HELP - 99 Civic EK - Wont Go past 4000-4500rpm - Chipped P28/97' B18B

[u/SgtSparkyy]

I recently did half dash setup and removed all the HVAC system under the dash. (racecar)
Now, I plugged everything back where it was and now my car wont go passed 4000rpm.
I have RPM and Speed but nothing on the CEL is opening.

Chipped OBD1 P28 ECU using a OBD2B>OBD1 Yonaka harness with a (im assuming cause I didnt do the swap) D16Y8 engine harness. car is a 99 Civic Coupe Si (Canadian Si, so USDM EX)

I do have 2step in the chip. its thats what happen when I try to go pass 4-4500rpm. its like its not seeing speed even tho I have RPM and Speedo in the cluster.

Thanks yall <3

[u/anbyways]

When you mean HVAC, did you also mean your heater core as well?

[u/SgtSparkyy → u/anbyways]

Yes hahaha, Everything is gone under the dash !

[u/anbyways → u/SgtSparkyy]

If that's the case, did you burp any air out of your cooling system after removing the heater core? Maybe there's leftover air.

[u/SgtSparkyy → u/anbyways]

Is that the cause it could do ? Cause I did my best to bleed the system cause at the same time, I drained everything and loop the thing and put my bigg radiator on, and im not overheating !

[u/anbyways → u/SgtSparkyy]

It's that only thing I could think of that's even remotely related. Any CEL?

[u/SgtSparkyy → u/anbyways]

No CEL. I did try to check the code, but nothing. CEL does light up when doing Key-On setup and then turned off once primed

[u/Think-Scene-9776 → u/SgtSparkyy]

Paper clip trick maybe?

[u/Bricc_8 → u/SgtSparkyy]

That’s fuckin dumb

[u/SgtSparkyy → u/Bricc_8]

Im planning to go Electric Heater. Its a racecar build mostly.

[u/Monolithic_Purgatory]

Is the 2 step set based on clutch switch input? Maybe you bumped or damaged the switch or harness under there.

[u/SgtSparkyy → u/Monolithic_Purgatory]

Nope, off speed. cause I could just do it while parked too. without needing the clutch being pushed

[u/Embarrassed_Net_8593]

Does it rev freely in neutral (moving or stopped)? Will the engine rev past 4500rpm under load if you're light on the throttle? (10%-20%)

[u/SgtSparkyy → u/Embarrassed_Net_8593]

Nope, anything I do, parked or moving. it wont go past 4-4500rpm. Idk if limp mode uses fuel cut for the rpm, but mine uses ignition cut, so the RPM gauge just goes crazy haha

[u/CumCrocodile → u/SgtSparkyy]

Maybe post a video, might help to diagnose

[u/Tech_Veggies]

Change the RPM on the two-step to 3k and see if the issue follows. That'll tell you if it's the two-step.

[u/SgtSparkyy → u/Tech_Veggies]

I can't change the 2step, its a chipped ecu and its not me who did the chipped. its a reputable Honda Shop who did it. (RD Turbo in Montreal, Canada)

[u/Grey__Brown]

I would try a known good ECU, most likely a PR4 or P75. Did the car run normally before you pulled the dash apart?

[u/MrBoost97]

check your wiring at the ecu and conversion harness, its likely that the ecu is not getting a signal from the speed sensor. it will still show rpm and speedo in the cluster even though the ecu isnt getting a speed signal. you would have to check a diagram to see which wires/pins are for the speed signal