04 V11sport loses power and starts misfiring at trailing part throttle

[CzDavec]

Hi All, new here and new to these "modern Guzzi's" so be kind. I just gave in and purchased a low milage 04 Sport from a reputable shop out here. I mainly run vintage bikes." SP 1000" . So Bike runs great on the test ride and runs great on the 80 mile ride home. I give it a good once over and take it for a ride on Sat. morn. Bike runs sweet has a little cough when pulling out from a stop but nothing major or unexpected on a big twin. about 20 miles in the bike feels like its losing power /not pulling as hard and upon entering a very tight off camber corner,on trailing throttle the engine suddenly starts popping through the intake/miss firing badly. Almost went on my head. twisting the throttle open and the bike smooths out but still not running right. Now it won't idle and when trying to run at partial throttle the engine continues to pop through the intake/run rough etc.So after carefully making my way back towards home "at a greatly reduced pace" the bike suddenly starts running right again like nothing had happened.

So after going over this forum and reading the common trouble spots. I give the bike a thorough going over. Check for airleaks,check the tank venting, check the valves, the sync on the throttle bodies,cleaned-checked connectors.You get the picture. I take it for a short run and all seems fine. So head out for a run and on the way home on the freeway you can feel it lose power and it starts popping/backfiring again.On the off ramp agin won't idle and requires judicious use of throttle to pull out from a stop. It wont quit but it dang sure doesn't wanna run.

So I am stumped/confused and regretting falling for the lovely red Italian lady. I am hoping someone here might see what I have missed/overlooked etc. I am hoping for some guidance and wisdom from those of you more familier with these fuel injected bikes. Sorry for the long post.

CzDavec

[fotoguzzi]

battery terminals tight? check ground wire to frame.. sidestand switch loose? relays tight in receptor? ignition switch clean? if it has seimans relays I'd change them out.

possibly the TPS?

[thumper]

How many miles on the bike? Sure does sound like a failing fuel pump or tank not venting.

Fotoguzzi's ideas are the ones I would check first.

[luhbo]

What if you visit the reputable shop again? It's probably closer to the bike as the whole internet.

Besides that I bet it's just some connection, as the failure is intermittend and 'self-healing'. For the relais it's enough to pull them once and then push them back in again. Also check the connection of the head temperature sensor, it's the blue thingy on the right head.

Everything else would cause the engine to stop, I guess. Same for the relais, but a little whiggling them wouldn't hurt.

Hubert

[Kiwi_Roy]

It sounds like electrics to me as well, my bike did much the same with a dirty ignition switch, I think the ECU relay drops out.

Thats easy to check, just flick the switch a few times to get a better contact.

Try re-seating the relays, you may have a loose connection there.

Do you have the electric fuel petcock?

I think if your TPS was bad it would pick up again at a different throttle setting.

 

Could also be low fuel pressure perhaps, failing pump, plugged filter, bad pressure regulator but I have never experienced that.

 

Don't give up, the bike is just trying to bond with you

[Chuck]

I'm betting on relays/relay bases. If it were me, I'd get me a can of Caig DeOxit Gold (they call it gold because that's the way it's priced) and pull the relays, squirt, wiggle, take apart *every* electrical connection, squirt, wiggle, etc. That stuff is magical, and I can't tell you how many intermittent electrical problems it's cured for me.

[CzDavec]

Ok . a little more clarification. The bike has about 8,220 miles on it,completely stock, no mods. Barely run in. I did check the battery connections,ground wires,reseated all the relays and fuses. I have not messed with the in tank fuel pump and havn't found where the fuel filter is yet. I havn't had it back to the shop where I purchased it from as they won't be open until Tues to talk to them and they are an 1 1/2 hrs away. When the bike is misfiring and popping it appears to be running extremly lean,and it is only on partial throttle/trailing throttle and when trying to idle it along as at a redlight or stop sign. Once moving it doesn't quit but is sluggish and unresponsive but runs ok. As soon as you close the throttle it goes back to surging and misfiring with the attendent popping through the airbox. I was wondering if either the cyl head temp sensor could be bad or perhaps the Intake air temp sensor.As it seem to be self healing I am thinking of perhaps a damaged wire harness or broken wire as the connections all seem to be tight and clean.

[Bbennett]

I wonder if the fuel might be bad since it is a new bike, was sitting for God knows how long etc.

[CzDavec]

Still working on it. But some new observations. Been riding it to work everyday and checking things. The bike runs excellent in the early morning going to work.5a.m. Idles nice, runs excellent. On the way home in the afternoon as it gets hot it starts acting up again. Yesterday out here was about 100 degrees and pretty humid and she acted up again. Seems to be temp related. This bike has the in tank fuel pump not the external so it shouldn't be getting hot. I ohmed out the Intake air temp sensor and accoerding to the charts @38 Celsius or around 98 degrees it should have been reading around 1600 Ohms and instead was @ 1224 Ohms. Does this seem to be too far out of range for the sensor?

