O2 Sensor Port Issues On Jjr Split Dump Pipe

[Scratch]

Hi all,

Just wondering is anyone else in here has a stagea with a JJR split dump pipe and whether they are having any problems with fuel consumption, possibly related to their o2 sensor? Apologies as a lot of info is going to follow this, but I'm hoping more info will help the stagea pro's give me more educated guesses at what might be wrong.

Problem:

I've been told by my mechanic that the 02 sensor port on the jjr split dump does not place the o2 sensor deep enough into the pipe to get a proper sample of exiting gasses. The result to this is the o2 sensor sending false readings and potentially causing my fuel consumption to go wacko. They recommend replacing the split dump with a new custom one ($$$) or ordering a japanese one. Really want to check with everyone before spending the dosh on the split dump.

Background:

I've got a 97 rs4 stagea (s1, auto) with a JJR split dump pipe, K&N panel filter in the standard airbox, a semi performance aftermarket exhaust system (cat back) with no other mods beyond that.

The story so far:

Fuel consumption was horrible when I first got the car, barely 280K's to a full tank (my driving style test case is stated below). I recently sent the car for a 100K service at reputable workshop here in perth, this covered a full fluid flush and change, mobile 1 oil, new platinum plugs (gapped at 6.5mm i was told), oil and fuel filters, etc. I've also purchased a genuine nissan o2 sensor for the stagea and got it changed during the service. I'm currently at 215K's and i'm pretty much at 3/4 tank. Mechanic says its very likely because the o2 sensor isnt deep enough into the split dump.

Test cases (might or might not help, but included anyway):

-------------------------------------------------------------------

Fuel: BP98 only

Route:

The car is only driven from home-work-home using the same route everyday at the same time (+/- 5 mins) to encounter virtually the same traffic conditions.

The entire route is city driving (<>60KMH) and I always try to keep +/- 3kmh at the speed limit).

Driving style:

Absolute NANA, staying OFF boost back off when i hear the turbo spooling up, zero spirited driving and getting overtaken by barina's (hurts me plenty, but i need to see how far she will go with the most economical driving I can manage.

I also leave the OD OFF for city driving (<60 kmh) and ON for freeway driving (but for my test it was purely city driving so the OD was always OFF)

I coast to a stop, slow down by getting off the throttle earlier (i.e fuel saving driving techniques) and dont try to be the 1st off the lights.

Anyone encountered similiar issues or any ideas on what could be causing my fuel consumption crisis? I'm really just aiming for 400K per tank city driving which isnt unreasonable i believe.

Cheers!

Edited January 8, 2008 by Scratch

[ssshonky]

is he 100% sure that the o2 sensor is performing correctly?

ie .. did he stick a consult computer on it and monitor what the o2 sensor does?

also have you tried resetting the ECU .. so that it can " learn " your new setup ( ie new o2 sensor etc )

I would double check that the o2 sensor is definately giving a readout before you go too far down the path of changing dump pipes etc

in regards to the o2 sensor not going deep enough into the exhaust stream .. why not see if you can get the nut ground off and get a fabrication workshop to make it so the o2 sensor can be screwed in deeper.

hope that helps.. its all a wild stab in the dark .. but seems logical

[ssshonky]

we are currently scraping in at around 400k till the orange light comes on .. though due to being super povo and the price of fuel what it is now . the stag hardly ever gets a full tank

[darrinspencer]

I have a JJR split dump and the factory cast dump pipe sitting on the floor at home. I can tonight measure the difference in the tread depth of each to confirm if there much of a difference if any between the two. At least that theory can be solved.

Running the bigger exhaust will cause an extra 1-3psi in boost pressure which is not helping you.

Nissan turbo cars run very rich, so best fix is to fit some sort of fuel correction computer

Have you read the fuel economy thread for comparison?

Have you had it on a dyno to check air fuel ratio's?

It may have a leaky injector? Possibly get them cleaned or run some injector cleaner.

When I had my r33, I was happy if I could get 280k's from a tank and in my Stagea I am still on my first tank of fuel in 18 months, it is very economical

[_Ryan_]

we are currently scraping in at around 400k till the orange light comes on .. though due to being super povo and the price of fuel what it is now . the stag hardly ever gets a full tank

ditto

[Scratch]

is he 100% sure that the o2 sensor is performing correctly?

ie .. did he stick a consult computer on it and monitor what the o2 sensor does?

