Hmm misfiring..

[Minigirl]

Very Old thread bump lol.. What sorted your problem in the end as i have the same or similar issue.. Thanks

[ethanol-smart]

Re: Hmm misfiring..

Why get concerned/confused about a generic picture of a coil that isn't on a manufacturers website but just a shop, phone them up and ask them to explain maybe?

as it says on the site

I guess U are right!

[madDan]

Re: Hmm misfiring..

Why get concerned/confused about a generic picture of a coil that isn't on a manufacturers website but just a shop, phone them up and ask them to explain maybe?

as it says on the site

If you have questions...

... contact us at any time by E-Mail!

fragen@autoteile-teufel.de

[ethanol-smart]

Re: Hmm misfiring..

Im confused..
Following the advice to use original Smart coils, I found this:

http://www.autoteile-teufel.de/FEBI-BILSTEIN/Zuendspule/28549/?vehicleHsnTsn=

But this and other coils have not 3 connections, but 4..
Are there 2 variants of this coil?
I have only 3 connections on the LT-side, and the primary resistance is between the two outer pins. (4 Ohms on all coils when cold, didnt measure when engine is misfiring)
To the middle, I didnt measure anything else the infite resistance, on all 3 coils.

[ethanol-smart]

Re: Hmm misfiring..

Why don't you just move the existing SMART coils off the cylinder head and use longer leads? That would at least be compatible with the ECU without any more fuss.
John

Its also an option, I agree!
Only that they are more expensive and less possible to find cheap on ebay it seems. If I get it to work wiht these Merc-coils, we have a better sourcing for all Smarts. All for science!
If it doesnt work well, I intend to use the coils on my AMG instead, which also need the same upgrade. (I dont see any issues with using twinspark coils on a waste spark engine..).

[heinkeljb]

Re: Hmm misfiring..

Why don't you just move the existing SMART coils off the cylinder head and use longer leads? That would at least be compatible with the ECU without any more fuss.
John

[Thrumbleux]

Re: Hmm misfiring..

Would be intresting to know what CR a Biland SA 250 have.

13.5:1 I think. Pretty sure the SA250 runs at 12.5:1 - with double the cylinder volume, and the torque peak for the twin is only 500rpm lower (7500 vs 8000 for the single). Both have enormous rpm headroom - 13500 and 13000 for the single.

[ethanol-smart]

Re: Hmm misfiring..

Aha they took a Biland SA 250, and put a turbo on it...
Now I understand why it was so easy to raise the compression ratio!
Would be intresting to know what CR a Biland SA 250 have.

[Thrumbleux]

Re: Hmm misfiring..

No, tell me more about Swiss auto, I have no clew at all in fact!

http://www.swissauto.com/e/motor/projekt_detail.jsp?ID_Display=20000N

This one's a belter >>http://www.swissauto.com/e/motor/pro...Display=20000I
if it has to be a four-stroke, that is!

[ethanol-smart]

Re: Hmm misfiring..

No, tell me more about Swiss auto, I have no clew at all in fact!

[Thrumbleux]

Re: Hmm misfiring..

to a 18v (90!) deg V6 with single OHC twin spark, could mean some progress for man kind.....

Not a fan of the V6 then...
I'd forgotten Merc had gone twin spark with that engine.
Are you aware of the Swissauto and smart connection - from where the turbo and twin plug concepts apparently originate?

[ethanol-smart]

Re: Hmm misfiring..

I know about the pioneers at SAAB (RIP)..
They are as far as I know, the only example so far of ionisation detection.
Im thinking now of simply using Merc own twin spark coils. They should have no issues giving 2 good blasts simultanously in one compresssed cylinder, apart from a normal waste spark coil, which might have lower power.

Will make some measurements of the primary and secondary resistance of the coils in the Smart and try to get the correct figure of the Merc twinspark coils. Hopefully they are not too far away from each other, both being Bosch units.

If it works, at least the horrible engine degrade Merc made 1995, when going from 24v straight 6 DOHC-VVT, to a 18v (90!) deg V6 with single OHC twin spark, could mean some progress for man kind.....

[Thrumbleux]

Re: Hmm misfiring..

Post #12. Suspect you have it covered there ES. For the knock sensor to detect a 'miss' it would have to be detecting regular combustion - and then still it would have to be able to detect abnormal combustion, ie knock. That's treble the capability compared to knock detection alone, and knock detection itself is (well, judging by the price of aftermarket electronics to run knock sensors) a tricky task.
The Diesels monitor the variations of crank speed - for starting at least, via one crank sensor. Possibly the petrols can detect a miss.
Good spot on the Lambda - and cylinder shut-down. If you are wrong - then smart are wrong for not configuring it that way!
Definitely though - combustion monitoring via the plug electrodes re ionisation, is or has been used by some. Pioneered by Saab IIRC on their Trionic(?) system. Careful with coil selection ES!

[ethanol-smart]

Re: Hmm misfiring..

Are you sure that the knock sensor is involved?
Isnt it enough to look at the crank variantions to see wich one is misfiring?
Posssibly in combination with that a too rich mixture is detected by the lambda sensor, (which in fact also can smell from which cylinder it comes), that can relate the smell to a cyclic variation and the ECU can shut off the injector in order to save the catalyst form being flooded with unburned fuel.

[madDan]

Re: Hmm misfiring..

The Knock sensor detects a misfire, the ECU knows which cylinder is supposedly firing you know that timing ring thingy on the flywheel (quite handy that it does I guess )