Hello, I have a stock 04 749r that I use as a track bike. The last few trackdays it has started cutting out when the throttle is fully open in 4th/5th/6th. It cuts out when the throttle is opened fully on straights. The best way I can describe the issue is that it's like the throttle is suddenly rolled off. The bike jerks and as you can imagine this is a bit disconcerting... When it happens my natural reaction is to roll off anyway and when I roll back on again, it's fine. I managed a test 'of sorts' on the long straight at Almeria. I deliberately changed into 5th at low speed (around 50mph) and opened the throttle all the way. The revs built slowly up to around 8k and then it cut off - no where near the rev limiter. If I ride the bike being careful not to open the throttle on the straights more than 90% (approx) then the issue never happens. When I ride this way it will rev right up to the limiter with no issues. Things I have done to try and rectify it (with no luck): Tried different fuels. New Fuel Filter and fuel pump. Added a breather hose to the fuel tank. Dyno tested it and could not reproduce the issue (although it was nice to see the old girl is still putting out 113bhp at the rear wheel). A friend suggested it may be the ECU? Wondering if there are any 749r enthusiasts out there that may have experienced a similar problem? I love this bike and not ready to give up on it yet...
Jerry may be your man? I have a 749R track bike that conked out last year. Not the same as you describe but it basically wouldn't rev. Turned out to be the dreaded fuel pump relay and general deterioration of wiring connectors behind the battery box. Change the relay (behind the battery box) and also relocate it to the almost made for it position above the battery. Btw, mine has a supersport tune (heads,cams,pipe etc)....138bhp. :Happy: Good luck. R
Is there a throttle position sensor fixed to the engine that could be playing up? I don't know much about your model of bike however your symptoms seem very similar to one of my mates who has an RSV4 Factory, I know it's a V4 and a very different bike. The RSV4 has a sensor placed between the 'V' of the engine (crazy italian position to place it, slap bang in the middle of all the engine heat) Anyhow when the sensor packed in due to it being cooked in the heat, I'd say he had pretty much the exact same problem! If you gave it full throttle it would die off and give very little power almost like limp mode! Roll the throttle back off and eventually it would recover. If you rolled the power on on slowley it would pull like a train, but the moment you went from 90% to 100% throttle it would die again until you rolled off slightly! Without wanting to state the obvious I'd say you probably need to get the bike on a diagnostic machine otherwise you could be guessing and continually spending money until you work out what is causing the issue. :-( Good luck, I hope you find the answer and post if up here ;-)
does sound like t.p.s. put a multimeter across the terminals and watch the resistance rise or fall cant remember which way round then you will get a sudden spike or drop as it reaches full throttle. not 100% conclusive as it could be breaking down under load. 5v (i think)going in and the voltage coming out will vary dependent on throttle position.
does sound like t.p.s. put a multimeter across the terminals and watch the resistance rise or fall cant remember which way round then you will get a sudden spike or drop as it reaches full throttle. not 100% conclusive as it could be breaking down under load. 5v (i think)going in and the voltage coming out will vary dependent on throttle position.
If it is the TPS then it is a bit of a pain to get at. Read this How To - 749 / 999 Tps Replacement | Ducati Forum Do you have access to JPDiag? You can see the TPS behaviour using it.
Check that the tank is clean. I had a nightmare trying to diagnose a fuel starvation issue and it turned out to be crap in the tank. OK stationary, but as soon as it was moving, the rubbish moved and caused enough of a block that it cut fuel flow. Reading your post, it sounds like fist, second and third, you're drawing fuel, but in higher gears there's resistance and you're getting issues. Sounds like a fuel flow issue.
Thanks for your responses guys, really appreciated. I edited my original post to add that the fuel pump was also replaced. The fuel tank was cleaned out at the same time so I guess that rules that one out. Will have a look at the TPS but am still puzzled as to why the issue didn't show up on the dyno. Is it the case that a dyno puts slightly less load on a bike than when it's on the road? Another point worth mentioning is that it always cuts out suddenly, it never stutters or gives the impression it is struggling for fuel beforehand. So if it is fuelling, then it's a sudden shortage under heavy load..
Start with the simple stuff first Battery connections, earth leads, earth fly lead on the ECU, coil/injector/fuel pump relay, battery (itself).
The exact same thing has been happening to me with my 749 recently - If I try and give it full throttle in a higher gear it just bogs down, but off the throttle and roll it back on it is fine? I only seemed to notice it after I had a Power Commander fitted so I assumed it was this and planned on having a look at the map - are you using a Power Commander on your 749r? Can be a little concerning when you move out to overtake and nothing happens!!
No power commander on mine. I've dropped it in with the guys at Gtec Performance. If they find the gremlin, I'll post the details here.
So, the lads at Gtec can't find a single thing wrong with it. They even tested on the dyno with increased loading and the gremlin refused to appear. It's going to Almeria circuit again shortly so if it's still playing up I will try and catch it on the GoPro which might give some more clues...
