TPS and Performance issues?

[sideshowBob]

Sorry for the long post just skip it if you aren't interested.

There has been info posted on TPS in the past, mostly stating it has little effect on our 2000/01/02 SRXs performance. I have had intermittent performance issues and DCS issues since I aquired my 2002 SRX. I have been on the hunt for a while to sort this sled out, always suspicious it was an ignition/timing problem.

Background info:

Our TPS equiped SRXs have the same TPS that was installed on the early 2000s Yamaha R6 motorcycles. Yamaha did a recall on these motorcycle TPS sensors due to intermittent performance/idle issues[do an internet search for more info]. Yamaha never recalled the snowmobile TPS sensors...things that made me go HMMMM...

I built a test wiring harness for the TPS that I could use when the sled was running and finally got around to checking the timing and TPS readings on my SRX and found right away that at 1800RPM my sleds timing was 20 degrees BTDC TPS connected and 15 degrees BTDC TPS disconnected...5 degrees... thats a big change!
I won't bore everyone with all the rest of the testing and inconsistant readings and timing fluctuations I got with the TPS plugged in compared to it being unplugged but it was obvious my TPS definately had major issues!
I ordered in a new TPS sensor and sure enough found the part number had been updated twice!
I installed the new sensor and calibrated it as per the shop manual, THE EXACT SETTING IS CRITICAL FOR THE TPS TO FUNCTION PROPERLY! The voltage being supplied to the TPS from the sleds wiring harness was 5.0 volts regardless of engine RPM. It was the voltage the TPS was sending to the CDI that was the problem.
With no other changes, my sled now is consistant at all times and no inconsistant DCS issues! On my sled this updated TPS made a huge difference! I know, from my test procedures, that my TPS was sending intermittent and inaccurate voltage values back to the CDI throughout the throttle movement and I beleive it was triggering the DCS at times among other things.

Bob

 

[thunder66]

Sorry for the long post just skip it if you aren't interested.

There has been info posted on TPS in the past, mostly stating it has little effect on our 2000/01/02 SRXs performance. I have had intermittent performance issues and DCS issues since I aquired my 2002 SRX. I have been on the hunt for a while to sort this sled out, always suspicious it was an ignition/timing problem.

Background info:

Our TPS equiped SRXs have the same TPS that was installed on the early 2000s Yamaha R6 motorcycles. Yamaha did a recall on these motorcycle TPS sensors due to intermittent performance/idle issues[do an internet search for more info]. Yamaha never recalled the snowmobile TPS sensors...things that made me go HMMMM...

I built a test wiring harness for the TPS that I could use when the sled was running and finally got around to checking the timing and TPS readings on my SRX and found right away that at 1800RPM my sleds timing was 20 degrees BTDC TPS connected and 15 degrees BTDC TPS disconnected...5 degrees... thats a big change!
I won't bore everyone with all the rest of the testing and inconsistant readings and timing fluctuations I got with the TPS plugged in compared to it being unplugged but it was obvious my TPS definately had major issues!
I ordered in a new TPS sensor and sure enough found the part number had been updated twice!
I installed the new sensor and calibrated it as per the shop manual, THE EXACT SETTING IS CRITICAL FOR THE TPS TO FUNCTION PROPERLY! The voltage being supplied to the TPS from the sleds wiring harness was 5.0 volts regardless of engine RPM. It was the voltage the TPS was sending to the CDI that was the problem.
With no other changes, my sled now is consistant at all times and no inconsistant DCS issues! On my sled this updated TPS made a huge difference! I know, from my test procedures, that my TPS was sending intermittent and inaccurate voltage values back to the CDI throughout the throttle movement and I beleive it was triggering the DCS at times among other things.

Bob

Very intriguing stuff Bob. Without the testing I would want to believe that my sled suffers from the same ailments especially around start up and idle and lower rpm settings in the 2000 to 4000 range. Would you be willing to share more details with me? I'd love to know about the harness you built and the updated part # for the TPS (just to be sure that if I ordered one I am getting the latest).

Thanks, Mike

 

[sideshowBob]

Very intriguing stuff Bob. Without the testing I would want to believe that my sled suffers from the same ailments especially around start up and idle and lower rpm settings in the 2000 to 4000 range. Would you be willing to share more details with me? I'd love to know about the harness you built and the updated part # for the TPS (just to be sure that if I ordered one I am getting the latest).

Thanks, Mike

Nothing fancy...I just spliced in some connectors into an extra TPS wiring harness I had so I could test on the sled with it running.

