misfiring problem and flashing MIL

[mr-alternative]

Got a problem with my K20A2 with forged pistons and JDM camshafts.

Started with flashing MIL, then MIL stays on.

Error codes were:

Misfiring various cylinders
Misfiring cylinder no.2
Misfiring cylinder no.3

I cleared the DTCs and let it idle. It runs normal and so i did a test drive to a local auto repair shop.

While it happened after fuel-up we checked fuel in the fuel-rail, which had no dirt or other fluids like water, oil, diesel in it.
Then we let it idle at about 2000 rpm and it slightly misfired sometimes.

When this happened, MIL came on again and error code misfiring cylinder no.2 was in DTC.

I checked the ignition coils and have seen that no.2 coil got a deformed coil spring, so i changed coils of 1st and 2nd cylinder.

I drove again and first it all stays good, then when going from full to part load (german highway) knocks were detected, when i stopped and checked datalog i let it idle and MIL blinked again (flash MIL when knocks detected is activated, but it don't flash on highway).

Then Misfiring cylinder 2 come back again (spark plugs got changed last week).

for a short time it idled like having light misfiring then running normal.

Drove back on normal road and there was nothing. Back home again i let idle for a while and it flashed MIL again plus cylinder 2 misfiring again.


Could someone give me any support to that problem?

[Spunkster]

Have you checked the plugs since this has started happening again?

[mr-alternative]

I checked the plugs again, the engine runs hot/lean on 2nd and 3d cylinder.

NGK tested the damaged plugs and its not caused by faulty produced spark plugs, its a over-heating problem.

Engine is compression checked and has no leak air, valve clearance is ok.

So mechanically it seems to be everything ok.

Before the car was mapped it runs for about 7000kms with a Hondata vault map with no failure, after mapping about 4000kms.

I test drive the old map and stock k20a2 PRA map, but the problem is still the same.

Is there a way to check the ECU for failures?

I don't know the circuit diagram of the ecu itself, but maybe there is a problem in the ECU itself for 2nd/3d cylinder ignition coil output or fuel injector output.

The Kpro board is an V3, which is 1,5 years old.

[Hondata]

I've never seen an ECU coil output fail (but have seen coils fail), but it is far more likely to be a combination of the forged pistons being noisy and the lambda from tuning.