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Johan Bard

Rpm problems 2JZ

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Hi, I have a link g4 extreme installed in a jzx90 Cresta with 2JZ. To get the car running i used the supra plug in base map and wiering is pritty much the same as for the supra plug in though i am only using MAP sensor. And then I went to my tuner, everything was going pritty well untill we encountered what we belived was missfires at 6700rpm. We tried different coils, closing the spark gapp on the spark plugs with no result at all. It seems to be unable to rev more then 6700 regardless of temperature, load or anything. Even reving it standing still with no gear can't get past 6700. The stop is very rev-limiter-like and always the same.

We tried disabling all limits in the link ecu, logs show no limiter has been hit and no fault codes.

Can this be caused by me using the supra plug in base map on an extreme ecu? Can this be caused by bad cam or crank sensor signal without it logging any faults?

Do anyone have any ideas?

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Good morning,

There are quite a few reasons something like this could happen. Has the engine previously gone above 6700 with the standard ECU? Does your 2JZ have VVTi?

With PCLink connected to your ECU and the engine trying to pass 6700 RPM have a look at the 'Triggers/Limits' tab and see if the Trig 1 error counter is increasing.

Do you have a wideband O2 sensor on your setup? What is happening to the AFR when you reach 6700 rpm?

Scott.

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Hey again,

I think if you can borrow a wideband O2 sensor and then check what your Air/Fuel Ratio is like it will give a good indication of what is causing the problem. If you can not find what is causing the problem, record a PC Log (including wideband) and send it to us for a look along with your basemap. We may be able to see what your problem is.

Cheers,

Scott.

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Hey,

I checked with my tuner what happened with the AFR when we hit 6700 rpm and he said that the AFR showed lean at the 'limiter'. What does this indicate? I think the injectors were at maybe 70% duty cycle. But the same thing happens when just reving without any load.

Thanks a lot for your help!

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Good morning,

It is hard to say without seeing a log or the car, but normally having a lean AFR is caused by one of two things:

1) There is not enough fuel, if the AFR progressively gets leaner then this possibly could be the problem. However you mentioned your injector duty cycle is only at 70% and I'm assuming you've tried increasing the cell values in the fuel table.

2) You are having an ignition misfire. Possibly an ignition component is breaking down.

If you can send me your basemap then I can test it on a simulator and try and identify if the problem is a setup one.

You can either reply to this post and attach your basemap or email it to tech@linkecu.com

Scott.

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Update,

I did some measuring and it seemed like there was ignition signal from the link to the ignition box but the reference signal from the ignition box to the stock ecu and rpm meter died when the 'rev limiter' was hit.

I tried lowering the dwell time from 3ms to 2.5ms above 6000 rpm and now it hits the real limiter, although when logging the max rpm logged are 7400rpm and the limiter is set to 7600 rpm. And when the engine hits the limiter it don't sound 'smooth' but that's maybe just my imanination.

I am using the stock ignition box in my car which is for a 1JZ, should be same for soarers and mk3 supras with 1JZ. Is this a know problem or is there something wrong? I have tried two different ones but with the same part# and they both behave the same. 3ms shouldn't be any problem when running direct ignition like I am from what I know anyway?

Thanks

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Hi,

Good to hear you are making some progress. It sounds like your ignitor is definitely causing you some issues. The fact that you can lower your dwell and you can increase the rpm seems to confirm this. It is possible the factory ignitor has some sort of limiting built into it as protection. I would try swapping your factory ignitor out for an aftermarket type one.

Cheers,

Scott.

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