Part number of new TPS 5FL-85885-02

I CAN NOT OVER EMPHASIZE HOW IMPORTANT IT IS THAT THE TPS IS CALIBRATED AS PER THE SHOP MANUAL!!!

Bob

 

[thunder66]

Cool! Thanks!

 

[mrviper700]

the TPS has zero effect on Wide open Throttle.

just to add , yes the tps may have very well been defective in your application, but the function of the tps is to provide increased accelaration and mid range cruising performance with better fuel economy, the tps provides the inputs for the 3d ign. system which came out in the 2000srx. Your findings at low speed would be correct, but as for it making the dcs go off wouldnt, for the tps doesnt apply input at wide open throttle where the dcs would be starting to rely off the dcs senser. The dcs operates in a rpm window from 6500rpm-9000rpm, so your dcs light would have to be going off in the midrange cruising speed to be caused by the tps sensor. I have the window of the operation of the tps,maybe I can scan and post it for you to study and look at.
The function of the dcs is to retard the timing based off the vibration freq. picked up by the dcs sensor. If you have ever heard a mid 80's gm truck rattle mid throttle thats what the detonation sounds like(same thing the sensor is listening for).
If you retard timing in a 2 stroke you take heat out of the piston and apply heat to the pipe. With advancing the timing your adding heat to the piston and cooling the pipe. So going back to your sled, if you had less timing at the beginning it wouldnt make your dcs go off it would have less chance of having detonation.

I played with the tps settings on the dyno and we did 4 seperate pulls, one with as stock, one with tps disconnected,1 with tps set mid range and 1 with tps set wide open from the start, they all come up the same power output. You would need to to a very slow gradual rpm sweep to see any differance as it doesnt compute at wide open power output. I still have the little holder which the tps bolts to and has a lever so you could move the tps sensor during a run while plugged into the sled. if you would like it, I will send it to you and you can play with it on your sled. you would need to hook up like choke cable to it to move it while riding the sled.

 

[snomofo]

Bob,

I wouldn't be board with your detailed findings.

I assume since you had 5 volts input to the TPS the system uses a standard 5 volt reference, signal ground and signal return.

Were you getting verying signal output with a steady throttle angle? Was it going open, hi or low?

Since there is no other way to know rider input (i.e. no MAP/MAF) or load, seems to me the TPS would be critical in mapping spark advance.

Is the TPS stamped with an mfg. ?

Denzo/CTS?

 

[Netefrog]

Just ran a test on my TPS only to find out it's pooched. How much do these units usually go for? Brand new from Yamaha or Mikuni?

 

[WNYViper]

Just ran a test on my TPS only to find out it's pooched. How much do these units usually go for? Brand new from Yamaha or Mikuni?

$120 from Yamaha according to PortYamaha's website

 

[sideshowBob]

the TPS has zero effect on Wide open Throttle. Your findings at low speed would be correct, but as for it making the dcs go off wouldnt, for the tps doesnt apply input at wide open throttle where the dcs would be starting to rely off the dcs senser. The dcs operates in a rpm window from 6500rpm-9000rpm,

Isn't it interesting that the DCS starts to function coincidental with the power valves opening?
Your comments are obviously accurate for a properly fuctioning TPS, but my sensor was sending voltage to the CDI anywhere from .17 up to 4.3 at varrying throttle positions in an inconsistent, intermitant way. When my original TPS was hooked up and engine RPM was raised the timing was constantly varying and never remained stable, it was very hard to track with my timing light, with the TPS disconnected the timing was easy to track and very stable throughout the timing curve. I was triggering my DCS with the old TPS at part throttle settings, especially between 3/4 + full throttle, which makes sense to me because at times my TPS was sending voltage to the CDI that was telling it that it was at 1/4 throttle when it was actually at 3/4 throttle so the timing was being fully advanced the extra 5 degrees that the TPS was capable of triggering when the engine should actually be entering the timing retard curve.

Anyway...I just rode 200+ miles today, 300 miles since replacing my TPS and the sled has been running better then it has in the 4+ years 10,000 +++ miles that I have owned it!

Worked for Me!

Bob

 

[modsrx]

Isn't it interesting that the DCS starts to function coincidental with the power valves opening?
Your comments are obviously accurate for a properly fuctioning TPS, but my sensor was sending voltage to the CDI anywhere from .17 up to 4.3 at varrying throttle positions in an inconsistent, intermitant way. When my original TPS was hooked up and engine RPM was raised the timing was constantly varying and never remained stable, it was very hard to track with my timing light, with the TPS disconnected the timing was easy to track and very stable throughout the timing curve. I was triggering my DCS with the old TPS at part throttle settings, especially between 3/4 + full throttle, which makes sense to me because at times my TPS was sending voltage to the CDI that was telling it that it was at 1/4 throttle when it was actually at 3/4 throttle so the timing was being fully advanced the extra 5 degrees that the TPS was capable of triggering when the engine should actually be entering the timing retard curve.

