93 Cobra Engine intermittent cutout under hard acceleration and sluggish starter

[emba129_98]

Hi all,
I took my 93 Cobra out for spirited runs over the last couple of weeks. I experienced the following:

Issues:
- under hard acceleration the engine would cutout or feel like I was hitting rev limit at around 4000 RPM. It did it about 1/2 the time. Sometimes it would continue to pull past 4K. Its intermittent

- after a long drive, I parked at a restaurant for a couple of hours. When I went to start it is cranked very slowly like the battery was discharged. Its a new battery. On the way home, the charge indicator was reading low 12-13 v estimated. When I got home I measured voltage at the battery with the car running and got 13.2-13.7 v indicating to me that the alternator is charging. The next day with it was first started up it was charging at 14.4v. Not sure why it drops at operating temp. maybe regulator going bad

I did a little research and Im thinking:

- alternator/voltage regulator may be intermittent for the low charging issue.

- starter could be going bad. when car is cold, starts fine. it only slow started one time

- fuel pressure regulator or fuel pump for the intermittent cut-out under heavy acceleration, especially above 4000 rpm.

- Im seeing other things combing the forums.. timing, TFI module, BAP sensor

Also, the car feels like it should have more power. My stock 91 Lx 5.0 seems peppier

Maybe a faulty alternator/voltage regulator causing it all?

p.s. I did complete tuneup (new motorcraft plugs, cap, rotors, wires, ignition coil, battery) and timing to 12deg BTDC


Thoughts?? I dont want to start throwing parts at it quite yet. Im going to hook up a fuel pressure gauge and try to measure pressure on hard accel


Thanks
Chris

 

[MG0h3]

Just double checking you set the timing with the spout out? You can run 14-15 degrees on a stocker and it’ll be happy.

So charging systems and electrical circuits in general can struggle in heat. You are hitting peak torque around where you are claiming you have a hesitation. You might be losing spark monetarily.

This could also be causing the starting problem when hot. You may also be suffering from heat soak causing the starter to fail.

I’d want to see what the batt voyage looks like under heavy kid at rpm as well at batt vintage when cranking.


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[13COBRA]

Have you checked your grounds?

 

[emba129_98]

Thanks. Im going to measure fuel pressure under hard acceleration. I can see about measuring voltage as well. I assume about 40psi for fuel? and should that remain constant under hard acceleration? and for voltage, what should I expect to see under acceleration?

I wouldn't think timing would do it. Stock is 10, I have it at 12.

car only has 64k miles. Its clean, but I will check the grounds.

 

[emba129_98]

Just double checking you set the timing with the spout out? You can run 14-15 degrees on a stocker and it’ll be happy.

So charging systems and electrical circuits in general can struggle in heat. You are hitting peak torque around where you are claiming you have a hesitation. You might be losing spark monetarily.

This could also be causing the starting problem when hot. You may also be suffering from heat soak causing the starter to fail.

I’d want to see what the batt voyage looks like under heavy kid at rpm as well at batt vintage when cranking.


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yes.. spout removed

 

[emba129_98]

Another point on this car. Its was barely driven from 2007-mid 2021. Im unsure of the fuel that was in it... That said, I did all new plugs, wires, cap, rotor, ignition coil, Mass Air Controller, Idle Air Controller and fuel filter. Do these TFI modules on the side of the distributor cause this if they go bad?

I ran Seafoam through the intake and a can in a new full tank of gas. Maybe a good fuel injector cleaner if there is still some residual gunk.

Its runs fine under idle or normal load, but under hard acceleration it balks.

 

[triple-s]

I had the slow cranking problem before in my coupe I thought it was the starter as well but it ended up being the tfi coil getting to hot after a long drive. I had a factory one from 93 I bought a autozone unit till the one I wanted came in stock that was better but still had slow cranks. I ordered the dynamod one from lmr and even under crazy heat that thing starts right up.

