What could this be?? Flamage, Running too Rich, Ignition?

[meshmesh]

Guys the GTR has always run pretty rich, & made the "snap, crackle, POP" from the exhaust. But after tuning the Power FC, the car runs like a dream, very smooth & linear power, but I am getting some pretty bad "POPS" from the exhaust, I wouldn't be supprised if flames are coming out.

So I was at ICE yeaterday, & we changed the plugs to "Iritop 7", Changed the "I think its called" Inginition Heat Sink on the top of the Rocket Cover towards the back, cause it was upside down "for some reason". This seem to have help but, nothing major. The "BIG POPS" tend to happen during gear changes "Off Load" eg: In 2nd revving at 5K, Clutch in, Off the accellerator, Changed to 3rd, softly back onto accellerator "BIG POP, that sounds like a mini bomb just went off vibration through the car" then continue to accellerate.

My knock levels are around 14 the max doen't get over 21~23.

_also, I get around 300-320km per tank. At least 50% is hwy, with a fuel comsumption averaging ~15.5 - 17.0 ltr p/100km

ANy ideas what next, I've got it going in for a check up on Monday?

meshmesh

[Amaru]

Sounds pretty much the same as mine. Im running the same plugs, power fc, and around the same revs/load as you the car makes pretty big backfires when changing gears. The problem I was told was I dont have the stock GTR bov's anymore, they were replaced with Blitz Supersonic DD ones that vent to atmosphere, and its causing the car to overfuel a bit on gear changes. Unsure if you have stock bov's or not, but if you dont, this could be the problem Hope it helps a bit.

[owned]

maybe its just part and parcel of owning such a highly tuned car. Suppose u dont get a pat on the back from the coppers but oh well.

[meshmesh]

Sounds pretty much the same as mine. Im running the same plugs, power fc, and around the same revs/load as you the car makes pretty big backfires when changing gears. The problem I was told was I dont have the stock GTR bov's anymore, they were replaced with Blitz Supersonic DD ones that vent to atmosphere, and its causing the car to overfuel a bit on gear changes. Unsure if you have stock bov's or not, but if you dont, this could be the problem Hope it helps a bit.

We thought that aswell, but the BOV are stock. I'm thinking "no expert either" what if we leaned it out a bit? Could my knock levels be ok upto/around ~30. Currenlty the max I have seen is 21~23 but normal driving sees around 13~16.

If I understand correctly the backfire/bomb effect is due to unburnt fuel getting through the exhaust. Then would this be related to either ignition, timing, or air fuel mixtures. Could it be my air fuel mixtures, or my coil pack?

I dunno, the sound is awsome & sure scares the crap out of people, but it can get annoying & not really sure if it can cause harm to the motor etc...

[GTR R35]

it might be hidden antilag

[Mase]

Flames are awesome!!! I saw this orange 32 cruising in the city blow a massive one out the back. My guesses are your still running uber rich mate. I get the odd pop but not every time. Has changed a lot since i removed the vacuum line of the stock fuel reg and installed a malpassi rising rate fuel reg and set the base pressure.

[GT-Rmgedon]

I have this same problem. I got an R32 GTST running an RB25 with a

GCG stage 2 400hp turbo, hi-flowed, plus a malpassi fuel pressure

regulator and an old skool Apexi air fuel controller (the dial version).

I get massive flamage between gear shifts. Its good for keeping

those pesky tailgaters away but heaps scary when you are driving

around town where it is dark and all you see are huge flashes like

fireworks goin off behind the car. Could it possibly your exhuast?

Cat been gutted? I am nowhere near competant on problem solving

these things as i only just bought my car but I think there are a

number of different reasons for different cars. I'm tending to think

mine could be a combination of what Amaru said about the

aftermarket BOV's & my exhaust. I got the older model HKS SSQ and

it is atmo venting, plus my cat is gone. I am running

heaps rich but it is better than making the car run lean my mates

have told me. Be interested to find out the solution to your prob

Meshmesh, keep us posted.

