Miss Fire On Dyno Rb26 Any Ideas?

[portaz]

Hi guys,

My r32 Gtr is on dyno and has a missfire on gate pressure of 9psi. Engine is a forged std stroke 26 with jun 264/270 9.5 mm lift cams (I think as these were purchased before my surgery) it has adaptronic ecu, split fire plugs running map sensor . New coil pack harness and bosch 2200 cc injectors with resistor removed. My tuner (jez) is awsome and has tried plugs, coils, harness , cas, adjusting cam timing as well as tune. He has adaptronic guy coming tomorrow to hopefully fix it but any ideas are welcome. He also did comp test which came back perfect. The engine also has new -5 turbos with ported manifolds and the head is mildly ported if that helps and smoke test showed no leaks at 2psi. The car was and is very difficult to tune and was a pig to get running at first, right now it has fresh shell 98 but has a flex fuel sensor waiting e85 tune if we can sought this miss out. Any help is appreciated

Scott

[Sinista32]

Qualify - I don't know much.

But I would place a bet on your adaptronic ECU.

and therefore the course of action being taken by Jez and yourself.

Not much help but I think your on the right path.

Edit: Don't stress over it tonight

Edited May 28, 2013 by Sinista32

[portaz]

Good advise you know me too well lol but it did make nearly 250 kw on gate so that's not too bad lol

[MrStabby]

I also dont know much, certainly way less than Jez. Maybe a dwell issue not giving the coilpacks enough time to charge?

[Guilt-Toy]

put a set of stock injectors in it and see if you can get rid of the miss fire first.

[portaz]

Have resistor removed pretty big job to put stock ones back in

[Guilt-Toy]

its an adaptronic. it can handle the low ohms injectors, unlike its competitors plug in versions.

do it.

[portaz]

I will see what jez says as it would mean changing plugs back to std too wouldn't it?

[r32-25t]

Did you check the seat pressure on the valves when the engine was built?

[portaz]

I didn't but it was built by an engine builder in qld and was running 387kw without dramas when I purchased the engine it had travelled about 2000ks inc dyno work only change is cams and big end bearings just because I had sump off

[portaz]

Andy and jez spent 4 hours with it last night, swapped to another adaptronic , swapped injectors and problem still there so it's thought that its either due to wasted spark system or a mechanical fault yet undetermined. Jez is installing a nistune to see if it makes a difference other than that only thing we can come up with is put cams back to stock ones and if that doesn't work I guess engine out and full strip rebuild and blue print if all cc size of ports and seat pressures , ring gaps and clearances etc, fingers crossed but I'd love some ideas or if someone has experienced similar thing? I've search for at least 6 hours and I've found cams with Hyd lifters can cause missfire but these are solid type drop in juns? So no idea really

[SiR_RB]

oh that was you that came past Jez's yesterday (he told me when u left) that was me working on my car while it was on the dyno...

he did mention (and I herd when he started it) that your top end is Very noisy, not sure if this may result in the problems you are having ?

[portaz]

Nice car mate very neat Install and nice power too! It seems I was ripped off with cams from a seller on here whom I can't remember due to surgery well there is a lesson don't buy important parts after brain surgery lol. Jez changed cams and it silky smooth and quiet. It seems I must have measured clearances wrong in thou instead of mm or something cause clearance was at least .75 when should be .30. Base circle much shorter as was duration and lift about the same. So stock cams back in and see how it goes tonight! Fingers crossed as we have both had enough of it that's for sure!

[SiR_RB]

thanks mate she is my baby !

exactly lol always important to check clearances with every cam install !!! and if the base circle was smaller then it would definetly need new shims etc

well fingers crossed all goes well now keep us updated !

[SiR_RB]

on a side note, do you know if your head needed to be relieved to to be able to swing the 9.5mm lift cams?

[portaz]

Yes the head is relieved but as the cams were not what they were supposed to be they were fine. You should hear it now just injector noise absolutely no cam noise at all

[scotty nm35]

So the injectors are fine buddy? Good to hear. Are you back to stock cams now?

[portaz]

We hope so but really we won't know till its run, injectors seem fine though but here's hoping the missfire is gone under load

[portaz]

And yes stock cams now :-( see what it makes and address it another day if needed but with new items for reputable seller. Gee I learnt some lessons with this one

[portaz]

And yes stock cams now :-( see what it makes and address it another day if needed but with new items for reputable seller. Gee I learnt some lessons with this one