TheSamba.com :: View topic - Type4 D-Jet Stalled Need Help

Fri Jan 04, 2008 1:32 am

Car: 1973 412 Coupe with stock 1.7L and D-Jet fuel injection previously running great as daily driver. More here http://412coupe.blogspot.com/

Problem: Drove to work the other day and all was fine. Rained all day as usual. Leaving work, car would not fire up. Finally fired up but stumbled terrible for about 5 seconds before stalling. Next day, same but did run normal a few times for 5 seconds then stall suddenly. Repeat starts crank fine, but doesn't fire up.

Recent work: Replaced alternator with rebuilt 70A AL108 alternator and new Bosch voltage regulator (0-192-062-007). Replaced oil cooler seals (had coil disconnected). No problems after work done until other day when all the sudden, no start.

Trouble-shooting:
1. Fuel pressure, tapped off left side fuel rail, gives 30psi cranking, 20psi after cranking -> good pump and regulator.
2. Timing light strobes on each spark wire during cranking -> all sparking.
3. Condensor green wire to ground measures 0.2 ohms; test light flashes connected to negative side of coil when cranking -> condensor not fried, points working.
4. White spark off original black bosch coil wire grounded to case; primary coil measures 2.9 ohms (spec 3.0 ohm); secondary coil measures 9.37 kohms (spec 9.83 kohm)-> coil good.
5. #4 spark plug pulled and found dry after cranking; disconnected cold start valve plug and bypassed fuel line around valve with no change -> not flooded from cold start valve.
6. Fuel pump relay activates pump for a second after key on, then stops. Relay output to pump is 10 VDC while cranking -> good fuel pump relay.
7. CHT sender measures 2.25 kohms at about 50F -> good sender.
8. MPS measures 91 ohms for primary coil (outside pins, spec 90 ohms) and 33 ohms for secondary coil (inside pins, spec 350 ohms) -> injectors should be firing.

Next up, test trigger contacts and injector pulses.

Nothing wrong found yet - please verify my conclusions and suggest other tests to locate problem.

Thanks,
Bill

Fri Jan 04, 2008 11:55 pm

Bill K. wrote:

Next up, test trigger contacts and injector pulses.

That would be my next thing to check. Could be an issue with the manfold pressure sensor not working right. I'd also probably pull the brain and test all the components via the wiring harness to verify no problems with either the components or the wiring, and that the system power and grounds are all good too.
-Andy

Sat Jan 05, 2008 11:16 am

glutamodo wrote: Bill K. wrote:

Next up, test trigger contacts and injector pulses.

That would be my next thing to check. Could be an issue with the manfold pressure sensor not working right. I'd also probably pull the brain and test all the components via the wiring harness to verify no problems with either the components or the wiring, and that the system power and grounds are all good too.
-Andy

X2. Good sequence (cheap and easy first, time-consuming but likely second, expensive and esoteric third).

Sat Jan 05, 2008 3:00 pm

Thanks for the review. It was the trigger contacts. Worn cam rubbing blocks. Replaced with new trigger contacts spare on-hand and fires right up.

Interesting that contacts were opening one at a time by checking continuity between middle and pins of trigger contacts, but due to cam rubbing block wear, the duration of open cycle must have been too short for the ecu to detect. No signal to injector was also verified by checking voltage across injector plug disconnect from injector during cranking. Once fixed, the voltage read about .5 VDC on digital DVM with car running.

Good D-Jet troubleshooting guide here (thank you Paul Anders):
http://members.rennlist.com/pbanders/DJetParts.htm

Sat Jan 05, 2008 7:21 pm

Bill K. wrote: It was the trigger contacts. Worn cam rubbing blocks. Replaced with new trigger contacts spare on-hand and fires right up.

Cool, that was a pretty easy one!

Sat Jan 05, 2008 9:33 pm

glutamodo wrote: Bill K. wrote: It was the trigger contacts. Worn cam rubbing blocks. Replaced with new trigger contacts spare on-hand and fires right up.

