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Help please VW VR6 no spark under cranking (not 12v related)


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Hi All, looking for some help please on a G4x install with on a VW VR6.
The head scratcher at the moment is the ignition coils fire perfectly off ign1,2 and 3 under test, the ignition is set to wasted spark, however the coils never spark when cranking, we have bypassed the coil power relay and running direct to battery positive and ground, and the problem persists, this leads me to think its the triggering thats not triggering the coils.
The trigger scope looks good using either holden v6 pattern or missing tooth 60-2, I have fiddled with all combinations of rising / falling, pullup on/off and even swapping wires of the crank trigger, to no change, if it had to try to run or conssitently backfire i could pinpoint it to timing itssue, but it seems to stubbornly refuse to fire coils when cranking
I have changed ecu firmware from 16.odd to 18.11
Injection is set to sequential
Help please !
Thanks

floris vr6 map 3.pclx ECU Log 2020-11-28 5;15;29 pm.llgx ECU Log 2020-11-28 5;15;38 pm.llgx TriggerScopeLog.llgx TriggerScopeLog.llgx.llgx

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17 hours ago, Adamw said:

Your crank sensor is wired incorrect polarity.  Swap the +/- wires at the sensor connector.  

Also, you only have a single tooth on the cam so that wont work with the holden trigger mode.  Set up you trigger like below.

Nsv8nMI.png

 

cool thanks for looking over the logs and info, we did swap the wires over to see if any difference, will put them back they were and try again, i did also try with just a 60-2 crank trigger and no cam just see if any activity could be seen from coils under cranking and nothing was seen either, is it possible that the ecu unlock process wasnt correct ?

 

 

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Hi, here is an update on the crank trigger wiring

so here we have the trigger scope capture with what i believe to be the correct crank trigger wiring and following your trigger settings screen shot

the "trigger scope capture" and "zoomed in trigger scope capture" are the same settings and wiring which to me looks correct

the cam synch is every second crank revolution, the engine compression effect can be seen in the crank

if the crank wires are swopped the result can be seen in the "wiring reversed on crank trigger...." file whats interesting here is that the cam signal disappears, but that wiring is not touched, any ideas why that would happen ?

 

The end result is the same

the ignition coils fire in test mode perfectly, coil 1,2 and 3 but not while cranking, and battery voltage remains above 11v while cranking,

I have changed the falling / rising of the cam signal to all options as well as the coils firing on rising / falling and no change, I also moved the synch tooth to every tooth from 1 through to 8 and i have also moved the offset from -360 to 360 in 5 degree increments hoping to find the right combination, as without it getting to idle or at least run i cant get it "zeroed"

 

Please tell me what you want to see in the logs so I can get the correct parameters in for you to see

 

thanks for your effort and help

 

 

 

 

trigger scope capture.JPG

zoomed in trigger scope capture.JPG

twiring reversed on crank rigger scope capture.JPG

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The bottom one is the only one showing correct polarity.  So for it to work you will need to find why the cam sensor disappears.  It suggests to me that the cam sensor is only getting a ground through the crank sensor wiring somehow, so you either have some wires crossed or the pinouts of one of the sensors is wrong.  

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Hi, here is a bit of an update on this

 

The crank and cam sensor appear to be reading correctly ! - please see screenshot of the trigger scope

We now have spark consistently throughout the crank cycle and the ecu is calculating dwell - previously this was absent

encouragin noises are heard but the car doesnt actually start and run, attached are the map and the pc log (hope i have enough parameters for you, please shout out what needs to be included)

Feels like something else is missing in the settings, is there anything that needs doing around the sync tooth ? I have moved the "offset" from 276 to -84 as per other usccesful VR6 setups and from 100 / 20 to -100 - 20 and it makes very little difference, I have moved the master fuel up and added cranking enrichment as well and it didnt make a difference and neither did start spray, so it has to be timing at wrong spot or synch tooth, the timing light attached to the motor is not good / fast enough to help with ignition offset at cranking rpm of 200 odd - new one on its way

 

Any ideas to get it to run ?

 

Thanks for help so far

 

 

trigger scope 1 capture.JPG

trigger screen shot 1 Capture.JPG

PC Datalog - 2020-12-13 12;19;56 pm.llgx floris vr6 map 17.pclx

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Kind of sounds like you have a an ignition timing issue if adding starter spray doesnt help.  You really need to confirm that you are somewhere close with a timing light.  Note since you are wasted spark it should run even if your offset it 360 out so you dont need to try both say 276 and -84.  

If you got some signs of life at 276, then you could try advancing it say 30 deg (306) to see if it gets better or worse, but really a timing light is the best way to confirm.  

I just noticed it is pulling a lot of vacuum for only cranking so that may suggest the throttle is very closed/not letting any air in, I would hold that open a bit to see if that helps too.  

Otherwise as far as the log goes it appears it has fuel and spark so should be capable of running assuming the timing is close.

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It might be worth running a trigger scope with 5 of the plugs out and just cyl 1 installed.  You will see the crank position slow down on the compression stroke of cyl 1 and from the distance to your sync trigger edge in the scope (number of teeth) it should let you know if you're in the ball park, as well as let you know which tooth offest is really the right direction for syncing sequential injection timing.  I know VR6 are typically not equipped with timing marks that are easy to see, being that one is required to look through the transmission inspection hole typically, but a timing light is really what is required to sync timing properly.  

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  • 3 weeks later...

Great news update

 

She starts, she revs cleanly and she idles

Thanks everyone !

new timing light and lots of white paint on the pulley to ascertain which coil is triggered where in the cycle were key to getting it running

thanks again for the help

 

now to solve the coils triggering on power on via ignition switch and relay, the ecu serial is 500398, any ideas on this ?

 

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