620ie idle adjustment

[900Rebuilder]

Hi All,

We took Louise's 620ie on the Nottingham egg run yesterday and despite being a little cramped two-up it coped with the ride just fine. One thing I did notice was that the idle was set so low that it kept dropping onto one cylinder around the 1,000 rpm mark but was fine over 1,500 rpm with the fast idle lever slightly open. I had a quick look but couldn't see an obvious way to adjust the idle to increase it by 500 rpm - is there an easy way of doing this as I'm used to simply turning one screw on the carbs.

I also wonder if the bike needs balancing in some way like you do to carburettors?

Thanks - Ben

 

[Mr Gazza]

I'm pretty sure there is a stop screw on the throttle quadrant on the rh side of the bike where the throttle and fast idle cables connect.
It will be either on the throttle or fast idle quadrant.
To be honest you might just as well do it on the fast idle lever till you can fix it, as it should idle at 1000rpm or even a little lower. 1500 is racing, wasting juice and making it hard work in the 20mph limits!.
I'd start by putting some new plugs in or cleaning and gapping the existing ones, then look further if that doesn't work.
next down the list would be an ultrasound clean of both injectors followed by balancing the throttle butterflies if the problem persists.
Very last on the list would be investigating the TPS, but don't mess with that unless all else fails would be my advice.

Of course very bad valve adjustment might cause this as well, but I'm assuming you keep those in order?

 

[dacs]

Isn't the idle speed controlled by the ecu on the injected engines? Not used it (yet) but my reading suggests it can be set using JPDiag, or the official Ducati workshop tool.

 

[Mr Gazza]

I don't think so Dacs.
Not if you have a manual fast idle lever?
Besides which, it shouldn't be idling at 1500rpm.

 

[Dukedesmo]

Depends on the bike, some have a simple throttle-stop screw on the quadrant/throttle cam (916 does) but the later bikes got a system where it is pre-set and so not so easy to alter, not sure how the 620 is, maybe using air bleed screws but that will affect the mixture and balance?

I don't know what was wrong with the old stop screw method?

As for speed, IMO 1,000rpm is too slow, I have both my Ducatis set to idle around 1,200 (both have lightened flywheels though).

My old Guzzi idles around 1,000 which is OK once warmed up as it has a huge flywheel but it needs 'tickling' when cold or it will stall - I can't increase it though as the idle screws are fully in.

 

[900Rebuilder]

I'm pretty sure there is a stop screw on the throttle quadrant on the rh side of the bike where the throttle and fast idle cables connect.
It will be either on the throttle or fast idle quadrant.
To be honest you might just as well do it on the fast idle lever till you can fix it, as it should idle at 1000rpm or even a little lower. 1500 is racing, wasting juice and making it hard work in the 20mph limits!.
I'd start by putting some new plugs in or cleaning and gapping the existing ones, then look further if that doesn't work.
next down the list would be an ultrasound clean of both injectors followed by balancing the throttle butterflies if the problem persists.
Very last on the list would be investigating the TPS, but don't mess with that unless all else fails would be my advice.

Of course very bad valve adjustment might cause this as well, but I'm assuming you keep those in order?

Its just been serviced including valves by my friend who is Ducati trained so that (the valves) shouldn't be the issue but will bare it in mind. First stop will be looking at the plugs and the possible adjustment on the throttle cam.

 

[Nickj]

'IE' so it's a fuel injection system.
You can adjust the air screws and you can check the TPS between them that should do the trick.
Don't adjust the cable or fast idle, the adjusters are there for setting slack in the cables only.

Start off baselining the TPS & the intake body sync and only then move onto the air screw fine adjustment.

There's 4 things that might be a little out and cause this so you really need to go through it a bit more methodically than starting half way through. Say the sync is good, the TPS is a little out, one air screw is right and is cutting out, the other is wrong and keeps running OR the TPS is good, the airs are good but it's the sync setting causing the problem.
You might even have a linear or non-linear TPS, it's usually assumed that linears are found with some ECU's but in the usual Ducati way it isn't something you can count on! Sometimes they can be no-linears on the same ECU but use a slighly different ECU map.
This does make a bit of difference as you see different voltages from them at the same throttle positions, found that out on a 750IE after fitting a new TPS when it went from being just glitchy to being a hugely confusing throttle response.

Heres a good guide >> https://bikeboy.org/ducati2vthrottleb.html

 

[Mr Gazza]

Start off baselining the TPS & the intake body sync and only then move onto the air screw fine adjustment.

you really need to go through it a bit more methodically than starting half way through.

