96 cobra breaks up under WOT

[Pedrothecobra]

will update once i try it. still need to know where the signal to open and close the relay is fed from

 

[Buffalo5Spd]

specialized wire?

Yes, at least on the couple fabricated hangers I’ve made there is a special Teflon insulation on the in tank wiring. It’s been many years since I’ve done that stuff lol.

 

[Monday]

"

Have you looked at the capacitors in the computer? Two of them. I replaced mine when I did my intakes and never looked back.

You can get them off eBay

ECU is new


So. New doesn't mean anything.

Did you check it?

From what you've written, all you say is what you have? All You have told my electrics guy is you are going in circles. He read your posts and said that exact thing. Going in circles. You have no manufacturer numbers.


You done a Gas Cap yet?



MAF?



Trans speed sensor?



PCV Hose?



This is all a problem I had before - target the hierarchy. Also, we have the same manual Pedrothecobra.



Go to town then:



Throttle Position Sensor
Mass Airflow Meter
EGR Valve Position
Heated Exhaust Gas Oxygen
Air Charge Temperature
Engine Coolant Temperature Sensors
Vehicle Speed Sensor (VSS)
Idle Air Controller (IAC)
Relays
Thermactor TAB/TAD and EVR Solenoids
Canister Purge
All the SMOG Stuff

 

[ttocs]

according to your diagram its the white/red wire that goes to the pcm that triggers the relay

 

[Pedrothecobra]

"

ECU is new


So. New doesn't mean anything.

Did you check it?

From what you've written, all you say is what you have? All You have told my electrics guy is you are going in circles. He read your posts and said that exact thing. Going in circles. You have no manufacturer numbers.


You done a Gas Cap yet?



MAF?



Trans speed sensor?



PCV Hose?



This is all a problem I had before - target the hierarchy. Also, we have the same manual Pedrothecobra.



Go to town then:



Throttle Position Sensor
Mass Airflow Meter
EGR Valve Position
Heated Exhaust Gas Oxygen
Air Charge Temperature
Engine Coolant Temperature Sensors
Vehicle Speed Sensor (VSS)
Idle Air Controller (IAC)
Relays
Thermactor TAB/TAD and EVR Solenoids
Canister Purge
All the SMOG Stuff

what do you mean in circles? i mean systematically going through and troubleshooting to rule out each system and its components isnt going in circles its basic troubleshooting 101. and when you say your car was doing the same thing, you were losing fuel pressure at the rail? along with not seeing full body voltage at the pump in the higher rpm range? also what do you mean by manufactures numbers? i probably have the info if you can be more specific as to what your referencing. have you read the recent post where im finding a slight short to ground through my pcm or are you just reading the initial post? im not trying to come off as a dick but i dont really understand what your comment is eluding to or how its informational to the issue im having. im trying to not continue throwing parts at an issue and actually understand how the system is supposed to be working so i can fix it. if you go back and read this entire thread youll read how ive found bad splices (repaired them) throughout this entire troubleshooting process

 

[Pedrothecobra]

according to your diagram its the white/red wire that goes to the pcm that triggers the relay

thats what we were thinking last night while we were rd testing. but it never changed state, i know im getting a good tach signal from what i can see on my data stream. but if you follow the red wire out of the CCRM it goes to the other side of that relay and also the injector circuit. i did find a wire spliced into my CCRM on the AC field coil wired back to my heater controls. im wondering if the CCRM has an issue or could be causing the PCM to not remove voltage at the fuel pump relay in the higher RPM range.

 

[ttocs]

Just to be stupid, its been a while and you have been in the wiring, make a run through your fuses and make sure they are all good.

 

[96blak54]

I watch a mechanic on tictok. Trouble shooting a new chevy truck lead to the computer being the problem. Pulled the computer noticed oil in the comp harness. Turns out the oil sending unit sensor diaphragm broke within and was applying oil psi to the wire which eventually traveled through 5ft of wire into the computer!!

I think your troubleshooting process is on par. Keep up your spirits and dont give up!

 

[Buffalo5Spd]

I watch a mechanic on tictok. Trouble shooting a new chevy truck lead to the computer being the problem. Pulled the computer noticed oil in the comp harness. Turns out the oil sending unit sensor diaphragm broke within and was applying oil psi to the wire which eventually traveled through 5ft of wire into the computer!!

I think your troubleshooting process is on par. Keep up your spirits and dont give up!

I agree, your methods are sound from where I’m sitting.
I know it’s supposed to be new but I think you should drop the tank and inspect the pump, related hoses and wiring in the tank. I would also replace the entire sending unit unless you can be sure everything is holding pressure in the line.
At this point, even though a stock pump isn’t up to a power adder, if you can get the problem with cutting out to change, you’ll know where the problem lies. I’d bet that someone here has a stock sending unit you can try out. I know dropping the tank is a PITA but it sounds like you’re up to the task. My $0.02

 

[Pedrothecobra]

Just to be stupid, its been a while and you have been in the wiring, make a run through your fuses and make sure they are all good.

