MIL flashing at high load and rpm problem

[Jim_H]

Hi!
Just recently tuned a Euro EP3 with K20a engine, and now it's having problems with the MIL flashing at high rpm and full load. The specs:
K20a oversize bore 2.1 liter
JDM DC5 cams
CP Pistons CR: 11.7:1
Pipers exhaust manifold
Hondata intake gasket
Injen Cold Air Intake
Hondata PRB K-Pro with wideband
Running 95 octane fuel

The owner bought the car with the engine freshly built, so he never pushed it above 4000 rpm before tuning, therefore we cannot know if the car had the same symptom before tuning. But it probably had. The MIL comes on at high revs and full load, and starts flashing until you put it in the next gear. This does not happen on every run either, sometimes he can do four runs and nothing strange, then the next run the MIL flashes. He has had the random misfire code like two or three times too.

Things he has tried:
New spark plugs
Switching to working ignition coils
Higher octane fuel
Compression test: OK
Valve clearance adjustment
Better/different grounding point

None of this gave any results. I have also tried removing 4 degrees of ignition timing and add 5 % fuel at WOT but the same thing happens. The cars runs great and there is no tendency of the engine actually misfiring, you can't feel a thing. Just pulls very strong every time. Tuned some EP3's on my dyno now and have never seen this problem.

We got a tip about that it could possibly be the mugen twinloop exhaust that's causing quite some exhaust backpressure, but it's just a thought.

Attached the calibration file and two datalogs of runs with the problem.
Thank you for your time.

Best Regards Jim

[Spunkster]

What is the serial number of the K-Pro board inside the ECU? From Help, About, what version of software are you using? Are you sure that this is the calibration that was loaded in the ECU when this datalog was made?

[Hondata]

Never seen that before. I'd try a code reader to see if there are any error codes which KManager is not seeing. Then I'd create a new calibration and import the tables (fuel, ignition etc).

[Jim_H]

Spunkster: I don't know if the customer wants to open up his ECU if there still is warranty. That is the right cal. file.
Hondata: I've tried with a code reader but nothing. I will try with a new cal file and copy the files. Thanks for the tip.

[Jim_H]

Here's a picture of the serial number I got from him. I did 2 new calibrations and copied every map and parameters and sent to him yesterday. He tried them out this morning but no difference at all. He will try to replace his Mugen twinloop exhaust with some straight pipe to see if it helps.

[Jim_H]

Problem solved. Customer changed out his Mugen twinloop(probably causing too much backpressure) exhaust to a 2,5 inch with better flow. No more flashing MIL.