Any old school mechanic will tell you that before even touching the carb(s) (or fuelling, to bring it up to date.).
First check all the valve clearances. Then the points gaps and timing. Then the condition and function of the spark plugs and the air cleaner.
It's pointless trying to tune carbs unless the rest of the mechanical and electrical systems are in order and the same applies to a "modern" fuel injection system.
In this case it can be taken for granted that valve clearances and timing are okay, at least initially.
That only leaves the spark plugs, which are very easy to deal with.
Starting with the TPS is madness even if it does turn out to be the problem.
My TPS has not been touched since new, after over 50000 miles. The paint markers are still intact on the screws.
I do change the plugs at about 6000 miles though, and give the injectors an ultrasound bath when ever I can.

 

[jerry]

On that model the TPS is very critical for tickover and low speed running needs to be set at 152mv with throttle stop completely slack and screw backed off ,, , there is also a small adjuster for the Throttle on the cam where the cable is attached ,,, once that is done airscrews can be sat but You need to do it by ear unless you have an exhaust gas tester ... Your 620is may be able to have a TPS reset using JP Diag ,, depends on which year ??? if its 2001 or earlier it cant be done on JP Diag but later ones 2003 up can be

 

[900Rebuilder]

This one is 2005 - tbh we were out riding and I completely forgot about it but will investigate when I get the chance

 

[Nickj]

A small change in the TPS setting on both of the IE750's I had did make a big difference.

 

[900Rebuilder]

Is there something I need to purchase to be able to adjust this at home? Ideally not a genuine gadget either as I imaging the factory / workshop kit is mega bucks from Ducati

 

[Dukedesmo]

Not sure on the 620ie but on a 916 you only need a voltmeter to set the TPS. There is also 'Guzzi diag' which you can download for free and then use a cable into the diagnostic port to bring the info up on a laptop, the cables are cheap enough but, obviously you need to get the right one.

 

[900Rebuilder]

Not sure on the 620ie but on a 916 you only need a voltmeter to set the TPS. There is also 'Guzzi diag' which you can download for free and then use a cable into the diagnostic port to bring the info up on a laptop, the cables are cheap enough but, obviously you need to get the right one.

I had visions of having to buy one of those hand-held scanners that the newer Ducati's seem to need.

 

[Dukedesmo]

Baseline setting TPS on 916, note I have fitted a 2-core lead to the ECU with an external terminal block to connect a voltmeter to as it saves piercing wires and holding probes etc.

Simply undo and rotate the TPS to get the correct voltage (150mv in this case) with the throttles fully closed.

This to be done before messing with mixture/balance etc.

 

[900Rebuilder]

Baseline setting TPS on 916, note I have fitted a 2-core lead to the ECU with an external terminal block to connect a voltmeter to as it saves piercing wires and holding probes etc.

Simply undo and rotate the TPS to get the correct voltage (150mv in this case) with the throttles fully closed.

This to be done before messing with mixture/balance etc.

That sounds like a very sensible and ingenious way of doing the job! Do you have a picture of the connector at all?

 

[Nickj]

150 mv works on these too, reading taken off of a 1.6M ECU between Pins 16 and 30.

 

[Dukedesmo]

That sounds like a very sensible and ingenious way of doing the job! Do you have a picture of the connector at all?

Opened up the large plug/connector to the ECU, located the 2 pins for the TPS voltage (0-5v) and soldered on a short length of 2-core cable which I then fed through the sheathing/trunking to keep it weather-proof and fitted a simple screw-terminal block externally, that way I can connect a voltmeter to be 'hands-free' to adjust - can even run the bike with it connected.

Sits just in front of the ECU under the seat.

As for the other settings, as I have a bigger airbox on the 916, one that has the throttle bodies inside it, access to the TPS, balancing linkage, air bleeds and idle stop screw are all inside the air box so can't be got at with the tank fitted as would normally be the case.

I initially thought about making fuel line extensions so that the tank could be left on the bench but then realised that I can just fit it backwards and have access to everything.

I'm not sure that the 620 has this kind of setup but it is likely, otherwise you can get the OBD cable and software to do it via a laptop, here's what I use;

The 'Ducati/Guzzi-diag' (used to be called Ducati diag na dGuzzi diag depending on which version you had but the Ducati name was dropped, IIRC for legal reasons so is now called Guzzi diag but it works on both) software can then communicate with the bike, bringing up various data onscreen such as TPS voltage, RPM, water temperature, air temperature, air pressure etc. but, to be honest I find it easier and more consistent to use the voltmeter method but it is still useful for checking the other parameters and eventual fault finding (faulty sensors etc.).

 

[900Rebuilder]

I need to get me a laptop as I cant reprogram the Ignitech on the M900 at the moment either - also many, many thanks for the detailed response,

 

[Darren69]

Pagr 31 of the 620 workshop manual has the full procedure but its number 7 to adjust the idle which should be set to 1200 rpm +/- 50rpm