Club Cobra Keith Craft Racing  

Go Back   Club Cobra > Engine Building, Tuning, and Induction > Ignition

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

MMG Superformance
Nevada Classics
MMG Superformance
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
MMG Superformance
MMG Superformance
Advertise at CC
Banner Ad Rates
MMG Superformance
Keith Craft Racing
Keith Craft Racing
Keith Craft Racing
May 2020
S M T W T F S
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31            

Kirkham Motorsports

Like Tree4Likes

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
  #1 (permalink)  
Old 05-16-2020, 05:00 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default Engine dies while driving - tach drops to zero (MSD)

My FFR Cobra just developed a problem. I can be driving, idling, anything, then all of a sudden, the tach drops to 0 and the engine stalls as if someone turned the key off. If I'm moving, I can turn the key off and then on again and let the clutch out, or just restart it, and it's fine. I was thinking the ignition switch might be going bad, but I do not lose any other electrical at all (gauges, lights turn signals all remain on). Plus, today I was driving and decided to turn the key off while in gear and the tach does NOT drop to zero when I do that; then I turned the key back on and it continued running of course. The problem is happening more frequently now too.

I've checked the spark with the paper clip trick and it's fine, which MSD says that means the box is fine. I've checked the ohm reading on the magnetic pickup and it's within their specs. All grounds appear to be ok. I'm at a loss as to what to look for.

The car is a new-to-me Factory Five Cobra that only has 1,600 miles on it, but is 6 years old. It's a 347cid with a holley DP and mechanical fuel pump.

IGNITION SYSTEM:

MSD Digital 6AL box, MSD 8598 distributor. Coil blaster 2. I actually replaced it last month because the coil died on me. Totally different symptoms: car stumbled and died when I first started it and wouldn't restart. Coil did not have continuity. New coil fixed it right up.

Cap, rotor and plugs are new. Car runs great when it's running.

The tach is from Speedhut.

I hate to point to the little red box, so please advise on how to troubleshoot. As I said, the entire car looks brand new, so no rusty ground bolts, and every ground wire I can see is really well secured.

Thoughts and suggestions welcome!
Attached Images
  
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 05-16-2020, 08:06 PM
CC Member
Visit my Photo Gallery

 
Join Date: May 2020
Cobra Make, Engine:
Posts: 4
Not Ranked     
Default

Check your ground wire off the MSD box. Loose or bad connection can cause the intermittent issue as you described.
Reply With Quote
  #3 (permalink)  
Old 05-16-2020, 09:43 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

That wire comes into the car behind the dash and right to the frame. See pic. Seems solid.
Attached Images
 
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #4 (permalink)  
Old 05-17-2020, 07:36 AM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2008
Location: Tahoe/Truckee, ca
Cobra Make, Engine: Ford Racing 363/8-stack injection, SPFR0012
Posts: 255
Not Ranked     
Default

We found that the MSD box, FI computer was on the same circuit as the fuel pump, and radiator fan. When the fan would come on the motor would stumble at the voltage drop.

Just a thought.

Mark.

Last edited by Moto One; 05-17-2020 at 07:42 AM..
Reply With Quote
  #5 (permalink)  
Old 05-17-2020, 08:13 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

I don't have fuel injection and I have a mechanical fuel pump. This is definitely electrical, not fuel related.

That ground wire I posted a pic of looks VERY secure, it's certainly very tight. I can't see how much paint was scraped off around it, but the bolt goes into the frame. And as I said, it's not moving or loose, that's for sure.
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #6 (permalink)  
Old 05-17-2020, 08:51 AM
spdbrake's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2015
Location: Lyman, SC
Cobra Make, Engine: BDR #53, 408W
Posts: 884
Not Ranked     
Default

I'd suspect its the Ignition switch or the MSD box. My trust level in the 6AL boxes is pretty low. I switched to a MSD Street Fire 5520 after the last failure. It has the same options as the 6AL but not the same MJ amperage output. $100 cheaper. Meets my needs fine.

You don't have a heavy key ring per chance?

I've had pushed back pins (not locked) on the Green/Purple Dizzy connector at the MSD dizzy giving intermit connections. A wiggle check with the engine running should work.