Cool, that was a pretty easy one!
Ya, I'm glad it turned out to be a part I had a spare for. This was my first time troubleshooting DJet and it wasn't as bad as I thought it could be. I just had to work through the systems testing for normal values with a DVM and fuel pressure gauge. I didn't replace any parts until I found a reason to and it was rewarding to have it fire up when I thought it would based on the test results. This breakdown was an opportunity to learn a lot about the car and that's how I approached it. The thorough approach has proven to payoff! Being able to fix my car is a big reason why I drive aircooled :vw: \:D/

Sat Jan 05, 2008 10:40 pm

Bill K. wrote: work through the systems testing for normal values with a DVM and fuel pressure gauge. I didn't replace any parts until I found a reason to

If only more D-Jet owners took this rational approach!

Mon Jan 07, 2008 7:25 am

Yes, I agree, with all the help, manuals and other Internet resources available D-jet faultfinding can be made wery rational and purposeful. There are wey few situations involved where one should give up...

/Lars

Mon Jan 07, 2008 10:37 am

Like many, I have an irrational of the fuel injection on my 412 BUT thanks to forums like this one I shall endeavor to learn more about it and understand the steps to keep it running and should (or rather when) the need arise understand the steps to repair it.

Well done on getting it going yourself...fingers crossed it is now running as it should.

Mon Jan 07, 2008 2:02 pm

wshawn wrote: ...fingers crossed it is now running as it should.
After adjusting valves, setting timing/dwell/idle, and changing oil this weekend, it is running better than ever. Previous checks of MPS and Auxilary Air Regulator for vacuum leaks make for good mileage, throttle response and idle.

For bonus points this weekend, I got the BA4 heater running =D> Man that thing pumps out some heat :twisted:

Mon Jan 07, 2008 2:03 pm

nice job bill! now i wish i could just get my L Jet working that well! btw, what did you have to do to the heater? mine's in place, but won't light off

Mon Jan 07, 2008 3:08 pm

I second vwfye, how did you get the heater working and does it work all the time?

My BA4 is tempremental only working without the engine running which isn't much good this time of year :lol:

Shall have to check for vacuum leaks on mine as it a tad rough at idle :?

Mon Jan 07, 2008 3:31 pm

wshawn wrote: I second vwfye, how did you get the heater working and does it work all the time?
See http://412coupe.blogspot.com/2008/01/heat-boost-ba4-tune-up.html
Runs fine so far. Cooked me on way to work today :lol:

Mon Jan 07, 2008 3:46 pm

so, you wanna come back down and get mine working? hehe, how hard is it to get to the fuel line for the heater? i wonder if my heater fuel line is part of my crappy MPG?

Mon Jan 07, 2008 11:31 pm

vwfye wrote: so, you wanna come back down and get mine working? hehe, how hard is it to get to the fuel line for the heater? i wonder if my heater fuel line is part of my crappy MPG?
Come on, why would you want anyone else to have all the fun fixing your car? Isn't that why we all have these things? :oops:

There are so many interlocks in the system, that I doubt you are loosing fuel through the heater if it isn't working (unless it's leaking on the ground :wink:). On my car, the heater fuel pump can be heard ticking from inside the car with the engine running and the heater on. Fuel pump only runs when the heater fan is turning (1 fuel pulse per 33 revs of fan). If it doesn't run, then the safety switch could have tripped and needs resetting (see black box under variant seat with red lever; throw lever to reset breaker). If the glow plug is fried like mine was, it won't run. If the limit switch for the vent lever isn't working, it won't run. The troubleshooting guide in the manual and checking the basics step-by-step should get you there.

Fuel pump lines are basic stuff - 5mm for inlet, 3.5mm for outlet.

Tue Jan 08, 2008 8:47 am

wherre did you get a new glow plug? i've reset the switches under the back seat and still get nada... timer works, i can hear the thermostat click on as i turn the knob to warmer, but i get no fire.

Tue Jan 08, 2008 9:07 am

vwfye wrote: wherre did you get a new glow plug? i've reset the switches under the back seat and still get nada... timer works, i can hear the thermostat click on as i turn the knob to warmer, but i get no fire.

One of my first thoughts was the glow plug on mine so I found some part numbers that might be of use to you for the BA4

VW 411 963 319 or the Beru GZE 16

As mine fires up sometimes :roll: my glowplug works so the fault must be somewhere else on mine. Need to check all the wiring I think and follow through the steps on this link

http://manuals.type4.org/ba4/ch2/ba4_12a.htm

was just trying to cut corners by seeing what problems others have had. :lol: