RESOLVED: 3 weeks troubleshooting, still stuck

Rocket Scientist said:
If I was in this situation, I would be looking for another MAP sensor. You've done a very comprehensive job of troubleshooting. It could be just the worst coincidence imaginable that it picked this moment in time to fail.
Click to expand...
Yes, my plan initially. But RIIITurbo fortunately guided me towards vacuum measurements. One of which shows that the MAP sensor is fed practically zero vacuum. I.e. it reports correctly what it's fed.
 
Yes, going to pressurise the entire vacuum line under water. But I'm pretty sure they prove leak proof as I've pressurised all lines and 3 into 1 connector individually.
These hoses are 16 years old, could be they have lost rigidity and flex instead of pass through vacuum
 


Here is what I managed to scrape together with wht was available. Not ideal and certainly not a permanent solution but I just wanted to see if I could get more vacuum fed to the MAP sensor if I eliminated the 3 into 1 piece and the hose that connects to the MAP. No difference. I'm leaning towards witchcraft again.
Pulled the plugs for a re-check of compression with a quality gauge (205-200-200) and the #2 and #3 plugs were clean and very wet. #1 was severely sooted.
I also noticed it has pumped through incredible amounts of fuel. after the problems started. Like 5-10 liters, probably during 15 minutes cumulative runtime.
I guess all the latter relates to completely useless data fed into the ECU, but I am starting to question ignition again (though I shouldn't)

While I wait for the vacuum parts to arrive I am going to set the F/L swith to 0 across the entire RPM range. If I still get no heat on cylinders 2 & 3 I should probably (very reluctantly) revisit ignition again? I do still have the OEM coils and wires.


 
I'm hoping for your lead on aged and softened hoses could be the case. I've already ordered anything elastic that see vacuum from hoses to transition pieces and their o-rings to injector o-rings(!). If that doesn't do the trick I'm considering exorcism
 

That vacuum hose arrangement looks like it would cause problems anyway.
The 3 tubes from throttle body nipple to the merger need to be all the same length and same length as the factory ones (255mm iirc).
And then the tube from merger to MAP sensor has to be same length as factory.
Does the local auto parts shop not have a X shape connector?

This is all because the ECU takes the vacuum reading (that it bases the fuelling off) in a fraction of a second, at a certain time vs the crank sensor. So any change to the vacuum tubing can have an adverse effect on the fuelling, as it impacts the timing of when the vacuum pulse hits the pressure sensor.

Changing F/L switch to 0 should in theory tell ECU to fuel based on throttle position rather than MAP value, and therefore circumvent an issue with the vacuum, but in my experience it doesn't work.


Plugs in cylinders 2 & 3 being wet indicates they're not sparking - could be because of massive over fuelling caused by the vacuum leak problem. Or could be an ignition issue - didn't you check for reliable spark on the plugs?
 
No luck finding any suitable x-connector. T, L,Y and straight yes, but x variant will be by mail order. I.e. at least 1 week.
Yes, I had plugs out, grounded and saw excellent spark on all 4 (cylinders 2 & 3) and there is no apparent reason that should have changed. So I am probably best off waiting for oe parts to arrive, before second guessing everything. But I need to get the pure throttle position fuel control test out of my system, just to see if I can get some combustion in cylinders #2 and 3. I have bought an IR temp gauge to get reliable readings
 
Just something to try
I do this on cars never tried on bike
On cars if you disconnect the electric connector from map the motor runs rough for a little while then sets a code then sets a default code then the ecu will set a default voltage and the motor will run w/o the map working.
 
i once had some champion plugs that had got very wet because of a carb flood and after i fixed carb it would never run right until i change the new champions to ac plugs. have also seen other new plugs that would not preform correct.
ps i have put plugs on the stove top and heated them to get the gas out of the plug to make them work also
 
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