I did that a few times already, but at this point it doesn’t hurt to check em out again

 

[Pedrothecobra]

I agree, your methods are sound from where I’m sitting.
I know it’s supposed to be new but I think you should drop the tank and inspect the pump, related hoses and wiring in the tank. I would also replace the entire sending unit unless you can be sure everything is holding pressure in the line.
At this point, even though a stock pump isn’t up to a power adder, if you can get the problem with cutting out to change, you’ll know where the problem lies. I’d bet that someone here has a stock sending unit you can try out. I know dropping the tank is a PITA but it sounds like you’re up to the task. My $0.02

Yea that’s kinda where I think this is leading to. I’ve been keeping the level low for that reason lol

 

[ttocs]

I also think its time to check inside the tank.

 

[Riles]

It’s the hood decal I’m telling you!! That’s your whole problem!!

 

[Adultingsucks]

You can use my motorcycle lift for when you decide to drop the tank.

 

[07GtS197]

I don’t remember if it was ever determined but what pump is in there? It could be drawing too much current resulting in lower output. Or it could be a bad pump.

I get what you’re trying to do but I think you’re going a little overboard. The wiring is fine. Looking more into it, it’s normal to see around 1v to 1.5v of voltage drop across the fuel pump circuit. Regardless, it’s rated at 12v so a little lower isn’t going to kill it’s output like that. I think you have another issue. I think it’s relegated to the pump itself. If you’re na I wouldn’t run anything over a stock replacement pump.

 

[Adultingsucks]

I get what you’re trying to do but I think you’re going a little overboard. The wiring is fine. Looking more into it, it’s normal to see around 1v to 1.5v of voltage drop across the fuel pump circuit.

I hear what you're saying, and I wouldn't have suggested checking the wiring if we didn't find the flying splices into the CCRM as we did. In my line of work, and with this car, I felt need to eliminate all variables and verify individual functions systematically. There is still an issue with the PCM not switching the state of the FPR. Since the PCM has been replaced, and the CCRM has been tampered with, is the CCRM failing? That's what I've been asking myself. Sure, you could make the argument that a 1 volt loss is negligible, and I wouldn't disagree too much. And the car may have a fuel delivery issue that hasn't been isolated yet. But if there is a PCM or CCRM issue, I'm curious if the other outputs such as injectors are affected. Is the fuel/air ratio accurate at >3250? How far off are the process variables from setpoint? If I knew what the permissive was that commanded the FPR to change, I would try to induce it as a test. I also ask, does that same permissive subsequently affect injector frequencies? I would think that if your RPM's reach >3250, the pump is stepped up to a higher output, the injectors are open at a different duration, probably a multitude of other changes are being made.

At the end of the day, if the fuel delivery checks out good, there is still that FPR not dropping out, and who knows what else is happening/not happening that we haven't identified.

Sorry for the ramble.

 

[white95]

^^ The fix

 

[Pedrothecobra]

View attachment 14618

^^ The fix

Yea I haven’t ruled that out but that’s an expensive work around for an issue that will still be there. I want to fix it before I run out of motivation and just bypass the whole system lol

 

[Pedrothecobra]

It

I don’t remember if it was ever determined but what pump is in there? It could be drawing too much current resulting in lower output. Or it could be a bad pump.

I get what you’re trying to do but I think you’re going a little overboard. The wiring is fine. Looking more into it, it’s normal to see around 1v to 1.5v of voltage drop across the fuel pump circuit. Regardless, it’s rated at 12v so a little lower isn’t going to kill it’s output like that. I think you have another issue. I think it’s relegated to the pump itself. If you’re na I wouldn’t run anything over a stock replacement pump.

was just replaced with a factory cobra pump, about a month ago at a shop. I haven’t physically verified the new pump with my own eyes. But I’ll probably be dropping the tank this weekend to check it out. And blow at the lines out while it’s down and disconnected

 

[white95]

Yea I haven’t ruled that out but that’s an expensive work around for an issue that will still be there. I want to fix it before I run out of motivation and just bypass the whole system lol

Expensive, sure. Work around for an issue that will still be there? Hardly the case unless you piggyback the CCRM. The best method, we found, was to yank the CCRM and use relays to run AC, fuel pump and PWM fan controller. The only caveat is getting the gauges to work as you're removing the factory sensors they're tied to. @lwarrior1016 monitors his with Autometer gauges while @ttocs and I are using the Holley dash.