The Dyno showed my something about my GTR today....

[JUN R33]

Here is a quick rundown of my recent dyno run with my R33 GTR and a problem I found:

at 14.3 pounds, the car showed a Air Fuel Ratio of 15.6 (lean)

the Air Fuel Ratio went from 15.0 at 116KPH all the way to 15.6 at 130KPH

Temp was 37.2

The car has no boost controller and was running stock boost (1 bar)

Max power output for the run was 173.8KW

Is this a 'average' power output for a near stock 95' R33 GTR non v spec with cat back exhaust, pod filters and Nismo chipped ECU?

I know car is running dangerously lean so, is there anything I can do temporarly until I get a Power FC unit??

I dont want to buy a APEXI AFC as I see it as a waste of money as I'll be getting the PFC which does everything that this device does and more.

Any advice you guys can give would be great.....Thanks.

[JimX]

It sounds like you have one or more blocked injectors. Have you had them cleaned and flow tested?

Edit: Could also be a faulty O2 sensor.

[amosite]

could be your fuel pump, injectors, air flow meter etc etc

Most probably that "chipped" ecu.

try swapping it over with anotheer and see what you find

You should be running more then 200 atw with those mods

[Sil8ty]

You let them power run with mixtures like that... Damn... I would be checking fuel system for faults or try fitting a std ECU back in it.. With some decent mixtures that should be close, if not over 200kWs at wheels..

[Mick Trainer]

I'm with the others here. Try putting standard comp back in it to start with and see what that does. Second (and my money is on this) that the oil from your Pod filters has burnt onto the air flow meters and screws up the signal from them. (This was happening too my car when I got it). Take them off and get some carb cleaners and contqact cleaner and clean them up. This should fix them. Then if this does not work, start checking fuel pump pressure. I would put large sums of money on it being one of these things. Where are you located??

Mick.

[Guest Robo's]

That is very lean, anything over 13 is lean and asking for trouble.

12.0 - 12.5 is perfect

[4 Doorz]

what about running toluene in your car until you get pfc (like 5-8%)

[S14Drift!]

You would almost be better to create a boost leak in order to get the mixture rich (a small boost leak would really help at WOT)

But it's really a BandAid solution....I wouldn't push the car until you fix this....

At this A/F don't push it otherwise you will ear BBBBBOOOOOOMMM

[b2barker]

If you have some electrical knowledge you can do it simply/cheaply/temporarily by amplifying your AFM signal across the board. ECU thinks there is higher load and adds more fuel. This AutoSpeed article how to do it with two potentiometers, but you may need to be a member to see the whole article.

It doesn't address the root cause of the problem, and if it was my GTR I would park it until the PFC arrived.

[JUN R33]

I ordered a Apexi PFC with hand controller and boost controller today so hopefully when I get it, it will fix up the problem.

I would love to leave it parked but it is my everyday car so, as long as I dont strap it - I should be fine *fingers crossed*

I've also booked it in with my local mech who will check the fuel pressures and perhaps give my injectors a good clean also.

Any ideas on the right spark plugs to use and also the correct gaps for a stock GTR?

I was also going to upgrade the fuel pump to a Bosch 910, is this much better then the GTR pump? 190 vs 210 for the bosch if I remember...

I would love to put a stock GTR ecu in but, being in Darwin - not many GTR's are up here to borrow one from.

Gav.

[Mick Trainer]

Check your air flow meters, check your air flow meters. If theseare dirty no matter what you do you will have problems. It is a 1/2 hour job to clean them and will cost next to nothing. At least get this done as well as check your fuel pressure. If these are not right then tuning the car will notwork.

Mick.

[RS500]

JUN R33,

firstly, i'd get my fuel system checked out while running it up (i.e., fuel pressure, fuel volume flow, injector duty cycle, etc)

although, it could also be due to your intake charge being mixed with oily mist from the small amount of piston blow-by being produced by the engine and recirculated back into your intake.

you can confirm this by checking to see whether your intake pipes (before the turbo) are oily.

if this is the case, the air/fuel mixture being forced into each cylinder is not able to burn properly causing lean mixtures, therefore, i would recommend you get an oil/air separator fitted.

good luck and let us know how you go.

[amosite]

Have you done any tests yet?

[greygirl1976]

tryed puttin a fuel pressure reg in to up the fuel pressure to conpensate for it leaning out up top

[\\\Wiktor]

If it leans out at high revs. an other fuelpressure regulator won't help.

then it's most proberbly your fuel pump thats the problem.

the problem is that it can't produce the fuel flow that the engine needs. Easy too check. Just fit a pressure gauge temporarly on the fuelrail before the reulator and see if the pressure drops at high revs. But what ever you do!! DON'T get any leakage and don't have the gauge inside the car!! Clamp it under one of the wipers. I promise you that you don't want fuel in your eyes. You go blind quite a while!

Wiktor

[Penfold]

isnt stock boost for a r33 gtr like 0.82 bar?

Makes you wonder what the nismo ecu thingo is doing.

[Lippo]

Why couldnt that dyno place tell you why your car is running lean? If they are worth any money at all,then they should be able to find out what is causing the problem otherwise i would take it elsewhere.Up my way,the dyno operators can determine the problem and fix it usually in a day or two without band-aid solutions.

[JUN R33]

Thanks to everyone who offered their solutions and ideas to my AFR problems.

well, here is an update:

My O2 sensors are not faulty and are in working order.

The car came with a set of uni filters which might have had oil burnt onto the air

flow meters and screwed up the signal but, I cleaned my AFM's anyway and even though I

didnt notice a difference,it was a good thing to do to the car.

I have a set of M's K & N pods on their way to replace my uni filter pods.

The car is booked in this week to have a fuel pressure check and BOSCH 910 fuel pump

fitted.

My guess to the AFR problem is that the fuel pump could be faulty.

Hopefully the changing of the fuel pump fixes the problem or I start pointing the finger

at the injectors or Nismo ECU.

I Was going to get a stock GTR ECU to see if it made any difference but since the PFC

is only a few days away, I will wait for that to arrive.

Anyone have any idea what type of spark plugs are best used on a GTR and the proper gap

measurement?

I can only wish that I had more then one 4WD dyno place to choose from but, there isnt and

I have to put up with the only one we have here including our 'best' available 95 RON PULP

fuel.

Anyway I will keep you all updated and post up some pics of the dyno run and a few

pics of my GTR in the next couple of days.

Gav.

[dkonig]

Really interested to hear the outcome of this, is the vacuum line to your fuel pressure reg leaking? this could cause it not to give enough fuel at full boost