Engine running bit weird, how to proceed?

And sorry I can't type worth a damn on my phone :) sorry for typos and such

Bladerunner919 wrote: I had a Honda Blackbird that would throw an engine light intermittently, but with no impact on how it ran. I was about to start checking all the wiring to the various sensors and realised that the rubber/elasticated strap that hold the ecu in place was broken. On a hunch I cable-tied it in place and never had another problem. Seemed that the odd pothole was causing it to to be rattled enough to set an engine light.  So, making sure everything is firmly where it should be is not a bad place to start.

Ok my Mivv oval carbon can (not the GP shorties that steal power and ruin all relationships with your neighbours) arrived and I did hook up my old throttle sync guages to the engine to get a proper starting point. On my 2000 model year ME, the front cyl is not a problem as it has it's own bung, unused with a cap; but for the rear I had to unhook the fuel pressure regulator (next to the tiny tube connecting both throttle bodies and going to the intake pressure sensor), which meant I only kept it running for a little bit. I also checked it with the pressure sensor disconnected electrically as I found suggested in some , didn't make a difference to the pressures in the throttle body (unsurprisingly). 

Anyways, I ended up with somewhat surprising settings - front at ~1.5 turns out, rear at like 2.5 turns to get it to around 0.3bar vacuum as per the manual... Is that reason for concern in any sense? The throttle response is definitely much improved.

ah ok that is probably a better idea - I just had no fitting replacement clamp at hand and the cramp style clamp that's on that line looked a bit single-use... yesterday I double-checked (reversing the measurement) and it does seem to be in sync the way it's set. is there a known good way to set the trim pots with a CO meter/EGA - on a carb I'd set the mixture by lowering the idle and trying to find a setting for the mixture screw that slightly raises the idle, and then lower it again using the idle screw, basically trying to get it to still idle with increasingly lower idle-screw settings - does something like that work on those trim pots? Anything (sensors etc.) one should disconnect for that?

Ok thanks to your help today I re-synced using the correct line (with a significant change - weird how the bike also ran good with the completely different setup...?) and did a bit of testing when riding - I now ended up with the settings about like this: Air screws, fr/r 1.5/0.75, Pots at like 9o'clock with the left pot (= rear I take it) a bit more clockwise, like at 9:30/10:00. The bike pulls SIGNIFICANTLY stronger at 3-5k rpm, and sounds deeper, really good response. It falls into a slow-pulsing, pretty regular idle. Think I'm fairly close to ideal settings, even though I set the pots when the bike was hot already, but I didn't adjust by ear but just experimented with small steps - the 12 o'clock starting point was probably way too rich for both. I did go even leaner and felt the bike was pulling probably even stronger, but it also became a bit harsh and janky when at cruising throttle. Let's see how it runs the next time from cold.

Yes have a go at it I'd say - it's a bit more complicated to set good idle I think than on a carb (with accessible mixture screws, that is - oh how much I hated setting that on an SV650 where the screws are pointing towards each other, at odd angles, in the small space between the carbs, where three other lines are in the way), but well worth it. 

The difference in road driving between really small turns of the trim pots with a screwdriver was absolutely noticeable. Perhaps some with more experience on these bikes can still clear it up for us late-coming newbies: I'm assuming that both trim pots running exactly the same will result in roughly the same mixture - as in, on a leak-free engine (sprayed it liberally with starter fluid to find vacuum leaks, as I always do with a bike that idles bad) if they're both set to x, both cylinders will have roughly mixture y for a given rpm/throttle setting - correct? As in, a proper setup with the air screws in the right area probably won't end up with one pointing at 10 o'clock and the other at 3 o'clock, right? right?

So with that assumption in mind, I started at 12 o'clock, drove it to my regular local testing road, the bike was fully warmed up by then, 84°C on the water. There I set it to 11 o'clock and noticed that somewhat improved the response at 3-5k especially from what I felt on the way there. Went to 10 o'clock both, then 9 o'clock both, both improving that section and the pick-up alround, then even something below horizontal close to fully counterclockwise, like 8 o'clock which still pulled strong (perhaps even strongest) but it felt a bit "metallic" and "harsh" in response, aka too lean for my taste - so I went back a step on both and added a bit of safety-richness to the rear (left pot) for thermals as suggested by Spoonz (and several other posts as I remember).

Tip: it definitely helped me to control and remember what I did, to record right into the pots with my phone, taking a video with light enabled. Nothing like getting a visual "yes that's the way it's pointing" to confirm what you think you're doing at the end of a screwdriver (at least if like me you're a bit hamfisted when it comes to those and you need to go back and forth).

The ecu trimmers just adjust injector time. So in theory if set the same then fueling should be the same, assuming everything else being equal. 

Yes same for me - I think by now (and please, someone correct me if that is not quite right!), the throttlebody screws are acting bit like a mix between a throttle offset, allowing to balance load between the cylinders at idle (allowing in more or less air), but also have a general "lean/rich" influence ONLY at idle rpms, with the trim pots providing a general mixture setting that affects everything else, but is most noticeable at low-mid rpms. I found the diagram of someone measuring such an engine on a dyno with an a/f measurement, switching between his normal trimpot settings, fully ccw and fully cw - and the trim pots indeed worked completely linear across the rpm range, creating a +/- x air-fuel-ratio offset across the board! (wonderful IMO - no more "yes that flat spot at 6k rpm could be fixed by a bigger main and setting the needle one click further out and the mixture slightly too rich, or by just clicking the needle further in and living with another flat spot at 4k rpms). The area where you see most differences in power output is below 7k indeed, but the mixture definitely gets applied across the entire rpm range!

Chris your assumption re injector duration etc are correct. The trim pots will bias the injector timing +/- across the rev range in theory. But if adjusted correctly will have minimal effect as revs/throttle increase. Eg. The offset might be 10% of the total injector time at idle but 0.1% at 7k rom at WOT.  The bypass screws just determine the amount of air bypassing the butterflies when they are closed. If your idle is raised via the idle adjustment screw then the butterflies will already be open a little bit making the bypass screws less effective at setting idle. 

I get what your saying but ill try and explain why its less simple.. The ecu will adjust injector duration with revs etc as part of its mapping. In the case of the rsv, the map is 2 stage with the basic map just using rpm and throttle position as inputs. That map is active across 100% of the rev range. The second map uses additional inputs such as manifold pressure and air temp etc but is only active at certain throttle/rpm/load. It will overlay the basic map to modify it for cold, altitude etc. 

D/J is the base map with only 2 input parameters and will be altered by trim base settings.  Under load/rpm etc you get a combination of both map stages so although the trimmers will still have an effect, it’s reduced as the overlay map modifies the base fueling. The picture doesn’t make that particularly clear.  From what I gather from the technical training docs, after all the environment variables are calculated by the ecu, and summed with the total input variables,  a trim figure is produced. 1 being no change +1 richer etc, many times a second.  Taken to extremes but if you started your cold bike below sea level  in say -10 degrees c, the cumulative correction to the base map would be over 50%

Without getting too techy

Haha so you mean I'm just placebo-tuning in my head (on my ECU there is definitely a label A63)? Would be too funny actually... now I totally agree that it doesn't make much difference to the idle at all, but the response definitely seems to change with the setting. I'll record it tomorrow if time and weather permits.

You only have the option of the bleed screws if your trimmers are disabled. If you adjust the trimmers you will notice an engine tone change if enabled. Don't expect the bleed screws to make significant changes if the bike is generally a bit rich. Quite common for a mate or even your own nose to tell you your exhaust gasses stink of fuel.