RESOLVED: 3 weeks troubleshooting, still stuck

Changed cam chain, i.e. removed alot and refitted alot.
(Timing is spot on, verified)

Engine started and idles (sort of) but only consistent combustion is on cyl 1.

Removed cam cover and clutch cover again, double checked timing, checked valve clearance, all good. Refitted and started engine, exactly same. Cylinder 1 hot, cyl 2 & 3 much colder.

Checked compression, consistent and good all 3

Had plugs on cyl 2 & 3 out, grounded by copper wire to frame and cranked. Excellent spark on all plugs.
Plugs were dry when pulled out.

Checked fuel pressure: 43 psi when pump primed, slowly descending to 40. 43 when engine running.

Throttle body pressures are high on all 3: 800-900 hpa. Pulled the throttle body and transition pieces, checked for damage. All good including orings. Checked vacuum hoses. All good, but secured them with strips anyway.

Checked 12v to injectors (key on, pulled connectord and measured), 12v feed ok on all. Checked continuity from injectors ground pins to ECU plug: full contact.
Checked injectors duty cycles: At least the ECU thinks they open and close.
Pulled the fuel rail (key on, primed fuel pump and applied 12v to each injector): Good spray pattern on all 3.

Loaded stock map onto ECU, no difference.

Still runs like sh*t.
Help!

Valaas said:

Throttle body pressures are high on all 3: 800-900 hpa.

Click to expand...

This, I am sure, is an indication of the problem.

Normal MAP reading at idle is like 500s, 600s, depending on altitude and some other factors.
8 or 900 is indicative of a leak, that's the kind of pressure the MAP sensor sees when nearing wide open throttle and approaching atmospheric pressure i.e. 1000 or so.
When the MAP sensor sees 900 then the ECU thinks the throttle is quite open as it appears a lot of air is going through, and hence injects lots of fuel to keep up... and since your throttle is closed, in reality, this means an overfuelling scenario and the engine bogs and dies, smell of unburned fuel etc.



In order to change the camchain you had all the stuff atop the engine moved etc so I really think there is something to do with MAP tubing or the nipple blanks on the throttles.
Something is leaking and letting more air in for the MAP sensor to see, but not into the engine.



The yellow circled nipples are where the 3 MAP tubes connect to, and the 4 circled in blue should have blank plug/boots over them (unless you have a Cali bike and the emissions control system is plumbed to these then).

Anywho the leak in the MAP sensor / throttle body tubing is most likely the culprit - this will make the bike run like it's on 1 or 2 cylinders.

There is also the possibility that there is a fuel/ignition issue on 2 & 3 that prevents it running right, this causes lower vacuum and of course when the MAP sees lower vacuum it exacerbates the situation by making the ECU inject more fuels (too much fuel).
But more likely to be an air leak issue imo.

Does it run better when you rev it up a little?

You know, I totally agree with your reasoning. After verifying timing, valves, compression and fuel pressure I firmly believed the solution would be finding a vacuum leak. Have chased down false air successfully in the past, and you are right, the ECU is told near full throttle (i. e. near atmospheric pressure)
But I can't find a leak. Even secured both blinds and hoses with cable ties. Never though I'd remove the transition pieces, but wanted to cover anything that can possible allow false air in.
Your point is valid nonetheless, the ECU is continuously fed false pressure data.
MAP sensor failure? (but has that ever failed? Worked fine prior)

Yes besides the intermittent intake blowout it runs much smoother above 2-3 kRPM.

it may be where the throttle bodies fit at the bottom
a shot of starting fluid at the bottoms might locate a vacuum prob
a few guys have had this problem

Few thoughts - are your tubes the stock factory tubes, untouched?

Did this problem start only after reassembling the engine?

You could splice a T piece and analog vac gauge (oil filled best) from local auto hardware shop in beside the MAP sensor and see what it's reading just to verify the MAP sensor is accurate.

R-III-R Turbo said:

Few thoughts - are your tubes the stock factory tubes, untouched?

Did this problem start only after reassembling the engine?

You could splice a T piece and analog vac gauge (oil filled best) from local auto hardware shop in beside the MAP sensor and see what it's reading just to verify the MAP sensor is accurate.

Click to expand...

Fitted new vacuum hoses (same id as stock) no difference. Those are replaced now with stock untouched but cable strip tied tubes.
Problems started after reassembly yes.

Very good idea, bought a vacuum gauge today (unfortunately no oil filled available) and will check what pressure the MAP sensor actually sees.

Ok good. Unfortunately I had a similar problem years ago so have felt this pain.
The non-oil-filled needle will bounce around a LOT but if you note the min & max deflection and just go with what's the mid point, it will do, for indication.
Are you T'ing the vac gauge in beside the MAP sensor?
(If just using vac gauge then best disconnect the MAP sensor from its plug, or it will see atmospheric/1000hPA and tell the ECU so)

Apr 19, 2018
1,146 views • Apr 19, 2018
Using a vacuum gauge to show engine is pulling normal vacuum, but the MAP sensor is reading low vacuum due to problem with the vacuum tube from throttle to it, which in turn causes ECU to overfuel, which causes engine to bog & die

TURBO200R4 said:

it may be where the throttle bodies fit at the bottom
a shot of starting fluid at the bottoms might locate a vacuum prob
a few guys have had this problem

Click to expand...

Thanks, I'll get new transition pieces and o-rings to eliminate this very possible false air source. Appreciate your input!

R-III-R Turbo said:

Ok good. Unfortunately I had a similar problem years ago so have felt this pain.
The non-oil-filled needle will bounce around a LOT but if you note the min & max deflection and just go with what's the mid point, it will do, for indication.
Are you T'ing the vac gauge in beside the MAP sensor?
(If just using vac gauge then best disconnect the MAP sensor from its plug, or it will see atmospheric/1000hPA and tell the ECU so)

Apr 19, 2018
1,146 views • Apr 19, 2018
Using a vacuum gauge to show engine is pulling normal vacuum, but the MAP sensor is reading low vacuum due to problem with the vacuum tube from throttle to it, which in turn causes ECU to overfuel, which causes engine to bog & die

Click to expand...

I tee inn the gauge. The readings translates into "hardly any vacuum".. The needle vibrates between neutral and 100 hpa, which I believe clears the MAP sensor.
Going to order 3 new transition pieces + o-rings and clips + oe tubing, just to be sure.

OK good so MAP sensor may be ruled out.
You could try put the vacuum gauge (on a short piece of hose!), connected to each of the 2nd set of nipples on the throttle body, in place of each blank, one at a time.
The idea is to see if there is a vacuum leak on any of the 3 cylinders' throttles.

I doubt all 3 transition pieces have the same leak.