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Hondata A2 ECU on Z1 harness: Can you?

4666 Views 8 Replies 4 Participants Last post by  timot_one
What I have:

K20Z1 engine, harness, transmission.
K20A2 (apparently) Hondata ECU.
1977 Fiat X1/9.

Hondata, in their usual style, essentially just told me to go jump in a lake. The tech guy said that the adapter harness to adapt an A2 KPRO to a Z1 harness is only good IN a 2005-6 RSX. He had no tangible explanation as to why this is so. He just did a Pontius Pilate: "we don't support that. You're on your own."

Because I already know that the Z1 A, B and E connectors plug in to the A2 ECU, it *could* be as simple as re-pinning the Z1 harness to A2 spec. I am already aware of the high-frequency v. low frequency speed sensors and am willing to take the chance since the high frequency sensor will merely send a higher-than-correct signal to the A2 ECU. I wouldn't *think* this would affect VTEC as long as the computer doesn't ask questions like "why am I going 500 miles per hour?"


1) Has anybody used a Z1 harness with an A2 KPRO by repinning the Z1 harness?

2) Can anybody call BS on Hondata for saying that the adapter harness won't solve the problem outside of an actual 2005-6 RSX car?

3) Does anybody have experience to advise me on what I should do OTHER THAN "buy a 2002-4 harness and transmission?"
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Thank you for your reply. I figured somebody had to have done this before.

What is the difference between K-Tuned's harness and the Hondata one that we paid for and didn't receive? The tech guy at Hondata (for what he is worth) told me that the adapter harness is only for 2005-6 cars and swore that it wouldn't work outside of a 2005-6 CAR. He gave no substantive reason, saying only that there would be electrical problems and that "we don't support that."

Does Hondata make internal changes to the A2 ECU for a Z1 car, or is this still truly an A2 ECU regardless of whether it was intended to go into a Z1 car or not? In other words, can I proceed with repinning to A2 spec regardless of what they did to the A2 ECU I have?

And does the VSS really need an adapter if I am not using a Honda speedometer? I am building the car with a Marshall speedometer, which I have to calibrate anyway. Does the VTEC really need a CORRECT speed signal, or does it only need to know that the car is moving?
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Technically, no. There is a setting in kmanager where you can set the VSS to a constant speed signal so VTEC will engage. I had that issue with my kpro where it wouldn't read the VSS and VTEC would not engage. All I did was change the setting in kmanager and it cleared that up to make sure everything else was working. However, I do not know if setting the VSS signal to constant will affect anything else in your application.
In my application, I have to route the signal wire from the VSS to the speedometer, then back to A18 to make the speedo work. Otherwise, the speedo does not work. On my first build, I wired the speedo exactly as Hondata's diagram prescribes and absolutely could not get the speedo to calibrate or VTEC to engage.

NOTICE: Thanks so much to Mike at K-Tuned. He has spent probably an hour on the phone with me today helping me sort out exactly what is going on. He was far more willing to help me sort out my problems with Hondata than Hondata was. That is service!

This is MY first build with a Z1. The fabricator before me built a Z1 conversion, but he is gone and with him, whatever he learned about making the speedometer and VTEC work. I have since figured out how to make the speedometer and VTEC work regarding speedometer wiring.

I still wish I knew for certain if Hondata made any changes on pinouts to the ECUs destined for Z1 cars or if the necessary changes are 100% done in their adapter harness.
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