifreeze from the overflow, i mean gushing out. Its not my truck and my sister took it in for an oil change and she can remeber if they added any fluid. I have never heard of a coolant overflow with out someone over filling the bottle. I also hear a slight hising from the brake booster gromet should i replace the hose and grommet or just rtv the gromet? Theres one other stange problem, on the coil pack (if your facing the vechile under the hood) the farthest in the back to the drivers side has corrosion dust when you pull the plug wire. I have dielectric and it is still firing the spark plug, should i be woried about it? No other coil socket has the problem. One last question does anyone know why the anti theft sometimes chirps, and other times dosent
maybe a bad siren?

anyways TIA

 

[ExplorerDMB]

your IAC is fubar. When you said you unplugged it and it idled fine that's a perfect indication that the IAC is gone. If you want hit the IAC while its running and see if it trys to lower the idle any. I think you need a new one.

-Drew

 

[marragtop]

The gushing anti-freeze could be a bad radiator cap or a blown head gasket. Start by checking the cap.

 

[91expy]

well heres an update i changed the rad cap, IAC , pcv, cleaned the maf, cleaned TB, and did the seafoam bit. it ran and idled great for a bit with the old IAC while the seafoam smoke screened my area. But now the new iac makes the idle race to 2k till i unplug it and get 800. I did notice the over flow seems either to have steam or exhuast billowing out of it. I hope its not HG's b/c the car runs fine regardless, just the idle problem and the antifreeze anyone shed some light?

 

[savagefan]

You still have that vacuum leak at the brake booster to take care of, make sure it is the only leak, sometimes hard to track down so listen close. Is the anti freeze brown or smelly?

 

[91expy]

i checked the lines and put some rtv around the booster gromet. The anti freeze looks green, but it shows its a year or so old. i guess ill try checking with some propane tommarow

 

[BrooklynBay]

Welcome to this forum! The reason that your vehicle is racing with the new IAC is because the computer is going through a new learning process. When it sets a new pattern that is correct, it will lower the idle to the proper amount. Don't unplug it. Just drive with it plugged in, and it will be OK after a while.

 

[91expy]

I wouldnt be so sure about that, it runs great when you start it up but after you drive ten miles or so it will race up to 15oo rpm if you put it back into park. Ialso notice the temp gauge goes pretty close to hot Impretty sure that the tstat is working due both hoes being equal temps, and the clutch fan works fine. Could it just be the temp sender, and could the tps cause the high idle?

 

[BrooklynBay]

If the TPS would be bad, or misaligned, it would show a CEL. Did you try to flush out your cooling system lately? Maybe there is a sludge buildup which is causing the overheating problem. The thermostat could be sticking at various times (intermittantly), so it might not be apparent that it is bad. It might be possible that it is not overheating at all. The temperature sending unit could just be out of spec at certain temperatures. I've replaced that part, and it is pretty cheap if you want to try it.

 

[savagefan]

For the dust at your coil pack, how are the relevant spark plugs? Pull the intake hose offf the throttle body and see if it's dirty if so clean it up inside may be holding the throttle open slightly.