Need to adjust Idle on FRPP 70mm T/B!!! (ASAP)

The throttle blade set screw is not the problem. By unplugging the IAC from the harness you are elminating the ECU control for idle and relying soley on the TB blade position.

The car would do exaclty what yours did when you removed the IAC from the harness, idle down to the point of almost stalling. That means the TB blade position is correct.

I wouldn't play with the TB blade set screw. It will not alter the idle.

If your tps is now within range, and your throttle blade is closing, my guess it you've got a vacuum leak. somewhere. You can use a propane torch to find it.

You might want to tell him how to use that

You can do the same thing with carb cleaner or brake clean. When the motor is cold and running, spray a small amount of either around any connection and listen for a change in idle. If it changes you have a leak. If it doesn't move on to the next one.

UDTBadkarma said:

Hmm i'll try and give this a shot. And wouldn't you use propane for for a failing or misfiring piston/cylinder? Why or how would you use it for vacuum leaks?


yeah the motor is still throwing the "vacuum leak" code. Think my ported intake has something to do with it?

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While the engine is running, pass the UNLIT torch over all vacuum lines, past the intake manifold gaskets, etc...should you pass the nozzle of the UNLIT torch near a vacuum leak, the idle speed of the engine will increase momentarily because the propane will be sucked in through the vacuum leak and burned as fuel inside the engine. Listen carefully for a rise in engine rpm's.

UDTBadkarma said:

Yeah figured thats where you were going with that. So maybe i'll look into it this weekend when i have access to one at my shop.

Also....what if there IS a vacuum leak?? put a clamp over the hose to seal it better?

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Depends on the leak, could be a gasket leak around the throttle body or plenum, or it could just be one of the small hoses wasn't hooked back up or came loose.

Yes, the o-ring gasket is normal it's the only one under the plenum.
Sounds like it's your TB to P gasket unless you have a crack in your plenum after it was ported, just a thought!

Go to Autozone & buy the gasket material - they sell rolls of it for $4. Then just trace & cut your own.

drill 1/4 hole on blade !

a97mustang said:

drill 1/4 hole on blade !

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do not do this!!

I sure wouldn't be drilling that, personally.

I'm beginning to think your problem may lie elsewhere. If you didn't hear a hissing or something when you put your hand over the throttle body when it was running, then there is a major problem somewhere. Unless, you didn't cover it completely. My hand gets sucked to the TB when I get about a centimeter away from it, and it holds on for a second, while the engine stalls completely. Your IAC can allow air in, but I wouldn't think enough to keep the car running with a completely blocked TB.

I would check that IAC, the gasket it has mounting it, the EGR and it's gasket, and the upper plenum mounting gasket.

Remove any mods like the IAC restrictor, whether it be the plate or the copper cap, and start it up.

Make sure the two hoses running to the intake tube are connected, and that the clamps that hold it to the TB and to the MAF are snug.

Make sure the IAT sensor is in place, and the MAF is plugged in.

Look everything over, and make absolutely sure that there are no openings at all between that TB and the MAF.

Start it up, and listen for where you hear the most wind noise. If the idle never drops, while it is running, go to town with carb cleaner. Spray everything shy of the COPs. If the spray doesn't change the idle in any way, then the problem isn't anything you did, it's a coincidence that happened elsewhere on your car. Try a little spray around the lower intake to head connection even. Hell, spray by the coolant crossover. Those hairline cracks can be hard to see on black plastic.

Do you have a tune loaded, or a chip perhaps? Something may have been adjusted, because the last plenum may have had a defect that caused a low idle.

Did you mess with the set screw that holds the new TB blade open at all? The blade should just come to complete close on it's own, and not stick at all. If it's held open at all, too much. If it closes too far and sticks a little when you try to move it, not open enough.

Last thing I can even think of, is possibly the DPFE EGR pressure sensor. There may be something funky going on with that. You should try to get a good video of everything that is happening; maybe we can see something you do not.

Just take it to a shop and be done with it.