Spitting and popping..?

[docc]

Al, I'd need one of those nifty digicams to do it up right. Plus, I feel like the "How - To" threads otta be penned by someone more qualified than just tinkerin' me.

 

One of the things that complicates it is how much we've each changed our bikes. Lot's of different exhaust, air filters and then there are Power Commanders. It's a case of what works for me may not work for you.Further, some of us are hacking into the ECU with a voltmeter and others are using software and a PC. How would we proceed with a task like that?

 

Gio, yes, the 'idle screw' would be the horizontal stop screw which determines the minimum opening of the throttle at idle. The manual calls it the "adjustment screw." It is also careful to say not to use it to adjust the idle ! The idle is a balancing act between the CO level, TPS setting, air bypass and synchronization.

 

BTW, what is "LHS?"

[al_roethlisberger]

..hrmm, understood, but then again the basic procedure of setting idle, etc... and which screws we are talking about would be a great pictorial how-to if anyone wants to take it on

 

al

[RichMaund]

LHS?

The Chrysler my Dad used to own?

Sorry, couldn't resist!

[Gio]

Hi,

 

Point taken - what is an accepted abbreviation for one person may be meaningless for another. I use LHS and RHS to denote left and right-hand side respectively.

 

I sure hope this elusive synchronisation is my ticket back....the motor was running just peachy before this episode.

 

Gio

[Gio]

This is not intended as a "how to" but since I have been making some notes during my education on syncing (an on-going project..) thought I would at least share them for review / possible basis for expansion by others.

 

This is what I have so far and is based on a V11S fitted with a PC and using conventional mercury "carb stix". I do not have access to a CO analyser so that part of the procedure is missing.

 

Checking TB sync....(?)

 

1. Install manifold adapters and verify synchronisation (vac spec = 7mbar or ~0.5cm Hg). Re-install blanking plugs (or temporary ones if adjustment required - I used small pieces of tube with one end sealed)

 

2. Check / set TPS. Closed should read 150mV (black/violet wrt violet at the ECU connector - thanks Docc) but I used the set-up page from the PC to verify that % throttle was from 0 to 100%.

 

3. Adjust idle to either 1050 (manual) or 1100 +/- 50rpm using the horizontal stop adjuster (2mm hex) on the LHS (left side) TB. This overides the stop on the RHS. Again I used the display from the PC to monitor rpm.

 

4. Fully close both air by-pass screws located on the underside of both LHS and RHS (right side) TB's (should have been between 1/2 and 3/4 open)

 

5. Bring the adjuster on the RHS TB flush with the stop (I had ~0.5mm gap following the above step) by loosening the screw, sliding the plate and re-tighten).

 

6. Adjust the balance using the thumbwheel on the connecting rod...*

 

7. Re-open both air by-pass screws between 1/2 and 3/4 turns (mine were set at ~5/8) out from closed.

 

* This is the part I'm still struggling with. I found that I can only do this by holding the lock-nut on the RHS end of the rod (8mm) to prevent the link twisting and then turning the thumbwheel on the LHS.

 

How much would anyone expect to need to turn the adjuster if the imbalance was say ~2cm Hg as measured using a carb stick? I have tried +/- 1/4 to 1/2 a turn each way but the readings are all over the place (hence the inquiry about the Twinmax as an alternative).

 

I always "calibrate" each tube using a syringe before using (eg 15cc on the syringe gave 43cm Hg on # 1 and 2 etc). See earlier post for results.

 

Please feel free to add or correct anything - this is a first attempt.

 

Gio

 

(now with even LHS - as in less head shake...)

[docc]

Gio,

 

Thanks for taking the time to give us a procedure on this.

 

 

I would expect about a full turn of the thumbwheel to move the mercury 2 cm. Holding the throttle steady "off idle" should stabilize the columns. This is 1500-2000 RPM and up to perhaps 3000 rpm. Use caution releasing the throttle as the vacuum will increase and you don't want the motor to ingest the mercury!

 

Do the Hg columns still jump around at a steady, off-idle throttle?

[Gio]

No worries - least I can do in return for the help.

 

I turn of the wheel sounds reasonable but I was finding that much less would alter the results both ways (eg with 1/4 turn LHS/RHS went from 18/17, 18/19, 27/26 and 33/35 cm at 1,2,3 and 4k rpm to 24/24, 21/22, 26/26 30/34cm) but yes, the readings do stabilise at steady throttle.

 

Now I must admit the old carb stix have seen better days, and at least some of the mercury has already made unwanted excursions. I was also getting some water condensing out into the tubes (who knows where that comes from?) which sometimes breaks up the mercury columns. The Twinmax product sounds like a much better alternative to me.

 

So since I leave for my trip shortly, I have decided to visit my dealer this morning to have them diagnose the problem. In preparation for this I checked the valve adjustment last night (1 thou loose on both inlets, 2 thou loose on both exhausts) and adjusted (I use 0.1 and 0.15 mm = 4 and 6 thou respectively).

