New Lambda Sensors or a Fuel Controller?

[pedrosixfour]

So all the computing and converting has been carried out before the graph is commited to paper?

 

Speaking of computing power, check out all the grey matter in MY thread. Thanks guys.

 

Can anyone comment on the ACIS not opening at 4.5k revs possibly being the root of the problem. If the ratio starts out fine but gets a little rich at the top end surely this would make sense. Or would the ECU compensate for the lack of extra air and just wind off the petrol to try and maintain a proper ratio?

[pedrosixfour]

Yes which is precisely why i apologised to pedrosixfour for making the cock up, which Ryan pointed out,

I'm not used to RR graphs, and was going more on the RR tuners comments about it being very rich, and so fell into the mistake of seeing the RR scale in AFR my bad!

 

Jesus Tricky, no need to apologise mate. I asked for opinions and you were decent enough to give yours. Nobody is infallable and nothing you suggested has cost me any expense or loss of time.

 

This is all completely new to me so I am really extremely grateful to everyone for taking the time to come to my aid and I now have a better understanding of how this procedure works which will allow me to gain more from my next session.

Edited March 5, 2010 by pedrosixfour (see edit history)

[Wez]

So all the computing and converting has been carried out before the graph is commited to paper?

 

Correct, its just this plot shows lambda instead of AFR

 

Can anyone comment on the ACIS not opening at 4.5k revs possibly being the root of the problem. If the ratio starts out fine but gets a little rich at the top end surely this would make sense. Or would the ECU compensate for the lack of extra air and just wind off the petrol to try and maintain a proper ratio?

 

There shouldnt be any less air unless you have a leak, but the tuning of the runners will affect torque/power delivery, so in short you could be down on power and possibly using more fuel, IMHO of course, its more of a IanC type question

[Ian C]

No pressure then, thanks Wez

 

Do we know exactly what RPMs the valve is supposed to open? And did you witness it failing to open? If the split in the hose was small, it would probably seal when the engine was running due to it being a vacuum of some sort under all conditions. Of course if it's a massive perished gash then yes it wouldn't work well

 

Do we know if NA's normally fuel at 11.5:1 on WOT? We might be arguing the toss here over a car working perfectly OK (well, fuelling normally anyway, it's rather down on power). I could see it overfuelling perhaps if the ECU expects better cylinder filling at higher revs due to the valve opening, and it's a MAP based system (MAF would detect the increased airflow).

 

Lets have a think about this - it's running 11.5:1, which is 11.5 parts air to one part fuel. If we think it should be around 12.5:1 instead but it's rich because less air is coming in than there should be, we are missing 8% of our air. (11.5 is 92% of 12.5). So crudely, that's 8% of our power. 8% more power takes us to 202bhp corrected at the crank figure. That's about 15bhp so not a ridiculous gain.

 

So yeah, it is plausible that the butterfly is causing a power loss but you're still about 30bhp down according to the dyno I believe?

[pedrosixfour]

No pressure then, thanks Wez

 

Do we know exactly what RPMs the valve is supposed to open? And did you witness it failing to open? If the split in the hose was small, it would probably seal when the engine was running due to it being a vacuum of some sort under all conditions. Of course if it's a massive perished gash then yes it wouldn't work well

 

Do we know if NA's normally fuel at 11.5:1 on WOT? We might be arguing the toss here over a car working perfectly OK (well, fuelling normally anyway, it's rather down on power). I could see it overfuelling perhaps if the ECU expects better cylinder filling at higher revs due to the valve opening, and it's a MAP based system (MAF would detect the increased airflow).

 

Lets have a think about this - it's running 11.5:1, which is 11.5 parts air to one part fuel. If we think it should be around 12.5:1 instead but it's rich because less air is coming in than there should be, we are missing 8% of our air. (11.5 is 92% of 12.5). So crudely, that's 8% of our power. 8% more power takes us to 202bhp corrected at the crank figure. That's about 15bhp so not a ridiculous gain.

 

So yeah, it is plausible that the butterfly is causing a power loss but you're still about 30bhp down according to the dyno I believe?

 

Massive perished gash just about covers it This valve had no more vacuum going to it than I do, sitting here, right now.

 

Do you mean 30bhp down from stock factory figure of 220bhp new? Is that not a little optimistic for a 15 year old 2JZ-GE?

[Ian C]

Massive perished gash just about covers it This valve had no more vacuum going to it than I do, sitting here, right now.

 

Do you mean 30bhp down from stock factory figure of 220bhp new? Is that not a little optimistic for a 15 year old 2JZ-GE?

 

I thought they were 232, am I getting confused with the 7M-GTE

 

Well, OK, it's 15 years old, but age doesn't determine engine condition, neither does optimism - factors more like mileage, service history, and if it's been caned all its life are more meaningful. And I don't know the answers to those I wasn't trying to say it was about to explode, just tempering your expectations that fixing the valve alone might return it to factory power. It's off by 33bhp, which is 15% down. Sorting the valve, if that is a contributory factor, might improve that to 10% down.

 

The rest is probably piston ring wear which a compression check would show, but if you're happy with it, who cares.

 

-Ian

[pedrosixfour]

I carried out a compression test last year and was very happy with the figures, I might do another one for fits and giggles to see how a few track days have affected it.

 

Theres 100k+ miles on it so 200 bhp was the magic number I really was hoping to see on the dyno but I wasn't even confident of seeing that. Martin, the dyno tester, reckons he has never seen anything better than 190bhp from a stock 2JZ-GE, for whatever reason. (Waits to be shot as a traitor to his kind!)

 

The power isn't the concern, I really just want to ensure the car is running as it should, for its age.