Anyway...I just rode 200+ miles today, 300 miles since replacing my TPS and the sled has been running better then it has in the 4+ years 10,000 +++ miles that I have owned it!

Worked for Me!

what happend i u rode the engine without the tps ??? never did it just asking ...

 

[sideshowBob]

Bob,

I wouldn't be board with your detailed findings.

I assume since you had 5 volts input to the TPS the system uses a standard 5 volt reference, signal ground and signal return.

Were you getting verying signal output with a steady throttle angle? Was it going open, hi or low?

Since there is no other way to know rider input (i.e. no MAP/MAF) or load, seems to me the TPS would be critical in mapping spark advance.

Is the TPS stamped with an mfg. ?

Denzo/CTS?

On the 5 volts, I had the sled running and used the voltage supplied by the sled to the TPS, it was a consistant 5.01 volts regardless of rpm. Using the maintenance manual test procedures , I multilpied that by .136 to get the calibration voltage setting of .68volts...this was for the calibration of the new updated TPS.
When I checked the voltage output of my original TPS it was intermittent and at times supplying a lower voltage to the CDI at a higher throttle setting then at a lower throttle setting[opposite of what it should be], when tracking the timing with a timing light it was hard to track and all over the map.
The TPS is marked on the front by just the brand name Mikuni but on the back the original TPS had "A1" on it the new one has "A2"


Bob

 

[mrviper700]

Isn't it interesting that the DCS starts to function coincidental with the power valves opening?

Bob, glad you fixed your sled. How were you able to track the timing with the sled at part throttle load conditions? I am guessing it would depend on the load apllied to wether or not the dcs would go off, sitting on a stand revving it up would not likely yield the same results as in the field I would think, curious. I am also curious as to how you know you were adding 5 degrees in part throttle cruising or if you were just checking the sled in the garage setting with your timing light? Not asking for debate reasons.

I would have to guess(dcs) its the same rpm as the p/v circuit is already built in the cdi, so they would merely spike on to it. I dont know, I am not electronics guru for yamaha so I have no idea what it takes to add or subtract a function in a cdi box. I can tell you a viper and a srx have a differnt rpm for the p/valve opening also, so the srx with dcs vs the viper with dcs would be interesting swap/comparison if someone was into testing.

It wasnt any intention to sound like I was saying you were wrong about fixing it, just was trying to say it merely only has limited abilitys for input,as like snomofo mentioned theres no other inputs in the system, not anywhere advanced like automobile.
I played with the tps for the thinking I might find a little extra timing to be had for a "stock" prep race sled,where you cant use keyways,but to no avail.

 

[mopar1rules]

Isn't it interesting that the DCS starts to function coincidental with the power valves opening?
Your comments are obviously accurate for a properly fuctioning TPS, but my sensor was sending voltage to the CDI anywhere from .17 up to 4.3 at varrying throttle positions in an inconsistent, intermitant way. When my original TPS was hooked up and engine RPM was raised the timing was constantly varying and never remained stable, it was very hard to track with my timing light, with the TPS disconnected the timing was easy to track and very stable throughout the timing curve. I was triggering my DCS with the old TPS at part throttle settings, especially between 3/4 + full throttle, which makes sense to me because at times my TPS was sending voltage to the CDI that was telling it that it was at 1/4 throttle when it was actually at 3/4 throttle so the timing was being fully advanced the extra 5 degrees that the TPS was capable of triggering when the engine should actually be entering the timing retard curve.

Anyway...I just rode 200+ miles today, 300 miles since replacing my TPS and the sled has been running better then it has in the 4+ years 10,000 +++ miles that I have owned it!

Worked for Me!

Bob

bob, glad you got your sled straightened out. now you got me thinking about the TPS sensors on my srx and viper. will have to check them out now. lol. thanks for the descriptive posts and pics. when you said you were getting the timing to add an extra 5 deg of timing and such, that got me thinking if that would be part of the reason to all the blow ups in the last 2 yrs?? you know.....bad gas w/some hotter timing or something, = booom!! any opinion or take on this?

 

[sideshowBob]

Bob, glad you fixed your sled. How were you able to track the timing with the sled at part throttle load conditions? I am guessing it would depend on the load apllied to wether or not the dcs would go off, sitting on a stand revving it up would not likely yield the same results as in the field I would think, curious. I am also curious as to how you know you were adding 5 degrees in part throttle cruising or if you were just checking the sled in the garage setting with your timing light? Not asking for debate reasons.

