overheating a distributor?

[STOICH]

I have a 16 valve vw jetta engine in my baja bug. I have a stalling issue once engine is warmed up, and was curious if anybody has a thought on this. I have learned that if I run a big fan across the back of the engine (distributor area) that the engine will continue to run for as long as I let it. If I unplug fan, car will die within a minute or so. I have a megasquirt FI system, and can watch the Rpm signal drop from idle to dead zero as it starts to fail. This will get better as soon as I turn the fan back on. I have run the fan over the external oil cooler to see if cooling oil would help keep dist. temp down - no help there. Anybody ever heard of this before?

[Piledriver]

The hall sensor in the distributor is a sensitive electronic device, and being heat sensitive as a failure mode is not unheard of.
It's not a crazy idea.

OTOH, in the original app, the radiator fan also blew directly on it.

The only way to be sure would be to swap in another unit.

.. or perhaps temporarily rig up something that could blow cool air on it and isolate it from the heat.

Another option is to add a toothed wheel to the crank pulley on the other end of the engine, the MS can "read" that as well via a Hall sensor or VR sensor, and you would likely have more accurate timing/less jitter. A missing tooth wheel is sufficient for anything but full sequential setups.

[STOICH]

The hall sensor in the distributor is a sensitive electronic device, and being heat sensitive as a failure mode is not unheard of.
It's not a crazy idea.

OTOH, in the original app, the radiator fan also blew directly on it.

The only way to be sure would be to swap in another unit.

.. or perhaps temporarily rig up something that could blow cool air on it and isolate it from the heat.

I suppose I should have stated that I have replaced the distributor because of this - no joy - right with you there...

[Piledriver]

I suppose I should have stated that I have replaced the distributor because of this - no joy - right with you there...

In that case, wiring or connectors become the next suspect.
IIRC you had a "suspect" section of cable already.

[STOICH]

I suppose I should have stated that I have replaced the distributor because of this - no joy - right with you there...

In that case, wiring or connectors become the next suspect.
IIRC you had a "suspect" section of cable already.

You are correct. Because of this, I have re-wired all wires related to distributor, checked for cold solders on MS2. I have found reliably, the car will run with fan on distributor, and I was able to video tape the car running for 20 minutes, and dying within a minute of unplugging fans. This occurs at idle, road vibration not part of the equation yet. I really suspect the distributor is getting heat soaked, not quite sure what I'm gonna do about it yet- The trigger wheel is an option, but don't know quite enough about it to attack it yet- still hoping to figure out why the dist is becoming out of range

[david58]

Let me throw this out there for what it is worth. I think it may be a ground issue. Couple easy test to find out would be to use a jumper cable straight from the battery - to see if the problem goes away. A multi meter from battery - to the dist housing would also tell what the ground path is where you can see it. A bad ground could cause the dist to overheat. And another thing just came to mind, if you have or can beg borrow or even steal a infa red temp gauge and read the temp of the dist housing when it dies might help in the diagnosis. As pile pointed out that dist gets cooled by the engine cooling fan in it's original configuration, so that could very well be the problem. I would like to see what raygreenwoods thought are on this. Like pile he is one of the icons around here. I don't remember seeing ray post anything in a while so I will send him a PM to this thread.

[STOICH]

Let me throw this out there for what it is worth. I think it may be a ground issue. Couple easy test to find out would be to use a jumper cable straight from the battery - to see if the problem goes away. A multi meter from battery - to the dist housing would also tell what the ground path is where you can see it. A bad ground could cause the dist to overheat. And another thing just came to mind, if you have or can beg borrow or even steal a infa red temp gauge and read the temp of the dist housing when it dies might help in the diagnosis. As pile pointed out that dist gets cooled by the engine cooling fan in it's original configuration, so that could very well be the problem. I would like to see what raygreenwoods thought are on this. Like pile he is one of the icons around here. I don't remember seeing ray post anything in a while so I will send him a PM to this thread.

Both are avenues I hadn't thought of. I will play with the ground theory tonite, I guess I could just make a ground wire for it to be certain, (can't hurt anything) I do have a buddy with one of the thermometers, I think I will be borrowing it soon...

