97 F-150 Running REALLY rough - IAC Motor? - Ford Forum - Enthusiast Forums for Ford Owners

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Old 10-28-2005, 02:41 PM
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Join Date: Oct 2005
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Default 97 F-150 Running REALLY rough - IAC Motor?

O.K. This is a big one but I don’t want to leave out any details:

1997 Ford F-150 4x4 extended cab XLT
186,000 km
Owned the truck since spring of 2001, 130,000 km’s when I bought it

Plugs and wires changed around 150,000 kms
Catalytic converters cut out, simulators installed
New fuel filter October 24, 2005

The truck has always had a wee bit of a rough idle (sometimes at a stop light it seemed a little rougher, but generally not a big deal) but I’ve heard other similar trucks have the same rough idle. About 1 ½ years ago I had it in at Ford and the mechanic couldn’t get it to throw an error code so they couldn’t diagnose it. I carried on.

Late this summer it started to run rougher. The exhaust had been getting worse the last year or so and I knew that I was going to have to do something about that. I thought my injectors might be dirty so I ran a bottle of STP cleaner through the tank and it started to run A LOT worse and the check engine light came on almost immediately. I read online that the O2 sensors might have been screwed from the fuel injection cleaner. I took it to a muffler shop and decided to get the cats cut out and simulators installed (one side wasn’t too bad, the other side had one almost completely plugged cat and one that was smashed?). It seemed to run O.K., (still not great) and the simulators were throwing the varying voltage like they are supposed to. That didn’t last long though and it wasn’t long before it was running rough again. You could find a “happy place” if you played around with the accelerator but generally it was pretty rough, especially at medium acceleration (although if you kicked it down hard it wasn’t rough, but still not a lot power/kick).
I had a buddy of a buddy put his $10,000 MAC computer on it (he has been studying engine management for a couple of years) and after 1 ½ hours of looking at a million screens/voltages/readings he couldn’t pin point anything accept a P301 which I understand to be a misfire on cylinder 1.

I pulled the plugs (looked fine) and regapped. We did a fuel injection flush (proper one at the shop, direct through the fuel system) and still no improvement. I changed the fuel filter and cleaned the IAC Motor and now it seems to be even worse. In addition to running rougher at idle and during acceleration, I can smell fuel once in a while and the fuel seems to be going down a little faster that it should. I see no leak around the filter but did find out later that my IAC type with built in solenoid is not supposed to cleaned but rather replaced.

I still think that it is a fuel problem and nothing electrical. My next try I think it going to be the IAC motor, but again from what I understand that should only affect idle, not acceleration.

In addition to this a really annoying squealing has started, usually under load but getting worse to the point of all the time, load or not. I changed the tension pulley and idler wheel (both bearings were pretty rough) as well as the belt. The squealing is still there. Someone mentioned a PCV might be blocked?
Any input at all would be much appreciated. Thanks in advance!!

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1997, 2001, 250, 97, f150, ford, gt, iac, idle, load, motor, mustang, problem, rough, windstar

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