NO SPARK ISSUE, Any help much appreciated!

An alchemy of sparks, copper wire and earth

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rycoombs1
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NO SPARK ISSUE, Any help much appreciated!

Post by rycoombs1 »

Hi All,

Drove the van 2 weeks ago and was fine, parked up.. Now won’t start, just turns over but no combustion going on..

Pressures now on.. I’m booked to go to Norway end of July! :S

Van is a T25 California - 2.1 WBX Digifant 1 (as written on ECU).

The tacho is not moving when it cranks, from what I can understand this means its not getting a return message from the coil?

So far I have:

Removed lead from spark plug, put spare plug in, held to earth and cranked - NO SPARK

Removed coil lead from distributer and held to ground and cranked - NO SPARK

Checked power & ground on distributer plug - voltage OK

Coil is getting power OK when ignition on/cranking.

Removed coil lead from distributer and held to ground, with key ignition on, removed the distributer plug and grounded the middle pin…

From what I can tell, its supposed to send out a short clean spark each time the middle pin touches ground.. instead it sends out a noisy long spark with a buzz..

Rather than troubleshoot further, is this an indicator of a dodgy coil or ECU?

Checking the ohm/resistance on the coil its coming back with the following:

Primary resistance: 0.9.. Bentley is stating 0.5-0.8 so its just out

Secondary resistance: 3.085.. so this is within spec 2.4-3.5

I’ve also measured voltage across terminal 1 and 15, then with ignition on & ground centre wire on distributer plug and it has gone up to 4.5 volts briefly which suggests control unit ok?

I’ve checked around all the grounds/brown wires and all look ok from what I can tell..

Any ideas on next steps or is it new coil time?
1990 Westfalia California - 2.1 WBX

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bigherb
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by bigherb »

rycoombs1 wrote:
Removed coil lead from distributer and held to ground, with key ignition on, removed the distributer plug and grounded the middle pin…

From what I can tell, its supposed to send out a short clean spark each time the middle pin touches ground.. instead it sends out a noisy long spark with a buzz..

If you get a spark from the coil lead then the ECU and coil are working.
Check you have more than 5V across the two outside pins of the distributor plug if you have then the distributor Hall unit is not working.
1982 Camper 1970 1500 Beetle Various Skoda's, Ariel Arrow

rycoombs1
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by rycoombs1 »

Hi bigherb,

Big thanks for the response on this.. much appreciated..

Yep I've got over 5V going to distributer plug..

I was watching the below video where he does the same test at approx 1:21 and it puts out a neat white spark each time he grounds.. mines a 1 second buzzing spark.. is this indicative of anything?

https://www.youtube.com/watch?v=95PkgSavOCo" onclick="window.open(this.href);return false;

I've now undone some electrical tape and it looks like the distributer plug green wire has been replaced at some point, I've followed it back to the ECU as expected. on the wiring diagram in Bentley it looks like the green wire splits and goes to box 45 (I'm assuming this is the ground on engine block where I can see the brown wire going?) however I have no clear view on where it splits, in the manual its saying Th1 which is "single, engine compartment, left side"

Is there any check I can do the make sure the ground is good?

Or am I wasting my time here and get ordering replacement hall sensor?

Image

The fix..
Image
1990 Westfalia California - 2.1 WBX

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bigherb
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by bigherb »

rycoombs1 wrote:Hi bigherb,

I was watching the below video where he does the same test at approx 1:21 and it puts out a neat white spark each time he grounds.. mines a 1 second buzzing spark.. is this indicative of anything?

Just means you are getting multiple sparks. Don't keep trying or you will fill the cylinders up with petrol.

If you are getting sparks then that proves everything else is working and the problem is the distributor, usually the hall sensor but make sure the distributor is turning, has been known for the drive to disengage.
1982 Camper 1970 1500 Beetle Various Skoda's, Ariel Arrow

rycoombs1
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by rycoombs1 »

hall sensor replaced, fired straight up.. happy days.

Thanks for your help bigherb!
1990 Westfalia California - 2.1 WBX

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bigherb
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by bigherb »

:ok
1982 Camper 1970 1500 Beetle Various Skoda's, Ariel Arrow

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DevonAid
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Re: NO SPARK ISSUE, Any help much appreciated!

Post by DevonAid »

Appreciate this thread, its been most helpful.
The van has been getting very little use of late (750 miles between the last MOTs) and highly unusually wouldn’t start this week.
No spark identified, so after a review of the steps in this thread, promptly identified as corroded coil connections- and away she went.
Thanks all and what a great club, as always.
1983 T25 Devon conversion 1.9DF

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