[david58]

The ground path back to the battery is most important if you lose it you lost it. Just like losing power. Most people say they have a short when in real life they mean a open. You do have a good ground srtap on the tranny don't you? You can check it the same way with a multi meter. We will fillet this fish just hang on and give good feed back. I am watching this thread with both eyes wide open. This is a problem that you have put a lot of thought and time in to diagnose I have great respect for that. Collectively the STF will diagnose this

[Steve Arndt]

Put the dizzy in the freezer for an hour, then try it.... :p

[STOICH]

it was recommended to me today to try VW Vortex... I was asked a question I had been trying to best answer in the Megasquirt forum

-----------------------
Are you sure it is not the ignition driver?
It has to be mounted to a heatsink. Too hot voltage to the hall coil? 7 volt I think is correct
-----------------------
Im assuming your refering to the black 7? pin ignition control module-ish box connected to distributor. This issue was occuring when I had it hooked up. I tried 4 different ones, until a buddy that is more familiar than I with electronics, removed it altogether. I now have a 1k ohm .5 watt pullup resistor wired inbetween the signal wire and the power wire replacing the module. The engine would run for 30 seconds exactly, and then stall when the module was in use. His theory was that the ecm was not seeing load, and would shut off the injectors. When we switched out for the resistor, the car became driveable. Per his request, I am upping the resistor tonite to a 2k ohm resistor to see how this affects it. I will report on this soon

[Piledriver]

Another few thoughts---

Are you using the VR circuits or the opto with a pullup for the distributor signal?
(I don't have a v3 board setup memorized, but I think both are an option)

If you are using the VR, you may need to play with the adjustment.
The opto is bullet proof by comparison.

The Hall sensor needs a pullup resistor to 12v, I'm using 1K and have identical sensors on a Vanagon distributor.
It also needs switched 12v to power the hall.

If you are using the opto, you may need the remote ground return config or one of the many minor possible documented tweaks for that circuit.

Once you nail this vehicle-specific setup issue, it should be pretty bulletproof.

I may be getting my MS install threads mixed up in my head...
This is MS on a turbod 16V, right?

[STOICH]

Another few thoughts---

Are you using the VR circuits or the opto with a pullup for the distributor signal?
(I don't have a v3 board setup memorized, but I think both are an option)

If you are using the VR, you may need to play with the adjustment.
The opto is bullet proof by comparison.

The Hall sensor needs a pullup resistor to 12v, I'm using 1K and have identical sensors on a Vanagon distributor.
It also needs switched 12v to power the hall.

If you are using the opto, you may need the remote ground return config or one of the many minor possible documented tweaks for that circuit.

Once you nail this vehicle-specific setup issue, it should be pretty bulletproof.

I may be getting my MS install threads mixed up in my head...
This is MS on a turbod 16V, right?

Yes it is turbo, and sounds like your thinkin of the right car... I am also using a 1k pullup. was just about to trade it out for a 2k, until you wrote this. Your working ok on 1k... hmmm.. you have removed the control module also?

[STOICH]

The ground path back to the battery is most important if you lose it you lost it. Just like losing power. Most people say they have a short when in real life they mean a open. You do have a good ground srtap on the tranny don't you? You can check it the same way with a multi meter. We will fillet this fish just hang on and give good feed back. I am watching this thread with both eyes wide open. This is a problem that you have put a lot of thought and time in to diagnose I have great respect for that. Collectively the STF will diagnose this

Thanks bud, you are right... this has been kicking my ass now for a while...

[Piledriver]

you have removed the control module also?

I only use the distributor for TDC#1 sync, it has 3 "wings" hacked off the internal trigger wheel and only has one.
(Running full sequential MS2-extra) 6/1 "wheel" setup using the flywheel vent holes for the "6" tooth crank wheel.

I feed it directly into the MS, MS provides pullup power and 12v switched from the MS box power relay so ~everything's common.

I am set up so ALL grounds are at the MS except for coil power ground (LS2 coils) and the ground for the CIS cold air valve heater, those go to the block (engine tin, actually) to keep the ground paths short. (OK the heater probably doesn't matter, and runs off the OG coil power wre, along with the backup light circuit ala factory)

My 12v to the coils/injectors goes through another relay vs. the MS with some filtration downstream.

The "sensor" and ignition/injector power harnesses are physically separate and physically separated as much as possible, and feed through flex conduit routed on opposite sides of the car.

My coil and injector drivers live in a physically separate MS1 box, with their own power wire//relay and fuses/grounds etc.

I don't have any weird with this setup.

It was more work, and I might not do it again, but it has proven to be bulletproof.

[Dale M.]

Why are you even messing with distributor..... All the trouble shooting time wasted you could have installed a trigger wheel, VR sensor, coils and modded the MS accordingly.... for simplicity and a place to start learning curve I would get a EDIS setup and convert from distributor and then go forward from there....Maybe try putting a Pertronix or Compufire module in distributor if you want to retain distributor... What about aftermarket distributor, does MSD make one or some other "shop" make one that fits your motor.......

http://www.ebay.com/itm/EDIS-4-Ignition ... 1c22e3c17e

Dale