 

[Bdubbs]

I had the slow cranking problem before in my coupe I thought it was the starter as well but it ended up being the tfi coil getting to hot after a long drive. I had a factory one from 93 I bought a autozone unit till the one I wanted came in stock that was better but still had slow cranks. I ordered the dynamod one from lmr and even under crazy heat that thing starts right up.

This seems to be a common problem. They get hot and then the car will just shut off.


I've had brand new motorcraft TFI modules junk right out of the box. Car would start up and run for 5-10 seconds. Generally if they get too hot you could be sitting for some time before it will start again....

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[slowcpe]

I'm willing to bet its the TFI. I battled this issue for about a year. Factory one would cut out just like you where saying. The warmer the car, the worse it was.

Bought a new Motorcraft and fixed the issue until the car got warm then it would just shut off while driving down the road. Ended up being bad out of the box.

Borrowed a distributor from a buddy that "ran good when pulled". Swapped the whole distributor w/TFI and the car would cut out like before.

Had a spare distributor with a generic TFI. Installed that TFI and the car has run good for over a year now.

I can't wait until I get a Terminator X and get rid of the TFI distributor!!!!

 

[Bdubbs]

I'm willing to bet its the TFI. I battled this issue for about a year. Factory one would cut out just like you where saying. The warmer the car, the worse it was.

Bought a new Motorcraft and fixed the issue until the car got warm then it would just shut off while driving down the road. Ended up being bad out of the box.

Borrowed a distributor from a buddy that "ran good when pulled". Swapped the whole distributor w/TFI and the car would cut out like before.

Had a spare distributor with a generic TFI. Installed that TFI and the car has run good for over a year now.

I can't wait until I get a Terminator X and get rid of the TFI distributor!!!!

I had the terminator x setup but sold it. For now I'm running a relocation TFI module setup. But the other two foxes are stock...


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[triple-s]

Yeah I've been looking real hard at that terminator x too.

 

[03cobra#694]

Did you change the fuel filter?

 

[MG0h3]

Typically the TFI failure on these was a loss of spark, usually after heat soak.

He said his car was cranking slowly, this has zero to do with the ignition system.

Op if you still have that old of gas, dump it. Didn’t catch if you replaced the fuel filter and/or have fresh fuel in there.


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[Mustang5L5]

I had a similar cutout with my car. Over 3500RPM the car would lose power and stutter.

Ended up being the ignition coil. I had a new Accel unit and it just failed. a Good used OEM unit went in and the car runs great.

As for slow crank, i would double check and clean your connections. When the engine bay gets heat, resistance in the wires goes up, and that can give you a voltage drop.

 

[ford fanatic]

I'm considering the Terminator X also, anyone know if they are still on backorder?

 

[Mustang5L5]

I'm considering the Terminator X also, anyone know if they are still on backorder?

Summit shows them in stock

https://www.summitracing.com/parts/hly-550-937f

I'd be running this system if i wasn't already committed to a Megasquirt setup

 

[ford fanatic]

Summit shows them in stock

https://www.summitracing.com/parts/hly-550-937f

I'd be running this system if i wasn't already committed to a Megasquirt setup

So tempting. This might be my project for next winter.

 

[Bdubbs]

So tempting. This might be my project for next winter.

Should have bought mine . I sold it last fall when they were on backorder.

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[Detroit Iron]

I had a similar problem with my 92 coupe a month or two ago. It seemed like it had a rev limiter at 3500 rpm. It ended up being the TFI module. I swapped in a NOS Motorcraft unit and that fixed it. Car revs out real nice now. The PIP sensor in the distributor also can give similar issues. These parts are guaranteed to fail somewhere down the line and finding good replacements is a crap shoot today. I would trust a used OEM Motorcraft distri butor and TFI module over the junk that is out there today. I doubt you have fuel issue or clogged cats from the problems you described.

 

[ford fanatic]

Should have bought mine . I sold it last fall when they were on backorder.

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Damn, I might have had I known lol.

I'm so on the fence of which way I want to go with this car.

What made you decide not to use it? Seems a lot of guys are going that direction the older these cars get.