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Discussion Starter · #1 ·
Last time I asked for help the engine was running rich at idle. Thanks Jan for the link to checking the FPR. I did find a clamp that was not tight enough on the return side, fixed that, but didn't completely solve the issue. It runs perfect 14.3-7 at idle but when I turn the air on it goes to 12ish...??? and the pressure doesn't raise when I block of the return.
Onto the problem at hand! Now the idle is high, around 1400ish. My idle was around 1k so I tried to do an AIS/idle reset to bring it down a couple hundred. Now it idles way high and the adjustment screw is all the way in. This is a 85
T1 just fyi. I've tried hunting for an answer but came up empty. Could it be my AIS acting up again? I took it out once before and cleaned it and that solved another idle issue I had(low that time I think).
Oh yeah, vacuum at idle is 18ish, no vacuum leaks, fuel pressure is good around 46psi at idle.
:bang head
 

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High Idle will be caused by...
1)Central Vacuum Leak
2)TPS Closed Throttle Voltage Too High
3)Coolant Temp Low or CTS Out Of Range
4)Incorrect Base Idle Setting
5)AIS Circuit Problem
 

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Don, Here's an article I found online by Paul F. Schikora
I don't know him but thought you might find it interesting.

Thanks
Randy


I had the Dodge 2.2 Turbo I engine with a 3000 RPM idle problem. The AIS controls the idle speed by letting air bypass the throttle plate. All it is is a valve that opens up to let additional air into the throttle body. It has a semi-circular opening, with a semi-circular shutter that opens or closes to allow air to bypass the throttle plate.

The shutter is designed to rotate 180 degrees, and then it hits a stop to keep it from rotating any further. The shutter sits inside a circular sleeve, and the sleeve is what's turned by the motor. The sleeve holds the shutter snugly enough to turn it when it's free to move, but the sleeve can continue to move when the shutter has stopped, so the motor won't burn out accidently.

Not only is the shutter designed to rotate, it is spring loaded, so it can be pressed down into the motor housing. Doing so makes a closed shutter effectively useless, because air can bypass it. I believe the spring is there to allow air bypass even if the shutter is closed, if there is enough of a pressure differential in the throttle body to force the shutter down into the housing and let air bypass it, perhaps to avoid other damage.

There is one flaw with this design -- when the shutter is depressed, it can be moved past its stops. If that happens, and the shutter then pops back up, it gets locked 180 degrees out of phase. When the computer tries to close it, it is actually opening it. It will keep trying to close it until it opens full up, and then your idle is racing at 3000 RPMs. The computer keeps trying to close the shutter, but since it's wide open, there's not enough pressure differential to force the shutter back down so it can again go past the stops into its normal position.

This is apparently what happened to mine. For all I could tell, the motor worked fine. Applying voltage to it opened and closed the shutter, only I couldn't tell that it was out of phase, opening when it should close and vice versa.

What compounded my problem was the fact that the shutter was gunked up with carbon and sticking in the sleeve. So it got stuck down and stayed there, allowing it to pass the stops. Eventually, it popped out enough to lock into an out of phase position. That's when the problem wouldn't go away. I finally figured it out when I noticed a rattle in the motor, and that the shutter was moving up and down slightly as I shook it. I was so fed up at that point that I ignored the service manual advice to the contrary, and took apart the AIS. I didn't ruin it -- it's a pretty simple design. I cleaned the parts and got the shutter to where it wasn't binding in the sleeve anymore. I then reassembled it (praying I had it in phase, which I did) and everything was fine (if it still raced, I would have taken it apart and reassembled 180 degrees around).

After "fixing" the problem, I went for a test drive. Everything was OK for a few minutes, but then the racing returned! Back to the garage where I found the following (warning -- more conjecture coming). In the top of the throttle body, there are two more ways for air to bypass the throttle plate. One is an orifice which is controlled by a set screw (idle set screw?). A while back I had apparently closed off the orifice -- some carbon gunking didn't help either. Running the engine at various speeds created the pressure differential needed (which couldn't be compensated for by the closed off orifice), and the AIS shutter passed its stops again. I backed the screw off, re-fixed the AIS, and got the engine running again. I then sprayed some carb cleaner into that orifice. No problems since then!

The second air bypass is a small hole in the side of the throttle opening just above the plate. It had some carbon buildup too, so I sprayed it out as well. (Yes, I know, I should use throttle body cleaner. I just didn't have any handy.)
 

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Discussion Starter · #7 ·
Thanks GLHS60, I took the AIS out awhile back when I had a high idle issue and cleaned it. What's aggravating is I did the reset and had it running perfect last night, shut it off and restarted it and the idle was back up to 1400 and A/F was rich. I'm losing my mind. I may have to do a good cleaning on the throttle body also and recheck the AIS to make sure it's still in phase.
Thanks
 

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Some hacks like me unplug the AIS and use the screw only for idle.
Have to plug a spare in the connector to keep the computer happy.

Thanks
Randy
 

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You can if you can find a way to connect it to your existing harness and run wiring for the heater circuit.

The purpose of the O2 sensor is simple, it is a "fuel trimmer" used to bring fuel control into a tighter range for emissions control and mpg.

The difference between a single wire and 3/4 wire O2 is the heater circuit.

The O2 sensor creates a small voltage through a chemical reaction when exposed to oxygen, however for this to happen the O2 sensor must be hot.
The problem with a non-heated O2 (single wire) is that at idle when exhaust flow slows the O2 sensor temp decreases and the car goes back into "open loop" operation.
This creates three problems...
1)Emissions increase
2)MPG decreases
3)The constant cooling/heating decreases O2 sensor life.

This problem was corrected by adding a heater to the O2 sensor to keep it at a constant temp at all times.

If you want to use a 3 wire O2 you need to add power and ground for the heater circuit.
On most vehicles power for the O2 heater comes from the ASD relay which is internal to the PM on 85-87.(ASD output is from PM 10 Pin Connector Cavity 6, DG/BK Wire).
The ground circuit is usually through a controller ground circuit.
(There are 2 on 85-87, PM 10 Pin Connector Cavities 9/10, BK Wires)
 

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Discussion Starter · #13 ·
Thanks, Just to clarify because I'm still learning about this system. The PM is on the driver side fender well correct? I just find the 10 pin connector and tap into those two wires and run the respective leads to the new O2?
I'll probably do this before I go any further with trying to correct the idle situation.
 

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Yes, the PM is the underhood controller.
Just keep in mind that I have no idea if the added electrical load of an O2 heater circuit will create any problems with the PM.
My suggestion would be to wait to see if someone that done this chimes in to be sure you do not run into any issues.
Also, be sure your main controller ground is in absolutely perfect shape and has a clean mounting point and is tight.
 

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Discussion Starter · #18 ·
So I think I got it fixed. Finally had some time to look at it and I took the AIS out. I think it jumped the stops and was out of phase because my idle was insane (2000+). Without touching anything just fixing the AIS and doing the reset procedure it idles around 900.
A/F buries at 10 under full throttle, not sure if that's too much but at least it's not lean. I still have a problem, as the full pressure never spiked like it should've during the testing of the regulator. Those two are probably related.
Thanks for the help guys
 
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