As for the gas I run either Chevron premium or Union 76 and have run about 3 tanks through the bike so far.

[CzDavec]

Again this morning. Starts up and runs perfect. "At least as perfect as I expect" Air temp out is around 20 C or around 70 F. Get to work let the bike sit for a bit and rechecked the Ohms on the Intake air Temp sensor and it reads 1954 Ohms. and acording to the charts I have it should be reading around 3700 Ohms. So I am thinking the IAT sensor is faulty. Or am I missing something obvious. I really want to get her running like she does in the morning all the time.

 

Dave

[Kiwi_Roy]

Again this morning. Starts up and runs perfect. "At least as perfect as I expect" Air temp out is around 20 C or around 70 F. Get to work let the bike sit for a bit and rechecked the Ohms on the Intake air Temp sensor and it reads 1954 Ohms. and acording to the charts I have it should be reading around 3700 Ohms. So I am thinking the IAT sensor is faulty. Or am I missing something obvious. I really want to get her running like she does in the morning all the time.

 

Dave

 

The temperature seems to read about 10 degrees hotter than you expect but that could well be heat coming from the motor, besides I don't think 10 degrees is that significant.

To check the sensor you could remove it and dip in water at 25 C it should read 3000 Ohms

I suggest you also read the head temperature sensor, it should read the same at same temperature try it when the bike is hot also.

It's easy to read the sensors from the ECU plug, you can also check the TPS for smooth operation from there,

Dont unplug the cable unless the key is off.

Radio Shack sell a kit for making up the old style computer cables, the little gold plated pins are the correct size to fit the plug or if you have an old cable laying around you can salvage the pins with wires already attached.

On the attached PDF you will see the sensor readings I observed on my 2001, I left a spot for you to fill in yours.

ECU Test Points.pdf

BTW the head temperature sensor is the one called Oil temperature on my sketch

 

BTW the ECU has a diagnostic connector, I have never used it but apparently you can attach a light and it blinks back a code to tell you what's up, does anyone here know how to use that?

[thebronze]

Unhook the air temp sensor and hook up your leads to it. Then put a heat gun about 3' away from it and you should see the ohm reading drop severely. I did this with mine and watched it go from something 1.3 to .3, or 1300 to 300.(I cant remember the readings but it was working really well). I relocated my air temp sensor under the seat by the ECU where its a lot cooler. The bike runs better with the air temp sensor isolated from engine temps.

 

I think the stock map is lean and when you mix in hot temps the sensors lean it out further and cause problems.

[CzDavec]

Unhook the air temp sensor and hook up your leads to it. Then put a heat gun about 3' away from it and you should see the ohm reading drop severely. I did this with mine and watched it go from something 1.3 to .3, or 1300 to 300.(I cant remember the readings but it was working really well). I relocated my air temp sensor under the seat by the ECU where its a lot cooler. The bike runs better with the air temp sensor isolated from engine temps.

 

I think the stock map is lean and when you mix in hot temps the sensors lean it out further and cause problems.

I agree that the stock fuel map is lean. Most of the bikes are, from them trying to get them through our lovely EPA. Then you add in hot days and the problem compounds itself.Not to mention Ca's crappy oxygenated gas. If it comes down to that, does anyone know a reputable shop out here in Southern Ca. That could dyno tune the bike and map it correctly ?

[emry]

My bike started the same heat related issues at about 11,000 miles. around 2008, it is a 02. Ran great in the morning, stuck in traffic on the way home when it was warm out, stall, cough and spit. MyECU was the only fix I found. While I am always opposed to "ECU failure" in my case I am fairly sure something happened there. I have since tried my OEM ECU again and it goes right back to the odd running when warm. Put the MyECU back on and it runs like a champ.

[thebronze]

 

I agree that the stock fuel map is lean. Most of the bikes are, from them trying to get them through our lovely EPA. Then you add in hot days and the problem compounds itself.Not to mention Ca's crappy oxygenated gas. If it comes down to that, does anyone know a reputable shop out here in Southern Ca. That could dyno tune the bike and map it correctly ?

 

I have the same problem. I dont know of any shops that do guzzi ECU work around Dallas but you might have better luck where you are.

 

If your running the stock air box and exhaust you should be able to reset the TPS to 150/530mv and get it running pretty good. Its possible the air temp, engine temp sensor, or TPS are flaky and are causing the problem. If its still too lean you can advance the TPS but that hasnt worked for me. It seems like there are LOTS of v11's with this issue. Might be worth replacing the air temp sensor or TPS sensor with the harley parts. They are about $40 each on ebay. Mine are 10 years old and it might be time to replace them.

 

Check this threadwhere someone swapped in a resistor that fools the ECU into thinking its 65f. Might be a $3 fix.