Hondata

Hello all,
On the dyno trying to tune a customer car heres some details:

s300 version 2.2.4
piston/rod engine
built head
resistor 7 plugs ngk wires
precision turbo
id1000's


Problem is timing drifts from what i've programmed in timing tables. If i LOCK timing and do a pull and watch with a timing light....the mark either scatters +/- 5 degrees or progressively retards as rpms rise say from 4000-8000. i've locked at 27 degrees seen it retard to as low as 18 on crank.

Heres what i've done:

logged situation: log shows no signs of abnormal operation. locked timing values all sensors showing consitently correct data.

different distributor: same situation

different ecu from a well running all motor setup: same situation

o'scoped the following: cam, crank, tdc, icm output at ecu and at icm/distributor.....all signals looked good. correct phase/edge triggers of all pickups and integrity of icm signal through harness was good.

called local hondata dealer: suggested playing with new tables in ignition comp tab rpm compensation and dwell angle......ended up not really doing anything for me and i think icm failed when i was about to give up.


So what i'm about to do is try to find an old software version of hondata, put another distributor on the car and check for problems. If i still have them i'm going to just program in data to make the timing result at the engine where i want it to be for the customers setup.




Any ideas?

No datalog showing this

Nothing in the datalogs to show anythings wrong. Unless you can see something i cant in a normal hondata datalog. Today i'm going to be checking the end of the camshaft at the dist tang for wear, and the timing belt tension. Other than that i'm out of ideas. Do you really need a log of a pull at locked timing that shows a consistent timing value in the log? Therein lies the problem. The ecu knows to lock timing but thats not what the engine is seeing. Inconsistency and drift is what the engine is seeing.

tensioned the timing belt a little tighter and inconsistency and drift greatly reduced. now only seeing 3 degrees of drift from 4000- 8000 rpm. fyi