Breva 750 air temp sensor

[drdwb]

Hi learned ones. I'm working on reviving a 05 750 Breva that  has issues, this bike was Eric and Lori from Morehead Mn. If you go back and search the forum and everything Eric tried to revive this bike you might wonder why any sane person might take this on.  But since when has any Guzzi rider/ owner claimed to be totally sane.
Brief history, bike has Lambda sensor disconnected , several maps and another  brain box latter, no improvement, has had injectors gone through, a canisterectomy, new TPS, new fuel filter, I believe new dash board. New coils, new voltage regulator, new relays , the power to relay bypass installed, new side stand switch, also bypassed,

With Beetle help we have tried a few maps ( thanks Mr.Beetle). Well one thing I decided to try was putting the original ECU back in with the original map which didn't have the Lambda sensor disabled. The bike ran like a champ for about 20 minutes than EFI light comes on and we crawl back home. Guzzi Dia  showed the fault of Lamda sensor fault, accurately. Cleared fault reinstalled a map from Beetle with lambda sensor disabled and again bike ran as suppose to for about 20 minutes. Which is how it's been since I got the new regulator and bad relays replaced. It gets about 20 minutes and reverts to sputtering and no power, with occasional bursts/ surges of power. At least I can get it home now. But since the maps are not fixing it, Beetle suggests  and I agree that I should think of sensors, yet The Diagnosis program is not showing any faults.

So I pulled the sensor from the right hand side of the air box With the pink and black wire and found it to be covered with oil,  So finally here's my question is this normal? Is there a resistance test for this sensor and can it be by passed also.
I'm working on getting to the  sensor in the right hand manifold but this is a royal pain to get to, any body got a quick way into this one?

At this point I'm open to any and all suggestions.  Every time I have checked or changed maps I have reset the TPS and auto learning  and the program always says they are ok .

Thanks in advance for knowledge,wisdom and prayers to the Guzzi Gods.
Dave

[beetle]

According to the service manual, the intake sensor should be 3.7kΩ at 20 degrees C (68F). The cylinder head sensor rates the same, but should also measure 220Ω at 100C (212F).


I've been thinking about the lambda error. With the later ECU's, the O2 sensor heater current is monitored as well as the sensor output. Turning off lambda means the output signal is ignored, but the hearer current is still monitored. I didn't think the 15RC did that, but maybe it does?

[drdwb]

Beetle  @  79 F or 26.11 C. Mine is reading 2.66 K resistance  I'll put in the fridge and lower the temp see if it's close.
What about the oil on the sensor, is this normal  with the canister off, and wouldn't that moisture affect heat transfer?

[beetle]

Blow-by into the airbox is fairly normal for Guzzi's that had been overfilled with oil. Oil is a good thermal conductor, so I would expect an oil coating to make little difference to functionality, provided it didn't get into the sensor, where it might interfer.

Temp function looks OK at those numbers.

[drdwb]

So here is result of fridge test
@ 40F reading on sensor was at 4.50K I watched for about 5 minutes as the temp came back to shop temp 79 F  it was a gradual drop back to 2.66 where it stays.

The sensor  in the cylinder head reads 2.97 K  the cylinder head reads 70 degrees F.

The only explanation I can come up with for the difference in the base line of both is I have a fan running drawing  more air by the bike than  by my bench where I'm testing the sensor

Base line air box sensor = 2.66
Base line. Cylinder head sensor = 2.97
If I can get the sensor out of the cylinder I'll stick it in the fridge and test that also.
Just a bugger to get to it.

[drdwb]

Fridge test on head temp sensor
@ 50 F sensor reads 4.15 K resistance I again watched as it warmed up to 79F  and it also had a nice very gradual change back to 2.69K at room temp.
I suppose I really ought to be heating the sensors up but I'm assuming if they work going from old to warm they would work the other way.

I now have a question about the tightness of the cylinder head sensor, when I took it out I didn't have to apply force to get the thing out, it wasn't finger loose but it certainly wasn't in tight.
I've read someplace that this sensor needs good conductivity and in one thread I recall reading something about using a ceramic paste or gel or also using anti seize  with copper in it,
What do you think , could this be the source of the problems which start  after 15-20 minutes of running?

[beetle]

I've read someplace that this sensor needs good conductivity and in one thread I recall reading something about using a ceramic paste or gel or also using anti seize  with copper in it,
What do you think , could this be the source of the problems which start  after 15-20 minutes of running?

More than likely. I've heard this was an issue in the 1100 CARC models, so no reason to believe it's not the cause of your issue either.

[MikeW]

It would also be worth checking the fuel pressure.

Mike

[Kiwi_Roy]

As MikeW says

And the fuel filter, could that be blocked off so there's not enough fuel to meet the ECU demand.
Shut down and some of the crud falls off the filter, runs for a while then plugs off again

Been there seen that.

[sign216]

As MikeW says

And the fuel filter, could that be blocked off so there's not enough fuel to meet the ECU demand.
Shut down and some of the crud falls off the filter, runs for a while then plugs off again

Been there seen that.

