Dan M Posted June 3, 2009 Share Posted June 3, 2009 I thought I'd add something to the always volatile temperature subject. A few seemed interested in what Ratchet was (is) doing on the subject so I thought I'd show my approach to the same end. I know that several don't agree with this method, this post is to give those who are interested an easy alternative. I discussed using an air temp sensor with RH both on and off the last, now closed thread. From my experience I believe this is the best way to do it on the pre-feedback FI Guzzi motor. I finally took the time to lift my tank and do something with mine. The OE sensor comes out easily on my bike but the plastic holder feels pretty tight. I put a wrench on it but felt like if I pushed any harder it would crumble. My solution was to get the same GM spec air temp sensor I found for RH's project. I cut it down to a diameter that would allow me to cut some 12MM /1.5 threads matching the original sensor. The result is a tapered, shorter unit that snugly threads into the original plastic holder. I'll splice in the pigtail and be good to go for about $30. The pic shows the air temp sensor before and after altering it, the pigtail and the OE sensor. Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 3, 2009 Share Posted June 3, 2009 Seems there's more miles yet to go on the oh-so-wrongedy-wrong SQUARE WHEEL EXPRESS after all -- eh, Dan? And wot's this -- No dyno in a wind tunnel? No multi-channel data logger? Nary as much as a thermometer?!?! Kudo's. Your approach is one big step more direct than mine, more of a plug-'n-play solution for those who found either cold weather bad mileage due to low-temp sensor body rich running with the OE plastic holder intolerable, OR who found hot weather sensor body heat-soak hot lean-burn feedback loop symptoms with the brass holder intolerable (more'n a few, by the PMs I've received). O'course, those who shattered their OE plastic holders still need to either source a replacement, or fab up their own, as I did. By my measure, assuming the sensor is seated as far as it will go in the holder, the air gap between thermistor tip on the GM sensor and the base of the OE holder as you've used it would come out close to the same ideal gap I arrived at, 5 mm -- including just about exactly the right clearance for an o-ring for a seal. How convenient is that?! I figure it's only a matter of time this summer before this starts to catch on hereabouts. Too much value for too many not to eventually figure it out. Too bad those who managed to get their egos so heavily invested in this being Voodoo won't ever allow themselves to get it, huh? I'm pretty sure I know EXACTLY how well this will work for you on the road. But by all means, please keep us apprised! Link to comment Share on other sites More sharing options...
GuzziMoto Posted June 3, 2009 Share Posted June 3, 2009 There's more spin left on the oh-so-wrongedy-wrong SQUARE WHEEL after all -- eh, Dan? And wot's this -- No dyno in a wind tunnel? No multi-channel data logger? Nary as much as a thermometer?!?! Kudo's. Your approach is one step more direct than mine, more of a plug-n-play solution for those who found either cold weather bad mileage due to low-temp sensor body rich running with the OE plastic holder intolerable, OR who found hot weather sensor body heat-soak hot lean-burn feedback loop symptoms with the brass holder intolerable (more'n a few, by the PMs I've received). O'course, those who shattered their OE plastic holders still need to either source a replacement, or fab up their own, as I did. By my measure, the air gap between thermistor tip on the GM/NAPA Echlin sensor as you've used it in the OE holder comes out close to the same ideal gap I arrived at, 5 mm -- including just about exactly the right clearance for an o-ring for a seal. How convenient is that?! I figure it's only a matter of time this summer before this starts to catch on hereabouts. Too much value for too many not to figure it out. Too bad those who managed to get their egos so heavily invested in this being Voodoo won't ever allow themselves to get it, huh? I'm pretty sure I know EXACTLY how well this will work for you on the road. But by all means, please keep us apprised! I guess for Hack, that's about as "civilized" as it gets. Link to comment Share on other sites More sharing options...
dlaing Posted June 4, 2009 Share Posted June 4, 2009 By my measure, the air gap between thermistor tip on the GM sensor as you've used it in the OE holder comes out close to the same ideal gap I arrived at, 5 mm -- including just about exactly the right clearance for an o-ring for a seal. How convenient is that?! Looks more like 20mm gap to me. Link to comment Share on other sites More sharing options...
Dan M Posted June 4, 2009 Author Share Posted June 4, 2009 Looks more like 20mm gap to me. I've made no measurement. It is sensing the air temp inside the cavity so I really feel the difference between 5mm and 10mm will not be of too much consequence. If it were in a large space or in open air there would be a great difference but the holder is a pretty confined space. When the plastic sensor is screwed in fully, I'd estimate the reach is within 10mm of the old brass unit. Remember, RH's has the plastic cage on it. The actual thermistor is a few mm above that. If it is an issue I can simply cut more threads to screw it in deeper. Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 4, 2009 Share Posted June 4, 2009 EGADS, another EDIT: Per Dan's post above, now it's clear that his sensor isn't threaded all the way in up to the stop, so now I understand where Dan's estimate of 10 mm came from. As Dan says, the air gap is not critical with an air sensor, but a 5 mm gap seems to work as well as it's likely to work for me (a few thousand miles now). By my measure, assuming the sensor is seated as far as it will go in the holder, the air gap between thermistor tip on the GM sensor and the base of the OE holder as you've used it would come out close to the same ideal gap I arrived at, 5 mm -- including just about exactly the right clearance for an o-ring for a seal. FWIW, I measure 2.5 mm from the tip of the thermistor to the end of the protective "cage". On my version of this, I measured the gap from the cage, so it's really 7.5 mm. By my testing with different gaps, it ain't critical until you get the gap down around 3 mm from the thermistor, when funny stuff starts happening at low RPM and full operating temp. Link to comment Share on other sites More sharing options...