 

A final test ride indicated that I still have the original problem (maybe slightly better but this could be wishfull thinking) so I'll report back later.

 

Thanks again for the advice,

 

Gio

[Gio]

Update :

 

So the conclusion from my dealers diagnosis was that whilst everything appeared to be set up ok (TPS, throttle opening, idle) and synchronisation was within one or two cm (considered ok) the bike was clearly not running correctly. So finally the mechanic removed the fuel filter and back-flushed it into a pop bottle for inspection....

 

Holy *#%! you should have seen what came out - a thick suspension of very fine particles, dark grey in colour. This is the original filter with only 27,000 km on the clock so it was a bit of a shock (I always try to fill with a decent grade of at least 91 octane). So they replaced the filter and added a good dose of injector cleaner to the tank.

 

Anyone else seen this happen?

 

I put on a couple of hundred km this afternoon and although the problem has not gone away, it is definately better. According to the support desk at MG, it is not possible to "backflush" these injectors so I'm hoping that things will continue to improve over the next few tank-fulls (with cleaner), otherwise new injectors may be required...?

 

So pay attention your filter - if not replaced regularly, it is probably a good idea to at least backflush once in a while.

 

Gio

[dlaing]

I have a few more kilometers on mine. 18,000 miles (30,000km) and I too had dark grey crud come out. Replace your filter every 20,000 km or 12,000 miles maximum.

I thought since we get better gas mileage than a car, we would need to change the filter no less often. I was wrong.

The Isuzu Rodeo (and I am sure many others are) is recommended a new fuel filter every 15,000 miles and may go through many more gallons of fuel, but clearly that is not enough.

Interestingly, the nylon mesh filter attached to the petcock was almost completely clean! So what is getting into the filter is pretty fine crud. It looks dark like it could be dissolved neoprene hosing. Perhaps from the line that sits so close to the cylinder head....

[docc]

Fuel line degragation is not unlikely. I guess changng lines with the filter change is not a bad idea. Remember, much more fuel is being pumped and filtered than burned because of the closed loop return system. You'd think the fuel would get cleaner and cleaner. But if there is line degradation new particles would be washed off with every pass.

 

Because of the reduced surface area in the IsuZu filter the interval would be safer at 6000 miles.

 

The water in the mercury columns is ever present and must throw off the readings. I've tried keeping mine next to a dehumidifyer but they still get the water.

 

Ordered a Twin Max from Chapparal yesterday for around $64. Hate to give up the sticks. They're so . . . (old fashioned?) (arcane?) . . .(primal?) Oh, well, technology marches on and even the Guzzi will be advantaged to follow.

[Gio]

Further update :

 

I too wondered if the crud could be from a hose - the stuff in the pop bottle has now settled out - it's like charcoal powder - very fine and easily disturbed so the particle size must be very small.

 

Now for the interesting develpoment. I just did a few runs with the PC disconnected (ie back to stock map) and the problems experienced whilst setting off under power are no longer present...? I double checked by re-connecting the PC and the problem returns.

 

So I'll try re-loading the map I was using (m706.002 - Mistral mufflers with stock x-over and air-box) to see if this was corrupted in some way.

 

The plot thickens still further...?

 

Gio

[Gio]

Update on the update :

 

Re-installed PC map - same as before. I'm now working on the theory that if I do have partially blocked injectors then the symptoms would be worse with the PC map as this is richer than the stock map...?

 

Gio

[Mike Stewart]

Re-installed PC map - same as before. I'm now working on the theory that if I do have partially blocked injectors then the symptoms would be worse with the PC map as this is richer than the stock map...?

 

Gio,

Your theory is correct, a leaner map will may cause a partially pluged injector to be leaner, and make the bike run worst. In my experence with fuel injection, the filter is there to prevent any particles to get through to the injectors. A plugged fuel filter will cause loss of top end performance first. It is quite normal to get the black carbon looking stuff that the fuel filter traps. I think alot of this stuff comes from the fuel pump. On the other hand, injectors do not like water and some do not do well with cleaners.

 

If your bike runs better without the PCIII, I would think your problem is in the PCIII.

 

Mike

[emry]

According to the support desk at MG, it is not possible to "backflush" these injectors

 

Even though MG does not want to do it there are a great deal of companies that not only do this but also balance the flow rates. Do a quick Google search for more info try "injector cleaning"

 

Also about the fine particulate in the gas filter. Don't forget where the fuel come from in the first place. Those huge underground storage tanks.

[docc]

And I'm trying to imagine that those tanker trucks and the hoses they use are more sano than your Guzzi.

 

No, fuel filters are a good thing!

 

I continue to read the angst over Power Commanders. Without a doubt this introduces another aspect to be sorted and tuned.