Surge at 2.5k part throttle

[Bronco]

As it says above.
I have a 3.4 twin plug running Xdi twinplug ignition and the motronic runs the fuelling.
I have had the motronic professionally (live by the Uk's best tuner) chipped for the 3.4 increase (from 3.2).
On part throttle cruising at 2.5k I get a slight surging of maybe 200rpm which is very noticable but not harsh.
The tuner could not adjust the xdi for part throttle as it is not possible.
Any suggestions?

Db

[Steve@Rennsport]

Hi,

Your issues are resolved with tuning (ignition or fueling), but the bigger question is why you are not using the Motronic to control timing???

Engine Management systems are just that: integrated systems designed and intended to control all aspects of engine parameters. This is accomplished by using all the sensors at hand to determine optimum timing and fuel mixture at all throttle openings, RPM and temperatures, all in software.

Having done quite a few engines like yours over the past 30+ years, these run very well when the Motronic system (or Motec) is allowed to control everything as its designed, and using custom software. JMHO, but there is no performance benefit to using Xdi's on these things.

[Bronco]

Thanks for the quick response Steve.

I think at the time of shopping for bits i got a bit carried away.
I did look at the andial signal splitter,964 dizzy,twin coils etc, but the whole package looked more expensive than the XDi system which at the time I was told by Clewett and EBS that it was compatible with the Motronic.

This is the only issue i have with the build as it seems to be reliable and makes steady power. 260bhp and 241 thingies of torque.

Any way out of this without swopping out the xdi for the other kit and letting motronic run everything?

Db

[Steve W]

Since XDI gives up your part throttle mapping, then you give up throttle response, part throttle efficiency, and fixing your part throttle hesitation problem. You should never give up part throttle mapping as that is where you spend at least 80% of your time. Also with the XDI you are adding another layer of complication and unreliability. The Motronic does everything you need and reliably and that's what you should go back to. The factory Motronic gives up nothing to aftermarket engine management systems which often aren't as reliable and will cost more to sort out and tune.

[Bronco]

Straight talking thats what I like to hear.

So what's it worth on the used market? A complete XDi twinplug set up 1000 miles!

Db