Skyline R33 S2 Running Rich Bad Fuel Economy Etc

[brn_20B]

Hey guys

I recently bought my car and it was running rich, did a full service on it once i installed spark plugs and gapped them to 0.8 it kind of fixed the problem, but now I installed a fujitsubo exhaust with a 4" cannon tip cat back (ALL FUJITSUBO) to my stock cat and dump pipe and its running rich but im not sure because i could smell the car running rich before hand aswell, but now i think its a little more? and it backfires on gear changes. its got me very confused :S

Mods include Turbosmart T boost controller set to 10PSI

Hybrid FMIC

Fujitsubo 3" catback with 4" tip

greddy turbo timer

HKS SSQV(ITHINK) BOV

thanks guys

[chilzzi]

Mines running the same mate, ever since I did the turbo back exhaust upgrade. Im still running with the stock ecu which cant 'reset' to suit new mods. That's my theory anyway. I've since invested in a power FC. A proper tune should sort things out. Stock ECU's are read only. So not much you can do I think. My 2 cents anyway.

[GTSBoy]

Obvious causes for poor fuel economy rich running are;

1) Buggered coolant temperature sender (the ECU one, not the guage one),

2) Buggered O2 sensor.

Beyond that you're looking at severely dirty air filter, dirty injectors.

But, because you're talkjing about an R33 shitter, the #1 likely cause of richness when under load is that your mods have increased the air flow through the engine to the point where the standard ECU has thrown an emo and is richening and retarding. This won't cause rich running at cruise or idle, so you still need to look at the causes listed above, but it is still likely to play a part in your problem.

Edited August 17, 2012 by GTSBoy

[Dose Pipe Sutututu]

Plumb back the atmospheric BOV to begin with.

[AngryRB]

when i had stock computer, i had black puff's of smoke just reversing the thing, seemed to run very much on rich side, that was with the FMIC and 3inch exhaust...

id put stock blow off valve on for a start...then get a power fc and tune..

whats your compression like and how much city driving/squirts you doing? mine was always bout 10-12L/100km with a mix of driving but improved alot with a power fc

[rondofj]

My fuel economy is just rubbish- 19-20L/100kms everytime, new O2 sensor, new plugs, oil, filters etc, also when I suddenly put pedal to floor the freakin thing pulls timing or something, groans and theres no power for a few secs before it goes properly. But if I gradually stab the throttle then it goes much much better. Getting a turbo upgrade soon so will definitely have these huge inconvenience issues sorted through a GOOD TUNE which is what she needs most.

Edited August 17, 2012 by rondofj

[AngryRB]

that is really bad economy... somthing wrong there big time..you must have a lead foot with a shitload of short cold start drives or the tuning is terrible...

try a power fc .. or other computer.. when i switched the car was completely different.. im getting 17L/100km on ethanol for ffs.. so that tells you how bad it is...

your problem to me sounds very much like a major vacumn leak or exhaust restriction, bet your intake manifold gasket is gone or hoses.....when mine was gone there was nothing for a few seconds then it accelerated..

Edited August 17, 2012 by SliverS2

[Moodles2]

If the previous owner put a HKS atmo bov on, then he is an idiot. And god knows what else has been done to that car.

Checklist of things that can make car run rich (on an untuned factory ECU):

Atmo BOV (sell the HKS thing), and replace with either a stock BOV or a stock GTR BOV.

Bigger AFM such as a Z32. (needs to be tuned for)

Malfunctioning/dirty AFM, might get away with cleaning it (with contact cleaner or proper AFM cleaner) to get it working right again.

Ebay special performance chip. (god knows what the 'tune' consists of)

Bigger/highflowed injectors (that or they're clogged to shit and need cleaning. again bigger injectors is something that needs to be tuned for).

Wrong or non-working oxygen sensor.

Aftermarket adjustable fuel pressure regulator set to the completely wrong pressure.

Base timing is wrong (timing belt skipped a tooth or teeth).

Broken/malfunctioning coolant temp sensor (car will be stuck in cold start enrichment and drink fuel)

Massive boost leak, metered air is escaping out the cooler piping before it gets to the engine (joiner blown off, common on the ones near/on the intercooler). Though it would hunt badly while idling

Wrong spark plugs (wrong heat range can cause the plugs to foul up, fouled up spark plugs don't work well)

There are probably more things I haven't thought of.

[rondofj]

that is really bad economy... somthing wrong there big time..you must have a lead foot with a shitload of short cold start drives or the tuning is terrible...

try a power fc .. or other computer.. when i switched the car was completely different.. im getting 17L/100km on ethanol for ffs.. so that tells you how bad it is...

your problem to me sounds very much like a major vacumn leak or exhaust restriction, bet your intake manifold gasket is gone or hoses.....when mine was gone there was nothing for a few seconds then it accelerated..

Yep somethings definitely wrong bigtime, I dont have as much of a lead foot as pretty much any average joe blow with a Skyline, I do do a lot of short cold start runs to work and back, this economy has been consistently bad for as long as I can remember, I did once have a cracked litle hose on the intake and that caused my engine to shut off under sudden deceleration or normal. braking. Could be my intake mani gasket or the tune.

