Stumble after shift, issue with tip-in retard

[Corey872]

- serial number of your K-Pro: 2227
- KManager version: 3.0.3
- the calibration: attached
- a datalog of a problem: attached
- what sort of vehicle you have: 2002 RSX Type S
- what sort of ECU you are using: Stock PRB ECU


E85 fueled
Mahle 12.5:1 pistons, Eagle 4.470" H beam rods
Precision 5857 Billet turbo
RBC Manifold, Custom adapter, stock throttle body
Custom 3/32" Teflon intake manifold gasket
ID 1000cc injectors,
TiAl 38mm wastegate
OBX sidewinder manifold

I've been chasing reasons for a stumble/bog right after shifting gears. In looking at the datalog, I see timing swing sharply down, sometimes even negative for a period of time after each shift. Curiously it only does it in 1-4 gear changes...right where I have tip-in retard set. So I zero'd the tip-in retard and the stumble after shift / wild timing swings went away. The thing is, tip-in retard has a max RPM cell of 1500, and the timing is going negative at 2300+ RPM. In the attached datalog, one shift has -3º timing @ 2350.

In summary, the tip-in retard settings seem to be active 800-1000+ RPM after the last cell indicates. I can zero out the tip-in retard and get great shifts, but the car is a bucking bronco at low speeds.

PS - Guess I should also add, this has been an issue in 1.5.X (possibly earlier) and 3.0.X, I've only now had time to track it and get all the datalogs together.

[Corey872]

Hondata? Anyone?

[Hondata]

The tip in retard is to prevent knock, not to smooth out the engine. I see the cam angle is set to 55 degrees upon overrun conditions - it should return to 0 during shifts. You may need to create a new calibration, copy over the fuel and ignition settings & injector size, to see which part of the calibration is causing the problem.

[05typeR]

Hi,

i am not experience in the kpro as yet but looking at your cam angles they are really far advanced (55 degrees which is full advanced).

maybe you can try taking out some of the advance moving all to maybe 30 degrees and see what happens.

[Corey872]

Thanks for the additional input. To clarify a bit, when I eliminate the tip-in retard, the car runs fine, so I don't think this is a cam advance issue (I'll discuss those a bit below). The main issue is the timing going very low or even negative at each shift when I add the tip-in retard.

For the function of the retard, I was referring to the help file:

Acceleration Smoothing Retard
Honda has a special ignition retard which will retard the ignition when the throttle is opened quickly in order to prevent lateral oscillations of the vehicle ('bunny hopping'). The ignition is only retarded when the engine is accelerating in order to dampen the acceleration of the vehicle. Often this is apparent in a datalog.

Is this incorrect? By turning up the tip-in retard multiplier and duration (as described in the help file), I was able to eliminate the bunny hopping. - ie - when driving through a parking lot with the car basically idling in second gear, the car will start jerking, progressively getting worse until I ride the clutch and break the herky-jerky cycle. So adjusting the retard seems to be effective for this purpose. The main issue seems to be the highest RPM cell I have for tip in retard is 1500, but when I shift, it still affects the timing at 2300+.

Re: Cam Angles

The cam angles are set high in two zones. Light throttle cruising to increase the EGR effect, preheat the incoming air, make sure no fuel blows through the cylinder and cut pumping losses. This increases mileage substantially in this zone. The cam is high at 'overrun' mainly to cut pumping losses and allow the car to coast substantially further/faster off the throttle - again improving mileage. (Again, all this works fine if I zero the tip-in retard)

So in summary, when I set tip-in retard to eliminate bunny hopping, per the Help instructions, the timing swings negative after each shift as if the tip in retard is kicking in - even though the retard is set for a maximum RPM of 1500 and the shift doesn't go below 2300+. If I change the tip-in retard multiplier to -100 (minimum), the dead spot after shifting goes away and the car runs fine - the only issue is bunny hopping at idle / very low RPM as described above.

[Hondata]

With bunny hopping it usually is not from too little tip in retard. Do a datalog and check that the ignition tables do not sharply increase around the point where you get bunny hopping.