bike-parts-ducati are a great source of diagrams & part numbers. A good first stop when comparing prices... https://www.bike-parts-ducati.com/ducati-motorcycle/Monster/2001/Monster_S4/103
The throttle bodies don't have to come off. They are only shown of thew bike in the illustrations to highlight where the adjustments are made. The only tricky bit is setting the TPS voltage to 150mV ± 5mV as it tends to move as you tighten the screws. I usually set screws just barely tight and tap the TPS in the direction I want to move it then tighten the screws gently. It the reading moves by say + 15mV then I try again by setting it to 135mV and see how that goes the I tighten the screws. After a few attempts you get the hang of it. I'm not aware of which after market air temperature sensors are available but the coolant sensor is the same as fitted to the Fiat Punto 1.2L.
The magnetti air temp sensor is readily available from numerous online car parts distributors such as autodoc, carparts online etc. That too was fitted to numerous European cars of the same era.
I got an injector off! I tried all sorts but what worked in the end was squirting some grease around the top and warming it up with a hair dryer, which freed it up and it came out with some long handled pliers. Connected the removed one (H) to a battery for the click test, it did. Tested the ohms on the multimeter, it bounced around a lot. (Manual says 14ohms at 20'c). I have 2 multimeters, they are quite new, one said 14.5 the other said 15.9. Kept trying, kept getting different numbers on the two meters 13.1 and 14.6. Check the V injector (still fitted) and that's 14.6 and 15.8. I tried the click test and then did a reading after that, it changed the numbers again. Some times it was 17, other times 12 on the H injector. The V one was consistently 14-15. So either both meters are fubar or the injector(s) are. Buying second hand won't guarantee they work either . Any thoughts, advice? I located the air pressure sensor under the headlight area, I'm going to get that off tomorrow and test it. I've decided not to touch the TPS. The more I think about it, the more I think that it's the injectors that are the problem. The sparkplugs etc should be arriving tomorrow or Tuesday. Cheers for your help
Have you checked the TPS baseline voltage setting and, whether it increases incrementally/smoothly? Try 'wiggling' it with a voltmeter attached to see if it moves - my 916 suddenly started popping and farting, wouldn't run smoothly and wouldn't idle at all. Turned out one of the screws holding the TPS in place was cracked and although appearing to be in place, it was letting the body of the TPS move slightly with the throttle shaft. Wasn't obvious until I completely removed both screws but, new screw fitted, closed throttle set to 150mv (TBs synced and CO set) and it runs as smooth as silk again.
I don't trust the 2 multimeters I have, I can't fathom why they come up with different readings to each other, on the same settings, unless it's the component that's faulty. The fact the injector has a big range of resistance, suggests that the spring is perished. There is an injector cleaning/refurb company, which is a far more attractive option than £100+ for 2nd hand parts or the £345 oem new. Thinking about it, both sparks were soaked with fuel, one is in range, the other isn't... it's overfuelling. Dammit this hurts my head.
TPS being wrong can cause over fuelling. I'm not saying that's the cause but I'd be making sure everything is setup properly before buying anything or even removing injectors for cleaning. I've never had the injectors cleaned on my 916 and it's done 53,000 miles and still runs perfectly.
Get a hold of Melcodiag. It will tell you if any of the sensors are faulty or giving erroneous readings. If the air sensor says -5° when the temperature is actually 15° then it's obviously faulty. It will also allow you to read the TPS voltage so that you can read the fully closed and fully open values. I would do this before spending money on getting the injectors cleaned. I did just under 50,000 miles on an St4s and 46,000 pm a 1200 MTS, none of them ever needed injectors cleaned.
With the multimeter , you may have resistance via the probes or the meter is not zeroing to 0hms. hold the red + and black - cables to together on the Ohms setting and see what is or if any resistance is measured , you can then subtract that from your readings. In a perfect case you would have 0.0 ohms. I know that I can put my needle probes in my works calibrated meter and get 0.2 ohms and if I put my clip on probes in I get 1.6ohms.
And when measuring low resistance values you will often get inconsistent readings just because of the lead resistance and how well they make contact with the sensor terminals.
Craig and Luke at Motorapido are used by a hell of a lot on the forum for parts. They are top class guys and know tons about old and new Ducatis. Quick to mail out too. Nelly (member in here) at Cornerspeed is not too far from you if you get properly stuck and although I have not used him personally he does come highly recommended. Hope this helps.