emry Posted June 4, 2009 Share Posted June 4, 2009 Caution!!! Langauge expressions following!! Sorry Japp ... The vodka is just right tonight. Temp sensor solution found!!! I just wet my @#$$#! and wave it in the wind and then adjust the potentiometer I have mounted to my seat which is wired to the orginal OE sensor. This way as I ride, if my @#$$#! gets cold, I just pinch my ass checks and that alters the fuel mixture. If my @#$$#! get hot I just fart. Nudity is best when enjoyed with a good clean running cycle. Sorry. I will now leave this thread alone. PS. Thanks for the symbol edit. Link to comment Share on other sites More sharing options...
dlaing Posted June 5, 2009 Share Posted June 5, 2009 So doesn't anyone wanna swap the "air temperature sensor" and the "'oil' Temperature sensor"? I swear the factory must have got them reversed. In the old thread three or four us all independently brought it up, but Dan and Ratchet seem to be ignoring the obvious. Do you guys have stock investments with GM? Link to comment Share on other sites More sharing options...
Dan M Posted June 5, 2009 Author Share Posted June 5, 2009 So doesn't anyone wanna swap the "air temperature sensor" and the "'oil' Temperature sensor"?I swear the factory must have got them reversed. In the old thread three or four us all independently brought it up, but Dan and Ratchet seem to be ignoring the obvious. Do you guys have stock investments with GM? Are you suggesting putting the brass sensor in the air box? Let me know how that works out for you. I'd also like it if you posted pics of how you mounted the MG air sensor to the V11 head. Thanks in advance. No obvious stuff ignored here. Any air temp sensor that has the same range will work. Ratchet asked me back when he was experimenting if I knew of anything that would do. I did some looking and the first one I found that had the same temp / resistance values was for a 2000 GM car. I'm quite sure other makers are similar but the GM sensor is compact, plastic, and cheap. If you'll remember we were looking for low mass. The GM unit meets all the criteria. It has the added benefit of a readily available pigtail for easy installation. There may be others that fit the bill even better but I'll leave that searching to someone else. (maybe you want to spend some time on it?) Like I said in the first post. I just added this info for those interested in the set up. If you are not, why not move on. Link to comment Share on other sites More sharing options...
dlaing Posted June 6, 2009 Share Posted June 6, 2009 I just added this info for those interested in the set up. If you are not, why not move on. I won't move on because I am being helpful, correcting misleading statements of 5mm air gaps and suggesting the Guzzi air sensor that precisely matches the Ohm/temp curve of the "oil" temp sensor. Why not listen to different ideas? Link to comment Share on other sites More sharing options...
dlaing Posted June 6, 2009 Share Posted June 6, 2009 If anyone is actually interested in using the Guzzi air sensor for this purpose, I was kind of joking about swapping the sensors, although I would not be surprised if it gave a better result. More likely, I think, using two air temperature sensors would be a better idea. (one to measure air temp at the airbox and one to measure cylinder head temperature) But the Guzzi air sensor is certainly more expensive than the GM air sensor, unless you get it second hand. In the other thread I posted a link to it being on eBay for a very low price. Earlier I thought an advantage of the Guzzi air sensor is that you might be able to bolt it down, rather than friction fit it like Ratchet did. But you showed that the GM can be threaded, so maybe that gives the GM sensor the edge?????? Still I prefer having the temp:ohms curve matching OEM brass sensor. Link to comment Share on other sites More sharing options...
Dan M Posted June 6, 2009 Author Share Posted June 6, 2009 If anyone is actually interested in using the Guzzi air sensor for this purpose, I was kind of joking about swapping the sensors, although I would not be surprised if it gave a better result. More likely, I think, using two air temperature sensors would be a better idea. (one to measure air temp at the airbox and one to measure cylinder head temperature)But the Guzzi air sensor is certainly more expensive than the GM air sensor, unless you get it second hand. In the other thread I posted a link to it being on eBay for a very low price. Earlier I thought an advantage of the Guzzi air sensor is that you might be able to bolt it down, rather than friction fit it like Ratchet did. But you showed that the GM can be threaded, so maybe that gives the GM sensor the edge?????? Still I prefer having the temp:ohms curve matching OEM brass sensor. Well, That is precisely what we did. Two air temp sensors. And, yes, the whole idea of using the GM sensor is it ranges the same as the MG sensor. Like I said, the difference between 5 and 10 millimeters inside that holder cavity is not of much consequence. Bolt in, screw in or interference fit, it really doesn't matter. The reason I went with screw in is because I didn't want to remove / break the stock plastic holder. Link to comment Share on other sites More sharing options...
