Consistent Warm dying issue

[Nditiz1]

I didn't want to put this in my conversion thread. Hopefully someone can chime in with a good test or answer.

77 US Targa
82 US engine with complete ROW CIS

I have been working with Tony on checking some CIS components.
Fuel numbers looked good per Tony
AAV and AAR were checked

I am uploading some videos to youtube of the progression.

1st video is the cold start. You can see the RPM drop down after it goes through the cold start cycle. The RPM's drop under the 950 as I had been adjusting the Air Bypass in the last test and it was up around 1100 after a full warm. You'll see me adjust it at cold to get the warmup back in spec. I probably don't need to do that since eventually the car will be warm and you will see in the other vids it running around 1100.

https://youtu.be/oES4XNNnWYU

Second vid is at about 11 mins, no problems. Temp is rising.

https://youtu.be/AsPZhB89xUU

3rd vid is close to the time to death about 21 mins. Everything still seems fine. Temp is around 180, but not to the break point.

https://youtu.be/SfwrOQewgrY

4th vid captures the stumble, drop in RPM, stall and an aftermath backfire that scared me caught me off guard.

https://youtu.be/_9kAjGGLTgk

It is pretty consistent that once it gets to ~190 temp the engine engages in some prevention measure to stop the engine as it thinks it is getting too hot. Is that even a thing?

I have not yet checked for Vac leaks, but the RPMs do drop slightly if I remove the oil cap. I will test the system. Would vac leaks cause this consistent issue once completely warm?

There is also the thought that the Bosch CDI is getting hot and failing. I do notice the pitch of the CDI is not as loud. Listen to vid 1 ~30sec and vid 4 ~26sec. This would be the only variable that was different from the 82 this came out of. Thoughts?

[T77911S]

you might post all tests done with tony.

will it keep running if you give it gas, or will it start back up
swap in another coil

[Nditiz1]

Tests done with Tony were to check the AAR, AAV, fuel pressure numbers SP, CCP, WCP. All were good.

Unfortunately I don't have a spare Coil, well except this blue coil from a 914, will that work?

FP relay still works post heat stall. If I try to give it gas it wants to stall faster and backfire more. It doesn't want to start back up and if it does dies immediately. If I give it 5 - 10 mins to cool down to 170 or below it starts up and idles smooth. Then as temp rises again it wants to shut off again.

[RDM]

There is no temperature protection built in to the engine, so the oil temperature isn't (directly) causing the engine shutdown. I'd guess it's a result of old electronics expanding in the heat, causing a loss of continuity somewhere in the fuel or ignition electronics (such as the FP relay or CDI box).

I had a similar problem a year or so ago while driving in the very hot, complete with backfires and easy restart. I spread the posts in the fuel pump relay and swapped the CDI and the problem went away. Not that this proves that they were the problem, but maybe they were....

[Jonny H]

Originally Posted by Nditiz1

There is also the thought that the Bosch CDI is getting hot and failing. I do notice the pitch of the CDI is not as loud. Listen to vid 1 ~30sec and vid 4 ~26sec. This would be the only variable that was different from the 82 this came out of. Thoughts?

The classic whining noise is caused by the the inverter frequency in the power supply. If you are absolutely sure it has stopped making the noise when the engine stops then this is almost certainly the issue. Unless of course, the box has lost its 12V (unlikely having watched your video).

Did you happen to notice if your strobe light was going 'intermittent' before the engine stop? That would be an indicator too.

[Nditiz1]

I still hear the sound, but post warm it was noticeably different.

I did notice the strobe was intermittent, but that makes sense since it was missing, backfiring, losing idle.

[Jonny H]

Originally Posted by Nditiz1

I still hear the sound, but post warm it was noticeably different.

I did notice the strobe was intermittent, but that makes sense since it was missing, backfiring, losing idle.

Then it’s almost certainly the CDI unit. Try some forced cooling (cold hairdryer) and see if it comes back to life.

(If it was missing due to a fuel problem the strobe would still be ok so this has to be ignition).

[nomore]

Try wrapping the cdi in a freezer gel pack and thin towel. might keep it cold enough
as a test; works for my sore back from working on the pcar. or bag of peas.

[Nditiz1]

The freezer and ice packs were a good idea. I decided not to mess with it anymore and ship it out to Bob Ashlock (CDI wizard). Worst case scenario it comes back all shiny and new, thoroughly tested, and I start looking elsewhere.

I'm asking if anyone has a loaner in the mean time to test the warm theory.

[boyt911sc]

Nick,

I have been out of the house since early morning and won’t be back home till after 10:00 PM. I will send you a PM for the details. BTW, you made a good decision sending your CDI for repair and it will be in good hands.

Tony

[Flojo]

Originally Posted by Nditiz1

There is also the thought that the Bosch CDI is getting hot and failing.

cant see the vids from where I am... is it the silver Bosch coil? the bad Brasil made?
they fail when warmung up.
swapped mine to a MSD 8222.

edit

left, the BERU, works, though no filling and does not like high temperature (summer/racing) and is recommended to be set up upright!
center, the well nown MSD 8222, high Vibration resistant (epoxy filled), used in Rallye Sport
right, the troublesome Bosch silber coil, oil filled



my silver coil blew...