Forum » General Tuning Discussion » Injector Dead Time, misfire!!

Injector Dead Time, misfire!!

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads

Page 1

Hello everyone,

I am running a set of Bosch injector, the problem I am facing now is that as Bosch claim, they are set as 980cc/min. and all information, in this case Dead Time, is set from an injector wizard on my ECU (to say, I am running ECU Master Black).

The problem comes when I am cruising and the injector DC is very low, I am stating to see misfiring in my data. Static fuel pressure is set to 3 bar (43.6psi) and even on part load, I get from time to time misfiring and I can see my lambda going lean. VE table values stays stable (+- 0,05% fluctuation) when the misfire occurs. I try also lowering my static fuel pressure and obviously injector DC increases and runs fine, but still misfires occurs.

My fuel pressure regulator is connected to the manifold with a Dash 4 line and Delta pressure stays stable and rising as boost does.

I am stating to think that this could be a wrong configuration on my Dead Time table but all I can find in internet, including information from different sources, I get different figures all over.

I would like to ask, if someone has some proof values for this injectors Dead Time?

Would be also great if someone has suffer similar problem or have an idea of what could be this issue.

Thank you so much to all in advance,


Hello best to post your map and a log with as much data as possible

Regards Ross

It's not likely a dead-time issue -- if you have those values wrong, you will just "bake in" any error when you tune the car. Now there might be a parameter for minimum injection pulse width, that causes it not to inject any fuel if the requested pulse it too low. Or Decel Fuel Cut Off might be activating. That's why your configuration is important.

If the car needs to cruise, perhaps you just need to fit injectors of a more appropriate size, not try to tune around a bad component choice.

Or maybe you have an intake manifold pressure leak? Does it misfire at idle?

BTW - A misfire will always shows a lean condition as uncombusted air makes it way to the exhaust, and the O2 sensor measures this.

Hello Again,

@Ross Honnor: I will try to prepare good information in that matter.

@David Ferguson: I notice that my fuel pressure fluctuate a bit on transition and acceleration but stays very stable during cruising, that could indicate a leak on intake, something that I will try to get my focus on before the car is back in the road.

About Idle misfire, I have to say, yes, I got misfiring on idle but is nothing constant, the car idle pretty nice until suddenly you get 1 obvious, Lambda stay stable at about 0,99 ~1,00..

I was thinking on Dwell time, very week spark, put the symptoms are more pointing direction Fuel System, at least to me.

I will try to upload some data as soon as I can.

Thank you all,