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Old 06-24-2013, 04:01 PM   #1
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Default vag 1.8t coil on plug overheating

Hi all,

I recently installed vag 1.8t coil on plugs to my 1992 mk1 1.6 turbo. I followed Braineack's how to guide, but I was getting no spark at all. So I grounded the tach of all of the coils to the head as I didn't think the signal was grounding properly.

I also have no rpm on the tacho, but I do have a reading in MS. Though I learnt that on my car the tacho is ECU driven.

The engine then fired straight away and ran well for 15 minutes until it started running on 3 cylinders and then cut out completely. After letting the engine cool down it ran again fine, until it started running on 3 cylinders again.

Black/white and yellow/blue are bridged in the hollowed ignitor as I believe this is the signal from the ECU and the signal to the tacho.

I originally had a 1k resistor between 12v and these two, but removed it on the advice of Reverent. Either way I have no rpm readout in the tacho and the coils are overheating or something!

Is there anyone out there running these Coil on plugs and could there be something I have forgotten to change in Tunerstudio?

msq is attached.

Any help much appreciated!
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File Type: msq EFI parts tune.msq (84.7 KB, 97 views)
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Old 06-24-2013, 04:10 PM   #2
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How much dwell you running 'em at?
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Old 06-24-2013, 04:19 PM   #3
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I have them at "cranking dwell: 3ms" "max dwell duration:2.6ms"

Is there anything else that requires changing?
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Old 06-24-2013, 10:23 PM   #4
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Please post the .ini file related to this MSQ. Can't open the tune file without it, and it's a proprietary .ini that is not available on the EFI Analytics server.
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Old 06-25-2013, 05:32 AM   #5
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Woops, sorry!

Added the ini, but it wouldn't upload without me compressing to winrar!
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File Type: rar msextra_310_rev_MEGAECU.rar (38.0 KB, 40 views)
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Old 06-25-2013, 02:37 PM   #6
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Quote:
Originally Posted by mrhanky View Post
I have them at "cranking dwell: 3ms" "max dwell duration:2.6ms"

Is there anything else that requires changing?
Do you know what dwell the VAG coils require?
Too much dwell will cause overheating.
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Old 06-27-2013, 02:01 PM   #7
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Quote:
Originally Posted by JasonC SBB View Post
Do you know what dwell the VAG coils require?
Too much dwell will cause overheating.
The MS3 maual states 4.0ms cranking, 3.0 ms running. The extraefi vag cops guide also corroborates this.

Would the engine run at all if I set the polarity of the pulse the wrong way? i.e setting it as going high instead of going low?
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Old 06-27-2013, 02:29 PM   #8
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Could be different VAG coils but my research shows 2.4 for cranking and 1.8 for running.
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Old 06-27-2013, 05:44 PM   #9
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We often use the 115L coils.

15V 2,3ms
12V 2,6ms
10V 2,8ms

Bad grounds can kill them. Make sure the two grounds dont conect to the same point. Losing contact with the plug can also kill them.

Tommy
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Old 06-28-2013, 02:52 AM   #10
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I think you need this:

Megasquirt MSEXTRA / MS3EFI • Spark 'booster' (PNP circuit) (View topic)

It says its for logic-driven coils, not dumb coils which need an igniter.
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Old 06-28-2013, 12:41 PM   #11
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Ah yes, some coils, if driven with insufficient current, will indeed overheat.
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Old 07-01-2013, 12:31 PM   #12
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Quote:
Originally Posted by Reverant View Post
I think you need this:

Megasquirt MSEXTRA / MS3EFI • Spark 'booster' (PNP circuit) (View topic)

It says its for logic-driven coils, not dumb coils which need an igniter.
The VW coils require an unusually high current logic trigger. I have used this circuit on the VW coils successfully.

MS3-Pro and MS3-Pro Module feature a similar high current logic ignition drive circuit.
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Old 07-01-2013, 07:24 PM   #13
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Quote:
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The VW coils require an unusually high current logic trigger. I have used this circuit on the VW coils successfully.
FWIW what you're driving is the actual power electronics circuitry in the igniters, so it's not "logic" anymore.
With insufficient drive current, the main internal transistor can't pull the normal max current through the coil.

The miata 99/00 coils take a bit more current than the AEM series 1 outputs can. This may be the reason for "99/00 coils are weak" claims when used with the AEM.

With sufficient drive current, the 99/00 coils are pretty strong.
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Old 09-23-2015, 03:16 AM   #14
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Hi,


sorry for digging out this old Thread. Has anyone a solution for the "RPM" problem?


I read a few instructions about cops and wiring. Most people use the Toyota cops.


There is a pin named "tach" but on all instructions for this VAG cops its named ECU ground.. I think they are differen and that is the reason.... but im not sure.


hope someone has information for me
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