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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Leaning out problem....
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Sun, 17 July 2005 02:16
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Arrgghhh, modified cars are going to send me to the loony bin (that's after I file for bankruptcy first)
My car is leaning out terribly and I would like the opinions of those who have either suffered and corrected the problems I am having, or can offer some sensible suggestions as to what to do next...
The basics
Car is MX83 Cressida with Aristo 2JZGTE fitted. Factory everything except for ... 3 inch Exhaust, Intercooler and Pipework, Walbro 255lph (in tank) fuel Pump. Only other mod is a Gizzmo Fuel Cut Defender (which seems to be working fine). Boost runs to about 9-10psi on the first turbo and then from around 4,000pm onwards, runs to 16-17psi on the second turbo.
The problem
It is leaning out to buggery at full throttle. At the toymods dyno day, It was not able to go above about 5,500 as it started to lean out very badly so the run was aborted (see attached dyno sheet)
However, If using up to around 75% throttle - it runs all the way to redline without any problem, and does not lean out, in fact the AFR is almost perfect.
what we have done so far
Measured the fuel pressure
- 42psi with regulator seeing vaccum and about 46 psi with the regulator disconnected
Measured the Voltage at the pump
- 12V Constant
Replaced spark plugs
- re-gapped to .8mm (from 1.1 previously)
There is no problem with the fuel filter
Re-calibrated the Throttle Position Sensor to be zero volts at 0% (although if anyone knows what the voltage reading at 100% throttle is supposed to be, it would be handy to see if the TPS is going over 100%)
any suggestions ???
[Updated on: Sun, 17 July 2005 13:50]
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Location:
Brisbane
Registered:
May 2002
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Re: Leaning out problem....
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Sun, 17 July 2005 07:45
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Did you check the fuel pressure at WOT with max boost? If you're having fuel pressure issues this is when you'll see it.
Another possibilty is clogged injectors. Get them cleaned and flow-tested if you haven't done this already.
Dodgy MAP sensor perhaps? See if you can arrange a swap with another 2JZ owner. If you drive up to Qld you can use mine. 
There's definitely something amiss though. My AFR's stayed uber-rich all the way to redline even when running 18psi.
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Re: Leaning out problem....
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Sun, 17 July 2005 14:38
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Thanks Norbie,
We only tested the Fuel Pressure at idle unfortunately - when I had the guage, I didn't have the dyno, and when I had the dyno, I didn't have the guage  And we didn't have enough fuel line to be able to see the guage from the cabin whilst driving (mind you I was getting desperate and offered a small video camera as a pair of eyes to record the pressure from under the bonnet - they laughed at me - (I was serious, - I am getting desperate..)
Clogged injectors is what I originally thought - however as I was told when I suggested this - the car would run rough all through the rev range, not just WOT at high RPM etc..
Hmm, MAP sensor - hadn't thought of that - is there a way to check the voltage/resistance if I can't get a spare to test ??
Yes, That is why I am so frustrated when everyone tells me that the ECU is making it lean out because of the high boost etc - but I mention how yours is doing it fine and that only confuzzles them more...
What other suggestions have been offerd - but may work out to be rather expensive if not the problem..
1. Run a second fuel pump (Bosch 044) with a surge tank.
2. Replace the factory fuel lines with larger size ones and remove the dampener from the line etc.
I don't mind spending the money if I have to, - I just don't want to spend money "willy nilly" on "possibles" unless they are a last resport and all other cheaper/more obvious possibilities are ruled out first...
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Leaning out problem....
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Sun, 17 July 2005 16:42
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as far as fuel pump goes, is it a 255 or a 255 high pressure?
http://www.supras.nl/index.php?option=com_content& amp; amp;task=view&id=49&Itemid=65
http://www.autoperformanceengineering.com/html/fps pecs.html
some links regarding flow rates.. they do drop a fair bit at higher pressures, however 60psi should be ok for 189L/hr and 197 for the HP version..
damper should not hinder flow, it just removes the "fuel hammer" as such... sicne the reg flows most at idle, it can't be a restriction, but maybe it is not increasing pressure enough at WOT (as Norbs is suggesting)
what are the injectors capable of??
from a quick calc, with 16-17psi boost and 400cc injectors (and 12:1AFR), you will have 100% duty at approx 5500rpm...
for 7000rpm, you need about 480cc/min injectors..(edit, MAXED.. 80% duty = 600cc/min... maybe injectors are becoming erratic in operation? Norbie, what injectors are you running?)
this is rough calcs tho, but but... ideas...
now, 400ccx6 = 2.4L/min = 144L/hr
480x6 = 2.88L/min = 172L/Hr
the walbro pump should support 17psi at 7000rpm wth maxed out 480cc injectors...just.. infact it should barely support 100% duty of 525cc injectors with no fuel return, and 660cc/min at 80% duty..
[Updated on: Sun, 17 July 2005 16:44]
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Leaning out problem....
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Sun, 17 July 2005 23:25
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with no calcs done but if 1j 380's can support 250rwkw then I would have thought it was injectors as they are 440's and should be good for 280rwkw or so. Unless they are clogged but as you say, that would happen all the time.
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Re: Leaning out problem....
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Mon, 18 July 2005 01:45
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Off the top of my head, the Pump was a GSS341 or GSS342 (which makes it a High Pressure 255lph jobbie..
