V7 Cafe Difficult to start when cold

[JasonC]

My 2010 V7 Cafe Classic is difficult to start when the engine is cold.

When the bike is warm it starts just fine, but when allowed to cool down it takes multiple attempts to start. I'm wondering if there is a temperature sensor that is sending the wrong information to the ECU because it acts like a lean condition. There's what appears to be a temp sensor in the air box, but is there another temp sensor somewhere?

Any other ideas on why it's difficult to start when the engine is cold?

Thanks!

Jason

 

[Kevin.NZ]

Its resistance gets lower the hotter it gets, its called negative temperature coefficient. Connect an ohm meter up to it , place it in water and heat it up, my manual give readings for every 10 degrees , It goes from around 9700 ohms at zero C down to 204 ohms at 100C. The air temp sensor is a NTC component too. This is read by the ECU which then controls the stepper motor, I would have thought there would be a stepper motor if its fuel injected. Could be wrong, it has been known.

 

[JasonC]

Its resistance gets lower the hotter it gets, its called negative temperature coefficient. Connect an ohm meter up to it , place it in water and heat it up, my manual give readings for every 10 degrees , It goes from around 9700 ohms at zero C down to 204 ohms at 100C. The air temp sensor is a NTC component too. This is read by the ECU which then controls the stepper motor, I would have thought there would be a stepper motor if its fuel injected. Could be wrong, it has been known.

Ok, thank you for the resistance instructions for the temp sensor.

Jason

 

[V700Steve]

It helps if you have cleaned the air bypass screw, they get gummy. No stepper but you do have a advance lever which will give it more fuel. You can also screw IN the airscrew to make idle richer & out is leaner. Both L & R should be the same.

 

[JasonC]

It helps if you have cleaned the air bypass screw, they get gummy. No stepper but you do have a advance lever which will give it more fuel. You can also screw IN the airscrew to make idle richer & out is leaner. Both L & R should be the same.

Thank you for that information.

Yes, I have a lever on the left handlebar but all it does as act as a throttle. So what is the black gizmo with the yellow painted screw in this picture?

 

[Kevin.NZ]

That is your Throttle position sensor, it tells the ECU how wide open the throttle is.

 

[JasonC]

That is your Throttle position sensor, it tells the ECU how wide open the throttle is.

Yes, of course, thank you!

Jason

 

[tobinh]

You should have an engine temperature sensor, an instrument air temperature sensor, and an intake temperature sensor. I would start just by checking all three with a multimeter, it's quick and easy. Although, I don't think the instrument temp sensor relates to fuelling, just engine and intake.

Page 31 in the manual has the locations, and the following pages have the relevant values.

I am seeing what looks like a foam air filter clamped to the throttle body in your picture of the TPS - so where is the intake temp sensor? It's a little u-shaped guy, usually in the air filter box. Have you removed this?

Since the GTM tool apparently does not reset your TPS, you'll have to find a shop with the axone tool or PADS. I think the TPS reset should be done regularly.

 

[john zibell]

Unfortunately, the Guzzi shops in the Houston, Texas area have a poor reputation for knowing anything about the brand and so I'm hesitant to let them monkey around with my ECU and TPS, especially considering that my throttle response is excellent.

Thank you for the suggestions.

Jason

Have you checked with MPH in Houston to see if they have the Techno Research software on hand? or the older Axone?

 

[john zibell]

No, but that's a good idea.

However, Mike at MPH is no longer a Guzzi dealer, but perhaps he will still work on them.

Jason

Worth a try. He still makes the relay kit for the starter relay on CARC bikes. Also he still has Guzzi tech info on his web site.

 

[tobinh]

When I purchased the bike it came with two K & N filters that were scrunched up beneath the gas tank; they were a pitiful sight. The air temp sensor was installed in the plastic end cap of one of the filters. So I removed the two K & N filters and installed two Uni filters and reinstalled the air temp sensor on left-hand filter.

Regarding the sensors you pointed out, I found them: "Head temperature sensor"; "Intake air temperature sensor" and the "Instrument panel air sensor" However, it's my understanding that the "Instrument panel air sensor" provides temperature read-out on my dashboard only and does not interact with the ECU; am I wrong about that assumption? At any rate, the instrument panel air sensor is providing accurate ambient air temperature, so I don't think it's at fault.