Negative on that, the assumption was its a brand new sensor hence it should be good as gold. I'm on PLMS now looking at buying a consult connector + software. We didnt put it on the dyno which is my next step, but i wanted to see if there was a known issue with the split dump and its o2 sensor port before i paid for dyno time. Would have much rather spent the cash on fixing the o2 port or a new pipe.

also have you tried resetting the ECU .. so that it can " learn " your new setup ( ie new o2 sensor etc )

I would double check that the o2 sensor is definately giving a readout before you go too far down the path of changing dump pipes etc

No i havent reset the ECU myself and dont believe my mechanic did either. The reason i didnt do it myself was because i read a post on the fuel miser thread (by sydneykid i believe, dont quote me) mentioning that a ECU reset isnt required with a new o2 sensor and wouldnt do a lot of good. I'll do that tonight and note the differences.

in regards to the o2 sensor not going deep enough into the exhaust stream .. why not see if you can get the nut ground off and get a fabrication workshop to make it so the o2 sensor can be screwed in deeper.

Thats what i'm planning on doing actually, i'm going to get quotes on this hopefully this saturday hopefully its cheap.

I have a JJR split dump and the factory cast dump pipe sitting on the floor at home. I can tonight measure the difference in the tread depth of each to confirm if there much of a difference if any between the two. At least that theory can be solved.

Running the bigger exhaust will cause an extra 1-3psi in boost pressure which is not helping you.

Nissan turbo cars run very rich, so best fix is to fit some sort of fuel correction computer

It may have a leaky injector? Possibly get them cleaned or run some injector cleaner.

When I had my r33, I was happy if I could get 280k's from a tank and in my Stagea I am still on my first tank of fuel in 18 months, it is very economical

Thanks mate, that would be awesome if you could post the results. I didnt know boost pressure rises when your exhaust is better flowed.. i honestly thought it spools up quicker but the boost pressure stays the same (i.e factory solenoid settings).. is this not the case? (sorry if this a n00bish question)

Injector leaks/cleaning is something i havent checked/done.. i'll look into that and whack in a bottle of cleaner for good measure.

At this point i'm looking the jaycar interceptor kits purely to correct this fuel issue and i'm not after upping performance..

One thing just occured to me, my mechanic mentioned that an SAFC will not helpwith fuel economy (something about the o2 sensor countering the effects) is this true? To my understanding the jaycar DFA kit does essential what an SAFC does (intercepts the MAF sensor readings), and numerous users report fuel savings with the DFA... does this mean the SAFC would work?

if it comes to a point where i need to get ignition timing control as well, then its pretty much a a greddy EMU..

Edited January 8, 2008 by Scratch

[Duncan]

re the SAFC making no difference - the 02 sensor is only used at light throttle openings (closed loop). moderate and full throttle switch the computer back to a map based on revs and airflow.

I think you should get a decent wideband 02 gauge onto it - that will tell you if it is running rich too often. Checking the standard o2 sensor is pretty easy with consult it will move around between about 0.2v and 0.8v at low throttle openings (at full throttle it should go .8v - 1v)

[darrinspencer]

I checked the JJR dump pipe compared to the factory dump pipe. The O2 senor actually protruded in further with the JJR pipe.

So that blow's your mechanic's theory.

[Scratch]

I checked the JJR dump pipe compared to the factory dump pipe. The O2 senor actually protruded in further with the JJR pipe.

So that blow's your mechanic's theory.

Thanks champ, that narrows the field down. Personally though, i was hoping it was the pipe.. atleast it would be an obvious fix. Looks like i've got to do some troubleshooting.

[ssshonky]

i dont want to sound like a doubting thomas .. but..

even though the o2 sensor is brand spankers.. you never know if there might be a cable fault further down the line etc etc. Getting a consult cable is an excellent idea. then at least you can see it with your own 2 eyes

I am also being hipocritial saying that as I myself have not gotten off my ass to connect my consult in yet

come back and let us know what you found ok ?

[Scratch]

reset my ECU this morning through the - "disconnected both battery terminals, hold down brake for a few seconds (15 ish second i did), reconnect" method.

Will monitor how the last 3/4 tank holds and fill her up again full (with fuel prices this week.. OUCH). I know filling it half tank will help bring the consumption down (less weight) but i want to eliminate any fuel gauge play. As with any old car, the gauge would never be 100% accurate and all my testing so far has been done with full tanks. I'll get my hands on the consult cable and post the results up here. thanks for the help so far lads.

[Tangles]

buying, installing and tuning a safc possibly would save you back the costs, in fuel savings, within a quart of a year.

[Scratch]

buying, installing and tuning a safc possibly would save you back the costs, in fuel savings, within a quart of a year.

Affirmative, deciding between the Jaycar DFA and SAFC. The DFA supports multiple load points, safc only does two, plus the DFA is cheaper and I'm an electronics nut so I'd enjoy making the DFA. The thing thats holding me off is finding a tuner who can work out how to tune the DFA.

