boost problem

[cav]

the other day i uped the boost on my r33 so that it know runs around 10-11 psi but dont know if this model has a boost cut or i have some bad fuel, or maybe time for some knew plug. once it gets boost of 10-11 it splutters and pops through the exhaust. the plugs have done 25000 kms and the fuel im using is mobil.

[awurth]

check the plug gaps. 0.8mm seems to work well. If it's a 33 series 2 i beleive they have a boost cut.

[Trust33]

more than likely plugs.Mine was in the same boat then i got new platinum plugs problem fixed.You should give them a clean too theres probably some carbon build up arround the gaps. :flamed:

[cav]

thanks guys i will check the plugs. when i put them in i did gap them to 0.75mm and they are NGK iridium plugs. it is a series 1. i dont know if they have a boost cut. problem is about 10-11 psi. do they have fuel pressure problems?. do i need a malpassi?

[awurth]

iridium's foul real easy, I used some injector cleaner and it started missing straight away. series 1 don't have a boost cut, i had one and could run 14 psi.

[improvin]

hey have gotten rid of the boost problem, coz i got the exact same problem with boost. are you guys sure theres no boost cut on series 1?...

[croat]

with the same problem i am about to change my irridiums. cav maybe your car is leaning out? Mine will back-fire and splutter out the exhaust like nuts from 5500rpm onwards. If i do have a fuel issue will a malpassi solve it or do i have to do the pump and all?

[awurth]

sorry as far as i know they have a boost cut for over boosting, I ran 14psi and no drama's, my car did suffer a broken land on piston 6, just when i bought it, because of a failing fuel pump, I found out after the rebuild that the fuel pressure dropped away under load. this was before I did any mods to it. a new 044 and she was a steady pressure again.

[Abo Bob]

If you do have boost cut it cuts timing first so what you have described doesn't sound right. Sounds like the plugs. Pull them out and have a look. 0.8 to 0.9 is the go. Maybe 0.75 is too small????

[shajar]

Cav its your plugs, I just went through the same prob last weekend, car loosing power like spark or fuel cutting at anything higher than 9psi.

I replaced the plugs from fairly new NGK's to Double Platinum Autolits $90 all up and was advised by two different GTR specialist one online in N.Z skylinesdownunder forum to gap them to .66 So I took them as close as I could to that and guess what, it bloody worked, boost is fine all the way to 12psi - not game to take any further till I get a front mount.

[Guest Robo's]

The problem is when you increase boost you increase fuel. So too much fuel is in the cylinders and the spark cant burn it all, hence the backfiring. Get a SAFC and lean the fuel out, fixed mine.

[cav]

have pulled the plugs to have a look at them and they look good, not fouled and they are a good colour. what should the fuel pressure be?

[cav]

have pulled the plugs to check them for fouling and they look good, both colour and gap. want to check fuel pressure, what should it be?

[awurth]

get it on a dyno with a fuel pressure gauge and run it up under load, you soon see the pressure drop away if the pump is failing. Not sure what the pressure should be but, when we turbo'd my mates FTO i think we set it at about 220lb can't remember the figure for sure though.

[[ant]]

i found iridiums to be shite in my S13 ... soon as i upped the boost with an EBC it started missing. took the iridiums out and put in just your normal cheapy plugs that are like 12$ a set and it worked a treat. id say find out what is the cheap copper alternative to your plugs (NGK brand still though) and put some of them in at the same gap of .75-.8. for $12 it cant hurt to see if it is just crappy plugs.

yeah u need to dyno your car with a fuel pressure guage to test the fuel pressure. however, if you are upping your boost, it is a sensible option to upgrade your fuel pump anyway, especially if your planning to run the higher boost all the time and more power in the future. an 044 intank replacement is usually a good bet.

if it still has issues and you want to go for a Malpassi pressure regulator, do that after you've done the fuel pump. the Malpassi wont do much good if you have a stock fuel pump coz the pump will struggle to keep up the increased pressure anyway. i had a misfire in my DR30 skyline, changed plugs and leads, reset ecu, upgraded fuel pump, and still had a misfire at around 1bar. after fitting a Malpassi Rising Rate regulator the misfire is now gone.

try plug changing and see how you go to start with though!

[cav]

guys i have changed the plugs with a set of ngk cheapies and still the same. got my mates to watch the ass of it and it is blowing raw fuel out the exhaust. do they have trouble with the coils, maybe one doesnt like the increased boost (extra load). it doesnt play up till high in the revs 5000-6000 rpm. i can run 10-11 psi low in the revs with no trouble.

[Keegs]

hey cav, did you end up sorting this problem out, my car has just started doing the exact same thing as yours last night.....it's really annoying me and I want to fix it asap!

Cheers

[cav]

sorry dude havent sorted the problem yet, am thinking coils, or an after market computer its got me stuffed need to get it to someone whos playing with them all the time. i might sell it yet, that will fix it.

[Keegs]

sorry dude havent sorted the problem yet, am thinking coils, or an after market computer its got me stuffed need to get it to someone whos playing with them all the time. i might sell it yet, that will fix it.

luckily it seems it was just my plugs...I hope you get yours all worked out though. Good luck!

[cameron]

guys i have changed the plugs with a set of ngk cheapies and still the same. got my mates to watch the ass of it and it is blowing raw fuel out the exhaust. do they have trouble with the coils, maybe one doesnt like the increased boost (extra load). it doesnt play up till high in the revs 5000-6000 rpm. i can run 10-11 psi low in the revs with no trouble.

Sounds like a fuel problem dumping too much fuel in and choking on it if its coming out the exhaust as a liquid :uhh: - SAFC ll can fix this.

Could be the coil packs, you'll need to tape them up with duct tape. Because the spark can ark out the side which results in the plug not getting the full spark. Do you run the black cover ontop of your coils - Saying Nissan 2498cc etc... ?

Hope that helps.