Dwell Time Drops to Zero Between 1500 - 2000 rpm

[Kerem Erdag]

Hi there,

Car is E34 5.35i turbo with 380cc injectors and Audi S4 individual coils running @ wasted spark mode. Engine has 60-2 trigger wheel with a brand new VR sensor.

 

There was some misfire problems but I cleared all. Now the engine runs just like a hi tech engine coils are brand new, spark plugs are brand new, injectors are brand new, no compression problems and sooooo on.

 

But there is still a misfire problem between 1500 - 2000rpm. 

I drove the car for a couple of kilometers logging mode enabled and when I checked the logs I realised that at the moment that misfire happens ignition dwell drops to zero although it's set to 3ms. 

When I check the forum for old threads I found one in which you guys claimed that the problem was with dirty crank trigger signal. But when I check my log for trigger errors the number of trigger errors is ZERO

 

So what else can cause dwell time to drop to zero? urgent help is highly appreciated.

 

Thanks,

Kerem

[Simon]

HI Kerem

You can have trigger issues with out the ECU clocking trigger errors.

If the ECU thinks the engine has reached a firing event early the dwell will reduce. If its really bad it will loose all dwell.

Are you running of the crank trigger only?

If only crank trigger then reluctor polarity and arming voltages will be the first things to check.

[Kerem Erdag]

Hi Simon,

 

Yes, I'm running of the crank trigger only. As both injectors are group fired and coils are wasted spark, there's no need for a second trigger.

 

OK I'll check both polarity of the reluctor and arming voltages then let you know.

 

Thanks for the help.