[ssshonky]

just be aware that the DFA - whilst a good unit indeed can only do so much before the computer gets in there and starts adding/subracting timing ! that is why people couple it with those SITC units

or just bite the bullet and go piggyback ecu

Affirmative, deciding between the Jaycar DFA and SAFC. The DFA supports multiple load points, safc only does two, plus the DFA is cheaper and I'm an electronics nut so I'd enjoy making the DFA. The thing thats holding me off is finding a tuner who can work out how to tune the DFA.

[Scratch]

just be aware that the DFA - whilst a good unit indeed can only do so much before the computer gets in there and starts adding/subracting timing ! that is why people couple it with those SITC units

or just bite the bullet and go piggyback ecu

Yes i've been reading a bit about it on the forums.. weighing in the cost vs benefits, I'm better off getting a EMU as it pretty much costs the same as a SAFC+SITC, plus i'll get more tuneability out of it. Another jaycar product caught my eye, the Programmable High Energy Ignition System (KC5442)..

description:

The system can be used simply to intercept and modify the factory ignition timing or turned into a stand alone ignition system with remapped timing, electronic coil control and anti-knock sensing. The unit will trigger from a range of sources including points, Hall effect sensors, optical sensors, or the 5 volt signal from the car's ECU. Timing can be mapped against engine load and RPM and adjusted in step as small as 0.5°

the knock sensing kit is optional. I searched SAU but cant find much info about people trying this out... it "sounds" like a SITC-ish device that works with the handcontroller that you use to tune the DFA. If anyone has any experience with it.. please share.

Edited January 13, 2008 by Scratch

[RS4StagMan]

The KC5442 (Programmable High Energy Ignition System) sounds good but would be interesting to find out more such as;

a) Does it use the crank angle sensor (CAS) or other sensors? and minipulate the signal and sends it to the ECU (like the SITC)

I.e Sits between the CAS and the ECU

OR

b) Relies on the signals already processed by the ECU then minipulates them to advance/retard timing?

I.e Sits between the ECU and the coils

OR

c) Some other way

Can it be used as stand alone unit or does it need the "KC5443 ignition coil driver/s" to operate as well?

I think method a) is the more desirable location for it, as the seperate Auto ECU can still work with the main ECU to retard or cut timing on gear changes for Autos anyway. Nice feature to be able to retain.

Also not sure about how many RPM points can be programmed with corresponding timing? and whether it is suitable for multi direct ignition coil pack engines such as our RB's?

[Scratch]

the KC-5442 was updated from its earlier revision which only supported distributors. I "think" only the old revision was published in the Performance Electronics For Performance Cars book, i'll double check tonight when i get home. If the book contains info about the kit, i'll post details about it and hopefully answer the questions above.

note: Older hand controllers do not support the new KC-5442 kits, some minor component level modifications is required and the details come with the new handcontroller kit. I got those details from the handcontroller kit I purchased this weekend along with the DFA (if anyone wants them, let me know and i'll scan/post the instructions).

(update 11.10PM: upon checking, the ignition control kit wasnt covered in the book. The jaycar store didnt seems to have answers as well.)

Edited January 14, 2008 by Scratch

[Scratch]

Its been a while due to work commitments, but I finally managed to get my car booked in for a dyno run. AF/R's were pretty much around 14 region but a little rich during WOT which my tuner tells me is typical of a nissan ECU, power-run showed 209.9 max hp. I'll scan the dyno chart and post it on here. I also picked up a Greddy intelligent infometer to monitor sensor readings from the OBD and has playback features as well. Looks like there is nothing wrong with my o2 sensor or maf although my tuner says the curve shows the maf is near its measurement limit?

For now it appears that this is normal consumption for the car, i'm blaming the autogearbox shift logic as the root of my problems. It goes into tall gears at the worse of times like climbing hills. Not suprising though when you consider the car designed for snow. I've put it on PWR mode now as it drags the time between gear changes and i'll try this and staying off boost for the next few tanks of fuel and see if it helps. If someone more knowledgeable thinks i wont be seeing any benefit from doing this, please let me know.

Edited February 15, 2008 by Scratch

[Scratch]

here's the dyno chart

its not a smooth, curve i'm wondering if thats normal for a stock car.

Edited February 19, 2008 by Scratch

[chef_stagea]

yeh my s2 stagea is guzzeling aswell... best tank is 300km and that was 100% nana spec... worst being 200ish.. just got my stag so havnt been light footed but yeh for the 300km tank i had to be to c what i would get... (using bp98 aswell)