TeamCapri

Please login or register.

Login with username, password and session length
Advanced search  

News:

New & potential members - due to overwhelming spam registrations, it's been very hard to sort through new registrations. If your account has not been approved, check your spam folder! If not please contact us at admin[AT]teamcapri.com and we'll sort it out for you.

Author Topic: Car intermittently dies with no tach signal  (Read 4002 times)

Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Car intermittently dies with no tach signal
« on: April 19, 2021, 09:31:35 PM »

I'm bringing my XR2 out of hibernation (I used to frequent this forum back when I drove the car as a daily driver in the 2007--2012 timeframe) and hoping to fix it up. I've had an intermittent issue dating all the way back to 2009 that pops up occasionally. It's bad/frustrating enough that the car is unreliable, and it's been haunting me all these years. I'd really like to get it dealt with once and for all.

Randomly, usually while the car is up to temperature but not exclusively, it will simply shut off (or not start). The engine cranks just fine, but it won't catch. And--this is the most valuable clue I have right now--there is no signal at the tach (even though the engine is very clearly turning over!). The tach also drops immediately to zero when it dies, even when you can hear the engine continue to turn over for a second or two as it dies out.

After a certain amount of time (anywhere from seconds to hours), the car will restart fine and drive like nothing happened.

When working this problem back in 2011, I replaced both the ECU and the distributor separately, and neither fixed the issue.

Coming at it again with fresh eyes, I've started to work the lack of tach signal. I've established that the signal comes from the ignition coil (not the distributor). I've established that if I disconnect the "input" to the coil (the two-prong connector coming in from the driver's side), I can recreate the fault: the car cranks fine, but no tach signal. (Not entirely surprising, since that's the source of the tach signal).

But I'm not 100% convinced it's the ignition coil itself. I'm wondering if it might be a ground--but which one? Another thought is a funny spot in the harness somewhere, which I'm not looking forward to tracing.

Any other thoughts, help, or advice on what this might be (and what I can do to establish that I "got it") would be very much appreciated! (This car was my grandfather's before I got it, and I can't wait to get it on the road again).
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Rocketman

  • Administrator
  • Old-Timer
  • *****
  • Posts: 5493
    • 91 BPT AWD Capri & 1991 XR2
    • http://www.werbatfik.com
Re: Car intermittently dies with no tach signal
« Reply #1 on: April 19, 2021, 10:23:11 PM »

You've got a textbook case of a bad ignitor module, it's the module inside the distributor that generates the tach signal. (very common issue on the Capri) They tend to fail slowly over time and the problem gets worse, usually working cold but causing issues as the engine gets warm. No ignitor = no tach at the dash, no tach at the dash = no spark and no injector pulses.

If you search the forum here you'll find info about replacing it. It live inside the distributor, it's fairly easy to get to.
Logged
1.8L Turbo All Wheel Drive Capri... the "GTXR2"


EShepherd

  • Sr. Member
  • ****
  • Posts: 487
    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: Car intermittently dies with no tach signal
« Reply #2 on: April 20, 2021, 12:35:14 PM »

Just to piggyback off the master there,

https://www.rockauto.com/en/moreinfo.php?pk=49895&cc=1196636&jsn=1585

that SHOULD be the part he's talking about. Not too expensive, either. Greywolf keeps a nice running list of discount codes for Rock Auto on these forums somewhere too, which should shave a little bit more off that.



The only thing I'd add is to check out the wiring to and from the module. Every single time I touch any wiring on my car, it's rotted, corroded, and just generally a mess. Granted, my Capri was very clearly abused, so it's possible yours might not be as bad. Before you order the part though, definitely make sure you are getting proper power and ground to it. Easy enough with a multimeter, just look for continuity from the source to the part. While you're in there doing that, check out the resistance in those wires. You should not see O.L, but you also don't want to see much more than, I don't know for sure, just a few ohms. If it's OL, you've got an open circuit (broken wiring). If it's more than a few ohms, pull back some of the rubber and look at the copper. It'll probably be green and nasty, at which point, it'd be best to just run new wiring too.

Oh yeah, and check all your fuses. It's intermittent, so I HIGHLY doubt it's a blown fuse, but hey. Easy enough to check, always the first thing to rule out when you've got silly electrical gremlins.
Logged

redsteve

  • Jr. Member
  • **
  • Posts: 65
    • 1991 Capri, the rest are red or appliances...
Re: Car intermittently dies with no tach signal
« Reply #3 on: April 20, 2021, 03:15:30 PM »

Hi all,

Having just had to put one of these in, by a shop because my car was waaaay out of position and the part wasn't available except by online ordering...,

....yeah...that's it.

I might even consider carrying a spare (which I used to do for a 260Z I had a long time ago).

Good luck!

Steve

P.S. I just posted a Rock Auto discount code I just received, in that thread on this forum.



Logged

Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Re: Car intermittently dies with no tach signal
« Reply #4 on: April 20, 2021, 06:20:09 PM »

Thanks for the responses, everyone!

