Hondata

So I have been having some issues with my Hondata S300 and I am hoping that someone can help me out as we have just about exhausted every avenue to fix the issue.

Details:

NASA Honda Challenge 2 race car
1994 Integra GSR with JDM B18C
S300V3 purchased last year running on latest version software 2.6.7
Full Rywire harness (power and engine)
P72 ECU socketed by Hondata

Basically when logging on the track, the information is all over the place. VSS reads as high as 36,000 MPH, IAT maxes out at 258 F, Coolant temp maxes out, short term trim goes all over the place. Originally I thought it was a grounding issue, but added extra grounds and it did not really help. We also thought we had an alternator throwing out weird voltage, but swapped that and no help. Occasionally I can get a clean log after a session on track, but now it seems to go nuts all of the time. I also get an occasional MIL light, but it happens so fast I never see it and it doesn't trigger anything I can see after I get out of the car. I couldn't load the log with the MIL errors on it, but I can e-mail it to someone if it will help.

Note, if you log the conventional way via a laptop (on the dyno), everything in the logs looks fine. We have also taken the ECU and put it in a street car and logged for hours and it runs just fine with no issues or codes or logging errors. It's also worth noting that I recently melted a piston in my engine and while we are still investigating, but I'm wondering if this issue may of been a contributing factor since we run closed loop targeting via a PLX wideband.

I'm really at the end of my rope here. I've not had the best luck with Hondata products, but I want to get the issue solved. Any help or suggestions you could provide would be very much appreciated. A short log and my tune are attached.

Regards,

Vincent

Are you using resistor or non-resistor type spark plugs?

Since it works on a normal vehicle it sounds like something related to your vehicle. Since the wiring is not stock that is also a prime candidate for causing an issue like this.

Well I reached out to Rywire and they said they have never heard of an issue like this. The spark plugs were original NGK and are BKR6E-11's (resistor type). I run Rywire's complete standalone race harness that has been used by literally hundreds of people and they have assured me that they have never heard of anyone having this issue. Only other non typical wiring is the fact that I have a cut off switch, but it is wired the same way I've wired other Honda's and I don't see how that would cause an issue.

Where do I go from here? What are some other things to check? Has anyone looked at the logs and tune? Maybe something is set wrong and I don't know?

-Vincent

Well if it works correctly in other vehicles and only does this in your vehicle you will have to use process of elimination to determine what exactly in your vehicle is the cause. But wiring is the most likely culprit here.

Seriously? This is the best you've got? I'm just supposed to start wiggling wires and replacing sensor's until we figure it out?

Thanks, you've been a HUGE help.

well, I would have said the same thing. If the ECU works fine in one car, and not the other, then it's not the ECU...it's something in the vehicle...

What else do you expect? There is no magic ball here where Spunkster can guess what is wrong with all your wires and sensors, and you clearly state that the ECU works fine in another car, so it has to be something else related.

I would suggest you to see if you can test the same behaviour with another ECU, which might be easier, if same patterns replays then you got your answer

For the record, I ended up having a bad spark plug wire which we believe was causing a noise issue that the ECU was picking up. Strangely this did not have a performance issue with the engine. Now that the engine is rebuilt, we are about to dyno the car and to make sure that was the issue.

However we also believe that because this engine harness doesn't have any shielding in it this most likely "amplified" the issue. So people with stock engine harnesses would probably not have this issue.

-Vincent