I am told the factory injectors are 430cc's - which one of the guys on the Supra forums say they should be good for about 500hp ((430 divided into 5)x6) = 516hp at 100%. so they should support around 410hp at 80%. I am at 300 Hp at the moment and don't really expect to break 350hp at the very most.
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Location:
Brisbane
Registered:
May 2002
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Re: Leaning out problem....
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Mon, 18 July 2005 04:04
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| oldcorollas wrote on Mon, 18 July 2005 02:42 |
from a quick calc, with 16-17psi boost and 400cc injectors (and 12:1AFR), you will have 100% duty at approx 5500rpm...
for 7000rpm, you need about 480cc/min injectors..(edit, MAXED.. 80% duty = 600cc/min... maybe injectors are becoming erratic in operation? Norbie, what injectors are you running?)
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I have the stock 430/440cc injectors. There must be something wrong with your calcs, I'm definitely not leaning out anywhere!
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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woo hoo - 245kW - Leaning out problem....fixed....:)
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Mon, 25 July 2005 09:58
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OK, sorted it out..
Appears that the FCD clamps the voltage and confuses the MAP into thinking it is running factory boost, so when tha MAP sensor does this, it stops increasing the fuel pressure... sounds obvious huh !!
anyway, a SARD Fuel Pressure Regulator has been fitted and takes care of the extra fueling required. This way it doesn't dump too much fuel in when it doesn't need it, and lean cruise is still there for economy...
Big thanks to Dale at www.braidedlines.com and Dave from Castle Hill Exhaust Centre for the tuning and dyno work and the new exhaust restriction to keep boost in check...
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Location:
sydney
Registered:
March 2003
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Re: Leaning out problem....
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Mon, 25 July 2005 10:04
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how does the ecu control fuel pressure
does it have a valve or something
is the sard fuel reg a boost rising rate reg
if this is the case then its raising the fuel press as boost raises
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Re: Leaning out problem....
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Mon, 25 July 2005 13:21
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Stuffed if I know..
I thought you were the guru on these things - LOL
seriously, all I know is that it was severely leaning out at the SAS Dyno day, now its not. and these are the opnly changes made...
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Location:
Brisbane
Registered:
May 2002
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Re: Leaning out problem....
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Tue, 26 July 2005 00:23
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The fuel pressure regulator is entirely mechanical - the ECU/MAP sensor has nothing to do with it at all. My engine has the stock FPR and as mentioned I have no lean-out issues.
Which FCD are you using? It shouldn't be clamping the voltage until it gets to 18-19psi (the max range of the 2JZ MAP sensor).
The RRFPR might appear to have fixed the lean-out issue, but it's really just hiding the real problem. You simply don't need to ramp up the fuel pressure to do what you're doing!
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Re: Leaning out problem....
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Tue, 26 July 2005 01:47
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So far, this has been the ONLY thing that has worked.
If there is a simple solution - I'm all ears !!!!
Seriosuly, if anyone can fix it - I am listening !! so far this is the only solution thatbhas worked...
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Location:
Brisbane
Registered:
May 2002
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Re: Leaning out problem....
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Tue, 26 July 2005 01:56
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http://www.gizzmoelectronics.com/product_fcd.htm
It would be interesting to see what that FCD of yours is doing. If it's clamping the MAP signal at 1 bar it could definitely be causing the problems you're having. An FCD designed specifically for the 2JZ will allow the full range of the MAP signal, ie up to 18-19psi.
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I supported Toymods
Location:
Sydney
Registered:
August 2002
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Re: Leaning out problem....
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Tue, 26 July 2005 02:27
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Yep...
That's the FCD I have....
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Location:
Adelaide
Registered:
June 2002
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Re: Leaning out problem....
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Tue, 26 July 2005 10:06
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Ah hah. I didn't realise you had an FCD in there. If that one is clamping the MAP signal at 1 bar then that's the problem without a doubt.
Grab the FCD with the suitable range as mentioned by norbie and you'll be able to get rid of the SARD regulator. My bet is that the SARD has a higer rate than the stock reg, effectively masking the leanout in the top end-but not actually fixing the problem as it is due to the ECU stopping increases in fuel supply at 1 bar.
One concern I have is that if you bump the boost up further with this FCD, that as the MAP signal is clamped the ECU won't drop ignition timing out. In an extreme case you could suffer detonation-and the associated damage to pistons etc.
Have you fitted the wheels up yet? I haven't sent off the nuts yet as we had a major family medical catastrophy last week and I have spent my time waiting in ICU for the last few days (looking good now though). I'll get them off before friday though mate.
Take it easy mate
Sean
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Location:
sydney
Registered:
March 2003
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Re: Leaning out problem....
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Tue, 26 July 2005 11:34
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i just did a 2jzgte aristo into a 95 supra today
very long day job took 9 hours
couldnt drive the car so dont know if it drives ok
i know abit bout the std ecus but i dont play with fcd and shit like that
i fit them but let the customers blow their engines up not me
from what i know the ecu changes from 8 or 10 volts to 12 volts at about 4000 rpm
u should put a multimeter on yr fuel pump and see what happens to voltage
maybe the fcd is adjusted too low and its cuttn the signal to ecu to early
anyway its one of those jobs that could take years and lots of money to find exact prob
and no one these days wants to pay me to solve things hehe
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