Anyone have non-resistored plug issues?

[zerb]

trying to track down a high rpm misfire issue here on my Audi, which has a 20v 4cyl vw motor in it.  using the stock vw 4 wire push down coils, runs amazing other then up top for a small rpm window there.  while the car was on the dyno last week it was having a misfire issue, it would seem to start to break up at the same couple 100 rpm window each time, but if we stayed in it, it would work itself out and continue to pull smoothly to redline.  finally got to drive it on the street after the dyno the other day, and it seemed to break up worse on the road then on the dyno, once again, around the same rpm. 

just throwing it out there to see if anyone here has had an issue with running non-resistored plugs on the VEMS ecu? 

the only other thing i found after going over some threads and then double and triple checking my car, was that with the 4 wire vw coils it seems most people place the wire from the number 2 pin on the same ground as the ecu ground is, which i did not have and just changed to see if that will fix this small issue. other then that, or possible 'noise' from the non-resistored ngk plugs we run, im as good as stumped.   

[Sprocket]

You should always be using resistor plugs or at least resistor HT leads (but not both) with any electronics!

[zerb]

Well, these are run in other high hp 20v vw motors, especially those that run on e85, which is why I run them in my setup as well, that run these plugs.  They do work on other cars without an issue, another b3 audi with a 4cyl20v in it that actually just went 9.90@141 this past weekend runs these plugs without an issue (on autronic sm4) that doesn't necessarily mean it's right, I'm just saying that as an example.

Say I wanted to stay with these non resistored plugs for the heat range and such, could I put something in there to 'clean' up any noise that they may generate in the system? Incan follow wiring diagrams, but am I no electronics expert by any means.

[Sprocket]

Electrical noise is a funny thing and can cause problems that are usually unexplained. If you are not tried resistor plugs, you will never know untill you do.

I also find it hard to believe that you cannot get a resistor plug of the same heat range that you are using, but then, I don't know what plugs you are using to begin with.

[GintsK]

You can try decrease ignition noise by installing capacitor at each coil supply. It clearly helped me with noisy IGN-1 coils.

Gints

[zerb]

the plugs i run are NGK race plugs, heat range 9.  R5671A9.  NGK offers them in a resistored plug i THINK, but they are $29 a piece compared to $4 a piece.  I am going to switch to a Denso Iridium plug, which is resistored, and lower the bosot way down to see if that helps the break up issue....which has really been something phantom that has plagued the car since day one.  im also hoping a resistored plug will fix my aftermarket speedometer issue ive been having since i first drove the car as well.  it works beautiful part throttle and cruising, but once you lay into it, it starts to jump all over the place. 

[JohnP]

Any news to the findings on the resistor type plug change? I am running the same plugs in my car as well. I have not been able to find the proper heat range desired with a resistor and a NON projected tip.

 I always thought that with distributors, the resistor helped to remove "shadow spark" at high rpms. And as far as noise the plug wires minimum ohms played a role in the prevention of noise. Now this may be news from the 80s but I am up for learning new findings..
   John

[zerb]

nothing to post here as of yet.  i am going to try a set of denso iridium plugs this upcoming season and see if they help with the "noise" that i think i am experiencing in my speedo.  i will report back once i do.