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Discussion Starter · #1 ·
I have been working on this car since I purchased it in January. Car ran but previous owner couldn't get it to shift (clutch cable was installed incorrectly) and the Procharger had shredded a belt (likely due to pulley misalignment). Got that taken car of and did some maintenance items new NGK TR6 plugs gapped at .030, new radiator and fan, and replaced negative battery terminal connector. The car is also running a slot style blow through MAF, and I pulled that and sprayed it down with MAF cleaner. Verified TPS voltage is in correct range and moves smoothly to 4.75 at WOT. Car has two brand new NTK OEM 02 sensors.

Took the Cobra for its maiden voyage and did one second gear pull on the highway before realizing that I had no brake lights, turn signals, emergency flashers. Took the Cobra home to diagnose, ended up pulling a junky Viper alarm, and reconnecting the ignition wire it taped into while investigating. Turns out it was a blown fuse caused by the clutch pedal arm rubbing through the wire causing a short to ground. I also replaced the fusible links from the voltage regulator on the alternator as the cover was split on each. I had been waiting to drive the car again until I got new tires as the old ones were cracked and not holding air.

Fast forward to present, got the new tires... later that day drove to the gas station and put probably 10 gallons of 93 in the car. Suspension was making some noise, but the car drove fine at part and mid throttle. Decided to do a pull and experienced a hard cut out around 3k to 3.5k rpm. The car again drove fine on the way home at part and mid throttle. Checked for glaringly obvious boost leaks like an elbow or connector that popped, couldn't find anything. That was a couple weeks ago, I recently had some new mufflers installed and driving to and from the shop it's still doing the same thing... under light load it's fine, but at wide open throttle it cuts out but doesn't die. I tried partial throttle and it accelerated fairly strong to 4k rpm in second. The car has no pending or stored codes, and no CEL illuminated.

I have yet to find anyone who has the exact same issue, and was hoping to get some troubleshooting help.



Things on my list to try:
  • Replace fuel filter, housing is crusty and rusty (the rest of the underside is spotless)
  • SCT X4 arriving Sunday for datalogging
  • Check fuel pressure at schrader valve, check with vac unplugged, potentially check while driving if I can find one with a long enough hose.

The plugs seem fine, they have less than 10 miles and while I haven't pulled them all I pulled number 5 and it was clean with no signs of fouling or preignition. What else do you think this could be or what else would you check?
 

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I was going to recommend checking the fuel pressure. Was this the first time that you’ve ever been able to drive it? Is it running the “stock tune?” If it is and it does then that is likely the problem. A blower needs a relative butt-load of fuel when at WOT. What size injectors does it have? Stock fuel pump as far as you know?
 

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I just watched the video. What rpm did it cut out? Will it cut out if you rev it in neutral? With your Procharger “boost” will come on around 3k and build to redline. Does it bog down as soon as you go WOT or at 3k+?
 

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Discussion Starter · #5 ·
I was going to recommend checking the fuel pressure. Was this the first time that you’ve ever been able to drive it? Is it running the “stock tune?” If it is and it does then that is likely the problem. A blower needs a relative butt-load of fuel when at WOT. What size injectors does it have? Stock fuel pump as far as you know?
I drove it about a month earlier on a few gallons of 93 octane I added to the tank and got a full second gear pull that felt strong. It sat for another month after while I cleaned up a shorting brake/turn signal wire under the dash. Unsure on fuel pump, assuming at least a 255 which would have come with the Procharger when it was initially purchased. The injectors are green in color, so I believe they are 42 lbs/hr injectors which is larger than what Procharger would have included.

I know nothing about superchargers but I did some Googling and saw something suggesting that cut off could be caused by belt slippage.
It has a brand new Gates Green Belt recommended by Procharger and I have done a solid second gear pull a couple months ago with this belt, no slippage. The belt looks great and no dust to indicate slippage.

I just watched the video. What rpm did it cut out? Will it cut out if you rev it in neutral? With your Procharger “boost” will come on around 3k and build to redline. Does it bog down as soon as you go WOT or at 3k+?
If I slowly ease into it and don't go WOT, I have gotten to 4k in second. If I got WOT the cutout occurs around 3-3.5k rpm, no boost building yet... prior to the cutout the car feels a little sluggish.


I do know the stock fuel filter didn't look great externally, and I have a new one to install... I've just struggled to find the time with my youngest son turning 1 last week.
 

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Discussion Starter · #6 ·
Swapped the fuel filter today, fuel came out clear on both ends... couldn't blow through it really but not sure if that's still a thing. I was able to pull the lines off without the disconnect tool, reinstalled new filter and clips, checked them over, and primed the car 3-4 times and no leaks. Don't think this is the issue, but needed to be done anyways. I ordered a new laptop today, so I should be able to update my new X4 and start datalogging next week. Hopefully someone can view the logs and the issue stands out to them.
 

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Discussion Starter · #7 ·
Checked fuel pressure today. KOEO I had 30 psi, 35 psi at idle, and 45 psi with the vacuum line detached. To me the problem seems like an all or nothing issue, if it was a bad wire, or plug, I would expect to get a CEL for misfire... or some bucking, but this is like the entire engine just cuts out without stalling, and as soon as I let out and drive part throttle it's fine. Where would you look next. The X4 should tell me if the MAF is ok... but I'm at a loss beyond that.
 

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Fuel pressure seems ok. I think I’d try to find a tuner (a human that tunes) and have him look at some logs. It’s gotta be a spark or a fuel thing I guess, but I don’t know where I’d look next.
 

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Discussion Starter · #9 ·
My new laptop arrives tomorrow… my wife has been using my last laptop for work. So the plan is to update the X4 and get it installed so I can data log. Im going to so some higher than optimal gear driving to put load on the engine outside of wot. Going to slowly try to pass 3,500 rpm at part throttle. Then finally try another WOT pull data logging it all.

Hopefully someone on one of the forums I’m on can help decipher.
 
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