96' Cobra Procharged - Engine cutting out around 3k rpm (Video)

01silverstang

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96' Cobra with 54k miles
- Procharger Stage 2 P-1SC with 3 Core Intercooler and Big Red Blow Off Valve
- VMP Blow through setup
- 42 lbs./hour injectors, unknown fuel pump
- NGK TR6 plugs gapped at .030 with less than 10 miles on them
- Stock Coils and Plug Wires
- Probably tuned by DynotuneMp based on stickers on the quarter windows, but since he saves tunes by owner name we cannot verify.

A few weeks ago I did a pull in second and had good power throughout the RPM band. I parked it to chase some wiring issues in the cabin related to brake light and turn signals. I also replaced my fusible links between alternator and engine bay fuse box. This past weekend I took it to get tires replaced which had kept me from driving it more, and decided to try a short first gear pull. Went WOT and the engine had an abrupt loss of power around 3k to 3,500k rpm. Yesterday I took it out to get some video, and monitored my AFR while it happens and AFR stays in the 11's so I don't think it's a fuel issue.

I plan to buy an SCT X4 tuner in the next week to datalog. Car will be getting fresh tune as well, but in the meantime wondering if anyone has ideas or had a similar issue?


 

96dreamer

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That seems very abrupt to be a mechanical issue. The car doesn't have an n2mb wot box or something similar on it does it? It reacts similar to how my car did when I had an n2mb box with no lift shift enabled. Even lightly touching the clutch when wot instantly kills power.
 

01silverstang

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That seems very abrupt to be a mechanical issue. The car doesn't have an n2mb wot box or something similar on it does it? It reacts similar to how my car did when I had an n2mb box with no lift shift enabled. Even lightly touching the clutch when wot instantly kills power.
I was wondering about something like that... I got the best mod list I could out of the previous owner but no mention of anything like that. Where would something like that be mounted?
 

96dreamer

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I was wondering about something like that... I got the best mod list I could out of the previous owner but no mention of anything like that. Where would something like that be mounted?
I mounted mine in my glovebox but it could be behind the passenger side kick panel. The N2MB box is about the size of a credit card footprint and bright blue. Hard to miss. I believe the ms2 2 steps were mounted in the engine bay piggy backing off the main harness and coil harness but I have never personally installed one.
 

DSG2003Mach1

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Couldn’t watch the video but spark blowout can definitely knock it on its face. I would think that gap would be ok but closing it up would be the easy way to confirm
 

01silverstang

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Couldn’t watch the video but spark blowout can definitely knock it on its face. I would think that gap would be ok but closing it up would be the easy way to confirm
If you get a chance and can access the videos let me know what you think. The cutoff is very sharp and abrupt, all the blowout videos I have seen seem like stuttering as the plug fires is blown out and then fires again. This is like a no-spark, fall off a cliff sort of cut.
 

thelonebean

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I kinda had a problem like this happen on my way home from school one day. Car would shut off completely after 3k rpms and then kick back on cause I never put it the clutch (essentially clutch kicking the car to start it back up) which caused a bucking motion and a huge backfire which sounded kinda cool but I knew wasn't good for the car. I figured out that it was a voltage issue from a drain on my battery because the previous owner had wired led interior lights straight to the battery. When the battery voltage got low enough, the alternator couldn't put out voltage cause I wasn't high enough in the rpms to charge the battery and my boost a pump and everything else in my car as far as electrical was demanding too much voltage and was ultimately interrupting the power to the ecu. Check to see if you have anything other than the terminals hooked up to the battery and if so trace those and rip them out or re wire them to come on with the ignition.
 

01silverstang

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I kinda had a problem like this happen on my way home from school one day. Car would shut off completely after 3k rpms and then kick back on cause I never put it the clutch (essentially clutch kicking the car to start it back up) which caused a bucking motion and a huge backfire which sounded kinda cool but I knew wasn't good for the car. I figured out that it was a voltage issue from a drain on my battery because the previous owner had wired led interior lights straight to the battery. When the battery voltage got low enough, the alternator couldn't put out voltage cause I wasn't high enough in the rpms to charge the battery and my boost a pump and everything else in my car as far as electrical was demanding too much voltage and was ultimately interrupting the power to the ecu. Check to see if you have anything other than the terminals hooked up to the battery and if so trace those and rip them out or re wire them to come on with the ignition.
Nothing other than terminals connected to battery.
 

01silverstang

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How are the coil packs condition?

Pull the plugs and inspect?
I’ve been advised to pull the plugs, but they are brand new TR6 gapped at .030 and I haven’t even put ten miles on the car since I installed them. The coil packs are OEM motorcraft. I do have a Procharger bracket for the passenger side coil that wasn’t tapped correctly from Procharger and one bolt snapped and another isn’t seated right… so those bolts ground the coil or is it ground through the connector?

I did one pull with no issues in second about a month ago, and then had issues with the taillights and brake lights shorting due to the clutch assembly having worn through the wires. I also found a Viper alarm during that which was removed.

Someone else suggested looking for a WOT box in the passenger kick panel… so I’ve got that on the list of things to check.
 
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me32

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I’ve been advised to pull the plugs, but they are brand new TR6 gapped at .030 and I haven’t even put ten miles on the car since I installed them. The coil packs are OEM motorcraft. I do have a Procharger bracket for the passenger side coil that wasn’t tapped correctly from Procharger and one bolt snapped and another isn’t seated right… so those bolts ground the coil or is it ground through the connector?

I did one pull with no issues in second about a month ago, and then had issues with the taillights and brake lights shorting due to the clutch assembly having worn through the wires. I also found a Viper alarm during that which was removed.

