Trinith Posted May 16, 2010 Share Posted May 16, 2010 I've got reason to believe the map sensor on my 98 has died. Aside from the occasional backfire and relatively impressive fireball, and the hesitation with low revs or not much throttle, what else is there to worry about? I don't really have the money to replace it at the moment, not at $200 a pop, and I don't mind the listed side effects too much in the short term. Will not fixing it damage anything other than possibly blowing the packing out of the muffler? Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted May 16, 2010 Share Posted May 16, 2010 Do you have an FI code showing that tells you 100% it's the MAP sensor? Also, some members here might have one on a parts bike. You might find one on EBAY? Just checked, there's two of them listed right now: http://shop.ebay.com/?_from=R40&_trksid=p3907.m570.l1313&_nkw=vfr800+map+sensor&_sacat=See-All-Categories Actually, looking at them again, it looks like the BARO sensor, not the MAP sensor....... Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 Do you have an FI code showing that tells you 100% it's the MAP sensor? Also, some members here might have one on a parts bike. Yeah, I ran the code check after work and checked the voltages listed in the service manual. Cleaned out the connections, made sure everything was tight, etc. I don't have the diagnostic thing to verify that it's the MAP sensor and not the ECM, but I'm not going to replace the ECM on a gamble. Fortunately someone here is parting out a 5th gen and is selling me his, but I've got a road trip coming up this weekend that will put a few thousand on the bike. Not 100% sure the replacement will get here in time. Apparently the sensor went out a month or so ago, but I thought it was just a fouled plug or two, so I changed them. Problem went away for about 10 days, then came back again. Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 Do you have an FI code showing that tells you 100% it's the MAP sensor? Also, some members here might have one on a parts bike. Yeah, I ran the code check after work and checked the voltages listed in the service manual. Cleaned out the connections, made sure everything was tight, etc. I don't have the diagnostic thing to verify that it's the MAP sensor and not the ECM, but I'm not going to replace the ECM on a gamble. Fortunately someone here is parting out a 5th gen and is selling me his, but I've got a road trip coming up this weekend that will put a few thousand on the bike. Not 100% sure the replacement will get here in time. Apparently the sensor went out a month or so ago, but I thought it was just a fouled plug or two, so I changed them. Problem went away for about 10 days, then came back again. Note that you can run the bike without the MAP sensor - it will be tough to ride at part throttle, but if the problem doesn't go away when the MAP sensor is disconnected, it's not likely to be the MAP sensor. I did some research on this last week. MAP sensors are extremely tough things to break, so keep in mind that the wiring could be faulty instead. Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 Note that you can run the bike without the MAP sensor - it will be tough to ride at part throttle, but if the problem doesn't go away when the MAP sensor is disconnected, it's not likely to be the MAP sensor. Ok, now I'm a little confused. How would disconnecting it fix the problem if it WAS bad? I thought that it not working is why it runs badly at part throttle...so disconnecting it should just guarantee it to run poorly? Link to comment Share on other sites More sharing options...
Member Contributer VFR Capt.Bob Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 My 98 suffered from poor fueling and intense back firing when I discovered my rear header pipes had a huge exhaust leak where they connect to the main exhaust pipe collector. (Not the slip on connection.) There are two clamps there. Loosen the exhaust canister mounting bolt or bolts depending on your slip on style. lift upwards and see if it feels loose. The exhaust gaskets at these locations get worn out from the lower header pipes being used as a support when removing the front tire or forks. You can take off the heat shield near the right foot peg heal gaurd to access these connections if you suspect an exhaust leak. Start up the bike and listen and for excess noise at this location for starters. Think I paid $15 each for new gaskets. Haven't put them in yet as the aluminum can shim I made is still working. I'm much more carefull in how I support the front end during maininance these days. Hanging it from the garage rafters with a stout tie down does the trick now along with the center stand. :fing02: If you aren't getting a flashing FI warning light I don't think it's the map sensor. Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 If you aren't getting a flashing FI warning light I don't think it's the map sensor. But I am. I didn't even notice the problem until one day I let off the gas approaching a light, light turned green, I hit the gas, then I heard the bang and saw the blue flash in the mirrors. Few seconds later the FI light starts flashing. Long story short, this morning I checked the codes, 1 flash, busted MAP sensor, followed the directions in the book and all the voltages are in spec. Pretty sure it's not the harness, but I suppose it could be an intermittent short. Since I found the sensor for only $20 replacing it isn't a big deal. If it doesn't solve the problem I'll keep hunting. The issue at hand is whether or not I'm going to destroy the motor by putting 2k miles on it with a malfunctioning sensor or not. Seems to me like the only real problem is that it runs incredibly rich at low throttle settings, which isn't terribly bad for anything but emissions and a little loss of smoothness. Link to comment Share on other sites More sharing options...
