• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

P8 ECU and pod filters question

AZRider

Tuned and Synch'ed
GT Contributor
Joined
Jul 27, 2013
Messages
25
Location
San Diego, California
Anybody here (Todd?) know enough about the vacuum-sensor that connects to the airbox on a '98 CaliEV to tell me what to do when replacing the airbox with pod filters?

I am doing a customization that won't fit with the airbox.

I assume that manifold vacuum is MUCH stronger than airbox vacuum, so I can't go directly to the intake manifold vacuum nipple. But I also assume that if the sensor is reading ambient pressure, it will be telling he ECU to do wrong things, too. I tried to fit a K&N dual-inlet filter where the airbox used to be, thinking maybe I could connect the hose into the large K&N, but I couldn't locate one that would align even halfway OK with the throttle bodies, so I am stuck with dual pods.

Thanks!
 
That isn't a vacuum sensor, it is a barometric pressure sensor. Leaving it open to atmosphere will be fine, or just have a short hose with a small filter to keep dirt out of it.
 
Thanks for the speedy reply! I had been reading the manual, and over-thinking as I am prone to do.

Since we are on the topic, any advice regarding barometric sensor and really high altitude on the P8 ECU machines? When I ride my other '98 EV with its stock airbox in the Rockies above about 10k feet, it just goes to crap, running rich as hell. Worse than my carbureted bikes. Is it going into some kind of fail-safe mode and running extra rich? The manual does show it cutting off the lean-out curve at a certain barometric pressure, but I didn't read it as going into limp-home mode.
 
Thanks for the speedy reply! I had been reading the manual, and over-thinking as I am prone to do.

Since we are on the topic, any advice regarding barometric sensor and really high altitude on the P8 ECU machines? When I ride my other '98 EV with its stock airbox in the Rockies above about 10k feet, it just goes to crap, running rich as hell. Worse than my carbureted bikes. Is it going into some kind of fail-safe mode and running extra rich? The manual does show it cutting off the lean-out curve at a certain barometric pressure, but I didn't read it as going into limp-home mode.


The P8 is an old system. It only compensates to a point. I don't think there is much you can do, perhaps leaning out the trim screw could have some impact but not much. A friend of mine has a 98 EV (P8) and his bike seems to do well at altitude, as did the 15M bike I was running with him. It could be the sensor on your bike is not functioning optimally. I did notice when in Colorado my 5AM bike got great mileage, but really suffered power wise while at altitude.
 
Thanks for the speedy reply! I had been reading the manual, and over-thinking as I am prone to do.

Since we are on the topic, any advice regarding barometric sensor and really high altitude on the P8 ECU machines? When I ride my other '98 EV with its stock airbox in the Rockies above about 10k feet, it just goes to crap, running rich as hell. Worse than my carbureted bikes. Is it going into some kind of fail-safe mode and running extra rich? The manual does show it cutting off the lean-out curve at a certain barometric pressure, but I didn't read it as going into limp-home mode.


The ECU in the Centauro and Sport were about they same. They under compensate for altitude. Most people never know if. But if you are at higher elevations, it is bad.
My thinking was that if the sensor failed at normal use, it wouldn't be a big issue. If they had full compensation in there and the sensor failed, you would be stranded.
 
My thinking was that if the sensor failed at normal use, it wouldn't be a big issue. If they had full compensation in there and the sensor failed, you would be stranded.
That's what I read. I thought it was in the Magneti-Marelli manual, so I went to the garage to get the exact quote. It wasn't there or in the EFI manual from Guzzi, so that leaves Guzziology (or my imagination), and it's too cold to go back to the garage tonight to look for a quote.
My recollection, though, is that once the system reaches the programmed-in baro correction factor limit, it holds steady at that limit no matter how much lower pressure the baro sensor indicates. That limit was determined to be just rich enough to prevent lean-running engine damage if the sensor transmitted false data at sea level. I don't think there was a point at the extreme altitude end of the baro data graph where the computer says, "this is clearly wrong, revert to a richer map to protect the engine." But that's what I think I am experiencing: At some point on the way up a REEEEALLY high pass, the bike goes all rich and craptastic and drops to about 24 miles/gallon which is a bad thing all in itself out in the remote parts of the country. It has happened on all of my trips across the Rockies.
 
Have you connect it to diagnostics to see if the sensor is working at all?
Maybe it is stuck a sea level type numbers.
 
Good point. I live at 400ft above mean sea level in CT, and all of my non-roadtrip riding is below 2000 ft. The first time it happened (2001) I brought the bike in to the Denver dealership, Erico Motorsports. They had just picked up Guzzi and didn't have the diagnostics yet so they just cranked the trim screw to lean and instructed me to set it back so many turns when I went back down. Which accomplished nothing.

I will attach the Mityvac to the VOES and GENTLY apply some vacuum, see what it reads.
 
Back
Top