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

01silverstang

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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.
I will check this out as well.
 

omj

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If it worked previous to removing the alarm system, I'd recheck your work there. It's possible the valet mode is still engaged. It's easy to overlook something in a bundle of wires.
 

01silverstang

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If it worked previous to removing the alarm system, I'd recheck your work there. It's possible the valet mode is still engaged. It's easy to overlook something in a bundle of wires.
The actual black box was removed which I assume would control valet mode.
 

01silverstang

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6074327-B-4618-494-B-B505-6-E0-BF00-CBDCA.jpg


Well back to the drawing board…
 

96dreamer

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Damn I would have bet money there would be a wot box hiding in there somewhere. Doesn't look like the wiring has been tampered with at all either. I'm at a loss on this one.
 

01silverstang

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So I have some new ideas to chase down.

I believe I have a faulty CCRM as the engine fan hasn't been activating and I don't hear the AC compressor kick on... this past weekend when I got my tires replaced on the way home it poured rain. I was nervous as the car has never had front fender liners (I have some and the installation kit just need to put them on). I have an Anderson Motorsport Power Pipe, and my fear was getting water on the filter. What I didn't think about was that the CCRM probably got wet, and probably had been wet before if the previous owner didn't run the liners.

Thinking about the CCRM led me to this information on another forum: "The relay is a small one that is mounted in the kick panel right above the EEC. The resistor (CCRM) is a big one that is mounted in the fender and is bypassed at startup and above 3250 rpm. The purpose is to reduce the stress on the pump when the car doesn't need as much fuel."

The car has been a little sluggish to start even with the battery full, and while I was guessing the engine cut out was 3k rpm, my bet is it's the 3250 rpm bypass. Maybe the fuel pump relay is going out?
 

Mpoitrast87

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My old terminator did the exact same thing and it was bad wiring going to my wot box. This may not be the best idea but to check if it has a wot box you could push the clutch in and smash the pedal to the floor and see it goes to redline or not lol.
 

01silverstang

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My old terminator did the exact same thing and it was bad wiring going to my wot box. This may not be the best idea but to check if it has a wot box you could push the clutch in and smash the pedal to the floor and see it goes to redline or not lol.
I really thought it was going to be something like that but the pcm and connectors are virgin. So even if the box was mounted somewhere tricky you would see where it’s been spliced.

I think I’m going to far down the rabbit hole. I’ll probably replace the fuel filter that was coated in rust and looked disgusting… get an X4 to data log and then ultimately drop the tank and replace fuel pump if the issue persists and the logs show fuel pressure dropping under load.
 

01silverstang

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Any update?
Not really, I replaced the fuel filter and while I couldn't really blow through it (not sure if thats a thing anymore) the fuel looked clean on both ends. I ordered a new laptop which should be here Tuesday then I can update the X4 and start data logging. In the meantime I’m going to borrow a fuel pressure gauge from the autoparts store to check pressure at idle and with the vacuum line disconnected to rule out fueling.
 

01silverstang

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Any update?

So I checked the fuel pressure today. Key On Engine Off I had 30 psi, at idle with vacuum line connected I had 35 psi, and with the vacuum line disconnected it jumped to 45 psi. The 5 min leak down held 35 psi. My AFR's were in the 16's to upper 16's the whole time.
 

MG0h3

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You should be able to blow through the fuel filter easily.

I’d 100% focus on what you did RE the wiring issue.

It’s always hard to look at something we did as being the culprit but what’s the chances that this issue popped up right after you worked on the wiring to include the alarm removal.

While it’s hard to tell from a video, that appears to be a complete lack of spark or fuel at a specific RPM. Neither of these typically present this way. Load tends to make the “typical” failure appear, not rpm.

Might have missed it, but if you run the Rpms up slowly, driving it in neutral, does the issue occur?

Saw the stuff about the CCRM and it would still be very coincidental and again, I’d expect you to be able to creep through your failure point until a heavy load is put on the fuel or ignition system.