Someone else suggested looking for a WOT box in the passenger kick panel… so I’ve got that on the list of things to check.

Reason i ask about the plugs is that if the coil packs or even one coil pack is failing it would cause a miss fire and checking the plugs could give you an idea which cylinder or cylinders miss fired. Coil packs have never been super great on boosted cars. Not saying that your issue for sure but definitely check that to rule it out. Also 54k miles on a N/A coil pack setup may not show signs. 54k and now boosted is a much bigger difference.
 

01silverstang

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Reason i ask about the plugs is that if the coil packs or even one coil pack is failing it would cause a miss fire and checking the plugs could give you an idea which cylinder or cylinders miss fired. Coil packs have never been super great on boosted cars. Not saying that your issue for sure but definitely check that to rule it out. Also 54k miles on a N/A coil pack setup may not show signs. 54k and now boosted is a much bigger difference.
The thing that’s weird about this is I’m not getting any check engine light and I would have assumed a misfire would have caused a code and CEL. This is almost like spark just being cut completely.

I’m going to try to go pick up the SCT X4 tomorrow or Thursday from my tuner, so I can get some logs this weekend. Hopefully that helps narrow my issues… I’d almost wish it would throw a code because then I’d at least know where to focus.
 

me32

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The thing that’s weird about this is I’m not getting any check engine light and I would have assumed a misfire would have caused a code and CEL. This is almost like spark just being cut completely.

I’m going to try to go pick up the SCT X4 tomorrow or Thursday from my tuner, so I can get some logs this weekend. Hopefully that helps narrow my issues… I’d almost wish it would throw a code because then I’d at least know where to focus.

Typically most check engine codes are emissions related. Now a miss fire should be an emissions related issue. But it was an early ob2 system so its not perfect. The video also looked like a spark cut out. Which leads me to believe the issue is some where in the coil packs,wires, plugs.
 

01silverstang

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I agree and hopefully data logging has
Typically most check engine codes are emissions related. Now a miss fire should be an emissions related issue. But it was an early ob2 system so its not perfect. The video also looked like a spark cut out. Which leads me to believe the issue is some where in the coil packs,wires, plugs.
I agree, hopefully the data logs will catch where the problem is.
 

DSG2003Mach1

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To trip a CEL requires a certain number of misfires within a certain a number of revolutions. My car was had spark blowout on the dyno around 5800 rpm and it never threw a cel after several pulls
 

01silverstang

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To trip a CEL requires a certain number of misfires within a certain a number of revolutions. My car was had spark blowout on the dyno around 5800 rpm and it never threw a cel after several pulls
I’ve had misfire issues before on an 03 WRX and it felt like stuttering. This feels like I suddenly have zero ignition, but the car doesn’t stall it just falls flat on its face until I let out and then drives normal at part throttle.
 

01silverstang

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I mounted mine in my glovebox but it could be behind the passenger side kick panel. The N2MB box is about the size of a credit card footprint and bright blue. Hard to miss. I believe the ms2 2 steps were mounted in the engine bay piggy backing off the main harness and coil harness but I have never personally installed one.
The last full pull with no hesitation I did was about a month ago. I did a pull in second and it pulled very strong, no issues. The car was parked after that because I had issues with my turn signal and brakes blowing their fuse as the wire was rubbed bare by the clutch arm and shorting to ground. While investigating that issue I found a VIPER alarm and removed it and a ton of wires including a relay and push button switch which I assume was to activate a valet mode? However if I removed wiring that may have led to the WOT box (if the car even has one) could that potentially cause it to cut ignition during WOT independent of the clutch being pressed?

Sorry that scenario is so screwy between the prior owner potentially not knowing they had one... to it being partially removed, that it's hard to google anything definitive.

Edit:
From another forum:
"i didnt read through it all because i dont have time i am at work. but i was tuning my turbo 03 cobra. fresh build. it would run awesome but once i hit wot it would cut out. i unplugged the n2mb 2 step and it doesnt do it anymore. i gotta mess with the 2 step see why it was doing that. but if you have the n2mb wot box installed unplug it see if it cuts out at wot."

Other potential data log might show is maxed out MAF?
 

96dreamer

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It is possible, I am not sure if the wot box looks for ground or 12v+ reference to signal that the clutch is in or not. If it was wired incorrectly originally or differently because of the remote start it could cause issues. If it is a wot box causing the issue it would happen at the exact same rpm every time and only under wot. If it goes past the troublesome rpm at 80-90% throttle with no issues but stops when 100% wot I would suspect there's a form of a wot box somewhere. Another test would be to take it up above the rpm its having issues at part throttle and floor it. If the moment you hit wot it cuts out the same way it would hint at a wot box as well.
 

01silverstang

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It is possible, I am not sure if the wot box looks for ground or 12v+ reference to signal that the clutch is in or not. If it was wired incorrectly originally or differently because of the remote start it could cause issues. If it is a wot box causing the issue it would happen at the exact same rpm every time and only under wot. If it goes past the troublesome rpm at 80-90% throttle with no issues but stops when 100% wot I would suspect there's a form of a wot box somewhere. Another test would be to take it up above the rpm its having issues at part throttle and floor it. If the moment you hit wot it cuts out the same way it would hint at a wot box as well.
I have attempted this two additional times after the cutout on Sunday. It happens at roughly the same rpm every time, and always at WOT. I'm going to pull the passenger kick panel, to verify if I can find anything tonight. The next step will be if I do find one, how to safely remove. Cars drives fine at part throttle, cruising, it's just WOT.
 

96dreamer

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Does cruise control work correctly? If it is wired in such a way it is always sensing the clutch is in, either the wot is wired to a completely different source or it should also prevent the cruise from working since it uses the same signal.
 

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