Sunday, September 20, 2020

Multistrada 1000 not idling - an ecu based solution.

I had an MTS1000 in for some work, part of which was a service after sitting for quite a long time.  One owner bike, but the owner's recollection of what has happened to it service wise over the years was one of the vaguest I've encountered, and the dash had been replaced twice under warranty so total km travelled was even less clear.  With the current odometer reading around 13,000km, I would assume it had had at least once valve clearance service, but I think that's possibly a poor assumption.

Compounding all this was the fact the bill, in dealing with a heap of other stuff, was rapidly closing on a number around the same as the bike's current value.  Which means I'm not too willing to go digging more than I need to.  On one of these, to get to the bits you need to for a valve clearance adjustment, you start removing the panels at the back, move all the way to the front, remove more bits then remove the tank.  Time consuming, and time is money and the money was running for cover.

So an "annual" service is what it got - fluids, timing belts, etc.  I checked the throttle set up, and that's where it went a bit hmmmmm.

The MTS1000 was the first Ducati with an idle control valve ("stepper motor", etc).  Being a 2003 model, it was also the first with the 5AM ecu, in this instance the 103 hardware version.  When they came out, I recall being told that the throttle opening, as displayed by the diagnostic software, was "throttle opening plus idle control valve equivalent".  So when you check the throttle opening angle cold you might see 4.5 degrees, and hot 3.5 degrees or so.  Confusing at best, but when that's what you've got to deal with, that's what you do.

Any model with an idle control valve doesn't need the air bleeds (the little screws on the sides of the throttle bodies that allow air to bypass the throttle blades) opened, as their primary function is to allow you to set the idle speed.  I also use the air bleeds to equalise the idle mixture between the cylinders, in which case you open the air bleed of the richer cylinder to lean it off to be the same as the leaner cylinder.  Meaning one air bleed should be fully closed, although some variation to that will be discussed later.

On this bike, the air bleeds were both open 1 1/2 turns.  The idle trimmer setting of +29 was also a bit concerning, but given the air bleeds were out that far, the trimmer setting didn't really surprise me.

I don't recall it being overly hard to start and get running when I first started it.  Not for a bike that had been sitting for 3 years anyway - the fact it even fired up surprised me.  As it warmed up I got set to check the throttle body set up and wound both air bleeds fully in to adjust the running balance, then got on to the idle mixture.

I found the mixture quite dirty, by which I mean it had a lot of Hydrocarbons and Oxygen in the sample.  This is usually an indication of richness, so knocking the trimmer back was the obvious thing to do.  Dropping it back to 0 both leaned it out (not as much as I might have thought though) and cleaned it up (not as much as I might have hoped though), but the dirtiness remained.  Sometimes, the best way to fix this is to crack the air bleeds a 1/4 turn.  It's amazing how it can drop the HC and O2.  I suspect it may have something to do with the black carbon crap that builds up around the edge of the throttle blade in its closed position, but when it's a couple of hours work to even check that out, you usually don't.

I ended up at 1/2 turn out on one, and 1/4 on the other for around 4.5% CO.  But the idle control valve didn't appear to be doing what I would expect on restart.  I tried doing the test via the diagnostic tool, but it didn't seem to want to do that.  I pulled the hoses off and blew air through the nipples into the manifolds, and they were clear, and with the ignition off the valve was open so I blew back through the valve into the airbox, and that was clear.  But when you turned the key on the valve went to the fully closed position as it's meant to, but then didn't come out again.  I sprayed some carb cleaner into the outlet nipples, then let it sit for a while, then blew that out and tried some Inox to lube it up and then it would, at key on, close then open again.  Fixed!

Not, as it turned out.  By this time the engine was cold.  With the little valve to manifold hoses back on, hitting the start button got a fire and run at very low rpm for 10 seconds maybe, then stall.  I pulled the hoses off, so it had no obstruction, and at that it idled a little longer before it stalled.  I could see the valve doing a little bit of movement during this, whereas previously it'd been doing nothing at all, and I was thinking maybe it's just too lean with the excessive air leak it now has.

Another trick I try with an idle control valve is to disconnect the valve with the ignition on, then with it disconnected turn it off and on again to make sure it has logged a fault, then turn it off, connect it again, turn it back on and clear the fault.  That can sometimes wake them up to some extent, but not here.

On a previous MTS1000 with an issue like this I had played with the base throttle opening (as in what I did to the SC1000 outlined in the Linear TPS setting report, which, I must say, hasn't really worked since) and tried different ecu files and it sort of ended up ok-ish, without being overly convincing.  But, as above, getting that into this one was not an option timewise.

When you have one of these idle control bikes that won't, one of the first things to do is a TPS reset, the electronic procedure via the diagnostic tool.  And, coupled with that, is making sure the idle stops haven't been played with.  There's a fairly obvious stop easily adjusted just behind the throttle cable wheel on the RH side of the throttle bodies, and fairly obvious tempts those that like to fiddle.  Not a good idea on these, but not uncommonly messed with.  The much less obvious stop between the throttle bodies is very rarely messed with, so you usually have a fail safe there.

