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Discussion Starter · #1 ·
So, this is going to be a lot. Given I have done a ton of diagnosis in attempt to resolve this.

What the car is doing. At part throttle enough to keep the car at the same speed say on the highway going 75 1900ish rpms it wants to miss spontaneously every 3 seconds or so. Lean into the throttle just even the slightest it stops. Throttle is so touchy it causes it to rock into idk what to call it a cam rock I guess I have to push the clutch in to get it to stop.

what I have done

replaced coil packs, All 8 Motorcraft coils.

Replaced plugs TR6 NGK gapped to .30, twice in the last 2500 miles. (obviously running in circles.)

3 spark plugs looked great white with little sign of being used. The other 7 spark plus are completely covered in black soot, its smooth looks like carbon build up to me. they are pitch black. 1200 miles on these plugs.

found coolant in cylinder 5 with a black light, I added some Pag oil to the coolant overflow before I left work.
all other cylinders looked fine under the black light.

Replaced intake manifold/Gaskets.

Replaced Cam/Crank sensors.

compression test came up with the following
cy1 155
cyl2 155
cyl3 155
cyl4 155
cyl5 170 (assuming the coolant in the chamber)
cyl6 160
cyl7 145
cyl8 155

boost gauge reads -18 at idle 850rpm. with the needle being very steady. its plugged directly into elbow with no tees.

Have I ruled out everything mechanically?

I have done a kam reset and set tps voltage to .98 This really seemed to help.

Noticed I had the wrong iac motor i had the iac with a little black cap vent. It was acting as a vacuum leak. NO more long crank starts. However no fix.

I used to have a window switch getting its rpm signal from pin 26 on ecu coil driver A/1. verified continuity from ecu to the engine harness connector to the coil plug itself. so that circuit is ok. I do not have a scope, or access to one at this time. I have not verified coil drivers on any other coil plugs.

I have removed the engine harness and Ohmed all coil driver wires to their corresponding plugs. I did the injectors this way as well. I verified i had 12v at all plugs before disassembly.

To really add the icing on the cake, I have no mode 6 data, Misfire detection has been turned all the way down (Tuners Words). Even better the 02 sensors are turned OFF due to a leaky exhaust on the dyno. He warned me of the possible issues and told me he could tune it without them although he doesn't like to do that. I told him to do it, I drove 300 miles, I wanted to drive the car. Tune has been good overly rich if anything. This was tuned in Feb. on a 50 degree day. Thrashed and beat the hell out of it seems to be good. Exhaust is sealed up now and I have a working wideband.

All I can remember off the top of my head. Internet you are my last hope before I put this thing up for the winter. Also i have a small video you can kind of hear it. Not sure.

· Super Moderator
4,908 Posts
You put pag oil in the coolant?

So the o2 sensors are turned off? That can be an issue since there is no feedback to correct the afr while driving. What does your wideband say while it’s misfiring?
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