Backfiring & ECU stuff.

[suzyj]

I've got my little 695 pretty-much sorted around town using a fatduc.  At the superbike school on Monday, I noticed (I couldn't miss it, as it was pretty loud) my bike enthusiastically backfiring occasionally.  It mostly happened just before turn 2, where I was going from insanely stupid revs to much lower ones.

ISTR that there's some sort of transition between closed loop (where the fatduc helps) and open loop (where the fatduc does nothing, because the bike ignores the O2 sensor).

Since Monday, my bike has been running... differently.  It idles a couple of hundred RPM lower, and feels perhaps a little sluggish.  I dunno whether that is just me perceiving things differently, given that I don't generally ride to work at 7000 RPM, or whether my day at the track had some actual effect.  But if it's the latter, the effect should be positive, right?  All that WOT on the rev limiter down the straight should have removed a lot of carbon deposits.

I pulled the plugs this morning to see if they were fouled, but they were really good.

I'm wondering if my ECU has remapped itself based on the flogging it received on Monday, perhaps as a result of the backfiring and stuff.  I'm pondering removing the battery for a while to get it to reset its map.

Anyway, if anyone has any words of wisdom, I'd appreciate them.  It's probably all in my head.

[ozducati]

Hi Suzy, backfiring is generally a sign it's running lean, the ecu can't remap itself..  it may feel a bit sluggish due to having it at WOT on the track compared to riding on the road with all those cagers maybe?

[vossy]

That's a weird one indeed.
Your ECU wouldn't have "remapped" itself because it hasn't got the capability to do it on it's own.

With the Fatduc, it may need a slight tweek again. I had one on my S2R and I had to tweek it a couple of times over a 6 - 9 month period to get it sweet again. (make it run richer)

Hooking the bike up to a VDST can also tell you what's going on with the ECU.

good luck with it suzy

[craigo]

You didnt fill up with Shell halfway thru superbike school did ya? My bike pops and splutters whenever I do.

[suzyj]

You didnt fill up with Shell halfway thru superbike school did ya? My bike pops and splutters whenever I do.

Aaah!  I filled up there in the morning, and then on the way home.

Before I do anything drastic, I might wait until I've put a tankful of the usual fuel I run through.

[ozducati]

good point too..  shell not good...

You didnt fill up with Shell halfway thru superbike school did ya? My bike pops and splutters whenever I do.

[Speeddog]

Homework assignment:

http://www.bikeboy.org/open_closed_loop_efi.html

 

[suzyj]

Homework assignment:

http://www.bikeboy.org/open_closed_loop_efi.html

 

Oh, I'm miles, miles worse than that.

http://www.microsquirt.info/

Actually, I was thinking my time at the track had affected this:

Adaption (or self tuning)

The Closed Loop system is not only used for instantaneous mixture adjustment at constant throttle /RPM conditions.  The changes the ECU makes to the injector pulse width to reach the cycling mixture as compared to the map pulse width is stored in what is commonly called an ‘Adaption’ table.  This table is then used to trim the map value in future.  Instead of having to work its way to the cycling mixture point in steps of incremental pulse width change, the ECU will start where it ended last time.  The constantly updated adaption table is the self tuning facility talked about with Closed Loop systems, but it is often misunderstood.

But then I have no idea, as the Marelli ECU is a completely closed black box to me.

[cakeman]

Mine is still back firing after the exhaust leak being sealed. Its shooting some large flames and pops on decel.

[suzyj]

Mine is still back firing after the exhaust leak being sealed. Its shooting some large flames and pops on decel.

I think this sort of thing is pretty common on newer monsters - they set them lean to pass euro emissions standards.  Fitting the fatduc helped for mine in the closed loop part of the rev range, but it's still lean open loop i think.

[Speeddog]

The older monsters were lean too, it's just a bit easier to deal with, at least the trim can be adjusted.

If you guys have a problem with the local Shell fuel, that could well be it.
Shell is good here, but I don't fill up in Australia. 

[cakeman]

The older monsters were lean too, it's just a bit easier to deal with, at least the trim can be adjusted.

If you guys have a problem with the local Shell fuel, that could well be it.
Shell is good here, but I don't fill up in Australia. 

Are flames out the exhaust normal though? I put in a mid pipe recently and its been tuned

[Speeddog]

From your avatar it looks like an S4R?
What year and what other mods to the engine??

Flames out the exhaust aren't 'normal' as far as I'm concerned.

Did it just recently start doing this?

suzyj, how high were you revving it?

[suzyj]

suzyj, how high were you revving it?

I can't say exactly, as I was doing >150 km/h and slowing for a really tight turn (after burning down the straight), so wasn't really paying attention to instruments, but I'd guess 7.5 or 8K.

[cakeman]

From your avatar it looks like an S4R?
What year and what other mods to the engine??

Flames out the exhaust aren't 'normal' as far as I'm concerned.

Did it just recently start doing this?

Yes its a 2004 S4R, it started doing it when i put the mid pipe in and got a tune. Header gaskets were replaced and silastic around all fitment points so no exhaust leak.