So, particularly if the paint is missing, you wind that out and make sure it has no influence.  You can see the throttle opening change on the diagnostic tool if it is an issue.  I've seen winding that previously messed with stop out and doing a TPS solve issues like this before.  I must add, at this point, that I've also seen too tight throttle cables have a similar effect, back to the BMW F650GS days.

Anyway, I did a TPS reset to no effect.  I read the file out of the ecu and flashed it back in again (seen that work before).  Didn't help.  Tried a different file with the same result.  I was thinking I might give a 610 ecu and file a go, just to see if anything changed.

But I thought I'd have a look at the original file anyway.  The specified idle speed is no higher than 1300 rpm, but given it was nowhere near that I thought I'd raise it to 1600, just to see if anything changed.  Also, given that the engine would start then peter out and I've seen that due to not enough enrichment, I got into the start up table and richened the soon after start columns to see if that helped.

Below are target idle speed maps (1 row x 16 temp breaks is how you would define this one), which is measured against engine temperature, for two of the MTS1000 files I have, plus what I tried setting it to.


With the original files, the idle rpm I would have expected to see (if all was going to plan) was 1,300 rpm cold and 1,200 rpm hot.  Keep in mind that I didn't put 1,600 rpm in the target rpm table because I actually wanted 1,600.  I put 1,600 in because I wanted to see if it could do it.  There's no point changing it from 1,300 to 1,350, because it's too small a change to really notice definitively.  Make a big change - if it works, great.  If not, move on to the next thing.

The start up table is a pretty cool thing.  Back in the P7 days, there was only an engine temperature correction table to give enrichment for both differing engein temps and cold starting.  Now that might sound like the same thing, but there's differences in fuelling required based in how cold you're starting from and how long it's been running from cold.  I tended to bump this up a bit on some bikes, so that, at say 5 degrees celsius engine temp, it might have in the range of 40% enrichment to make it light up nicely.  I actually think some of the early 851 start issues, where people would claim the bike was "flooding", were due to not enough enrichment to start, but enough to foul plugs and send it all pear shaped.  Sometimes a bike will crank and not fire from cold, but if you let it sit for a minute or two then try again will start straight up, and I think that's because the residual fuel from the first hit, when added to the second hit, is enough and off it goes.  Just a theory.  I've seen lots of late model stuff - M1000, M1100, Guzzi Breva/Sport models like this.

But, with my 851, I find that if it's a hot day - say 30 degrees ambient - it'll fire then not be so happy because it doesn't have enough fuel to keep running due to the trim at 30 degrees not being enough for a "cold start".  Bump that up and it'll start fine, but then on a cold day it's already up and running by the time it hits 30 degrees engine temp and then it's too rich and gets lumpy as it warms up.

The start up table adds fuel based on rotations since started, and is a decaying enrichment table.  Adds quite a lot more fuel for the first 4 or so rotations, then starts dropping it off in the next 4, etc, up to 2,000 or 4,000 rotations, depending on the ecu.  This first appeared with the 1.6M, and it means the engine temp trim table has much less enrichment - usually in the range of 15% maximum.  But add the start up table's 20 - 30% and it'll fire up and go.

This is why the 1.5M ecu runs rich every time you start them for the first 3 minutes or so.  It was annoying there, but better applied here with the 59M/5AM series.

In this instance I made it 10% richer for the columns of 8 to 510 rotations since starting, which would be the first 30 seconds or so of running.  10% is usually enough to pick them up nicely.

But, none of that shit made the slightest difference.  Well, it smelt a lot more fuelly after I turned it off after a couple of 10 - 20 second poor running start attempts.

The next step was to look elsewhere.  One of my pet loves when trying to make things idle is ignition advance.  As in adding more.  These bikes have a separate idle 
ignition advance table, a single line map if you like - 1 row, 32 rpm break columns - and with that you can set the advance when the throttle is closed.  As the lowest rpm break point is usually 900 or 1,000 rpm, it's well under the desired / target idle speed and you can usually taper the amount so at 1,000 rpm it might have 15 degrees, but at the rpm you want it to idle at - and here if it has an idle control valve you need to look at the target idle speed as set in the ecu file - you can drop it back to maybe 10 or so degrees, and then the same again at the rpm break above the target idle speed so the idle is nice and stable and not trying to hunt higher as it picks up engine heat, etc.  Meaning when it's cold and not wanting to idle high, the increased ignition advance at the low idle speed will help keep it running.

On old 851SP - 916SP, which have 290 to 300 degrees cam duration at 1mm lift, you can go up to 25 degrees or so advance at idle and the difference can be quite amazing.  I
gnition advance really is the best stuff.  I have an 851/888SP2/3/4 eprom that has the break points moved around a bit so it has 25 degrees advance at 1,000 rpm and then 15 degrees advance at both 1,250 and 1,500 rpm.  That way it has a heap of advance to support the low idle when cold, and less at the desired 1,250 rpm idle speed and then not changing for 250 rpm so that the idle speed is nicely controllable.