I would have to guess(dcs) its the same rpm as the p/v circuit is already built in the cdi, so they would merely spike on to it. I dont know, I am not electronics guru for yamaha so I have no idea what it takes to add or subtract a function in a cdi box. I can tell you a viper and a srx have a differnt rpm for the p/valve opening also, so the srx with dcs vs the viper with dcs would be interesting swap/comparison if someone was into testing.

It wasnt any intention to sound like I was saying you were wrong about fixing it, just was trying to say it merely only has limited abilitys for input,as like snomofo mentioned theres no other inputs in the system, not anywhere advanced like automobile.
I played with the tps for the thinking I might find a little extra timing to be had for a "stock" prep race sled,where you cant use keyways,but to no avail.

I appreciate the imput/discussion as I am no electronics expert either. I always was suspect of this sleds electronics as I only intermittently could get this SRX to wind out and pull hard on the hard pack, I never had any trouble
with any other tripple until this one and my 700 SX improved stock test mule has always owned this sled every where...until now.

I do not have a dyno or access to one...LOL...never have!
Tools I used were Digital Tach, Digital Multi Meter, home made test harness, dial indicator, + degree wheel, and Improved stock 700SX mule sled.
To trouble shoot this issue I installed a degree wheel on the clutch with an index and established and zeroed it for TDC . Most of the timing testing was done at relatively low rpm and with the original TPS installed. I also had an additional TPS that I would plug in and vary the setting on it at a fixed throttle postion to watch the effect on timing. It became obvious very quickly that my TPS was sending completely irratic voltage to the CDI at pretty well every throttle angle, with high and low spikes.
The rest of my testing was done up and down my 2000' driveway.

I posted this because it made such a huge difference on my sleds performance and thought someone else may benifit from my experience.

Bob

 

[crazykid]

This really makes sense to me, If the tps sensor isnt working right the cdi wont be getting the right signals as to when to advance or retard the timing. Mr viper you say the tps has nothing to do with wide open throttle? But how does the cdi know it is wide open if the tps isnt telling it that it is wide open? Not trying to be a smart *** or anything, Just trying to understand this a little more. Reading this post just made it click how important the tps really is. If you are wide open and the tps is telling the cdi that it is only 1/4 throttle wont the timing be still too hot if the cdi hasnt retarded the timing because it still thinks its only at 1/4 throttle? Or something like that? Hope you all know what i am trying to say. It makes a lot of sense now if i am understanding this the right way. Great post Bob

 

[mopar1rules]

This really makes sense to me, If the tps sensor isnt working right the cdi wont be getting the right signals as to when to advance or retard the timing. Mr viper you say the tps has nothing to do with wide open throttle? But how does the cdi know it is wide open if the tps isnt telling it that it is wide open? Not trying to be a smart *** or anything, Just trying to understand this a little more. Reading this post just made it click how important the tps really is. If you are wide open and the tps is telling the cdi that it is only 1/4 throttle wont the timing be still too hot if the cdi hasnt retarded the timing because it still thinks its only at 1/4 throttle? Or something like that? Hope you all know what i am trying to say. It makes a lot of sense now if i am understanding this the right way. Great post Bob

this has been pretty much exactly what i'm thinking. i'll have to test my TPS sensors this weekend now.

 

[Netefrog]

Thanks again for the quick PM reply Bob. I found this thread very helpfull as I am also going through this TPS issue at the moment. Tonight and tomorrow evening will be electronics for mechanics 101 for me as my ma's mechanic husband gives me a hand with getting this issue fixed. Again this site (and it's members) has been a big help, maybe I should break down and go for a VIP membership.

 

[tofastSRX]

yeah. you cheap prick lol you will be running tomorrow with that tps i gave you .i told you all these spare srx parts would be handy

 

[mopar1rules]

yeah. you cheap prick lol you will be running tomorrow with that tps i gave you .i told you all these spare srx parts would be handy

haha, that's what i tell everybody too. i do have spare TPS sensors laying around that i can test to see if they work properly. i see the sensor thru kawasakipartsnation is $101.07.

 

[mrviper700]

But how does the cdi know it is wide open if the tps isnt telling it that it is wide open?

simply by the pick up coil, the cdi gets its signal from the pick up coil which in turn sends the signal to the box. Its the same exact way a 98-99 srx can advance and retard the timing thru the cdi box as well as any other snowmobile without the use of a throttle pos. sensor.