I replaced the distributor (entirely) in 2011 and it did not fix the problem (the car died on my test drive, I recall). So I suppose this points to the wiring between the ignitor module and the ECU? (I also replaced the ECU, separately, with a similar lack of results). Or, I suppose it's possible that I got a similarly-faulty distributor (it was from someone on this forum if I recall correctly, so likely OEM off a parts car).

Does anyone know which wire(s) coming out of the distributor are the ones related to the ignitor module? Do they run straight to the ECU?

And where does the ignition coil come into this? Why does the tach signal test connector come out of the harness going into the coil, and not from something over on the distributor? (I am NOT an electrical engineer, admittedly!).
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Re: Car intermittently dies with no tach signal
« Reply #5 on: April 20, 2021, 08:48:29 PM »

Update: At Rocketman's suggestion, searched the forum some for "ignitor control module" and see that I'm about the 900th person with this issue, lol. It really does sound like it is exactly what Rocketman says--"textbook" (the "dies while hot, comes back to life cold", the lack of tach signal). I'm hung up on the fact that I replaced the distributor and had the issue persist. Any thoughts on whether wiring could be responsible for this--or is it just possible I had a "dud" distributor that happened to also have the issue?

I really appreciate the help! (I will try to use the search feature more before posting in the future, haha).
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Rocketman

  • Administrator
  • Old-Timer
  • *****
  • Posts: 5493
    • 91 BPT AWD Capri & 1991 XR2
    • http://www.werbatfik.com
Re: Car intermittently dies with no tach signal
« Reply #6 on: April 20, 2021, 10:13:44 PM »

Yes, it's entirely possible you got another bad distributor.

I'm not entirely positive on the chain of command with the tach signal, but I believe the ignitor talks to the knockbox. I'm not sure if the knockbox drives the ignition coil or if the ECU does, there is a Coil output on the ECU pinout but I think the dizzy/knockbox/coil can work somewhat independent of the ECU. The tach terminal in the engine bay is spliced off the ignition coil input, as I recall.

It is possible your knockbox is going, I had an issue with my GTXR2 where I had loss of spark and tach, I swapped in a known good distributor while still hot and it did not fix the issue. (I had a spare distributor & ECU in the trunk, swapped both to no avail) I think I figured out the knockbox was getting hot after the fact, I still have not resolved the issue. This happened the morning of the last meet I hosted and the car let me down, I parked it and have not driven it much since then.

If you have access to a spare knock box you could try that.
But it does still sound like an ignitor issue, worth pursuing to troubleshoot at least IMO.
Logged
1.8L Turbo All Wheel Drive Capri... the "GTXR2"


Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Re: Car intermittently dies with no tach signal
« Reply #7 on: April 21, 2021, 06:32:16 PM »

Agreed, thanks for the follow up Rocketman! I have an ignitor on order, should be arriving Friday.

If it comes to it, is the knock control box sold anywhere or is that one I would have to pick up from someone secondhand?

I will report back after getting this installed this weekend!
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Rocketman

  • Administrator
  • Old-Timer
  • *****
  • Posts: 5493
    • 91 BPT AWD Capri & 1991 XR2
    • http://www.werbatfik.com
Re: Car intermittently dies with no tach signal
« Reply #8 on: April 22, 2021, 04:44:46 AM »

The knock box is not available new, you will have to find a used one.
The Facebook capri group might be a good place to ask if anyone has one for sale: www.facebook.com/groups/210318449008872/
Logged
1.8L Turbo All Wheel Drive Capri... the "GTXR2"


Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Re: Car intermittently dies with no tach signal
« Reply #9 on: May 01, 2021, 03:08:43 PM »

Update:

Put in the new ignitor module. Have gone through a few test drives of increasing distance/time, and the car had seemed to be running well. Unfortunately, today while out for a drive, the problem resurfaced. At speed, the tach suddenly dropped to zero, the engine shut off, and (upon pulling over and attempting to re-start) the tach was not moving while cranking. A few minutes later, it re-started and I was able to drive it home.

So I'm looking for other thoughts. Rocketman, have you made any progress on your GTXR2? I see the knockbox as an option, as well as the wiring coming to/from the distributor.

Does anyone know what I should be seeing (12 V, ground, etc.) on each of the pins at the connector at the distributor? If I can get the problem to come back again, I'd like to confirm that the signals at that connector are correct going "into" the distributor.

Thanks as always for the advice!
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Rocketman

  • Administrator
  • Old-Timer
  • *****
  • Posts: 5493
    • 91 BPT AWD Capri & 1991 XR2
    • http://www.werbatfik.com
Re: Car intermittently dies with no tach signal
« Reply #10 on: May 01, 2021, 03:28:02 PM »

The GTXR2 has been sitting for 6+ years, it's in need of a tremendous amount of work at this point.

Seeing that signal from the distributor will likely require an oscilloscope, it's not something a multimeter will be able to see. They do make some neat pocket DSO's now, for not terrible money. I have a DS212 that I have used for some ignition related troubleshooting on other cars.