Anyway, I'm meandering - if you have an idle control valve as the MTS1000 does here, and it's doing its job, then you won't have a low idle speed at cold idle.  Well, you shouldn't, and that was the problem with this MTS.

Some of the files have quite surprisingly low ignition advance numbers at idle, in the range of 0 to 2 degrees.  Not as bad an many of the MV models, which have retard, but still enough to lead to some idle instability.  Part of the table from the MTS1000 file is shown below.


Now, some are possibly thinking that going from 0.5 degrees advance to 15 degrees advance is an extreme change.  Correct, it is, but again it's a case of making a change that is noticeable, and really a change that you want.  I usually use a rule of (preferably) at least 10 degrees advance per 1,000 rpm.  That's a bit ish, depending on what you're doing, but it's certainly a lot more valid than 0.5.  At low throttle opening cruise I'll usually add another 5 to 10.  Some of my revised ignition maps for the late models bikes will see an additional 10 to 15 degrees at low throttle over the original.  For an MV, more.

Given the target idle speed is no lower then 1,200 rpm, the advance under that is somewhat irrelevant as long as the idle speed does what it should.  But if it doesn't, or the engine speed drops under load, it should recover.  With 5 degrees less at 1,400 rpm, there's no chance of the idle creeping up, all else being equal.  The advance above that rpm can influence how the engine returns to idle once the clutch is pulled in, and having it low there gets rid of any holding up issues.  Some of the Guzzi Breva/Sport models would do that, and cutting the advance down a lot would fix the issue.  It's not really otherwise important - there's no actual running condition where the engine needs to support load at 1,800 rpm with the throttle closed.  I did have a 1098R like that at one point - it was an issue with them I was told.  I had one go at it, but I think the owner decided I was a dickhead before letting me have a second try (it can be an iterative process), so I didn't get to fix it.

With the increased ignition advance change, the bike idled happily from cold.  As the engine temp rose, the idle speed started creeping up too, getting to over 1,400 rpm before I turned it off.  That made me realise that the issue previously was it wasn't capable of reaching that rpm.  Why I don't know, as it would have been fine when new like that.  Possibly it had a lot of closing clearance, and the high hydrocarbons could back that up.  But it was much happier now, and a win's a win.  With that, I reset the target idle speed and start up tables back to their original setting, meaning the only ongoing change was the ignition advance at idle.  Well, that and the idle trimmer not being +29 any more, which I would hope had made a decent change to how it ran.

4 comments:

احمد said...
This comment has been removed by a blog administrator.
motoguzznix said...

Hi Brad

I follow your blogs for a long time. There was a lot to learn from - maybe the following is also helpful for you. Your Multistrada story reminds me on an experience with my Guzzi 1200 Sport some weeks ago.

The bike idled like crap, shot very loud when driving with closed throttle, sometimes stalled before getting hot after cold start.

The stalling issue was cured by increasing the ignition advance below target idle speed up to 20deg.

But still bad idle quality - my Zeitronix lambda tool showed an AFR of 16 at idle. This convinced me to multiply the idle stepper table by 1.24. Result was the AFR dropped to 13,5 to 14 and idle quality increased a lot. The downside was the idle speed didn't drop below 1800 to 2000 rpm most of the time.

Observing the stepper function with the guzzidiag software showed the idle stepper function was ok, it settled to the minimum of 50 steps possible. But still too high idle speed. A try to set the minimum steps to 25 was not successful, a lot of tables seem to influence that.
So I concluded there is too much air sucked into the engine at closed throttle and the better mixture given by my enrichment of the idle stepper table makes the engine rev higher. It turned out the throttle bushes and sealrings are worn and false air enters this way.
Since I did not want to tear down the whole throttle system to rework all sealers and bushes, I decided to touch the holy sealed throttle stop screw. I closed the throttle by about 60 deg - assuring I can return to the previous adjustment if necessary.
Bingo! Idle speed is now regulated exactly to 1150 rpm which is defined in the target table. With the lower amount of air now sucked through the throttle, the stepper is able to regulate the idle speed - it was simply out of calibration before.

My conclusion is the idle stop screw is only a calibration for the stepper table. For the main fuel table it is not relevant - the throttle reset is the calibration for.

Best regards
Ernst "Motoguzznix" Papousek from Austria, not Australia.

Vuk said...

Thank you Brad, amazing knowledge! A lot of ink on this issue on the MTS forums, with no avail. Thanks for sharing!

Vuk said...

An innocent question— shouldnot replacing malfunctioning IAV be the first optikn? I mena we the readers of your site / blog would cwrtainly lose the wealth of information you provided in this article, but I just wanted to check why you did not follow that path.
Thanks