2JZGTE vvti with MAF and MAP - Use of piggyback for adjusting mixtures and FCD?

[BrianRA23]

I have this engine in my IS200 with factory ECU and I am trying to get information on how fuel is controlled when the ECU has inputs from both the MAP and MAF.

Previously I had a 2JZGTE in a JZS147 Aristo and use a Digital Fuel Adjuster (DFA) on MAP output to correct for overfueling at some points and set the max voltage being passed to stop the fuel cut being applied. Tuning was done with the aid of a wide band oxygen sensor and display.

I understand the JDM 2JZGTE vvti uses the MAF for determining the fuel to be applied so I think this is the one I will install the DFA. I have a number of questions about this though:

1. As this engine has DBW instead of direct throttle control, does this engine cut fuel or close the throttle in response to the boost level being exceeded?

2. If the MAP is not used for too much on this engine, do I need something fancy or will the simplest of FCD suffice?

3. Is there any benefit in being able to intercept and adjust the points throughout the range which may impact the point that the EBV engages? This would allow the ECU to retain some control of the sequential turbo crossover and I can use a single boost controller on the wastegate. If so I would build and install a second DFA which can change the crossover point to eliminate the power dip before the second turbo is fully online.

thanks
Brian

[George]

Get a scanner => figure out everything in less than an hour. $50 at ebay.

[BrianRA23]

I have two different diagnostic cables on the way. I suspect it is going to take somewhat longer to find the information as it will require someone to watch the different actions under acceleration. Can you give some hints on how to determine that something happened due to the MAP voltage changing and it not being due to the RPM, MAF or some other combined sensor variable?

I would like to know what the MAP input does on these engines when fuel input is controlled by MAF. Once that is known, then I can I think about changing this input to the ECU.

When you can get a kits for under $100 that are easy to install and will change your mixtures plus give a boost cut, I am surprised this is not done more often. I always regret not having this ability on my old 1JZ Cressida that was not too economical and gave heaps of black smoke under acceleration.

There will be limitations sticking with the OEM ECU, but being able to change the engine characteristics with minor changes seems like a good thing. If there are less non-OEM things added to the car, then there are less things to go wrong or needing to be diagnosed when something strange happens. Other benefits with OEM ECU is legality of the installation and that it controls my auto transmission.

[triptek]

I'm using an emanage ultimate piggyback with plug n play harness on my 2jzgte vvti. Easy to install and works great.

[BrianRA23]

I'm using an emanage ultimate piggyback with plug n play harness on my 2jzgte vvti. Easy to install and works great.

Does that unit allow changes to both the MAF and MAP sensor inputs to the ECU? I would be interested to see what maps you are using for the changes. Have you worked out what affect the MAP sensor input has on the engine management?

[triptek]

It only changes the maf values not map. It can also adjust injector maps. I havn't messed with the maf settings yet only injector.

[George]

Can you give some hints on how to determine that something happened due to the MAP voltage changing and it not being due to the RPM, MAF or some other combined sensor variable?

Run separate MAP to the intake manifold, load engine somehow and compare their readouts