Fuel Cut At 11psi?

[markdem]

i installed a turbo tech boost controller a couple days ago and hooked up a boost gauge and set it to run at 10-11psi max. after tightening off the locking nut on the boost controller, i took the car for 1 more spin to check that the boost hadnt changed and then removed the boost gauge (i got nowhere to mount it right now). everything was running fine until i had 4 passengers in the car and floored it which was when i noticed a rapid "stuttering" (about 10-15 "beats" per second) in the high rev range just before it changes up a gear and lack of power. the car is an r33 s1 auto with stock exhaust and intercooler. am i hitting fuel-cut even tho im only getting 10-11psi? or is it something to do with the auto transmission not changing gear fast enough and therefore im bouncing off the rev limiter?

am happy to run any further tests that you guys think would help diagnose the problem

[Trozzle]

Sounds like a missfire to me. Check plugs aren't fouled. Otherwise could be coilpacks

[markdem]

it just had its major service so its got brand new plugs. coils are still the old ones tho. i will consider looking at the coils tho

[negativecamber]

what gap are the plug mate?

you want it to be about 0.8mm

[Trozzle]

NGK BCPR6ES, .8mm copper.

[markdem]

i got NGK laser platinum spark plugs. i dunno what gap they are (im trying to google them right now), i just dont wanna have to undo the bloody spark cover again to measure the spark gap. will google a bit more and if i cant find anything on google, ill pop the bonnet

[markdem]

just did a bit more searching on the forums. the PFR5G-11 sparks im using dont seem to be able to handle the heat at high revs. either that or ive just got tired coils

[Trozzle]

Also, the -11 suggests they're 1.1mm gap.

[markdem]

if i decrease the spark gap, wont i be getting a colder spark and therefore loose a little bit of power and fuel efficiency due to decreased rate of combustion and possibly incomplete burn? i guess its better than having the spark gap too big and getting no combustion at all tho lol

[markdem]

righteo! im getting the tools out. time to squash some spark plugs down to 0.8mm. i reckon you guys prolly know what your talking about so ill give it a bash. thanks very much coz i seriously had no idea what the problem was. you guys are pro's!

[Birds]

Four people in the car might have given it enough extra load to bring on a little extra boost and run into R&R?

[Mr.Massive]

Four people in the car might have given it enough extra load to bring on a little extra boost and run into R&R?

+1

[Brezza]

yeah i'd look at the plugs or coils.

i had 4 people in my GTR and it did the same thing up high, maybe around 6,000rpm.

but with just 2-3 people or just me it doesnt do it.

i havent had that many people in my car again so i cant tell you if my current tune is better.

[negativecamber]

let us know how the 0.8 gapping goes. it should fix it.

[markdem]

ooookayyyy bad news. ive re-gapped the sparks down to 0.8mm and the problem is still there. ive uploaded a video to youtube and you can see that the revs hang around 5000rpm for a while and you can also hear that something isnt right

[d1_drifter]

Sounds like spark breakdown. Coilpacks must be shot if you're plugs are already at 0.8mm.

[markdem]

yeah, i might have to get some heatshrink onto those coils and see if that solves something. im not gonna f**k around with sticky tape. ill try find some heat shrink tomorrow

[jjskyline79]

Heat shrink will do sweet FA. I would be getting new coil packs tbh with you, the last thing you want is det and damage you engine.

[defari]

+1 for coilpacks.. 10-11psi is getting pretty high if your coils aren't in good condition.

[markdem]

fair enough. im just unemployed at the moment so im trying to do things the cheap way. i know a guy that will sell me a full set of coil packs for $100 and theyve only done 60,000Kms so i think ill have a chat to him. thanks for the help guys