# JWT ECU on a 1990 JDM ga16de



## enjoydride (Jun 4, 2003)

Hello 
I currently have a gdm ga16de on a 1990 b13 chassis this engine comes with no EGR stuff and I’m about to do an upgrade on the computer but there is a lot to be discussed on this since you all know that our cars have VTC and when you have a 1990 to an early 1994 engine you are pretty much stuck with the current ECU and there are a lot off questions about this (why?)well I talked to one off the specialist at Jim wolf and I was told that this type of early computer could not be reprogrammed and that I have to find I 1990 to 1993 SR computer but they told me that I will lose my VTC because the SR computer does not have this feature then I don’t know if this is worth the money or not because Who knows here how does a ga16de with out VTC feels like?, I might end up spending 500+ and ending up with a slower car due to not having VTC at medium range power, I will like to see some opinions from the people who know cause I will hate to spend 500$ and see cars that I used to beat at the local road course passing me by and realize that I end up with a slower car.


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## wes (Apr 30, 2002)

enjoydride said:


> Hello
> I currently have a gdm ga16de on a 1990 b13 chassis this engine comes with no EGR stuff and I’m about to do an upgrade on the computer but there is a lot to be discussed on this since you all know that our cars have VTC and when you have a 1990 to an early 1994 engine you are pretty much stuck with the current ECU and there are a lot off questions about this (why?)well I talked to one off the specialist at Jim wolf and I was told that this type of early computer could not be reprogrammed and that I have to find I 1990 to 1993 SR computer but they told me that I will lose my VTC because the SR computer does not have this feature then I don’t know if this is worth the money or not because Who knows here how does a ga16de with out VTC feels like?, I might end up spending 500+ and ending up with a slower car due to not having VTC at medium range power, I will like to see some opinions from the people who know cause I will hate to spend 500$ and see cars that I used to beat at the local road course passing me by and realize that I end up with a slower car.



You MUST use the SE-R ecu and they can add a daughterboard for the VTC setup. Others have done this although it is an additional cost to the normal programming. Not sure why they didn't mention it but it can and has been done.


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## enjoydride (Jun 4, 2003)

They did mentioned but the cost was a rocketing 800+ and since I just race mine and the operating RPM range on a road course is from +- 4.5k up I was wondering if I really needed the VTC cause I ask the specialist and he didn’t know the operating VTC range,couse if he tells me that the VTC works from 0 to 4k I rather dump the VTC and save some 300 dollars for something else.


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## wes (Apr 30, 2002)

enjoydride said:


> They did mentioned but the cost was a rocketing 800+ and since I just race mine and the operating RPM range on a road course is from +- 4.5k up I was wondering if I really needed the VTC cause I ask the specialist and he didn’t know the operating VTC range,couse if he tells me that the VTC works from 0 to 4k I rather dump the VTC and save some 300 dollars for something else.


You talked to the wrong "specialist". The Advantage of the JWT ecu is that it keeps the VTC advanced all the way until red-line, whereas the stock ECU retards the VTC around 6000 rpm's. This means more top end power in addition to area under the curve.


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## enjoydride (Jun 4, 2003)

thanks a lot wes that was a lot of help man.


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## Petrovich (May 13, 2005)

If you want to save some cash, you can just rig up a switch for the cam advance - as far as I could understand the only thing that's compromised is the idle.
I'm surprised that JWT charges so much for what really is a mere rpm-based switch. You make one for next to nothing, and run it off your tach signal.
In fact, MSD sells them, ready to go, for about 100$. They're usually used for shift lights, but would work just as well for the VTC solenoid. I know BMW single-VANOS guys use it this way when running standalone fuel management.


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## Petrovich (May 13, 2005)

As for GA16 without VTC, unplug the VTC solenoid connector and see how it feels.


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## Mauricio Ayala (May 19, 2005)

Petrovich said:


> As for GA16 without VTC, unplug the VTC solenoid connector and see how it feels.


explain me that please you say that we only need a switch to be active like 5000rpm or something like that i want to discuse what happen if you program the VTC for to be active early like 2000rpm


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## sunnydet90 (Sep 10, 2004)

eventually it will burn up the solenoid


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## Petrovich (May 13, 2005)

sunnydet90 said:


> eventually it will burn up the solenoid


Why, a computer does no better job at cutting/resuming current than a switch/finger combination  Don't scare people for no reason.


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## enjoydride (Jun 4, 2003)

Well I did talk again with Jim wolf and told me that is not necessary for racing cause I will be racing over 5000 which is correct.


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## fanl (Jun 24, 2004)

As far I learnt from the sentra Factory service manual, VTC operation range is 1,5krpm to 4,3krpm then it goes ON at 6,6krpm
When it is ON the valve overlap get increased by 20 degrees, witch I imagin is not good for high rpm, the Idea is that the engine with VTC on is a normal 18degreed overlap, good for normal driving. But when racing or revving higher is necessary the VTC should be OFF.
So, if u wanna race, leave it off =]
Am I wrong?

Follow some picture:


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