Member Contributer VFR Capt.Bob Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 If you aren't getting a flashing FI warning light I don't think it's the map sensor. But I am. I didn't even notice the problem until one day I let off the gas approaching a light, light turned green, I hit the gas, then I heard the bang and saw the blue flash in the mirrors. Few seconds later the FI light starts flashing. Long story short, this morning I checked the codes, 1 flash, busted MAP sensor, followed the directions in the book and all the voltages are in spec. Pretty sure it's not the harness, but I suppose it could be an intermittent short. Since I found the sensor for only $20 replacing it isn't a big deal. If it doesn't solve the problem I'll keep hunting. The issue at hand is whether or not I'm going to destroy the motor by putting 2k miles on it with a malfunctioning sensor or not. Seems to me like the only real problem is that it runs incredibly rich at low throttle settings, which isn't terribly bad for anything but emissions and a little loss of smoothness. Didn't know about the FI from you description. Sounds like you are on track. When I inturpretted my FI flashes I believe the long flash =10 and the short =1. Double check. My back firing caused a stress crack on my staintune canister. Overly rich condition can reslult in carbon build up in your cylinders head and piston top. I'd get it fixed. pulling the head to clean up the carbon isn't cheap or easy. Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 Well, with any luck I'll get the replacement on Wednesday. Hopefully it won't be raining and I can get it dealt with. Don't really foresee it being a difficult replacement. Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 Note that you can run the bike without the MAP sensor - it will be tough to ride at part throttle, but if the problem doesn't go away when the MAP sensor is disconnected, it's not likely to be the MAP sensor. Ok, now I'm a little confused. How would disconnecting it fix the problem if it WAS bad? I thought that it not working is why it runs badly at part throttle...so disconnecting it should just guarantee it to run poorly? Disconnecting the MAP sensor forces the ECU to go Alpha-N for the throttle position and engine rpms where the MAP sensor would normally be operating. It is a sub-optimal fuel map, but it works. A sub-optimal map is better than one which could be completely incorrect due to a bad MAP sensor. MAP sensors are tough though. Don't be surprised if replacing it doesn't fix the problem. Heck, I stuffed around with MAP sensors for a week only to find out I have leaky fuel injectors. Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 A sub-optimal map is better than one which could be completely incorrect due to a bad MAP sensor. Hm, so what should I expect after disconnecting it? Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 A sub-optimal map is better than one which could be completely incorrect due to a bad MAP sensor. Hm, so what should I expect after disconnecting it? If you disconnect the electrical connector (which is how you should always start), the bike will just start normally. Take it for a ride - heck go for a long ride if you want - and see if the problems occur at all. If not, then you have confirmed the MAP sensor is sending you bad data. I assume your problems only happen at small throttle openings and low rpm? Because other than that the MAP sensor is ignored and the ECU just uses an Alpha-N (throttle-rpm) preprogrammed map. Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 I assume your problems only happen at small throttle openings and low rpm? Because other than that the MAP sensor is ignored and the ECU just uses an Alpha-N (throttle-rpm) preprogrammed map. Yeah, it's only at low throttle settings. I meant what to expect when you said it would be tough to ride with small amounts of throttle. Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted May 17, 2010 Member Contributer Share Posted May 17, 2010 I assume your problems only happen at small throttle openings and low rpm? Because other than that the MAP sensor is ignored and the ECU just uses an Alpha-N (throttle-rpm) preprogrammed map. Yeah, it's only at low throttle settings. I meant what to expect when you said it would be tough to ride with small amounts of throttle. It's fine, just not perfect. But hell, what VFR is perfect even with the MAP sensor doing its thing, eh! Link to comment Share on other sites More sharing options...
Trinith Posted May 17, 2010 Author Share Posted May 17, 2010 I assume your problems only happen at small throttle openings and low rpm? Because other than that the MAP sensor is ignored and the ECU just uses an Alpha-N (throttle-rpm) preprogrammed map. Yeah, it's only at low throttle settings. I meant what to expect when you said it would be tough to ride with small amounts of throttle. It's fine, just not perfect. But hell, what VFR is perfect even with the MAP sensor doing its thing, eh! Haha, very true. Mine is FAR from perfect, but I like to think of it as character. :) Link to comment Share on other sites More sharing options...
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