[Sideways Steve]

Recently started getting a nasty flat spot/misfire/stutter at the above mentioned RPM

Its mainly noticeable in 4th or 5th if your sititng on the motorway at 70ish and try to accelerate. It holds back and splutters a lot.

If you drop to third and get past it it comes on boost and drives as normal and pulls hard with no issues. its also silky smooth below that rpm range too.

Any thoughts ?

im thinking possibly plugs ?

 

[sxygirl]

Maybe plugs
I would say possibly coilpacks. Worthwhile changing the plugs first if you suspect them as thats clearly the cheapest. Do you know anyone else with an RB26 that you could swap the coilpacks over to see if that makes a difference?
Do you have the standard coilpacks just out of interest.
Something like this can be difficult to diagnose though - it could be a few things. Air Meter is worth giving a look over and clean too

 

[Sideways Steve]

wouldnt have thought coilpacks as they would normally show fault under full boost and not off boost/spoolup They are brand new oem ones that have only done about 5k miles

The AFM's are new z32 ones again which have only covered 5k miles. I have a mega rich flat spot around that RPM which chucks in fuel on spoolup and i think due to using it daily has caused it to soot up the iridium plugs.

thats my theory anyway, gonna pull the plugs at the weekend and check it out.

 

[2 Black Lines]

Steve, Iridiums are sometimes the business, but thru exp not the answer.

I'll have a look to check, but I think BCP 6R is what I've got on the 25, a cheap alternative, never had one go down after being mapped, but alwways had probs with Iridiums on.

Btw what fpr you using? and did you narrow down the spec?
If you want I've got the 33 there if you need to swap the coil packs to try If R33 and R32 GTR the same?

 

[Sideways Steve]

Cheers Gordon, appreciated. I agree the iridiums can be a right PITA !

Narrowed down more parts yeh but need to look up some part numbers etc, Not sure on the FPR yet.

BCPr6's are quite hot plugs ? Im running 8's just now but was going to go with either BCPR7ES or BCPR8ES instead of the 8 iridiums.

I ran the BCPR8ES's on the evo with no issues just regapped to 0.5 mm some of the tuners run them up at 700bhp too that way

Ive sorted the misfire now anyways though, wasnt plugs or coilpacks or afm's LOL seems theres a dodgy wire somewhere, Ill need to trace it though as its become intermittant and have narrowed it down to bumpy road surfaces LOL.

I have a feeling its the spliced wiring to the Z32 MAF's.

 

[Monster GT-R]

Solder them and use heat shrink

 

[Sideways Steve]

I intend too mate But wont be this weekend now as im going to kuala lumpar