Running Lean

[rondofj]

G'Day,

Could anyone tell me what I need to do to solve the running lean problem I currently found out I have. I took my r34 (full 3" exhaust, FMIC, 12psi boost, pod in cold air box, and just got Nistune installed) to get a road tune with NIstune installed (onto my stagea DET ECU) and my tuner told me I am getting a dangerous air / fuel ratio of around 13 to 14 which I saw on his laptop, idle is around 15, so I couldnt get it tuned and was told not to rev above 2500-3000 as my engine could blow.

I have been driving like this (running lean) for 10months and was told I'm lucky that my engine hasnt blown so far lol..

Please dont ask why I have a stagea ecu in my skyline, it was there..!! But the Nistune daughterboard has the R34 maps on it.

I was told to get a Bosch 044 fuel pump as my fuel pump could be gone. But he took the time to explain to check the voltage between the modulator and pump - if its above 13V, then I need to cut the ground wire to the modulator and ground it to the chassis. If it is less than 12v, then my pump is screwed. What is this modulator, any pics of it on a R34?

I think I might as well get the fuel pump done, but R34s are still kinda 'new' how can my pump be farked?

Not only that, he adjusted my timing (tapping on the cylindrical grey metal cup object (held by 3screws) on the front of the engine timing cover) to the factory 15 degrees as it was set at 10 degrees before? Is this the way to go?

Any suggestions anyone? (My tuner is excellent, a great bloke, and takes the time to explain things, I will not name him in case some of you don't agree to his advice).

cheers

[R31Nismoid]

R34's are not kinda new. They are over 10yrs old.

So of course the pump is struggling, you are asking more fuel of it given you've wound the boost up.

GT-t/GTS-t pumps are not well renowned for being decent when you ask anything more than stock, after 10 years.

Either way, read the FI Guide:

http://www.skylinesaustralia.com/forums/topic/66556-forced-induction-quick-ref-guide/

It has a link to wiring in pumps. Or simply look in the DIY section. There are some in there too.

[rondofj]

Thanks dude, looks like the fuel pump will need to go, and the 'thing' that he tapped to adjust was the crank angle sensor I think.

Before I end, I would like to add that my fuel sender unit is farked already a few months back (fuel gauge goin up and down), is this a good indication of the likelihood of my pump bein rooted as well?

cheers

[rondofj]

Anyone else think I need a new fuel pump?? Now I'm confused on whether I need a Bosch 044 or 040..

[DVS JEZ]

044 is huge. Dont think u will need that big.

Its either the fuel pump or the tune. As long as ur tuner knows how to tune nistune.

13afr under boost is quite dangerous. Would be getting pretty hot in the combustion chambers.

If u go to q workshop they should be able to fit a fuel pressure and flow gauge. This will tell u if ur fuel pump is running out of flow.

[89CAL]

Have you considered a tomei?

Same as a NISMO but slightly cheaper

Thats what I have and it fits perfectly in stock position, in its own cradle, Is quiet, pumps a good amount of fuel and has a good pickup

[rondofj]

Tomei which model no.? Will have a look on ebay. Tuner definitely knows his stuff, thats why he didnt tune it, said its too dangerous when he found out that its currently running 13+ A/F ratios. He suggested as I said above, to check the fuel modulator whatever that is and moreso the fuel pump.

[rondofj]

So I had Nistune installed and he retarded the timing to provide a bit of a safety net and told me to not go over 2500-3000rpm.

[rondofj]

Until I have the pump sorted. Tomei pumps are too expensive when a Bosch will do - do I need the 040 and not 044 correct?

[sinistaGTR]

040 or walbro with fitting kit

[Randon_I_Am]

So he didn't try tuning it because it was lean? Am I right in saying that a tune could stop it running lean? A stagea ecu in an r34, the injector multiplier is probably out causing it to not get enough fuel. And on idle it would be running on closed loop so it would stil idle on 14.7...

But either way I'd get a new fuel pump, as maintenance if nothing else...

[rondofj]

Nice point Pat, thats what I thought, why couldnt he stop the lean-out with a tune, but then he did, he brought the a/f ratios down slightly by using the stock maps or so he said, and retarded the timing for safety.

And excellent point about the stagea ecu multiplier, maybe thats the reason?? But yes I guess a new pump wouldn't hurt. Still dont know WHY anyone would put a goddamn stagea ecu in a 34..

[rondofj]

Walbro pumps on ebay are much cheaper and come with the full KIT - sock, hose, clamps etc, why is everyone saying they shitty pumps, are they?? Which Walbro model do I need for the R34?

cheers

[PM-R33]

Who is installing the pump?

Go the Nismo/Tomei, it's worth the extra money.

[QWK32]

stagea and R34 injection multipliers (K-CONST) are the same. they both run the same injectors and AFM. besides, i remember in your other thread you were getting matt to load R34 maps on when you got nistune, so that should clear any doubt over incorrect values. as for the reason someone put it in there, maybe they really needed a new ecu and a R34 one was proving hard to find.

definitely look at the fuel pump, try bypassing the dual voltage modulator. even the fuel filter my be all blocked up, when was the last time you changed it? walbro's are ok cheap and easy to fit, i'm running one in my stagea and have been for a year or two now without any issues.

Edited April 3, 2011 by QWK32

[rondofj]

I will give a crack at installing - just reading the Nissan Silvia forums, everyones recommending the walbro over the bosch for easy install, plus u get the parts like sock, plug, wires..

Nismo/Tomei are top shelf stuff not worth spending the extra quid on unless u building a dedicated dragster / time attack car etc..

[rondofj]

Hey thanks Josh, I changed the fuel filter almost a month ago and noticed a sharper and crisper response afterwards so thats cleared. Here comes the pump now. So which Walbro model?? I heard there has been a lot of fake Walbros floating around esp in ebay, hence giving the brand a bad name.

Who sells cheap genuine Walbros in Syd, I wanna know you..

[PM-R33]

I will give a crack at installing - just reading the Nissan Silvia forums, everyones recommending the walbro over the bosch for easy install, plus u get the parts like sock, plug, wires..

Nismo/Tomei are top shelf stuff not worth spending the extra quid on unless u building a dedicated dragster / time attack car etc..

Completely wrong.

They are "top shelf" because they directly replace the factory fuel pump in the exact location and are a direct plug and play.

Walbro and Bosch are not and require a lot of dicking around to get right. Especially for some one that has never done one. You will most likely install it to high and get fuel surge every time you turn a corner with less than a 1/4 of a tank as so many people on the forums do.

If you know how to install one perfectly, then fine go for it.

I have installed all three. In Skylines and in Silvias. The Tomei/Nismo is well worth the money.

[rondofj]

Is that right? The walbro looks like it is a direct fit according to a lot of blokes on the Silvia forums. Surely they wont all say that if its not..

[QWK32]

i'd start by looking at what deals the site sponsors (e.g justjap, kudosmotorsport, etc) have going. they may be $10-$20 more expensive than the cheapest ebay deal but at least you know your getting the real deal. a friend got one from autobarn about a month ago for around $170, might be worth seeing what they have.

if you want a walbro you will want to get a GSS-342 or GSS-341, the only difference between the two is the fuel outlet it to side on the 341 instead of in the center like the 342. the 342 is the more popular one.

edit: Phil, the walbro was a direct fit for me, electrical plug was the same and it was a perfect fit for the stock location. though a stagea has a different fuel pump mount than a 34 i think, its in a cradle/box on the bottom of the fuel tank.

Edited April 3, 2011 by QWK32