I think in the original post he said that the fuel filter was replaced.

With every change the bike runs well for 20 min, and then goes to barely running.  Normally I'd say the coils, but orig. post says those were replaced too.

[drdwb]

Kiwi  I had the crud on and off problem on my EV so I've been considering  this as well and since the tank us off again I'll probably change out the filter just to rule this possibility out.  I'll have to do some digging find an easy way to check fuel pressure.
I did the coils right off, took it for a ride at first smiles than stuttering stammering and dead bike.

Than I started digging into the electrical and found 3 bad relays,a blown 30 amp fuse,and a regulator that wasn't charging got all that sorted out took fo a ride and now all the warning lights were gone but still went from great running to crap in 15-20 minutes. So with Beetles help we tried different maps and always the same result. And Guzzi Dia program didn't find anything wrong - no faults.
Than I put back in the original ECU with stock map,again ran great about 20 min than stuttering stammering , but this time EFI light ,Guzzi Dia accurately finds Lambda sensor fault, so try one of Beetles maps with lambda sensor disabled and again runs great for about 15-20 min than same crap,

Beetle declares the bike haunted and now I'm checking sensors and wires / connectors to find where the ghost lives.   

So since I'm going to go into the tank and replace the fuel filter  I'm wondering if any one has ever had a reason to replace the thermistor in side the tank by the pump, it's $69 from Harper's and while I don't want to replace good components I also don't want to go through the hassle of taking the tank off again if I don't have to. My experience with Guzzi's says that if there's a problem with a part ,it's more than likely several others have also had the problem before me.

I'm open to any and all suggestions, unfortunately I like many of you has a full time occupation and its summer in Mn and lots of pre scheduled events don't allow more than a few hours here and there to devote time to finding the fix.

I like challenges and I'm only 61 I have time ,patience and tools, so far I've only got about $1600.00 into this project, I have threatened the Baby Breva that if all else fails I can part it out on e-bay,

[tris]

So I guess we're trying to find something that changes after 20 minutes running

Here's my random thoughts for what they're worth
A) is the tank venting?
B) coil dying when warmed up
C) dodgy connection to ..... something
D) if you leave it  idling in the garage does it do it
E) side stand / clutch / kill / ignition switch playing up

Good luck though

[drdwb]

Tris
New coils same result as old coils, ( anybody want to buy used coils?)
Side stand disabled, kill switch and ignition all function well, no problems when using Guzzi Dia, and so far connections look good, but I found one very loose connection to temp sensor on top back end of transmission case. Found melted repaired ground wires behind right cylinder, I haven't let it sit and idle long enough to find out if it  repeats pattern,  ( it's so fun to ride when it's working so it's a reward and motivation) but I will try that.

I also did the relay power bypass fix or what is referred to as status interruptus , prior to this every time I shifted the bike the high beam blue light on the dash would flash, but this may also have stopped when I changed the relays.

I don't hear or feel any thing different when I open the tank cap, and I e tried it with the tank cap loose and found no difference.

Thanks for the suggestions, I love this board!  Can you imagen trying to sort something like this out by yourself, I'm old enough to remember life before the Internet , but boy this just makes trouble shooting easier.

[CalVin2007]

 Does the baby Breva use a cam position sensor (phase sensor) like the big blocks do? They can behave this way.

[drdwb]

Cal Vin 
Thanks for suggestion.
According to the parts diagram it does have a phase sensor, Harper's has it for $178.31 spendy little thing,
Any idea what the symptoms are?
I found spec for resistance = 680+_ 10% @ 20 C  I can check that, but the source also give a reference for the air gap , So I'll have to find a way to check that.

[tris]

Does the baby Breva use a cam position sensor (phase sensor) like the big blocks do? They can behave this way.

..... and if it does does it have the correct gap? I guess that's something that will change with temperature

[beetle]

A reliable source tells me that Fiat & Lancia use the same phase sensor, and it's only 27 euro in Germany.

[CalVin2007]

 Magneti Marelli SEN813.  Used in many autos in Europe, and MV Agusta and some Ducati as well. Google finds a bunch of cross references and possibilities for purchase.

   The symptoms of running poorly/dying after heating up are a failure mode of this sensor. Approx 680 ohms at 70 deg F but measuring resistance may not find a high temp related fault.

[drdwb]

Testing of sensor, there are 3 pins the one in the middle has a 1 by it,only one combination showed resistance  1 and the pin to its right useing center key as reference.
At 70F it reads .71 @ 20K 
So I used a heat gun on low setting with a meat probe temp next to sensor ( crude but  resourceful I thought) I took it up to 100F ( which is hot to touch) and as temp rose I watched the resistance gradually increase to .86 @20K so at least it does rise with heat, this may not be high enough to see if it works in the necessary operational zone but it is changing.

Anyone care to do the conversion ?

[jrt]

Sounds like you are getting good advice, but I'll throw in a different direction- is the charging system working properly?  Could you be running the battery down, causing the ECU to read faults on various sensors?