Below is the FFR wiring diagrams.
https://www.factoryfive.com/wp-conte...ness-rev-T.pdf

The Gray wire on the MSD boxes is your Tach feed. Since the tach dies at the same time as the engine its either the Ignition switch or the MSD box or a loose connection. You can use a piercing probe to monitor the power wire to the the MSD box. https://documents.holley.com/6425.pdf
Reply With Quote
  #7 (permalink)  
Old 05-17-2020, 09:20 AM
Tom Wells's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: Mar 2000
Location: St. Augustine, FL
Cobra Make, Engine: E-M / Power Performance / 521 stroker / Holley HP EFI
Posts: 1,694
Not Ranked     
Default

Adam,

This may not apply to your immediate problem, but may bite you again in the near future: I notice you mount the coil to the engine.

If you want the coil to be reliable, get this one: MSD Blaster High-Vibration. It is epoxy-filled and will last much longer when bolted to the engine. The heat combined with the vibration of the engine will kill a normal oil-filled coil fairly quickly.

Alternatively, the coil can be moved to a structural location such as an inner fender or frame brace to isolate it from the engine a bit.

Just a heads-up,

Tom

PS: Way back I had a similar problem. It turned out to be a bad butt splice connector in a wire going to the coil. At first it was intermittent, later had to trailer the car home. Took some real detective work to find it as it was located under a fender in an enclosed space. The clue was no voltage at the coil. Maybe you could connect a voltmeter to the hot side of the coil and wiggle wires here and there while watching (or your assistant watches) the voltage.
__________________
Wells's law of engine size: If it matters what gear you're in, the engine's too small!

Last edited by Tom Wells; 05-17-2020 at 09:27 AM..
Reply With Quote
  #8 (permalink)  
Old 05-17-2020, 11:49 AM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 20,089
Not Ranked     
Default

About ten years ago I had a similar intermittent electrical problem. I was able to pinpoint it by having temporary 12v lights wired to the critical circuit points so that when the problem occurred I could just look to see what light was out and that tipped me off to where the problem was. Try wiring a light to the On/Off 12v+ feed to the MSD box right at the box itself. Take her for a run and, when she cuts out, tell us if the light is still on. Likewise, have a second light wired to the always-present 12v+ and 12v- feeds to the box. Since that light will always be on, what I did was just hook it up with alligator clips before a run. If it is indeed an electrical issue, this is a pretty good way of identifying it. It won't spot everything (like a flaky coil), but it will eliminate a lot of possibilities. I do like the MSD Hi-Vibration coil, and that's what I have. But don't start replacing things until you've exhausted the light bulbs trick. The problem with an intermittent fault is that you can accidentally "jiggle" a bad connection somewhere in to working right and you think you've fixed it, but you really haven't.

Last edited by patrickt; 05-17-2020 at 11:51 AM..
Reply With Quote
  #9 (permalink)  
Old 05-17-2020, 12:09 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

Yea, good idea. What do you suggest, Scotchlok wire taps?
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #10 (permalink)  
Old 05-17-2020, 12:30 PM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 20,089
Not Ranked     
Default

Quote:
Originally Posted by AdamIsAdam View Post
Yea, good idea. What do you suggest, Scotchlok wire taps?
I used Posi-Taps, but anything similar like that would probably be just fine.
Reply With Quote
  #11 (permalink)  
Old 05-17-2020, 01:30 PM
FredG's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2018
Location: Howell, NJ
Cobra Make, Engine: Backdraft Car #1209 Roush 427R
Posts: 252
Not Ranked     
Default MSD ughh

I too have suffered the ills of the 6al but mine have been limited to the coil. I would not trust any of them. I have gone through 2 MSD 8207 Baster coils in 2 years and the third isn't looking so good. First is the intermittent firing then it will shut off. Will start up again after a bit. They don't have a good reputation. I came across the attached document showing MSD recommended coils. I am going to research and see which of these are good. For now I am just going to go with one that is compatible from Summit. Going to look at the high Vibration coil a few people talked about but it will be fender mounted like the current coil.

https://manualzz.com/doc/9233513/coil-compatibility

Last edited by FredG; 05-17-2020 at 01:38 PM.. Reason: text
Reply With Quote
  #12 (permalink)  
Old 05-17-2020, 02:04 PM
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2016
Cobra Make, Engine:
Posts: 92
Not Ranked     
Default

temporarily disconnect tachometer and see if problem persists. I had same problem years ago and the tach was getting hot and shorting out ignition system thus the killing engine.
Reply With Quote
  #13 (permalink)  
Old 05-17-2020, 03:11 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

Quote:
Originally Posted by studebaker53 View Post
temporarily disconnect tachometer and see if problem persists. I had same problem years ago and the tach was getting hot and shorting out ignition system thus the killing engine.
I was thinking the same thing.