dlaing Posted June 6, 2009 Share Posted June 6, 2009 Well, That is precisely what we did. Two air temp sensors. And, yes, the whole idea of using the GM sensor is it ranges the same as the MG sensor. Like I said, the difference between 5 and 10 millimeters inside that holder cavity is not of much consequence. Bolt in, screw in or interference fit, it really doesn't matter. The reason I went with screw in is because I didn't want to remove / break the stock plastic holder. Yes two air sensors, good idea! Potentially much lower thermal inertia!!! Bravo! I don't have a problem with that, quite the contrary. But it is only a good idea if air gap is optimally set. Thermal inertia is nearly doubled if you double the gap, decreasing "accuracy". To reduce thermal inertia, the air gap should be set as tight as possible without the sensor becoming too hot. Ratchet wrote: My first iteration of this had the plastic cage within a few thou of the conducting stud. I got a few little low RPM hot lean burn pops this way at full operating temp, so I backed it off to a ~2 mm air gap, and the pops disappeared. To me, it seems that he found the ideal gap to be ~2 mm, but in this thread he suggested 5 mm is ideal. I assume the revision is the result of more research, or maybe he changed from measuring to the cage to measuring from the thermistor. Regardless, he has much less air gap than you. I sincerely think you would benefit by following his example. Why he does not challenge you on this is obvious. The counter argument to the suggestion that you narrow the gap, might be that you have already improved the thermal inertia issue so much over OEM that you don't really care if following Ratchet's recommendation would perform better. In the previous thread Ratchet posted the spec'd numbers for the GM sensor that you provided him, that were different than the Guzzi sensor. The GM sensor reads "hotter" which would necessitate more air gap than if you used GM rather than the Guzzi AIR sensor. TEMP/RESISTANCE OUTPUTS OF GM/NAPA ECHLIN SENSOR vs. OE GUZZI SENSOR: SOURCE: GM Tech Data chart sensor output data provided by Dan M. (Thanks again, Dan.) Dan has tested both the GM sensor and others for many years professionally. It’s found on countless GM models. OE Guzzi sensor output data from Guzzi Service Manual. °C/GM sensor Ω/OE Guzzi sensor Ω -40 100700 100950 -30 52700 53100 -20 28680 29120 -10 16180 16600 0 9420 9750 10 5670 5970 20 3520 3750 30 2238 2420 40 1459 1600 50 973 1080 60 667 750 70 467 525 80 332 380 90 241 275 100 177 205 The Guzzi oil and air sensors match not just closely, but identically. Why not use it instead? Link to comment Share on other sites More sharing options...
Velf 2003 Posted June 6, 2009 Share Posted June 6, 2009 [The Guzzi oil and air sensors match not just closely, but identically. Why not use it instead? Well, that`s what I`ve done. Since the GM sensor isn`t easely commercialy available here in the Netherlands I really had no other choice. I had a close look at the Guzzi sensor and decided that cutting away the brass end would be a good start. Ending up cutting so much of the brass end (some 15 mm length of it) that the tip of the sensor showed, covered in some sort of thermal paste. I have remounted the altered sensor and was suprised that my fuel consumption went down by some 10 % (measured over my last trip, 6 days, 3500 km), the engine heated up quicker, didn`t backfire under low throthle and idled perfectly, even hot. So in my humble opinion an easy enty into temp. sensor trials. I entered this forum to share my expirience with you all and with no intention to trigger anyone into trying this. Please decide for yourself it this is what you want. Thanks to Ratchethack, who trigged ne to try altering my temp. sensor into the GM variant, as said above, ending up altering the original sensor. Velf2003 I can resist anything, but temptation (Oscar Wilde) Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 6, 2009 Share Posted June 6, 2009 I had a close look at the Guzzi sensor and decided that cutting away the brass end would be a good start. Ending up cutting so much of the brass end (some 15 mm length of it) that the tip of the sensor showed, covered in some sort of thermal paste. I have remounted the altered sensor and was suprised that my fuel consumption went down by some 10 % (measured over my last trip, 6 days, 3500 km), the engine heated up quicker, didn`t backfire under low throthle and idled perfectly, even hot. So in my humble opinion an easy enty into temp. sensor trials. INNOVATIVE to say the least, Velf. This is the exact mileage improvement I acheived with the GM/NAPA Echlin sensor, and lines up perfectly with my results -- no more low RPM hot lean-burn feedback loop symptoms at full operating temps. Any chance you could post any photo's of your modifications of the OE sensor? Link to comment Share on other sites More sharing options...
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