2003 Eurovan stalling on highway in heat.

[Habbyshaw]

2003 Eurovan currently in Dallas (Driving cross country from Boston)

The issue is heat related. The motor is shutting down during the heat of the day. Starts back up after stall. Sometimes you need to wait a few minutes and pump the gas pedal. When the sun is out you can only drive a mile or 2 before it shuts down. When the sun goes down you can drive 100+ miles with no stalls.

Parts replaced
rebuilt transmission
External trans cooler (leaking)
Fuel pump (replaced twice in 2 months)
cam shaft position sensors (2)
crank shaft position sensor
New fuel pump relay

Last shop that worked on it diagnosed "loss of fuel pressure" and replaced the fuel pump. Claiming the one that was installed a month earlier could have been faulty. Drove it out of the shop and 100 miles later it did the same thing.

The engine has thrown 2 codes but they seem to be unrelated. One is a TCM code and the other is a Crank Shaft Position sensor code. these codes appear when the van is coasting to a stop and the motor restarts and the transmission is moving at a different speed then the motor causing it to clunk and throw a code.

I know this is totally insane but the last time we drove the van with the sun in the sky the van broke down every mile until the sunset. once the sunset the van drove with no problems for 100+ miles.

Can the sun cause electrical issues?

If anyone has any suggestions as to what this issues could be related to it would be greatly appreciated.

Also looking for shops in the Dallas area that might be able to help.

Thank You!

[CdnVWJunkie]

A crank position sensor code is a crucial one and shouldn't be ignored. I would suggest replacement. This is likely your issue.

On initial read I was thinking fuel vapor lock but with CPS code I'd start there.

[Habbyshaw]

CdnVW- thanks for your reply, I’ve checked for vaper lock - no evidence at the fuel cap. - I’m going to have a mechanic in Dallas check the Crank Shaft Position sensor today and report back.

[CdnVWJunkie]

If the CPS has triggered a code there's something amiss. Either wiring chewed/frayed, corrosion or the sensor is failing.

[EuroTec]

Old thread but I'm just going to throw this out there.
I have 2003 T4 that stalls when it's hot outside and the AC is on. I have seen at least three other owners have the exact same issue, especially with the AC on.

I think I know what the issue is. Overheated ECU. It has all of the classic symptoms of an overheated power transistor. They simply fail to operate when they reach a critical high temperature. After waiting a few minutes, they cool down and work again.

The relationship to operating the AC was a clue. Since VW decided it would be a good idea (NOT) to mount the ECU in the battery compartment, it is subject to a lot of heat from the engine, radiator and the AC condenser which can get very hot. With the AC on the air coming into the engine bay gets very hot as it passes through the hot AC condenser coil and overheats the ECU causing it to go into thermal shut down.

Yesterday, I pulled my ECU, removed the cover and was amazed to see that NONE of the power transistors have heat sinks! Adding heat sinks is usually common practice with these electrical components.

So, what to do? Relocating the ECU would involve splicing MANY wires to extend the harness. Yes it could be done but it's a daunting task. My solution is going to be reducing the amount of engine bay heat that reaches the ECU. While it does have a plastic barrier near the battery, it's evidently not enough. There are many places that hot air forces it's way in.

I plan on adding some insulation to the barrier and sealing off the battery compartment better. I also will look into installing a small muffin fan (like you would find in a computer power supply) behind the headlight assembly to bring in fresh air and help keep the ECU cooler. An alternate solution may be to add a vent to the hood to allow air to enter the battery compartment.

I've seen similar overheat issues with other Motronic ECUs in European cars. They stall, then run again after a few minutes cooling time. I once diagnosed this on a 1985 Porsche 911. The ECU is under driver's seat. After some drive time on a hot day it would run rough then stall and every time the ECU was so hot you could barely touch it! I removed it from it's mounting so that I had access to it, drove it to a failure point where it was barely running and stumbling at idle, pulled over and put a bag of ice on it. It immediately started running perfect again. That ECU did have heat sinks but the problem was aged out transistors. It got sent off for a rebuild.

I'll post results of my efforts with some pics in another thread which I will link here later. Hopefully I find a solution and solve others from going down many rabbit holes replacing sensors and guessing with no success in an effort to solve this very common problem.

[MrPulldown]

[OB Bus]

[EuroTec]

[TheOneTrueQuux]

[EuroTec]

Yesterday after driving for 3.5 hours in the Eurovan, it stalled at highway speed. I had my Autel scanner with me so I connected it up and pulled up the live data window. Monitored voltage at ECU. Of course it started up after a few minutes and I was on my way again. 3 miles later, stalled with ECU voltage at 13.5. That rules out a voltage drop as the issue. I then jumper wired the fuel pump relay, waited a few minutes for the cooling off period and started on my way again. A few miles later, stall. That ruled out the fuel pump relay. Immediately pulled up crank speed sensor live data and engaged the starter. It registered RPMs so that ruled out the crank sensor.

I then checked injector timing live data while cranking and it showed 0. That means there was no injector pulse which comes from the ECU as switched ground. The positive feed for the injectors comes from circuit G1/8 which is the V+ output from the fuel pump relay, same one that runs the fuel pump. It goes through fuse #18 20amp. For some reason, the ECU was not sending an injector pulse from pins 88, 89, 96, 97, 112, 113.

It got worse from there stalling every few miles. Fortunately it was only several miles from home. The gremlins were kind to me. It sits in my driveway now.

I have ordered a used ECU from Ebay that has the immobilizer deleted. The only key I have to the van is a plain cut key. The original must have been lost years ago. The PO had the ECU replaced once with a used unit, probably in a
"guess" attempt to solve the stalling when hot issue. It must have had the immobilizer disabled/deleted as well. I still think the problem lies in a component thermally failing in the ECU. I'm going to remove mine and trace the injector pins for the injectors and see if I can find anything.

The saga continues. I WILL find what this common issue is and post all details in a separate thread when I do but for now I'll keep it updated here.
_________________
If it ain't broke, don't fix it!

[TheOneTrueQuux]

[EuroTec]

[TheOneTrueQuux]

[EuroTec]

[EuroTec]

This is the Bosch 30381 ECU driver chip. It's job is to supply regulated power out of four outputs to feed power to the board.

If it gets very hot due to age and fails, that would pretty much kill everything.

In my 30 plus years of working on cars in ecu's I've seen this thermal failure scenario manifest itself in lots of different chips and transistors.. It's always about a drive cycle up until the chip gets hot and just will not physically work anymore. The only way to troubleshoot it is to get it to fail and either quickly cool it with some liquid CO2 (can of compressed air keyboard duster tipped upside down) and see if it comes back on or just swap out an ECU real quick and see if the car starts.

I did this once on a Toyota MR2. It would start run for about 10 or 15 minutes and then fail. If you waited about another 10 or 15 minutes it would restart. So, we opened up the ECU, had a can of CO2 ready, let the car run 15 minutes, sprayed and cooled down the two injector driver chips, tried to start it, bingo! Needed an ECU.

The beauty of the CO2 method is it's handheld, and you can pinpoint one chip at a time spray it, and try to start. If it starts right up after cooling one off that's your problem. You need an ecu or a repair/rebuild.
_________________
If it ain't broke, don't fix it!

[TheOneTrueQuux]

Have you thought about artificially heating suspected components to force a failure? I.e. hot air gun directed at the suspect power supply and driver ICs?

You'd need to be careful not to overdo it, but I'd think a stream of 160 degree air wouldn't permanently kill anything.

[EuroTec]

[TheOneTrueQuux]

[wannabecamper]

Did you ever check the coil pack to see if it is failing at higher temp?

[EuroTec]