Stepper Motor / IACV

[GWL]

Well, I'm still trying to get the old Tiger to run at tickover. I've been having to grab an hour here and an hour there due to health problems (3 slipped discs in my neck). I've changed the fuel filter (Ducati),spark plugs (very black and sooty) etc. I took off the IACV and separated it from the stepper motor to clean it. I happened to notice that the white plunger always seemed to be at the top, which would suggest to me, perhaps incorrectly, that as it is blocking the air holes at that position it would run rich. I manually pushed the plunger down then tried to pull it back up to see how free it was. When I did this the plunger came out really easily. Too easily!  :shock: There is a threaded rod that runs through the centre of the spring that is screwed into a plastic housing. I can only assume that this plastic housing pushes and pulls the white plunger to alter the amount of air. The metal rod has stripped the thread in the plastic housing. It can now push the plunger up but cannot pull it back down so the plunger is permanently at the top blocking off the air holes. Could this be the reason for all my non tickover problems? Starts fine , won't tickover for more than 5 secs then dies. Pulled the plugs again and they are sooty again. I'm going to araldite the threaded rod back in to see if it solves anything. If it does then I'll buy a new stepper motor and hopefully that will be job done. Has anyone else experienced this thread stripping before?

[GWL]

I guess that's a no then?

[Stretch]

Be patient.   8)

[GWL]

Yes, my apologies. Patience is not my strong point. I'm just really frustrated that I can't get this thing running.  Symptoms are:

starts fine
runs erraticly for 5 secs almost like it's missing (about 500rpm)
cuts out
starts again easily
runs erraticly for 5 secs   you get the picture.
I can rev it when I get it started but it runs very rough almost like its only running on 2 cyls. I then let it idle and it cuts out straight away.
lots of exhaust smoke like its very rich.
Any help would be very appreciated so I can actually ride the tiger.
Once again my apologies for my lack of patience :oops:

[Bixxer Bob]

IACV controls air at tickover and overrun so if it's rough once you twist the throttle, I'd be looking elsewhere.

You say it sounds like it's only running on 2 pots.  Even after a few secs, if you feel the downpipes you'll know if one pot isn't running as it'll be cold - and it won't tick over.

If you've been running very lean for a long time the ECU will have adjusted the long term trim very rich.  To reset this, you need either a Tuneboy (no need for the tunedit key for this one, just the free software and a cable) or it's dealertime I'm afraid.  The 12 minute tune would work but I don't think you can get it running that long.

Make sure the tubes from the IACV are not kinked, blocked or leaking.

Disconnect the air tube from the airbox (rear right side) and from the ECU (right side) and ensure it's not blocked or leaking (don't blow down it while connected to the ECU, you could damage the sensor).

That should keep you busy a while.....

Is the air filter clean?

[GWL]

Thanks BB I'll try what you've suggested today. I'm also keeping a close eye on your posts regarding the TB gasket replacement and whether that helps your problems.I trust you'll keep us posted. :)
The main thing that's puzzling me is how I can ride it back from Bath to Tenby (150miles approx) and it runs perfectly. It then sits for 2 days and I have all these problems and haven't got it running since :?

[GWL]

O.K I've checked the down pipes and they all get hot. There are no leaks or kinks in IACV pipes and no blockages or kinks in airbox pipes.
I'm only guessing here but it's like it's getting too much fuel and it's flooding.(as BB suggested) Like I said it will start o.k and run for 5 secs then cuts out. It will start again and run for 3-4 secs then cuts out. It will start again and run for 2 secs then cuts out. Then it starts again and stalls almost straight away. If I leave it for 5 mins it does the same thing all over (5 secs,3/4 secs,2secs etc). very confusing :?

[Bixxer Bob]

Sounds like you might have the fuel rail pressure sensor stuck, overpressurising, thus getting more fuel than you should through the injectors at each opening.

You need a dealer to check it out, it's not something you can do yourself without the proper tool.

A browse through the Trumph manual suggests the above, or the IACV valve stuck, but you've already been there.  Are you sure it's working?  Hard to do without a Tuneboy which can check it with the engine off.  A stethescope would allow you to hear it moving. But you'd have to rig up the tank next to the bike first.  I stand mine on my workmate when I'm balancing the TBs.  

It might be worth contacting one of the Tiger breakers that advertise on Ebay and see if they've got a spare.  Or maybe a mate that you could swap as a test?

[GWL]

Thanks BB. When you say fuel rail pressure sensor do you mean the fuel pressure regulator that is situated on the side of the tank next to where the fuel connectors are-- on the fuel pump mounting plate?(has a small bore pipe coming off it)  Sorry to sound really thick but as I said I'm new to working on bikes and am not "au fait" with some of the terminology.
By the way I know what you mean about being dragged off shopping..yawn!

[Bixxer Bob]

Sorry, yes that's what I meant.  Loose terminology..... :roll: