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Rb26dett Wiring Loom On Rb25

SKiT_R31

By SKiT_R31,
in Engines & Forced Induction

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SKiT_R31 Experienced

SKiT_R31

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Hi,

I'm looking at buying a Microtech ECU for my RB25, one has come up for sale cheap with a hand controller and loom, tuned for an RB26DETT. What issues will i have? Obviously the AFM's arent an issue, as microtechs run off MAP sensors, is the only other issue ill have with the injectors? Anything else that might be different? The ECU is mapped for 550cc injectors, which i have in my RB25, but i think the 26's would be low impedence, whereas my injectors are high impedence, this shouldnt be an issue on the microtech as its compatible with both?? So all i have to do is swap the injector plugs? Is the ignitor different, idle gear, cas?

thanks in advance

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SKiT_R31 Experienced

SKiT_R31

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Things i can think of

CAS

Injectors

Knock sensors

VCT (you'd be silly not to use it)

Does your tuner know Microtech's well? If not, then are many better choices out there.

So the CAS is definately different? Does it have a different output, or is it just a different plug..? Can i put a GTR CAS on an RB25?

I'm in tas, and my preferred tuner is good with microtechs, and i need a map sensor for my setup.

To throw a spanner in the works, its for a 25/30, N/A... with fairly lumpy sticks in it, so vct isn't too much of a concern, but an external controller, or custom tuning one of the extra outputs and manually wiring it could be the solution for that.

Knock sensors, fair enough, but once again, not overly concerned, as it is N/A, and i want it consistant.

Car made 151RWKW with less compression, choked intake breathing hot air, and restrictive exhaust (2.25" press bent, triple chambers), crap headers, on stock management.

It now has twin polished 60mm tb (mandrel 2.5" pipe) CAI's with no afm (OR will have jun bellmouthed front facing plenum with 80mm throttle body, ill test performance and output from each), fujitsumoto tuned length large primary headers, joining into a 3" mandrel single muffler (mandrel perforated centre offset) exhaust, had about 40thou taken off the head, spark plugs indexed facing intake valves, cam timing adjusted and accessories underdriven.

so anyway, the injectors..., if i have the same injectors with different impedence, it will still work? Appart from that, the cas will be the issue? can anyone confirm?

Also at somestage ill build another engine with a better bottom end (oversize lightweight pistons/rods, balance), and plonk on a 26 head (for the solid lifters) with some headwork and ITB's on it and push the peak power up 1000rpm or so... Meaning ill make adapters for the loom, so the whole 26 setup is neater.

Cheers,

James_03 Mentor

James_03

Posted
Posted
Hi,

I'm looking at buying a Microtech ECU for my RB25, one has come up for sale cheap with a hand controller and loom, tuned for an RB26DETT. What issues will i have? Obviously the AFM's arent an issue, as microtechs run off MAP sensors, is the only other issue ill have with the injectors? Anything else that might be different? The ECU is mapped for 550cc injectors, which i have in my RB25, but i think the 26's would be low impedence, whereas my injectors are high impedence, this shouldnt be an issue on the microtech as its compatible with both?? So all i have to do is swap the injector plugs? Is the ignitor different, idle gear, cas?

thanks in advance

I don't think you will have any issues. The CAS wires in the same way as does the knock sensors. I am actually running a S2 rb25 CAS on my gtr now. The ECU sends ground pulses to each injector to fire them regardless of low/high impedence. The drop down resistor in the GTR takes care of that, you don't need to change injector plugs on the rb25 you just wire it in the same with your 12v common back to ign relay, then each injectors ground to the corrosponding pinout on the ECU plug.

The tune will probably be out slightly because of the 25/26 difference. It will probably still run OK as the injectors are still matched but I would be getting a re-tune asap to suit your application.

You can get all the wiring diagrams off the mircoleb efi website.

SKiT_R31 Experienced

SKiT_R31

Posted
  • Author
Posted
I don't think you will have any issues. The CAS wires in the same way as does the knock sensors. I am actually running a S2 rb25 CAS on my gtr now. The ECU sends ground pulses to each injector to fire them regardless of low/high impedence. The drop down resistor in the GTR takes care of that, you don't need to change injector plugs on the rb25 you just wire it in the same with your 12v common back to ign relay, then each injectors ground to the corrosponding pinout on the ECU plug.

The tune will probably be out slightly because of the 25/26 difference. It will probably still run OK as the injectors are still matched but I would be getting a re-tune asap to suit your application.

You can get all the wiring diagrams off the mircoleb efi website.

awesome, thanks for that.

The car doesnt need a bullet proof race tune, just needs to be able to limp to tuner, and workshops

James_03 Mentor

James_03

Posted
Posted (edited)

Are you using the 26 loom on it as well?

Im confused now. You don't need to use the 26 loom on it hey, just wire the microtech into th 25 loom. If using the 26 loom you will need to change the physical connections for injectors and knock. You will also need to by-pass the drop down resistor plug.

Cheers.

Edited by James_03
James_03 Mentor

James_03

Posted
Posted (edited)

Ignitor should be fine. The LT12 has 6 ignition drivers meaning you don't have to wire the ignitor up using wasted spark like early microtechs. Use the ignitor with the loom you are using, ie GTR ignitor with the 26 loom, 25 ignitior on the 25 loom.

Both wire in the same way. Only reason I say that is I think 20/26 ignitors have a different plug to 25 S1. 20/25 S1/26 coils are all the same.

Edited by James_03
SKiT_R31 Experienced

SKiT_R31

Posted
  • Author
Posted
Ignitor should be fine. The LT12 has 6 ignition drivers meaning you don't have to wire the ignitor up using wasted spark like early microtechs. Use the ignitor with the loom you are using, ie GTR ignitor with the 26 loom, 25 ignitior on the 25 loom.

Both wire in the same way. Only reason I say that is I think 20/26 ignitors have a different plug to 25 S1. 20/25 S1/26 coils are all the same.

uhk, ill be using the RB26 loom, so rb20 have the same as the 26? As i have an rb20 silvertop ignitor sitting on my fridge...

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