jdm k24a turbo break up right after VTEC

[Kr4nG]

Hello Hondata,

Im looking for your professional input here on what or why this might be happening to my car. I have a jdm k24a turbo rwd setup running 8psi of boost. I have a misfire / break up occurring right into vtec. I can set the vtec from 4k to 5k and it will break up. But if I set the vtec to 5500 rpm the car will not break up but slightly something still might be there. I have a similar setup on my second car running same exact cam angles and same exact ignition table and my second car will not break up during the cross over. I have tried swapping sparks, coils, map sensor, and none seems to help. I datalog shows no knock no CELs nothing out of the norm. Here is my map and a few datalogs. PLEASE see what could be happening here. Is my ignition to low around vtec? Is my ignition to high around vtec? If more information is needed please ask me.

[Kr4nG]

my map file attached

[Hondata]

I would first investigate and fix whatever is causing he battery voltage to be very spiky and drop under load.

[Kr4nG]

That is another problem i cant figure out. Both of my cars are doing the samething with the voltage. Useing the ktuned any chassis harness both cars. 02-04 rsx harness and 02-04 manual crv harness on this car. No idea y its spiky like this. I even separated the fuel relay so theirs less draw. Im lost here. The pin at ecu shows stable voltage but the manager shows spikes.

[Kr4nG]

if this is related to a voltage not being steady. What are some other things to try? I've also disconnected the o2 sensor thinking its related but the fluctuation is the same. Any other thoughts?

[Kr4nG]

At which pin of the ecu does the Voltage come in from from that k manager displays? A2? A3? what if I just ran 12v from battery directly into that pin as a test?

[Spunkster]

You should try the ECU in a known working vehicle. If it does not have a voltage issue, then you most likely have a wiring issue in both vehicles that needs to be resolved.

[Kr4nG]

I think its just so strange that these conversion harnesses are being sold by reputable companies and no one can figure out why this voltage fluctuates. 2 cars 2 same ktuned "any chassis" harnesses and 2 kpros both showing non stable voltages. The harness is so simple it asks for 2 wires. 1 is 12v constant and the other is 12v ignition switched. I was going crazy last year with this voltage issue on the first car, that I even took another battery and straight fed the wires. Kmanager showed same thing, no change. So I left it alone as it wasn't showing any issues. But not until I built this second car and had this misfire problem.

Which pin on the ecu feeds the voltage display in Kmanager? I want to directly source this to the 12v battery terminal.

Will Hondata ever make a swap chassis harness? I know ktuned and hybrid racing are the only ones that make these "any chassis" harnesses. Would be cool to prove this voltage issue once and for-all.

[Hondata]

There's more to the electrical supply than the battery. The alternator control and ground path are there too.

In my opinion there are no good swap harnesses for sale. If you want to do it properly get the factory wiring diagram from the 02-04 RSX and then compare that to your vehicle and trace and check each wire. For engine swaps we made a circuit diagram a long time ago since we got sick of people not wiring in the main relay correctly. The diagram is available in our tech section.

Start on the ground side. Get a decent multimeter, clamp on lead to the battery negative terminal and then use the other lead to measure voltage around the vehicle with the engine running. You might have to extend the leads. Good spots to test is the transmission strap, a timing cover bolt, master ground (nominally on the intake manifold), then ECU ground pin A2/A3. DC voltage drop should be less than 0.1V. AC voltage should be also less than 0.1V You can also check o2 sensor grounds etc for voltage drops.

Then look at the positive side. And also the alternator control.

Hondata is never going to make a wiring harness because a) they are hard to make b) there are a lot of variants of vehicles it would need to work on c) you end up supporting every problem the vehicle has and d) as soon as we make a harness someone would copy it and undersell us.

[Kr4nG]

Understood.

Well I appreciate your replies here guys. I'm not gonna give up on these cars as these are amazing builds I made. When I figure out this fluctuation I will surely post it.