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Help...another one cylinder problem... this one is a mystery

marcus_b

Tuned and Synch'ed
Joined
Oct 30, 2008
Messages
70
Hi all,

Afraid the 1100 Griso is refusing to run properly for the summer... It will only start-up and run on the one cylinder (the left when sat on the bike). I've spent the weekend in the garage trying to figure out what the problem is but so far I am completely stumped. I'm hoping some of the experienced Guzzi guys on the forum can help me out before I start a complete tear down of the bike.

Problem: Bike only starts on the left cylinder (will not idle but will rev)

What I have done so far to try and problem solve:

Checked for a spark from the outside plug - Yes (via both DucatiDiag static test and cranking the bike over)
Pulled the injectors and checked they were delivering fuel (Via DucatiDiag static test) - Look fine
Swapped each of the following to see if the problem swapped sides... no luck with swapping any of the following:

Spark plugs (outer)
Coils
Leads (outer)
Injectors

I have even tried easy start to triple check It isn't a fuel issue.

Does anyone have any suggestions? :cry:
 
Re: Help...another one cylinder problem... this one is a mys

Have you done a compression test? Also the injector should deliver a fine spray. Just because it passes fuel doesn't mean it is good.
 
Re: Help...another one cylinder problem... this one is a mys

Thanks for the reply,

Just did a compression test... the bad cylinder actually has a bit more compression than the one which works!

Left Cylinder (Dry) just over 9 bar
Right Cylinder (Dry) just under 10 bar

I've ruled out the injectors as I swapped them over (and the problem didn't move with them)... I've even tried another pair that I had in the garage.
 
Re: Help...another one cylinder problem... this one is a mys

Did you visually confirm spark or just trust the software?
 
Re: Help...another one cylinder problem... this one is a mys

Visually confirmed... both when triggered by the software and when cranked over.
 
Re: Help...another one cylinder problem... this one is a mys

Any fault codes?
My bike seemed to be running fine except an occassional non-start problem, as in nothing would happen when I hit the button.

Diagnostics came up with faulty earth lead, and interestingly every component relating to the left cylinder also had a fault saying each time, "BAD EARTH".
ie. left coil, left injector etc.

Replacing the lead didn't fix the problem.
Moving the lead from its contact point just forward of the starter motor, via its 5mm mounting screw, drilling out the connector to 8mm, and re-attaching it to a case bolt about 50mm above cured everything.
 
Re: Help...another one cylinder problem... this one is a mys

marcus_b said:
Visually confirmed... both when triggered by the software and when cranked over.


This one is tough, with fuel, spark, and compression she should run. The only remaining question I can think of is this: Is spark at the right time?
 
Re: Help...another one cylinder problem... this one is a mys

Ghezzi: The only fault code I get is "P0352 Ignition Coil B Primary/Secondary Circuit Malfunction" ... but I am thinking this maybe a symptom rather than the cause as I know I am getting a spark.

John: I'm glad its not me that thinks this is a tough one. I've also been thinking along the timing lines... however I don't think it could be the crank/cam sensor as both cylinders share the same sensor. I've reflashed the ECU in case it was corrupted ECU software.. but still no joy. So far the only option to explore seems to be bad ECU hardware.... :(
 
Re: Help...another one cylinder problem... this one is a mys

Now that I see you have a fault code on the coil, that is now suspect. If it is tripping a fault, voltage or current conduction by the coil isn't within required parameters.

Just because it will spark a plug at atmospheric pressure, doesn't mean it has the juice to fire the plug under compression pressures. In the old days we tested coils by hooking them up to a machine and seeing at what pressure the spark plug wouldn't fire. So, check the connections to that coil. If the bike runs after cleaning all connections at the coil, then all is well, if it doesn't solve the problem, replace the coil. Please let us know what you discover.
 
Re: Help...another one cylinder problem... this one is a mys

I have previously tried swapping the coils with no luck.

I've just been out to check the connections/wiring loom. I couldn't really 'clean' the plug connections but could get access with a multimeter. On first inspection I found that:

ECU pin 38 (LH Ignition coil signal) to the ignition coil plug has a resistance of 0.01ohms
ECU pin 10 (RH Ignition coil signal) to the ignition coil plug has a resistance of 0.5ohms

However after a little waggling of a needle and some electrical cleaning spray I double checked the RH wiring loom resistance an it went back to 0.01ohms.

Unfortunately this didn't fix the problem. :( :( :(

Next job is to try and find the secondary injection relay and check that the non ECU connection is OK (but again this is a shared connection between both cylinders so it probably isn't this)
 
Re: Help...another one cylinder problem... this one is a mys

Now that you have cleaned up that connection, is the fault code still present? If so, I'd really suspect the wiring to the coil. since the other coil didn't work correctly in that placement.

If the fault is still present, I'd suspect the coil isn't getting enough voltage, current, or has a poor ground path. A poor ground would prevent proper charging of the primary windings of the coil. Unfortunately I believe ground is supplied via pin 10, A side of the ECU, which would point to a problem withe the wire or the ECU. If the fault is no longer present, I'm at a bit of a loss on where to go from here.
 
Re: Help...another one cylinder problem... this one is a mys

The ground checked out OK and the Fault code disappeared.... but I have managed to get her running again!!!!! :D :D :D

With your help I managed to determine that the ECU was the likely culprit... just to be sure it wasn't software I reflashed for third time back to the Stock GRS1103 map... This did the trick!

I basically found a little bug in the reflashing software which I was using.

Thanks once again for the help! I'm off out to play in the rain...
 
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