EFI University

[HR-1320]

I have 1 cam sync pulse and 4 ref crank pulse. Instead of being 45deg away from ref pulse I'm about 20deg. I have unstable timing at idle speeds. Could this be why?

[Martiens]

What ecu are you running?

Have a look at the channel "syncPos%" if you are runing a Mx00 ecu.

This will tell you at what percentage the sync occurs between the ref teeth. If you are running a hall sensor you might want to try and play with the trigger edge to get it as close to 50% as you can. Depending ont the slack in the cam drive( i guess thats where your sync sensor is reading from) the pos will change with RPM etc...

50% ideal
outside 25% to 75% ...gettting too close for comfort. Log it..best way to tell.

[Martiens]

btw....if it does go over 0% or 100% it will just use the next tooth as the referance tooth.....thats why the timing will be out if it happens. 60-2 or 36-2 in my opininion would be a better option because the 0 to 100% spacing that the Sync needs to happen is all the way from the -2 teeth right around till you get them again. Thus the margin for error is so much greater

[HR-1320]

I run a m400. I can adjust my ref pickup so that its good. Just wondered if I had to. My tuner setup my crip and I was nervous to screw it up. I'll just move it . Thanks for the reply.

[Martiens]

If you adjust the ref pickup position or the teeth it the Crip will go out.

Easy to re adjust..

Best way if you dont want to mess things up would be to take out the spark plugs...cranks easily and smooth that way.

Put your laptop on and go.....adjust,ignition,crank indexposition..
when you are in this screen the timing will be locked to the value displayed next to "test advance"

Crank the engine and make sure with timing light that the timing you are reading from cylinder1 is the same as what the "test advance" is locking it to. Change "crank index position" till its spot on. Remember to press enter to store the value. After this start the engine and make sure of the CRIP again.

"For good timing at cranking the REF wheel should be aligned so that
there is an active tooth edge at or slightly advanced from the
cranking advance point for each cylinder (Normally 5 to 10 deg BTDC)."

[HR-1320]

Right now my ref on cly1 hits at 20deg btdc. If I change it to 5deg btdc like you say that will get my sync pulse right inbetween my first and second ref trigger. So that should work good thanks. I just hope my timing is doesn't jump arond 5deg after this. Its pretty solid at higher rpm though.

[Martiens]

i didnt figure that out myself....

its writtin in the help file in your m400 software...look under the multitooth help

[HR-1320]

Ok without moving anything I checked my syncpos% while it ran and it was at 45%. Which I'm assuming is pretty good. My problem is my timing. I run a honda b series. I have a custom hall sensor and one magnet on the cam and a MSD crank trigger wheel with magnetic pickup. The wheel used to have 2 magnets and the timing would jump alot 10-20-30. So I put two more magnets in and its better but notlike when I plug into my magneto. So whats the deal do I really need a 12 magnet wheel or will a hall sensor on the crank clear my problems.

[Martiens]

45% is good. Is it stable at 45?

Im not too familiar with MSD trigger wheels, but i think that MSD mag sensor has a offset waveform. the mag sensor does not swing around 0v maybe something like 0.5 or 1 volt? You could check this by doing a ref/sync capture to check the voltages. Maybe somebody with more experience with these sensors can give some advice?

something that i have read on the motec site......

Honda Distributors - used for both Ref and Sync


We have noticed there are several different versions of this distributor which
are all very similar in appearance to the casual observer. The main difference is
in the mounting flange pattern and part number which can be found inside the bowl
of the distributor under the coil. Additionally there may be differences in the
location of the sensors in relation to the distributor shaft and to each other.
These differences change the relation of the sync and ref signals. In some cases,
the edges are so close to each other, that the sync position may hop a tooth.

This causes an instantaneous CRIp change of 30 degrees. All bets are off as far as
the direction the timing moves, it could be 30 advanced or retarded, typically it
is retarded but doesnt have to be.

We know that at least one P/N D02693 or D02693A Distributor gives sync errors at various speeds
as the position change happens. To fix the problem, the plate which the sync is mounted
on can have the holes slotted and be rotated enough to provide a nice stable 50 percent
sync position to cure the problem.

If you are getting Ref Sync errors and the edges are correct (should be both falling
if wired properly) then this would be a good place to look.


Shane Tecklenburg, Simon Wagner and JoJo Callos 10-11-02

These are the part numbers we know about and we think they come on these cars

D02693 GSR, Si, Type R, (B16A Engine) VTEC
D02691 Prelude/Accord
D02672 Single Cam standard Civic Possibly VTEC
D3179 - known to work without modification 30% revved up 40% at idle.