Regarding the TPS, I have crisp throttle response throughout the entire rev-range, so I'm inclined to believe that the TPS does not need resetting. But believe me I would if I could. I spent what I consider to be BIG$$$ on the flash tool only to discover it will not reset the TPS on my bike.

Unfortunately, the Guzzi shops in the Houston, Texas area have a poor reputation for knowing anything about the brand and so I'm hesitant to let them monkey around with my ECU and TPS, especially considering that my throttle response is excellent.

Thank you for the suggestions.

Jason

I think your assumption about the instrument panel sensor is correct, that has been my belief and the manual seems to suggest so. But, I don't know for certain.

TPS reset is a good idea generally, but no reason to get sidetracked - step one is still to pick up your multimeter

also - did this just start happening? or has it been the case ever since you owned the bike? maybe the lack of air box without appropriate fueling adjustment is the real reason.

 

[Vagrant]

Just guessing here but, on the 98 EV there was a setting that you could use a digital meter for setting the TPS and it worked better than the computer. Do some research on that maybe the same applies.

 

[JasonC]

also - did this just start happening? or has it been the case ever since you owned the bike? maybe the lack of air box without appropriate fueling adjustment is the real reason.

It has been difficult to start cold since I got the bike on very sporadic basis. Now, it's difficult whenever the engine has cooled down to ambient temperature.

Jason

 

[JasonC]

UPDATE:
I tested the relationship between resistance and temperature on the intake air temperature and engine temperature sensor and all seems OK per the published values in the shop manual.

One thing I found odd was that the engine temperature sensor did not seem very tight in its socket when I removed it for testing. Moreover, when I threaded it back in its "home" it would not get very tight. Also, the socket appears to be made of some sort of plastic material, which seems odd to me. Any thoughts on the strange fit of the engine temp sensor?

Jason

 

[V700Steve]

I have a thought-------------don't strip it. My 98EV is similar. Trick is to put some copper anti seeze on the tip for good transfer to sensor.
For mine there is an all metal one if needed. At least there were some.

 

[Kevin.NZ]

On my Breva, the plastic fitting has a copper base, washer and thread that goes into the cylinder, i put some heat transfer paste inside the plastic that I use on transistor heatsinks then put the sensor back in. Dont strip/crack the plastic fitting as V700Steve says when putting it in the cylinder or when screwing in the sensor. My Breva is 17 yrs old and the plastic is very fragile.

 

[JasonC]

On my Breva, the plastic fitting has a copper base, washer and thread that goes into the cylinder, i put some heat transfer paste inside the plastic that I use on transistor heatsinks then put the sensor back in. Dont strip/crack the plastic fitting as V700Steve says when putting it in the cylinder or when screwing in the sensor. My Breva is 17 yrs old and the plastic is very fragile.

I'm afraid the previous owner stripped the threads in the plastic receptacle, hence the inability for the sensor tighten much beyond finger tight.

I wonder if the plastic bit is replaceable?

Jason

P.S.: I answered my own question. The receptacle is P/N GU03163330 if anyone is interested.

 

[john zibell]

Jason, that receptacle being loose won't effect cold start, but might result in errant readings when the engine is hot. That is the sensor reporting the engine is cooler that it actually is.

 

[JasonC]

Jason, that receptacle being loose won't effect cold start, but might result in errant readings when the engine is hot. That is the sensor reporting the engine is cooler that it actually is.

Thank you for confirming my thoughts.

Jason

 

[JasonC]

Update:

Well, I finally figured out what my cold start problem is/was!

I followed John's suggestion about checking the throttle body synchronization. Following the instructions in the workshop manual I closed the two by-pass screws and checked the vacuum in each throttle body at about 2,500 RPM. I found them to have virtually the same amount of vacuum. At this point I would typically disconnect the vacuum gauge, reconnect the balance tube and set the idle speed to 1,100 rpm by opening each by-pass screws the same amount.

But this time I left the vacuum gauge connected and adjusted the two by-pass screws to achieve 1,100 rpm and have the SAME vacuum.

What a difference; it now starts with just a couple of engine revolution when cold--every time!

Thanks to everyone's help and suggestions I was steered in the right direction and solved my cold start problem!

Jason