nick84 Posted November 28, 2015 Share Posted November 28, 2015 So, I have a '05 VFR with Remus exhaust and a DNA aftermarket air filter. I also have disabled PAIR (just unplugged the connector). I've been told that with these modifications, my engine may be running too lean. I haven't noticed anything unusual when riding, except some exhaust "popping" when decelerating (but that could mean that I have an exhaust leak, which is likely). It seems that the engine runs just fine. I probably wouldn't mind too much, except that I know that running an engine too lean may destroy it! And I like my VFR, I would like to keep it for a long time! So, how can I tell if I'm running that lean? And if I'm running that lean, what should I do? I would rather keep the modifications mentioned above and not revert to stock, since I'm happy with my bike as it is. Do I need maybe to install a PowerCommander or RapidBike? What other options do I have? Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted November 28, 2015 Member Contributer Share Posted November 28, 2015 Why would an exhaust leak be likely? You have an 05, my 97 is not leaking..... Link to comment Share on other sites More sharing options...
Member Contributer dawson Posted November 28, 2015 Member Contributer Share Posted November 28, 2015 Sounds like you're still running the O2 sensors so you should be fine. If it has their feedback, the ECU can adjust the fuelling as necessary, and it's capable of richening the mixture significantly. If it revs up to redline fast without pulling, you may be lean. If you're really concerned and there's a dyno around, they should be able to measure your tailpipe emissions and tell you what's going on. When you unplug the connector to your PAIR valve it stays in the open position all the time and dumps fresh air into the exhaust. That's the probable cause of your popping. This will also create a false lean at the pipe and O2 sensors,so the ECU will react by richening things up. My feeling is that you're fine, but it's a lot easier to say that from this side of the computer. :o) Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted November 28, 2015 Member Contributer Share Posted November 28, 2015 Motor temp would be high and possibly better then average fuel economy , Link to comment Share on other sites More sharing options...
Member Contributer RDMcD Posted November 28, 2015 Member Contributer Share Posted November 28, 2015 Popping is usually a sign of running rich isn't it? Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted November 28, 2015 Member Contributer Share Posted November 28, 2015 Popping is usually a sign of running rich isn't it? Yes - on deceleration unburned fuel igniting in the exhaust. The A/F ratio can be measured on a dyno. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted November 30, 2015 Share Posted November 30, 2015 So much misinformation Sent from my A0001 using Tapatalk Link to comment Share on other sites More sharing options...
nick84 Posted December 2, 2015 Author Share Posted December 2, 2015 Motor temp would be high and possibly better then average fuel economy , 80-84 C motor temperature when travelling on the open road and as much as 105 at stop-and-go traffic. I think that's the norm, right? Also, my fuel economy is at about 6-6,5l/100km (sorry, not sure how to translate that to MPG). According to fuelly.com, I'm just average. Should be fine then... :smile2: So much misinformation Sent from my A0001 using Tapatalk "Misinformation"? Are you referring to the original post? Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted December 2, 2015 Share Posted December 2, 2015 I've been told that with these modifications, my engine may be running too lean. I haven't noticed anything unusual when riding, except some exhaust "popping" when decelerating (but that could mean that I have an exhaust leak, which is likely). It seems that the engine runs just fine. I probably wouldn't mind too much, except that I know that running an engine too lean may destroy it! And I like my VFR, I would like to keep it for a long time! A slip on and filter is not going to make your bike run drastically different or too lean. The way the bike is set up from the factory, the fueling is a little on the lean side up until around the vtec transition and then it starts to richen up after that. The top end at over 9000 rpms is actually on the rich side from the factory on a stock bike. The factory slip on and air filter are not restrictive at all in the lower rpms, so adding a freer flowing air filters isn't going to really effect low to mid range air flow very much. Now at higher rpms a performance air filter and slip on may help air flow a tad, but not too much, as you still have