You should be able to verify power/ground at least. There's wiring diagrams at TechCapri that will be of assistance: https://www.techcapri.com/Wiring.html

Logged
1.8L Turbo All Wheel Drive Capri... the "GTXR2"


chrispoe

  • Sr. Member
  • ****
  • Posts: 435
    • 91 BP Capri GT
Re: Car intermittently dies with no tach signal
« Reply #11 on: May 01, 2021, 05:01:51 PM »

From my notes/schematics:

The XR2 distributor wire connector C156:
Black/white= 12V supply
Black/yellow= knock-box and knock sensor (ground)
Black/green= ignition control module (cylinder id signal shield (ground))
Yellow= ignition control module (cylinder id signal output to ecu)
White= igniter module to knock-box
Green= igniter module to knock-box

XR2 knock-box wiring connector C164:
Yellow/green= 12V supply from main ignition relay
Black/yellow= distributor and knock sensor (ground)
White= distributor ignition module
Green= distributor ignition module
Black= input signal from knock sensor
Light green/yellow= input from ecu (adjust base timing a fixed amount for high altitude based on barometric pressure sensor)
Black/white= input from ecu (disable knock sensor for start/idle)
Yellow/blue= output tach signal that goes to ecu, tach gauge, ignition coil, and tach-test connector

XR2 knock sensor connector C169:
Black/yellow= distributor and knock-box (ground)
Black= output signal to knock-box

XR2 ignition coil connector C161:
Black/white= 12V from ignition switch
Yellow/black= tach signal from knock-box

My notes/schematics don't say specify what the green or white wire are. If the XR2 igniter only has 2 wires on the module itself, then one is power and the other would be the crank signal. If the igniter has 3 wires attached to it similar to the N/A, then the green and white wire would be crank signal and ignition advance.


Did you replace the ignition control module (closest to the rotor) or did you replace the igniter/pickup coil that's located deeper inside the distributor?
Where did you buy the igniter from, because I can't find the part at any store?

« Last Edit: May 01, 2021, 05:12:56 PM by chrispoe »
Logged

chrispoe

  • Sr. Member
  • ****
  • Posts: 435
    • 91 BP Capri GT
Re: Car intermittently dies with no tach signal
« Reply #12 on: May 01, 2021, 05:42:14 PM »

Replacing the ecu won't help with a no spark situation. The only control the ecu has on the ignition system is it can advance the base timing a fixed amount for high altitude operation or it can disable the knock-box from retarding timing when the knock sensor is triggered.

A bad ignition coil will cause a no tach signal too. The ignition coil serves two purposes, it creates high voltage for the spark plugs, but it also acts as a pull up resister for the tach signal wire. The tach pulse from the knock-box are sinking(ground) pulses and in between those the ignition coil pulls the tach wire high to create the tach signal.

Next time the issue happens with the ignition switch on, check for voltage on both wires of the coil, the black/white wire on the distributor, and the yellow/green wire at the knock-box. Then verify the black/yellow wire at the distributor and knock-box have ground continuity.
Logged

Nascarfan08

  • Jr. Member
  • **
  • Posts: 62
Re: Car intermittently dies with no tach signal
« Reply #13 on: May 07, 2021, 07:54:02 PM »

Thanks for the response Chris! This is really helpful.

The part I replaced was the ignition control module (closer to the rotor). Based on the part that was linked to above, that was the part I thought was being pointed to. Is it actually the ignitor/pickup coil that is the problematic one? (I did not realize there were two separate parts--I just thought that there were multiple names for the same thing).

Your list of things to check is really helpful, and I will dive into that. (In fact, I think I will first check out everything with the car acting normal, so I can properly compare). I'm getting back out there this weekend, so I will report back on what I find.
« Last Edit: May 07, 2021, 08:24:09 PM by Nascarfan08 »
Logged
1991 Silver Mercury Capri XR2 Turbo convertible

Gaz

  • Sr. Member
  • ****
  • Posts: 423
  • Do no harm, take no sh!t.
    • 92 XR2, 01 LL Bean Outback, 92 Concours, 86 F150
    • Saint Cloud Exhaust
Re: Car intermittently dies with no tach signal
« Reply #14 on: June 26, 2021, 11:08:39 AM »

Thanks for the response Chris! This is really helpful.

The part I replaced was the ignition control module (closer to the rotor). Based on the part that was linked to above, that was the part I thought was being pointed to. Is it actually the ignitor/pickup coil that is the problematic one? (I did not realize there were two separate parts--I just thought that there were multiple names for the same thing).

Your list of things to check is really helpful, and I will dive into that. (In fact, I think I will first check out everything with the car acting normal, so I can properly compare). I'm getting back out there this weekend, so I will report back on what I find.

What did you find? I'm poised to replace the ICM, and the CTS, for good measure, through exhibiting similar syptoms. I have diving/wavering RPM that will shut off the car if it's idling. EXCEPT when I have a high electrical load on it (A/C, Blower, and/or lights), which seems to stabilize it. Perhaps unrelated, it has developed a loss of power with rpm, like it's not advancing the timing or pulling fuel, I have yet to dive into it. I'm curious as to what you discovered, though.
Logged