[meshmesh]

Hi GT-Rmgedon,

I've had my Cat checked when I had the front pipes installed, It is as stock as they come. After speaking to a mate today "whilst out on the boat in beautiful port phillip bay melbourne amongst the 1.5metre swells" He thinks it could be a number of things, eg:

1. O2 Sensor "apparantley if this fails it should show an error code, but he has seen case where the O2 sensor was stuffed & shown no error code"

2. My rear bumper has to be cleaned every 2-3 days, because of exhaust stains. He thinks this could be 2 things, a) running rich or B) sh!t oil passing through the motor & into the exhaust.

3. I have also noticed the smell of petrol fumes at times. I had him follow me, & as I accellerated he stayed behind to see. He said the car "smells like its running rich" & thatalong with a puff of smoke, he could smell the fuel from the car behind.

Getting an oil/filter changed tomorrow using Mobil 1 fully synthetic, then back on the dyno monday. I read a post on SAU mentioning something about the Power FC needs to know that the car is fitted with PODS & not the standard air box/filter see link http://www.skylinesaustralia.com/forums/sh...68&postcount=17.

[kjb_r33]

Running to rich on deceleration......

[meshmesh]

Running to rich on deceleration......

Hi kjb_r33,

OK Thanks for that, but could you elabirate a little more, like how do we go about fixing it? Also, what's your thought about leaning it out a little more, if my max knock levels hit around 30 on the Power FC HC, is this ok?

[kjb_r33]

Not familiar with the power fc, nor the figures your using for knock, (have only tuned motec). Does the power FC have a tunable fuel map? Does it have accel enrichment and closed throttle decel?

If your knock meter as such is showing ANY signs of detonation i wouldnt lean it out at all, but i would be checking for a decel capability, and also checking your TPS adjustement. If its not closing the idle switch it may not go into decel mode at all. Is the power FC a piggyback type thing or is a stand alone engine management system.

[kjb_r33]

OK, just checked it out, has no decel mode, BUT, if you set it up to run VERY lean @ closed throttle above say 1500 rpm (well above idle) it will give you a decel mode at closed throttle (or less than 30 kpa absolute manifold pressure, which represents decel) and higher than idle RPM. Not sure what the adjustment parameters are but thats how i set my skyline up when running the M48 in it (Although the M48 does have a decel mode).

[meshmesh]

Thanks kjb_r33 :confused: to me I dunno WTF your talking about, but I'll let my tuner know I'm sure he'll understand alot better than this dumb @ss

[GTR R32]

what air/feul ratios are you running? If you don't know then your tuner should be able to tell you. This will give you a good indication as to whether its running too rich or not.

As for the knock level on the PFC. The dash warning light comes on at preset value of 60. So in general it should be ok as long as you are below this value. You'll get a diferent opinion from every tuner as to the maximum safe value. My tuner is happy as long as mine stays below 40.

[meshmesh]

what air/feul ratios are you running?

I'll be getting these, soon. Was supposed to go in today to the tuners, matbe later this week. I can occassionally smell fuel, so I dunno if that's also related to running rich.

My tuner is happy as long as mine stays below 40.

WOW!! 40. mine rarely get over 13~, the max I'll see is 21~ under hard accellerating.

Funning thing though, I had the car serviced with an oil & filter change using mobil 1 full syn, & the backfiring is still there but not as bad ??(maybe I'm just imaginin things)

[GTR R32]

If your rear bumper needs cleaning every 2-3 days then it is most definately running rich.

My knock generally reaches as high as 30-40 depending on what fuel I have in (we only have 95RON up here). The reason for a higher value than your car is because my car most likely has leaner air/fuel ratios and/or more ignition timing than yours.

Not sure about your oil change. Can't imagine it would have made a big difference.

[JimX]

WOW!! 40. mine rarely get over 13~, the max I'll see is 21~ under hard accellerating.

I'd say it's running too rich. Mine will touch on 30 sometimes and it's still too rich. The engine warning light comes on at 60 as previously said but the manual says that even at this level it's not necessarily detonating. The only way to tell is to get the AFR's checked on the dyno.