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Discussion Starter #1
Hello all

95 Tbird 4.6 200000 Miles.

Had the code for EGR excessive flow, blocked off the EGR. Fuel trims correct now, and ran great until this evening.

I started it up and it had a pretty bad miss at 1200 rpm until it warmed up and idled at 750 while in park.

As I drove it, it kept having that miss under light acceleration. It had this before but when I blocked off the EGR it went away, but now that its back I guess it was not the EGR. Has new plugs and wires, and coils look they have been changed.

I have the 95 thats apparently hard to get to the IAC, thoughts or ideas?

No additional codes or anything either, and all fuel trims are within +-3%, except at idle LTFT B2 reads +14% but as soon as I touch the throttle it goes to around 3%.
 

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Admittedly, I had the intake manifold off the car when I took of the IAC to clean in there, but it didn't seem like it would be a disaster to R&R it while on the car. It's just tucked down in there a little on the driver's side.

When I used to have the code for excessive EGR flow on my old 95, the car ran fine, and even got better gas mileage! A bigger problem at 200k is the EGR tube being clogged, of which there is no replacement, nor can it be cleaned on the car. I had four days of soaking that tube with heavy duty stuff to prove that! It is caused by leaky valve stem seals and high oil consumption.

Al
 

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THanks Al,

Is the IAC more on the bank 2 side of the manifold?

If so, this would definately be causing my +14% LTFT Bank 2 reading at idle only, as I understand the iac closes when throttle is in operation
 

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On my Toyota, the IAC is open any time the car is in vacuum, obviously to a lesser degree as vacuum decreases. But that is a different setup altogether.

I doubt the Ford IAC suddenly closes all the way just because the throttle is open. When you are coasting, it has to be open or the car would stall. I would venture to guess the IAC opening varies by vacuum just like my Toyota, only fully closing when vacuum is "0".

Al
 

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If so, this would definately be causing my +14% LTFT Bank 2 reading at idle only, as I understand the iac closes when throttle is in operation
For what I've observed, it doesn't close when throttle is applied. I have a part time IAC failure now. While driving the engine loses some torque and drops rpm when IAC goes down. All normal again when IAC wakes up. So, I assume IAC is supposed to be open.
 

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Discussion Starter #6
Interestingly,

After a removal, carb clean, then a good lubing with moovit, it seems to operate much better.

Also, I was expecting the IAC on a 95 4.6 to be just as bad of a nightmare as the EGR however it only took 5 mins to remove.
 
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