Bypass or PC?

[lemppari]

Ok, I've opened up the intake following instructions on the site, and I've changed the original pipes for open Mistrals. The bike runs surprisingly well otherwise, but for a small hitch:

 

Slowing down to a crossing with engine braking, if the revs fall under 1900, the engine starts coughing when on throttle again. That got me thinking that would it be something only a Power Commander can remedy because the mixture is obviously on thin side, or do the bleeds or bypasses in TB:s still play a role? Would turning them tighter a bit help in getting a slightly richer mixture between idle and 2000 revs?

 

The valve clearances and TB balance are OK, TPS is set at 245 mV because under that, the engine ran poorly.

[docc]

I'm not sure what you mean by TPS at 245mV.

 

The two standards are fully closed plate at 150 mV (+/- 10 mV) and idle at 5.10-5.35 (some like it higher).

 

Where are you setting the 245mV?

[lemppari]

I'm not sure what you mean by TPS at 245mV.

 

The two standards are fully closed plate at 150 mV (+/- 10 mV) and idle at 5.10-5.35 (some like it higher).

 

Where are you setting the 245mV?

Fully closed. When I bought the bike, it had torque from idle to top with a poor mileage and when measured, the TPS was set at 420 fully closed. After changing to Mistrals, I set it at 150 mV, resulting in an excellent mileage (appr.5 liters/100 km instead of 7,5-8), but poor and erratic running below 3200 revs. After gradually raising the TPS setting I ended up with 245.

 

Now I get a reasonable mileage but as I wrote, the coughing is disturbing when engine braking below 2000 and opening up.I know I'm probably running with a slightly thin mixture because of the better breathing and it would be wise to put the bike through a dyno test, but the symptoms got me to think wether it would be feasible to get a richer mixture below 2000 by closing the bypasses a tad.

[raz]

Your reasoning sounds valid to me but I'm not sure it will make enough difference. The bleeders are really tiny compared to even a small amount of butterfly opening. Trying it is cheap of course, so why not?

 

I guess the Right Thing^TM would be to check/reset the mixture setting (CO trim or whatever it's called) in the ECU. It's a pity you can't do that yourself without buying a semi expensive tool.

[lemppari]

Your reasoning sounds valid to me but I'm not sure it will make enough difference. The bleeders are really tiny compared to even a small amount of butterfly opening. Trying it is cheap of course, so why not?

 

I guess the Right Thing^TM would be to check/reset the mixture setting (CO trim or whatever it's called) in the ECU. It's a pity you can't do that yourself without buying a semi expensive tool.

That's the problem with me, I still think Dell'Orto way. With carbs, your idle circuit affects how the engine runs above idle, too. Well, I'll just as well phone a friend who does dyno and PC jobs.

[fotoguzzi]

do you still have the stock cross over on?

[c20500]

Sounds like time for a My15m ecu conversion. I was only getting high 30's with the stock ecu and now I'm getting 44-46mpg on the highway with my cored pipes.

[lemppari]

do you still have the stock cross over on?

 

Yep, didn't want an overly loud bike. If I want sound, I take my LM I for a spin.

[Tom M]

It seems you're having the same problem setting your TPS that I had a while back. This thread might help you out. If you decide to add a PC you might want to try and get the TPS, valve lash, and throttle body balance all set correctly so you have a known good baseline before having a custom map done.

 

When I added an FBF crossover to my bike it did get a little bit louder, but the increase in noise was not nearly as significant as going from stock mufflers to straight-through mufflers like your Mistrals. IMO the elimination of the 4k rpm torque dip that the V11 has with the stock crossover was well worth the slight increase in noise over the stock unit, but anyone within earshot who doesn't appreciate the sound of a fine Italian twin when I open it up might not agree

[docc]

It seems you're having the same problem setting your TPS that I had a while back. This thread might help you out. If you decide to add a PC you might want to try and get the TPS, valve lash, and throttle body balance all set correctly so you have a known good baseline before having a custom map done.

