98 ALH Hard Start only hot.

[markward]

Hello, I have a 98 ALH engine in my VW Vanagon. Have about 20,000 miles on the conversion. A problem showed up a little time ago, but was intermittent. Seems to happen more often. The engine starts fine cold, but if I drive it to temperature and then park it for 15mins, it will crank, but won't "catch"/run. Since it is a conversion, some of the obvious solutions are not applicable. Here is what I have done.

I redid all the power supplies to the ECU etc. I added a relay from the ignition switch to power the TDI ECU rather than running the ECU off the ignition switch. Vanagon's are notorius for ignition switches going bad. My ignition switch is relatively new. My Bentley shows the fuel cutoff valve getting power direct from the ECU. I have tried a jumper to power and to the solenoid just to be sure, but when it won't start, it is as if the solenoid is not opening. I can here something click. I removed the solenoid and visually tested it, it works fine. I reinstalled the switch and added a ground to the pump just to be sure. Same problem.

When it starts, the engine runs perfect, no smoke, miss or anything that would indicate an injector leaking down. The pump was resealled and has been fine for many miles. No visable leaks or smell.

Here is my question. I see the fuel cutoff valves for sale. I don't see how it could fail, but it seems to be "heat soak" that keeps the engine from restarting. Do these valves go bad? Can I pull the valve temporarily, remove the piston, install the valve and see if the problem goes away? I have never done that before.

I should add the shut down flap in the intake was removed some time ago. No codes, but is there a value I should be watching for when trying to start the engine in my VCDS software. It really is kicking my butt. Thank you mark

 

[KLXD]

You can remove the guts of the cutoff valve. The primary cutoff mode it the ECU setting the injection quantity to zero. I doubt that's your problem, though.

No first hand experience but I have read that the early ALH's had a hot start issue. I think there's a software fix a tuner can perform.

Search in the A4 Forum.

 

[markward]

Thank you for the info. I tried a switch from an early pump and have the same symptom. So, I don't think it is the switch itself and there is not much there to fail. I have noticed that working the accelerator pedal seems to help the hard start hot. Not sure why that would make a difference. A member in the conversion thread changed the adaption to automatic on the ECU and that seemed to help his starting problem, but I think his was a cold start problem. It also then started throwing a code because the auto was not present.

If I had to say, it is as if the ECU is preventing the engine from starting electrically. I'd like to catch it not starting and crack a fuel line to see if fuel is actually present. The problem is the engine is buried in the back. Thanks again. mark

 

[Vince Waldon]

early ALH's had a hot start issue. I think there's a software fix a tuner can perform.

This, most likely. If you pull the CTS and she fires up like a charm you've pretty much confirmed it.

"hot start issue" would probably be a good search term if you want to dig in deeper...should be quite a few threads on this one.

 

[markward]

Vince, what is CTS short for? I will try searching hot start issue as you suggest. This conversion has performed perfectly till now. So, I have not had much chance to dive into fixing any problems. mark


CTS= coolant temp sensor. oops. I wonder if the sensor is actually the problem. I realize the ECU could be mapped, but I'd imagine the problem would have been there right along. Thank you. mark