Rpm stutter at higher boost

Once I turn my boost up I get a machine gun style stutter.

15 psi I can rev to the 6.5k limiter

20+ psi and it goes E36 M3ty from around 4.5k. 

Ms3 pro full sequential, dwell @ 4.5, plugs gapped @ .028, d585 ls truck coils, autolites plugs, new magnecor leads.

Any ideas? 

My first inclination would be ignition related. The ignition has to be pretty strong the more load there is. I believe this was my main issue at the challenge last year, the coil plug had a loose wire so it was enough to run, but not strong enough to produce spark once it was under the load of boost. I would check and make sure all you connections are solid to start, then figure out the weak point. Your plug gap is already pretty small, which I am pretty sure is what you'll want. Spark Plug temp might have an impact as well?

Try closing the gap to .024 if it move the RPM band up it Ing related. 

On my old SVO (Ford 2.3) I had a similar issue. If it keeps running poorly for a few seconds even after you lift and then comes back to firing on all cylinders I would suspect weak valve springs. I went to some Crane springs on mine I think, nothing crazy, and it withstood 28 psi with my E85/HX35, ms3, truck coils combo. 

Jcamper

Spark is getting blown off. You need regap your sparkplugs with a smaller gap. 

Double check your wires for grounding out. I’m not a magnecor fan.

Ill also echo the weak valve springs comment. Seen it, lived it, and fixed it.

The truck coils have a NASTY habit of advancing your timing if you overwell them. Try backing the dwell down to 3.6 and closing your plug gap up a bit.

Any idea where your AFR's are?  Lean misfire?

Jcamper said:

On my old SVO (Ford 2.3) I had a similar issue. If it keeps running poorly for a few seconds even after you lift and then comes back to firing on all cylinders I would suspect weak valve springs. I went to some Crane springs on mine I think, nothing crazy, and it withstood 28 psi with my E85/HX35, ms3, truck coils combo. 

Jcamper

2.3 lima here too. I have 150lb seat springs in there. So I doubt I have float. I'm near sure its spark...

1988RedT2 said:

Any idea where your AFR's are?  Lean misfire?

Afrs in the mid 11s. But it leans when it stutters as I presume there's unburnt o2 getting through.?

MadScientistMatt said:

The truck coils have a NASTY habit of advancing your timing if you overwell them. Try backing the dwell down to 3.6 and closing your plug gap up a bit.

Didn't know that. 

Closed gap to .024, lowered dwell to 3.8 

Revs to red line at 25psi. 

In reply to AnthonyGS :

Read above. 

In reply to Craigorypeck :

Glad you got it working! That thing is going to be insane!

AWSX1686 said:

In reply to Craigorypeck :

Glad you got it working! That thing is going to be insane!

Its quite fun.!