 

When I added an FBF crossover to my bike it did get a little bit louder, but the increase in noise was not nearly as significant as going from stock mufflers to straight-through mufflers like your Mistrals. IMO the elimination of the 4k rpm torque dip that the V11 has with the stock crossover was well worth the slight increase in noise over the stock unit, but anyone within earshot who doesn't appreciate the sound of a fine Italian twin when I open it up might not agree

 

Whew! I forgot what a long thread that was! I found this for an answer: Raz's summation. :

 

"I'd just say try the pinned How-to and if it don't work out good, try Micha's method instead. Or the other way round if you wish. Probably one of them (or both) will produce a nice running bike."

 

Also, Ryland noted that low battery voltage could contribute to frustrating variations in results .( Now, I'm paraphrasing . . .)

[lemppari]

Whew! I forgot what a long thread that was! I found this for an answer: Raz's summation. :

 

"I'd just say try the pinned How-to and if it don't work out good, try Micha's method instead. Or the other way round if you wish. Probably one of them (or both) will produce a nice running bike."

 

Also, Ryland noted that low battery voltage could contribute to frustrating variations in results .( Now, I'm paraphrasing . . .)

To sum it up, it seems that the bleeds i.e. bypasses do not have a noticeable impact beyond idle, so any hiccuping at low to medium revs has to be corrected by altering the mixture, which translates to altering the standard map. PC it is, then.

[raz]

Well yes but check your CO setting in the ECU first. If that is the problem you will save a couple of hundred euros. If you like you can buy the tool yourself, but it is pricey and you may want to use the money for a PCIII in the end. I assume all Guzzi and Ducati dealers have one.

 

Even if you end up buying a PCIII, you want that setting right in order to use freely available maps.

 

http://www.mectec.nu/tools/vdsts.htm

[Tom M]

You're right Docc, Raz summed the thread up well.

 

Lemppari, I think you are correct and will need to alter your fuel map to get rid of the lean hiccups assuming your TPS is not set up too lean. The PCIII is the easiest solution for most of us in the US because there are lots of PC tuning centers here, but I've seen posts on this forum about shops on your side of the pond that can remap your ECU directly. I don't know where they are but it may be another option for you.

 

Raz makes a good point, if your idle trim is not set to zero it can cause problems with PC maps. Unless you know someone who already has the VDST package the easiest and least costly way to check it is probably to visit a Guzzi dealer and ask them to plug their diagnostic tool into the ECU and check the setting. I'd be happy to check it for you with my VDST but I'm not exactly right around the corner from you...

 

A caution on the VDST package: My wife got me the standard VDST package for Christmas after I was assured by Todd at Guzzitech that I could alter the idle trim setting with it if I needed to. I have found that it works great for setting the TPS and checking other engine parameters including the idle trim, but so far I cannot see any way to actually change the trim setting with it. My trim setting is at zero so I didn't spend a lot of time trying to figure it out, but be aware that you might need the Pro version to change the idle trim value.

[lemppari]

You're right Docc, Raz summed the thread up well.

 

Lemppari, I think you are correct and will need to alter your fuel map to get rid of the lean hiccups assuming your TPS is not set up too lean. The PCIII is the easiest solution for most of us in the US because there are lots of PC tuning centers here, but I've seen posts on this forum about shops on your side of the pond that can remap your ECU directly. I don't know where they are but it may be another option for you.

 

Raz makes a good point, if your idle trim is not set to zero it can cause problems with PC maps. Unless you know someone who already has the VDST package the easiest and least costly way to check it is probably to visit a Guzzi dealer and ask them to plug their diagnostic tool into the ECU and check the setting. I'd be happy to check it for you with my VDST but I'm not exactly right around the corner from you...

 

A caution on the VDST package: My wife got me the standard VDST package for Christmas after I was assured by Todd at Guzzitech that I could alter the idle trim setting with it if I needed to. I have found that it works great for setting the TPS and checking other engine parameters including the idle trim, but so far I cannot see any way to actually change the trim setting with it. My trim setting is at zero so I didn't spend a lot of time trying to figure it out, but be aware that you might need the Pro version to change the idle trim value.

Hmmmmmm....Oddly enough I've ridden some 500 km in these last two days with no rough running or hiccups and getting a decent mileage of 40 miles/US gal. One begins to wonder if the PC is worth the money and effort....

[luhbo]

.... One begins to wonder if the PC is worth the money and effort....

 

You could get Tuneboy or MyEcu for the same money. Tuneboy lets you alter the trim tables for altitude and engine temperature. In most cases that's all you need.

 

Hubert