Hi Jez One Last Question B4 I Totally Give-up

[VAROOM]

Hey,

As you know ive got this problem at 6k rpm which is doing my head-in now.

the car is going superb its totally flying and under normal driving the car is totally perfect.

but if i wheel-spin out of a junction and the revs fly up to the red line the car missfires/overfuels and looses power big-time...so i have to back off the throttle for a second then it clears and away i go running perfectly...or if i am excellerating in say 3rd or 4th the car pulls awesome'ly but as soon as the revs reach 6000rpm its like it missfires or totally overfuels.

ive changed everything apart from the cam sensor (cas) and the module on the strut-tower..these are the only parts i have not replaced.

ive been using the car everyday to try and suss out the problem and it seems at exactly 6000rpm this stutter/missfire/overfuelling happens.

do you think the cas or ign module could give this kind of problem? it doesnt missfire at all at anyother point...a few months back a turbo coolant hose sheared off and i lost all the coolant and overheated the engine causing the head to warp and ive only had this problem scince the engine was rebuilt...so was thinking if the head was under extreme high temp would this damage the cas?

[Jez]

I had this problem on a car that came over the other day. I'm really not sure whats going on. I tested loads of things and the only thing left was to check the cylinder head, valves and springs. On this car it mis fired at around 6krpm, but on the dyno the power dropped off massively before the misfire occured. I reckon it could be valve bounce or something like that - the head had been rebuilt. I've not got to the bottom of it yet...

Have you had any head work done or was it just refitted?

Is the cam timing definately correct? I'm guessing it is if its running ok the rest of the time.

[VAROOM]

this is what ive done scince head rebuild...

head was skimmed .6mm and fitted 1.9mm cometic gasket new valves.

stage2 with nismo 555's
sard fpr set to standard pressure and z32 fuel filter
new splitfire coilpacks and coilpack wiring loom
tried 2 new sets of denso plugs ik22 and 24's
a few extra earths from battery/engine/chassis
had datascan diagnostic check
timing set as per your website
new airflow meter
pressure tested sytem for boost leaks
new vvt sprocket and solenoid
ive got a blitz r-vit so i can see the oxygen sensor/throttle position sensor/coolant temp sensor..all working correctly
cylinder compression checked

:cry: :cry: :cry: :cry: :cry:

[VAROOM]

Sorry i didnt get new valves it was just skimmed with the valves removed and new valve stem seals fitted.

[Jez]

Hmmm... not going to be able to diagnose this over 'tinterwebnet I dont think - sounds like you've tried most things.

I might be able to help if you come over, but not sure where you are.

[VAROOM]

Im way up north Scotland about a million miles from you...but i would drive to you if i really have to.

Do you reckon i should get another cas to try it?

Could i record a "movie" road test with data scan and send it to you either by burning it to disc or email just to see if you can diagnose anything that isnt right?

Of course i dont expect you to do it free of charge...i totally dont mind paying you to do it.

cheers.

[Jez]

You could try another CAS to see if it helps - make sure you fit it correctly - details in manual.

Email over a data scan log, dont need the vid just yet.

[VAROOM]

You could try another CAS to see if it helps - make sure you fit it correctly - details in manual.

Email over a data scan log, dont need the vid just yet.

Kool,

i can get a brand new cas for £50 from usa so will prob take a week or 2 to get it....but at least it will be new so it cant do any harm.

ill let you know how it goes.

Could you let me know if you manage to get that other s14 with same prob as mine sorted.

cheers Jez.

[VAROOM]

If it is valve bounce...what would cause this?

[VAROOM]

Had a few road tests with the car today at lunchtime and the just wont rev higher than 6000rpm:eek:

i recorded a mini movie with my blitz r-vit and the highest the revs got to was 5970rpm and it just wont rev past this point.

kinda like the car is hitting a rev limiter.

it recorded 6 sensors and all look ok.

a/fc1 stayed at -128% what ever that is?

[Jez]

Could you email me a datascan log - just so I can have a look. To be honest valve bounce is unlikely...

[VAROOM]

Could you email me a datascan log - just so I can have a look. To be honest valve bounce is unlikely...

Hi there,

cheers for getting back to me.

i have just purchased datascan and datalog viewer and usb cable so i dont have to keep asking kkydd to use his.

im just waiting to get my software activated so i should get a email today with a code so i can use the datascan on my laptop.

ill give you a shout this week once ive got it up and running.

cheers dude.:thumbs:

[justbutts]

hello matey

i had this a while age on a stage two setting and have been experiencing it at the moment with my current set up, have you tried turning the boost pressure down a tad

or on the greddy unit you have a (gain) setting which is how quick you wish the turbo to build up the pressure try dropping that a tad as well

mark