I found the factory wiring schematics onto which the builder notated where he connected the MSD gray to the harness' purple which then goes to the tach. Of course, it's not a simple plug that I can unplug, it's hard connected. This would all be a lot easier if the darned thing wasn't so darned small behind the darned dash and the interior in general! At least the darned thing doesn't take up much space in the garage! lol Just venting.

(Before I start cutting wires, I want to figure out how I can access the wires to re-crimp them later.)

I'll play w/this all this week and report back. Thanks all for your suggestions.
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #14 (permalink)  
Old 05-17-2020, 03:33 PM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 20,089
Not Ranked     
Default

Just pull the fuse that feeds the dash gauges and take her for a spin. IIRC, that tach wire is just a 12v square wave.
Reply With Quote
  #15 (permalink)  
Old 05-17-2020, 04:02 PM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2007
Location: Carlsbad, Ca
Cobra Make, Engine: SPF 2932 with 438 Lykins Motorsports engine. Previous owner of FFR 5452.
Posts: 2,459
Not Ranked     
Default

Ignition switch is my bet. Start simple then go complex.
__________________
Jim
Reply With Quote
  #16 (permalink)  
Old 05-17-2020, 05:17 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

Quote:
Originally Posted by patrickt View Post
Just pull the fuse that feeds the dash gauges and take her for a spin. IIRC, that tach wire is just a 12v square wave.
Doh! I hate when I don't think of the obvious. That fuse controls all gauges, but also apparently the radiator fan, but I should be ok for a while anyway without over heating, not that I'll know without a temp gauge lol. I'll go tomorrow in the daylight. tnx

Quote:
Originally Posted by jhv48 View Post
Ignition switch is my bet. Start simple then go complex.
Yea, I ordered one (a different brand) already that someone (a professional builder) on the FFR forums said is more reliable. But with only 1,600 miles and it feeling so good/solid, I wonder how likely that is.

I verified that the ground being used has the same volts as when I put my meter to the battery directly. I'll relocate it anyway, but I don't think that's the problem.

My money is on either the ignition switch or the tach. I feel that if it's worked fine for the first 300 miles and a few months I've owned it, and assume it worked for the prior owner, then why would wiring suddenly go bad?

I don't think it's the MSD box itself and I am pretty confident it's not the coil, although I have a spare new one I can swap in if need be.
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #17 (permalink)  
Old 05-17-2020, 05:26 PM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 20,089
Not Ranked     
Default

Here, try just attaching a 12v light, via alligator clips, to the IGN post of your ignition switch and a good ground. Then turn your switch ON. The light should be on. Now, try gently tapping the ignition switch with the handle of a screwdriver and lightly wiggle the key without turning it to crank or ACC. The object is to get the light to wink when it shouldn't. If you can get the light to wink with a wiggle or a tap, you've found the problem.
rads42 likes this.
Reply With Quote
  #18 (permalink)  
Old 05-17-2020, 07:27 PM
Gaz64's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2008
Location: Brisbane, QLD
Cobra Make, Engine:
Posts: 2,399
Not Ranked     
Default

The tachometer will not be the cause since it would be connected to the "tach out" terminal on the 6AL. This is an output signal, and cannot be an "input signal" to stop the ignition system from operating.
rads42 likes this.
__________________
Gary

Gold Certified Holden Technician
Reply With Quote
  #19 (permalink)  
Old 05-17-2020, 08:02 PM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2019
Location: Long Island, NY
Cobra Make, Engine:
Posts: 83
Not Ranked     
Default

It's not easy, but I'm able to get a test light on the ING wire. It's illuminated with the key ON and tapping the switch or key didn't effect the light. It also functioned properly, illuminating only with key ON, but not on ACC or OFF.

Thanks for the info about the tach output wire.
__________________
Adam
Fulfilling my lifelong dream to own a Cobra... MISSION ACCOMPLISHED!
Reply With Quote
  #20 (permalink)  
Old 05-18-2020, 05:39 AM
CC Member
Visit my Photo Gallery

 
Join Date: May 2015
Location: Downers Grove, IL
Cobra Make, Engine: Backdraft SBF-302
Posts: 292
Not Ranked     
Default

MSD instructions state the box must be grounded to the battery.

I've had this twice. Both times, foe me, was connectivity to ground
Your mileage may vary.
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 10:39 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink