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Daytona Cylinder Head Temperature Sensor - Long

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
I'm posting this for what it's worth...............

My '93 Daytona started acting up a little late last year right as winter set in, where-in once hot it would sometimes, though rarely, go "flat" like there was water in the gas or something similar. It usually cleaned itself up when I added throttle, but as winter was setting in and I was starting the GSXR Fork install, I didn't check into that problem until this spring.

I assumed maybe the original fuel filter might be getting fouled (19,000 miles) so I installed a new filter and replaced all the fuel lines once I had the new forks, etc. dialed in. This didn't help, as the problem got worse to the point that once I got the bike warm it would run really rough and/or like there was a fueling problem. As the only sensors on the bike are for barometric air pressure, air temperature, and cylinder head temperature (called oil temp sensor in the shop manual, and cylinder temp sensor in the parts book), I tried unhooking the cylinder head temperature sensor wire once warmed up, and the bike ran fine.

When I tried ordering the sensor I discovered it was superseded by the more common one used for recent vintage Guzzi's, where-in the last number of the part number changed from a 0 to a 1. I tried MG Cycle, Harper's, and one other outfit that all showed the sensor as unavailable, which I assume means it was backordered significantly, as no one could tell when or if one would become available. MG Cycle had mentioned he thought one for one of the watercooled Ducati's might work, so I stopped at my local Ducati dealer to check it out.

Koup's Cycle Shop had a cylinder head temperature sensor in stock, I believe for an air cooled late model big twin Duck, that had the same connector, same manufacturer, and the same threads as the original I'd removed. Some of the numbers stamped on the flats of the "nut" were different, but as it was available and actually a little cheaper, I bought it and installed it. All the running issues are now gone and the bike seems to run just fine. I'm not sure if the temp sensor acts like a cold/hot switch, or if it provides a "ramped" output to the ECU to provide finer control of the injection system. When I get the bike safety inspected later this week I may have my exhaust gases checked to see what that shows, and if doubt may have it run on the Dyno to check AFR's at various points. Hopefully I haven't wasted a "C" note getting the Ducati version, but we'll see.

The Ducati part number for the sensor I got is 55240131A FWIW.

Bill

PS - The inexpensive, modified U-Joints I installed now have 1500 trouble free miles on them and seem to be holding up very well. This is explained in another thread started by MOTO510- "Swapped GSXR Forks to '96 Daytona".
 

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
Just a quick update:
Went to a local Hi-Perf shop I frequent to get the Daytona inspected, and the fellow that runs the place told me he was certain the cylinder head temp sensor is just basically an on/off type sensor (cold/hot), and that as the bike is running perfectly with the Ducati sensor, he wouldn't waste the time or money checking AFR's/CO levels, etc. Will keep an idea on fuel mileage to see if that changes appreciably, but as far as I can tell the bike runs like it used to - very well.
 

GuzziMoto

GT Reference
GT Contributor
Joined
Nov 7, 2008
Messages
1,894
Location
B'more, Md
The actual sensor is almost certainly a ramped output resistance sensor. What the ecu does with that very well could be more of a switched, high/low, response. Like a choke on or choke off response based on that value crossing a threshold.
 

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
I assumed the sensor would ramp resistance also, and figured the ECU might be smart enough to really use the info to the maximum advantage. When I checked the original sensor (on a times 400K scale) it read ~3000 ohms cold, and 330K hot. Real info on what it should be isn't available from any source I tried, but as i mentioned the bike ran fine once I unplugged the original "bad" sensor.

The new sensor read 300K+ ohms cold, and as it works I didn't bother testing it hot. I agree with it probably is being used simply as an "enrichment switch", as our "choke/starter aid" really only opens the throttle plates a bit for cold starts.

Take care
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,619
Location
Huntsville, AL
cloudy said:
I assumed the sensor would ramp resistance also, and figured the ECU might be smart enough to really use the info to the maximum advantage. When I checked the original sensor (on a times 400K scale) it read ~3000 ohms cold, and 330K hot. Real info on what it should be isn't available from any source I tried, but as i mentioned the bike ran fine once I unplugged the original "bad" sensor.

The new sensor read 300K+ ohms cold, and as it works I didn't bother testing it hot. I agree with it probably is being used simply as an "enrichment switch", as our "choke/starter aid" really only opens the throttle plates a bit for cold starts.

Take care

look here for sensor values guzzitek.org
 

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
Thanks John. I didn't have any idea such an info source was available, but really appreciate the link. It does appear the thermistor provides a ramped output, and I'd assume it biases the ECU the whole way from cold to its' max. Correct me if this is wrong, but it seems that other than adjusting fueling during warmup, it seems that once the sensors reached its' maximum of 125 degrees celcius (257 degrees F) it would have no further effect. While it's called an oil temperature sensor, it doesn't appear to actually measure oil temperature as it sits in a small well in the head that appears to me to be dry. In fact I'm pretty sure the sensors' called a cylinder head temp sensor in the parts book I have, while the repair manual I have calls it an oil temperature sensor. Assuming it measures head temp it would seem that once the bike is warmed up it would be maxxed out, while if it read oil temp if "might" not be.

At least the resistance readings in the article prove my original one was bad, as the resistance readings went totally the wrong direction. The fact that the new sensor started out much higher than the spec'd value (300K if I remember), is for the moment offset by the fact that the bike is now running fine, although I guess now I'll need to investigate further before I ride the bike too much. This probably explains the fact that I noticed the bike was running rich when I first started it after installing the sensor (traces of black smoke upon revving it a little when cold), which went away after it had warmed up. Guess I'll need to stick to riding the BMW SKRR :p for now.

Edit1: After reading the provided workshop manual some more, it seems that the pressure relief valve (fuel) should have a sensing tube connected from the spring side to the manifold to provide a reference for the relief valve. I know mine doesn't have anything connected to the top port, and am thinking maybe it should be connected to the manifold. Anyone know if this assumption is correct?

Edit2: Just looked at the manual some more and figure I'll print it out and study it. It looks like there is a connection made to the manifold in some of the testing procedures sections, so I'd better do my homework.

Thanks in advance.

Bill Goudy
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,619
Location
Huntsville, AL
Bill,

The pressure relief valve only needs to reference to atmosphere. No need to connect it to the intake.
 

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
Thanks John. That makes more sense as it's apparently worked fine that way for the last 17-18 years. I was wondering how negative pressure of varying degrees (vacuum) would work out anyway, and unless one were to connect to the manifold ports I don't see where to even make the connection. I did notice a slight surge/hunting today at very light "maintenance" throttle until the bike was entirely warmed up, which I assume may be caused by the Ducati sensor having a different resistance ramp than the Guzzi version. Other than this issue it runs fine both cold and hot.

While I'm being a PITA is there any chance Guzzitek.org has similar resources for the later model MGs? A good friend (a machinist/bike wrench) works at a high end classic car/antique shop that restores old Porches, race cars, etc. (and I thought bike guys spent a lot of money on their rides at times; these guys are in a whole different league) The shop took on MG within the last few years for some reason, and he gets no help from them with obtaining the type of info you posted the link for.

Thanks again.

Bill
 

john zibell

Moderator
Staff member
GT di Razza Pura
Joined
Oct 28, 2008
Messages
8,619
Location
Huntsville, AL
The workshop manuals in the download section of this forum provide that type of information for the newer bikes.
 

GuzziMoto

GT Reference
GT Contributor
Joined
Nov 7, 2008
Messages
1,894
Location
B'more, Md
cloudy said:
While I'm being a PITA is there any chance Guzzitek.org has similar resources for the later model MGs? A good friend (a machinist/bike wrench) works at a high end classic car/antique shop that restores old Porches, race cars, etc. (and I thought bike guys spent a lot of money on their rides at times; these guys are in a whole different league) The shop took on MG within the last few years for some reason, and he gets no help from them with obtaining the type of info you posted the link for.

Thanks again.

Bill
Art is a good guy.
That shop is a cool place.
 

cloudy

Just got it firing!
Joined
Jan 17, 2010
Messages
20
Location
Marysville, PA
John,
Thanks and I guess I need to check out what else is available here. Just haven't taken the time yet, but will now.

GuzziMoto,
You are correct on both counts. Art's even still my friend even after I wadded his T595 Triumph this past May, when we switched bikes so he could try out my newest addition. We'll probably be at the Mid-Atlantic Italian MC Festival in Shepherdstown, WV next Sunday, though he'll truck in his V7 (his wife is going and won't ride the V7 that far), while I'll ride the Daytona down if I can get free.

Take care gentlemen.

Bill
 

Paul smith

Just got it firing!
Joined
Jun 17, 2016
Messages
1
Location
Glasgow
I'm posting this for what it's worth...............

My '93 Daytona started acting up a little late last year right as winter set in, where-in once hot it would sometimes, though rarely, go "flat" like there was water in the gas or something similar. It usually cleaned itself up when I added throttle, but as winter was setting in and I was starting the GSXR Fork install, I didn't check into that problem until this spring.

I assumed maybe the original fuel filter might be getting fouled (19,000 miles) so I installed a new filter and replaced all the fuel lines once I had the new forks, etc. dialed in. This didn't help, as the problem got worse to the point that once I got the bike warm it would run really rough and/or like there was a fueling problem. As the only sensors on the bike are for barometric air pressure, air temperature, and cylinder head temperature (called oil temp sensor in the shop manual, and cylinder temp sensor in the parts book), I tried unhooking the cylinder head temperature sensor wire once warmed up, and the bike ran fine.

When I tried ordering the sensor I discovered it was superseded by the more common one used for recent vintage Guzzi's, where-in the last number of the part number changed from a 0 to a 1. I tried MG Cycle, Harper's, and one other outfit that all showed the sensor as unavailable, which I assume means it was backordered significantly, as no one could tell when or if one would become available. MG Cycle had mentioned he thought one for one of the watercooled Ducati's might work, so I stopped at my local Ducati dealer to check it out.

Koup's Cycle Shop had a cylinder head temperature sensor in stock, I believe for an air cooled late model big twin Duck, that had the same connector, same manufacturer, and the same threads as the original I'd removed. Some of the numbers stamped on the flats of the "nut" were different, but as it was available and actually a little cheaper, I bought it and installed it. All the running issues are now gone and the bike seems to run just fine. I'm not sure if the temp sensor acts like a cold/hot switch, or if it provides a "ramped" output to the ECU to provide finer control of the injection system. When I get the bike safety inspected later this week I may have my exhaust gases checked to see what that shows, and if doubt may have it run on the Dyno to check AFR's at various points. Hopefully I haven't wasted a "C" note getting the Ducati version, but we'll see.

The Ducati part number for the sensor I got is 55240131A FWIW.

Bill

PS - The inexpensive, modified U-Joints I installed now have 1500 trouble free miles on them and seem to be holding up very well. This is explained in another thread started by MOTO510- "Swapped GSXR Forks to '96 Daytona".
Not much on internet about Daytonas so I was amazed when your post came up, describing exact symptoms as I was experiencing With my 1992 bike. Had got as far as changing plugs, swapping fuel pump for a spare used one, and was considered more expense when I found your post. Bought a used oil temperature sensor for £12 from Gutsibits and problem sorted. Thanks for the advice, and for posting the solution. Cheers
 

Ray1150

Cruisin' Guzzisti
GT Famiglia
Joined
Aug 15, 2009
Messages
264
Location
London
I've had nothing but arseache from mine with one thing and another going wrong and just having started a new job not much free time.
The latest trick is after about 30 miles it just stops and after 20 mins will start again. So after a bit of reading I replaced both the oil temp sensor and the crankshaft sensor (buy the Fiat CS, exactly the same, hell of a lot cheaper) although the resistances were within limits when cold.
Problem solved! I was so happy last Sunday, I did notice that it felt a bit rough which was odd because I'd followed Aussie Mikes tuning instructions to the letter and it certainly had run better in the past. I took a faster route home along some nice "A" roads keeping up around 70 mph. When the time came to throttle off I did but the engine didn't, I hit the engine kill switch and coasted to a stop. Long story short the throttle stop screws had to be backed right off to allow the engine to tick over, once done the bike ran quite well. I had to do this by the side of the road but will tune the bike properly this weekend and I think I can actually get on with riding the damn thing rather than working on it all the time. I can only think something was stuck or blocked when I set the tune up and this was cleared by a longish fastish ride. I'm just going to get the shock rebuilt & resprung and we're ready for Mandello.
 
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