Engine cutting out at 3k rpm in WOT

Venompower

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So checked the CCRM last night, specifically PIN 12 and 24, which are both listed as PCM power. The battery was low (11.8v) because my son opened the trunk so the trunk light had been illuminated all day while I was at work. Key On Engine Off PIN 12 had 11.67v, however, PIN 24 had 0.0v.

EDIT: Checked the next day and must have not got the pin far enough in, because I had power to both when rechecked.
 
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Venompower

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I've been waiting on Ford Performance Plug Wires since last Thursday, unfortunately American Muscle had the best price and they use FedEx... so still not here. It's amazing how fast my RockAuto shipments arrive with UPS, even USPS shipped a silicone connector from Colorado to Elk Grove Village and then back to Colorado and back again for some unknown reason and it arrived faster than it looks like these plugs will.

That being said, in the meantime if we don't get a third night of severe storm warnings I'll be testing both coils.
 

ttocs

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were they both listed as constant power or could one of them be switched? Did you check with the key on?
 

Venompower

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were they both listed as constant power or could one of them be switched? Did you check with the key on?
They should both be constant and they are… I don't think this is wiring. It could be the fuel pump speed relay which should be activated by the PCM at 3,200 rpm to bypass thr resistor and send a full 12v… it could be IMRC’s that also open at that same RPM, it could be MAF, maybe plug wires… but all the wiring I have checked ends up being virgin or testing fine.
 

Venompower

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So set my multimeter to 20k ohms to measure secondary resistance on the coils which should be 6.5 to 11.5 K-ohms. The pairing of 2/8 registered 14.0 and the pairing of 1/6 wouldnt land on a stabke reading but fluctuated from high 13’s into the 14’s… woild this indicate both coils need to be replaced?
 

07GtS197

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How old are they? In my experience coils can ohm test out of range but still work fine so I personally wouldn’t put too much stock into that.
 

Venompower

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Sooooooo after reading through this post... I'm leaning towards fuel pump:


The Mustang in that post was a 95' GT but the symptoms seem very similar to mine, along with the steps taken to try and address them. I'm going to stick with the Keep It Simple Stupid strategy here...

I have:
- Replaced Plugs with NGK TR6 gapped at .030 (8 lbs. is not blowing that gap out)
- Replaced Fuel Filter
- Calibrated TPS to .98
- Cleaned MAF
- Brand new OEM 02 Sensors (wouldn't impact WOT)
- Replaced Plug Wires

I really think the lack of a check engine light is pointing to weak fuel pump as well. The regulator vacuum line didn't smell of gas, and behaved appropriately at idle with the line detached. The gas coming out of the fuel filter looked clean when it was replaced. I have also heard that you can have normal pressure, but not enough volume. So for $120 and an afternoon, I think an Aeromotive 340lph is in my future.

Thoughts?
 

Venompower

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It wouldn’t be a bad idea especially if you’re looking for more power down the road.
Looks @TrickVert posted in a thread earlier this year that he had a hole in the rubber s-hose at the fuel pump that only caused pressure issues at higher rpm. This may be the problem as well, but like you said a new pump can't hurt and will address both.
 

Venompower

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So did a data log on my lunch break and with my limited experience I'd say the MAF is dirty/faulty. It maxes at 1023 right when the cutout occurs, which I believe is pegged.

Green is MAF count, higher blue is RPM, and the blue that spikes is air flow.

Data Log - 8-19-21.PNG
 

Venompower

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I had to look back and see it is a slot style.

It would be easy to swap out and try another. If that one has the same problem it might just be in a bad location.
Need to figure out whats plug and play compatible to replace it and wont require additional tuning. Looks like this exact one is north of $200.
 

ttocs

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if you don't swap it out for the same one you might cause more problems and not even know if the maf was the original problem. I am not aware of a way to test the maf short of testing the voltage out of it.
 

Venompower

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if you don't swap it out for the same one you might cause more problems and not even know if the maf was the original problem. I am not aware of a way to test the maf short of testing the voltage out of it.
I agree I need to swap like for like, this one appears to support 650 whp so it should be fine.
 

ttocs

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I agree I need to swap like for like, this one appears to support 650 whp so it should be fine.
can you post a pic of where its located? Is there any way to turn/clock the pipe that its mounted in to move its location in the airstream? IT could be that when it gets up to that rpm there is some turbulence in that location. I heard of people turning the maf on the old fox bodies and it was better in one location than the others.
 

Venompower

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can you post a pic of where its located? Is there any way to turn/clock the pipe that its mounted in to move its location in the airstream? IT could be that when it gets up to that rpm there is some turbulence in that location. I heard of people turning the maf on the old fox bodies and it was better in one location than the others.
I found some wires on the connector had been rubbed by the tire and were exposed, wrapped them in Super 33 but will probably ultimately order a new connector and MAF from VMP.
 

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