You can eliminate the load vs pedal position correlation by trying WOT out of gear.


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01silverstang

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You should be able to blow through the fuel filter easily.

I’d 100% focus on what you did RE the wiring issue.

It’s always hard to look at something we did as being the culprit but what’s the chances that this issue popped up right after you worked on the wiring to include the alarm removal.

While it’s hard to tell from a video, that appears to be a complete lack of spark or fuel at a specific RPM. Neither of these typically present this way. Load tends to make the “typical” failure appear, not rpm.

Might have missed it, but if you run the Rpms up slowly, driving it in neutral, does the issue occur?

Saw the stuff about the CCRM and it would still be very coincidental and again, I’d expect you to be able to creep through your failure point until a heavy load is put on the fuel or ignition system.

You can eliminate the load vs pedal position correlation by trying WOT out of gear.


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I'm definitely not too proud to admit that I could be the cause.

I've actually thought about it and the only wiring I touched under the hood was replacing the fusible links for the voltage regulator on the alternator.

Inside the car, I have replaced the brake pedal switch, used a butt connector on the ignition wire due to space constraints, and wrapped the short to ground in the tail light brake light wire that had rubbed on the clutch arm. I can't think of anything in the inside wiring that could cause this? No fuses have popped either...
 

MG0h3

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I’m not even saying you did anything wrong, but potentially did something inadvertently if you removed something.

Never know when there’s aftermarket stuff in there.

I want to say the wot box taps into the TPS wiring and clutch switch so take a quick look there

I’d do the following:

Neutral: run Rpms slowly and see if you can get past the failure point.

Driving: run rpms up slowly and see if you can get past the failure point.

Yes: get past the failure point and go WOT.

This will help tell you if it’s a pedal position issue vs RPM issue vs load issue.

You can induce heavy load without going WOT which should create a fuel or ignition issue. Just use a higher gear and try both part throttle and WOT.

If you can tape the fuel pressure gauge to the wiper to monitor it while driving that would be a big help.


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01silverstang

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I’m not even saying you did anything wrong, but potentially did something inadvertently if you removed something.

Never know when there’s aftermarket stuff in there.

I want to say the wot box taps into the TPS wiring and clutch switch so take a quick look there

I’d do the following:

Neutral: run Rpms slowly and see if you can get past the failure point.

Driving: run rpms up slowly and see if you can get past the failure point.

Yes: get past the failure point and go WOT.

This will help tell you if it’s a pedal position issue vs RPM issue vs load issue.

You can induce heavy load without going WOT which should create a fuel or ignition issue. Just use a higher gear and try both part throttle and WOT.

If you can tape the fuel pressure gauge to the wiper to monitor it while driving that would be a big help.


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Well once the X4 is updated and married to the car tomorrow I will definitely be doing some drives to data log. I was able to get the car past the failure point to a little over 4k rpm in second by just holding partial throttle and it felt strong. I haven't tried the higher gear to put load on the system. I will say the complete absence of any codes or CEL is throwing me off. I'll see if there is anyway I can keep the gauge visible while driving.
 

MG0h3

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Ok so we know it’s not strictly RPM related.

Try going WOT at different RPMs and loads. That will tell you a lot.

Want to say your car is OBDII, but it’s still what I would call “dumb”. Someone else mentioned it and it takes time and events to set a CEL.


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01silverstang

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Ok so we know it’s not strictly RPM related.

Try going WOT at different RPMs and loads. That will tell you a lot.

Want to say your car is OBDII, but it’s still what I would call “dumb”. Someone else mentioned it and it takes time and events to set a CEL.


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Yeah I believe 96' and up all cars are OBD2.

Yeah I mean for a small random misfire yes, but for this kind of cutout it's just strange. There are CEL codes for fuel delivery, for system to rich or too lean, for the ignition coils, etc.
 

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