[drdwb]

JRT
Thanks for the thought, I believe the Charging system Was one of the original things that caused the problems, it is now charging around 13.5 goes up to 14 at 5000rpm, so I think I've got that part sorted. The battery stays charged now and hasn't had to be recharged since I put in new voltage regulator.
Thanks
Any and all advice welcomed
Dave

[CalVin2007]

Testing of sensor, there are 3 pins the one in the middle has a 1 by it,only one combination showed resistance  1 and the pin to its right useing center key as reference.
At 70F it reads .71 @ 20K 
So I used a heat gun on low setting with a meat probe temp next to sensor ( crude but  resourceful I thought) I took it up to 100F ( which is hot to touch) and as temp rose I watched the resistance gradually increase to .86 @20K so at least it does rise with heat, this may not be high enough to see if it works in the necessary operational zone but it is changing.

Anyone care to do the conversion ?

       .71-.86 on the 20K ohm scale will be 710-860 ohms. Pretty close to 680 ohm spec so its at least in the ballpark for resistance. Now....after 20 minutes of run time is it supplying pulses the ignition and ECU can read? That's the next question. You need another sensor to substitute to know for sure. Maybe someone here has an extra? Or,and this is a real stretch....maybe take along a cold bottle of water and use it to cool that sensor down as much as possible to see if it changes anything. If you have decent access to get the water on it of course.

[drdwb]

Thanks Cal Vin for the conversion, getting the gas tank off to reach the connector quickly might pose a problem. However what about putting the sensor in a container of water and bringing Temp up and holding for 20-30 minutes. 

The alternative like you suggest is buying or borrowing another sensor. 
I kind of like the idea of the hot water test though. 

Off the top of your head any idea what ideal operating temp range should be.

Unfortunately the next 3 weeks won't allow any shop time so I thank you all for your interest and suggestions.  I'll post here when I can.
Thanks Dave

[tris]

It's a bugger when life gets in the way of fixing / riding / polishing / looking at (delete as appropriate) your motorcycle 

Let us know the outcome when you get back to it

[Muzz]

In the good 'ole days 20 mins run time then fluff sounded like coils.

Lord only knows what this is. Sounds as though everything has been replaced three times already.

[drdwb]

The Breva runs again.
I'm posting these pictures as a  hint to what the fix was.

Here's a list of things that were done to the bike to locate the malfunction.
1 different ECU
2 Several different maps
3 TPS, Temp sensor, Oil sensor ,O2 sensor, replaced now disabled
4 Canaster removal
5 New coils
6 new relays
7 phase sensor
8 Valves set throttle bodies synch several times
9 Fuel filter
10 Voltage regulator
11 status interruptus  relay bypass
Hours of time by Eric and Lori (previous owner) and I believe they also took it to 3 Guzzi shops
Hours of time by me with numerous emails and assistance. From Beetle , to whom I am extream ly grateful to for his suggestions and assistance with maps and of course his expertise with Guzzi Diagnosis

I'm sure there's more I'm forgetting here but  the great news is the bike is running again,I'm not claiming total victory yet,perhaps after a  1000 miles of trouble free riding,  it' needs to be fined tuned to release the beast within but with a bit more time and tweaking it  will be there.
Thanks to all the Guzzi experts who offered suggestions, they all helped eliminate potentials to narrow down  sources.

In case you can't tell by the pictures , the connector your looking at is the plug going to the left hand fuel injector, the inside contact to the left of the pencil shows the contact pushed up in side the plug, the picture showing the yellow with the wire coming out is the back side of the plug , it's pushed out slightly.

If your interested in hearing how I finally found this, the next time you use Guzzi Diag and you go to reset the injectors listen very carefully as you clear both sides, What can you hear and feel as its clearing?

Thanks. To all Dave

[Kiwi_Roy]

Why didn't this show up as one cylinder cutting out similar to a bad plug lead?

Update:
I'm just saying if you had given us this information we might have saved you a lot of grief, it's pretty easy to tell when one cylinder is cutting out.

[tris]

WELL DONE DAVE

How did you fix the plug?

Did you just chop it off and fit a new one or were you able to grab hold of it and yank it back into position?

[drdwb]

Since I didn't have the right tool to push pins in place, I found a small flat tip punch to work it back in, And it worked.
My next plan of action was to replace the wiring harness,I found one on eBay for $45.00  so rather than spend all the time checking individual wires the plan was to can the whole mess,as it turned out  that might have worked. This just saved me about 2 weekends of work.

[malik]

Suggestions? I have found my twin throttle body unduly sensitive to air box & air filter contamination.  On the recent long ride, I had a lot of rough running at around 4,000rpm - solved for a while by using 91 unleaded, but since thoroughly cleaning out the air box & replacing the air filter with a UFI paper filter instead of the OEM paper version, some 10,000k back, that problem has disappeared.

The V7 Special had a bout of rough running at one stage on the trip. Nothing fixed it until, in desperation, I replaced the (almost new) spark plugs. Later examination revealed a fine crack in the porcelain insulator of one of them.

Just saying. It may turn out to be something simple. Good luck - really hope you get it sorted & trust you'll let us know the culprit when you do find it.

Mal