problems starting and blowing VB921's in vw 16v

scottymk2 · Post by **scottymk2** » Mon May 22, 2006 4:57 am

Hi there,

I have fitted MS2 V3pcb code 2.34 MT 2.25 to my Vw golf 16v engine (9A or KR).

I had the car running (but very roughly) on MS a few weeks back, but was waiting for new larger fuel injectors to arrive. I have now fitted these, and am having trouble starting. I have ideas what this might be but was after some general advice -

Firstly, the engine turns over alot faster with no ignition (whilst cranking) - so i think my cranking timing is too advanced? what would be a typical cranking advance - 0 deg?

secondly, the engine seems to have problems transferring from cranking to actually running, even when firing. do i need to either set my cranking RPM higher (its about 300rpm at the moment), to keep the cranking settings until the speed picks up, or do i need to just tune the low end of the ignition map more (assume req fuel is ok)? I have maps from someone elses identical setup, who runs about 11deg BTDC for 0 rpm and 1000rpm.
Therefore is going from 0 BTDC to 11BTDC to large a jump? im not sure whether to put the "0"rpm part of the ignition map as 0 BTDC, and allow megasquirt to interpolate as speed increases?

Thirdly, i have blown 2 VB921's. The first one blew due to wrong setup, but the second one seems to have just overheated - it produced a puff of smoke after about 10 minutes of intermittent cranking. My battery voltage was however low - did i blowing this due to the low battery voltage causing high dwell and overheating the VB921? any advice on how to stop this happening again?

Many Many thanks for any help!!

cheers

Scott

keithmac · Post by **keithmac** » Mon May 22, 2006 9:03 am

Cranking ignition settings aren`t in the spark-table, there a seperate menu for them, I run 6dbtdc while cranking, 400rpm cranking speed.

You`ll have to have a play to get the right fuel settings, it`s trial and error really.

I used the 16v TCI-H unit to drive the coil, it`s smart dwell so no chance of me melting it or the coil!

Think my lowest spark bin is 800rpm?

scottymk2 · Post by **scottymk2** » Mon May 22, 2006 2:37 pm

OK thanks, so if you set your lowest spark bin at 800rpm, does it use this value for the region of 400 - 800rpm too?

also, what is your timing at idle?

many thanks

Scott

keithmac · Post by **keithmac** » Mon May 22, 2006 3:01 pm

Yep anything under 800 rpm is the same as that bin (unless cranking is active).

I run 10 degrees at idle (6 degrees is stock setting).

scottymk2 · Post by **scottymk2** » Tue May 23, 2006 12:46 am

ok mate, thanks for that - i have another play with the settings after repairing the VB921!