the restrictive factory header and factory snorkel/flapper/velocity stacks etc. If you are getting any additional air flow up top, it is just going to get you closer to the ideal air fuel ratio. Now say you do get a power commander and a tune, you will find that the area that you will be adding the most fuel to will be in the 4000-6000 rpm range, not because of the exhaust and air filter, because that is just how the vfr800 comes from the factory to have clean exhaust emissions. Sounds like you're still running the O2 sensors so you should be fine. If it has their feedback, the ECU can adjust the fuelling as necessary, and it's capable of richening the mixture significantly. The factory o2 sensors are narrow band o2 sensors and are only used during steady state cruising, when the ecu goes closed loop, to get the air/fuel ratio as lean as possible. During anything resembling acceleration or throttle opening, the ecu goes open loop and ignores the o2 sensors. The o2 sensors will never be responsible for, ", the ECU can adjust the fuelling as necessary, and it's capable of richening the mixture significantly." Popping is usually a sign of running rich isn't it? Popping is a sign of overly lean, not overly rich. On a very lean overrun where exhaust popping can be heard, the air/fuel ratio is so lean that it can not be ignited in the combustion chamber, so eventually air and fuel will build up in the exhaust and combustion chamber to a point where it can be ignited and all the fuel that was in the exhaust piping is ignited with it. Popping is usually a sign of running rich isn't it? Yes - on deceleration unburned fuel igniting in the exhaust. Yes it is from unburned fuel reaching the inside of the exhaust piping, but the whole reason that the unburned fuel and more importantly oxygen reached the exhaust in the first place is due to the air/fuel was too lean to be ignited in the combustion chamber. "I haven't noticed anything unusual when riding, except some exhaust "popping" when decelerating " Again this overly lean event is only at about 0% throttle and high rpms, it does not indicate an overly lean air fuel ratio during normal running conditions. If you were getting popping at open throttle, you would be in big trouble.... Link to comment Share on other sites More sharing options...
Member Contributer MadScientist Posted December 2, 2015 Member Contributer Share Posted December 2, 2015 CR has this pretty much nailed. I wouldn't worry about anything remotely close to lean with that chunk of catalyst stuck in the exhaust. A bottleneck is exactly that, it doesn't matter how wide the funnel is on either end (slip-on & air filter), flow is pretty much limited by the resistance at that point. You may be getting popping from the disconnected PAIR connector. Unplugging it really isn't doing anything for you, so you might want to hook it back up and see if the popping stops. The main benefit of disabling PAIR is for dyno tuning or complete removal for reduction in clutter. Link to comment Share on other sites More sharing options...
squirrelman Posted December 2, 2015 Share Posted December 2, 2015 A QUICK LOOK at the business ends of the sparkplugs would answer your question. Link to comment Share on other sites More sharing options...
Member Contributer dawson Posted December 2, 2015 Member Contributer Share Posted December 2, 2015 Thanks for the clarifications CR. You're correct in that the O2 sensors are narrowband and the system goes open loop under throttle and development. However, when they're operating at idle and cruise, they build a short term trim that is then applied to the entire map, regardless of open or closed loop operation. This is how they can richen the mixture across the board. Hope that fixes my contribution to the misinformation... Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted December 3, 2015 Share Posted December 3, 2015 I do not believe the ecu is anywhere near that smart on the sixth gen, though I suppose anything is possible. Link to comment Share on other sites More sharing options...
nick84 Posted December 4, 2015 Author Share Posted December 4, 2015 OK... well, I'm relieved now. Just need to completely remove PAIR at some point. Thanks everyone for answering. Special thanks to CandyRedRC46 for explaining things in detail! Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted December 4, 2015 Share Posted December 4, 2015 A QUICK LOOK at the business ends of the sparkplugs would answer your question. Spark plug checks can be misleading. As the factory mapping is pretty lean in the 4000-6000 rpm range and pretty rich above 9000 rpms, you are not going to get all the info from a simple plug check. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.