[brn_20B]

Thanks for the replys guys, OK from day 1 when i got this car i serviced the shit out of it (3 weeks ago)

When i bought it i did the following:

Spark plugs- I bought these from mekong and the guy gave me the wrong damn ones or they werent gapped properly so i got them installed and gapped to 0.8

fuel filter

Oil filter

Valvoline Fully synthetic oil 10-40

Diff oil service

Gear oil service

bendix ultimates put in and disks machined

Then i took it to top secret imports where the spark plugs were gapped to 0.8 paid for a boost leak check (Smoke test) they found a little vacuum line leaking, was easily replaced the earth for the battery was too small and wasnt getting earthed properly got that fixed.

Just got the castor bush done bought polyurethane ones got them pressed new tyres took it for a damn wheel alignment and the guy who did it said that my left is 2degrees off so my car will still pull to the left anyway thats another story..

another time whenever i hit over the 180KM/H mark my car suddenly started heating up and i stopped checked it one of the drive belts litterally snapped (the one that powers the fans and the water pump etc) luckily didnt blow a head gasket etc. Got that fixed from top secret imports aswell but now I always get my battery light coming on when i go over 160 it feels like its going to snap again (anyways i dont think thats related)

so thats pretty much the history of the car

Im only getting about 330-350KM out of a FULL tank of bp ultimate 98 which is depressing, I will start looking for a BOV replacement, so all BOV's will do this? the only way to get rid of it is by going stock or putting a wastegate on from my understanding you cant do that to the stock turbo?

cheers guys.

Edited August 17, 2012 by brn_20B

[zebra]

Bag fuel economy, but you are doing 180km/h?

Lol

Ok

Put a standard recirc valve (bov) back on

Will make a big difference straight up

[brn_20B]

Bag fuel economy, but you are doing 180km/h?

Lol

Ok

Put a standard recirc valve (bov) back on

Will make a big difference straight up

Lol i wasnt counting the tank that i clocked over 180km/h on.. that tank gave me 280 lol

[rondofj]

330-350kms to a full tank and ur depressed? Im getting 250kms consistently man, how f**ked is that?? Am hating it, needs a professional tune bigtime lol, coming soon anyway as Im upgrading my POS stock turbo.

[brn_20B]

lol dude I used to drive a fiesta before this which gave me 550-600 on a 45 liter tank so its a big jump haha.

[GTSBoy]

Ron,

A nearly stock R34 that gives fuel economy that bad and isn't being thrashed around hard ALL the time does not need a tune. It needs whatever the problem is fixed.

My Neo is about the same as yours and I can easily get >400 km/tank. In fact, the last 4 tanks have been about 12.5 l/100km, and the 4 tanks before that (before it got quite as cold) were all <12. I expect that to get better once I tune it, although the extra boost will probably cost me in tyre smoke. Nevertheless, my economy is as bad as it is because the majority of my miles are start stop rush hour traffic. So I cannot believe that there's any good reason (apart from a sensor type problem) for your car to use as much juice as it does, and I definitely do not believe you cam make it go from where it is now, to decent-good fuel economy by tuning it. You will only likely be able to get it from where it is to merely terrible.

[Moodles2]

BOVs and wastegates are 2 different things, the BOV is the problem, not the wastegate.

Blow off valve releases air either to the atmosphere (which your HKS unit does) or recirculate back into the start of the intake piping (factory BOV does, which the factory ECU expects).

HKS SSQV can be made plumb back though via: http://www.nengun.com/hks/ssqv-option-parts . But in terms of plumb-backed BOVs, the GTR bov is the superior choice as it holds lots of boost (even the factory BOV for your model will be fine) and leaks air (by design) while idling which I'm not sure the HKS SSQV will do in plumb-back mode.

http://en.wikipedia.org/wiki/Blowoff_valve

I'll quote the line which affects you:

"In the case where a mass airflow sensor (MAF) is used and is located upstream from the blowoff valve, the engine control unit (ECU) will meter out excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation."

Wastegates are either internal to the turbo (stock turbo is internally gated) or external (attached to the exhaust manifold usually): http://en.wikipedia.org/wiki/Wastegate

[GTSBoy]

The thing is, you are all focussing on the BOV, when in fact unless it is leaking whilst driving normally (possible, but unlikely) then it should have no influence on the fuel consumption. Sure, it will cause stumbles and misses and smoke and whatever when throtle opening is being changed, but in cruise conditions or even under load, it should be shut.

I do not think the BOV is to blame for gross fuel consumption. Of course it is still a stupid thing to put on the car, but not the cause of this problem.

[Moodles2]

Personally I think it's a combination at least 2 or 3 things, BOV being one of them

[scotty nm35]

The thing is, you are all focussing on the BOV, when in fact unless it is leaking whilst driving normally (possible, but unlikely) then it should have no influence on the fuel consumption. Sure, it will cause stumbles and misses and smoke and whatever when throtle opening is being changed, but in cruise conditions or even under load, it should be shut.

I do not think the BOV is to blame for gross fuel consumption. Of course it is still a stupid thing to put on the car, but not the cause of this problem.

Most bov's are open at cruise due to the vacuum, unless they have the stiff spring fitted.

[gtsttrk]

If you're running an SSQV get a proper tune or HKS EIDS.

+1 on O2 sensor.