SV Talk, Tuning & Tweaking Discussion and chat on all topics and technical stuff related to the SV650 and SV1000 Need Help: Try Searching before posting |
|
Thread Tools |
16-10-11, 12:20 AM | #1 |
Guest
Posts: n/a
|
Throttle Position Sensor
On the carbed mk1s, does removal of TPS help smooth out low down fuelling? Someone mentioned this to me, I have no idea whether or not its complete bollox. I associate the TPS with FI - I know that the throttle sensor has played a part in aggrevating fuelling on some KTMs, for example, and the SV is a bit snatchy at low revs for a carbed bike. The jetting itself is pretty good, we had her on a mate's dyno and apart from running a tad lean coming off idle, fuelling was pretty much spot on (68 bhp at wheel). Which made me wonder about the TPS.
|
16-10-11, 02:54 PM | #2 |
No, I don't lend tools.
Mega Poster
Join Date: Jul 2003
Location: Skunk Works, Nth London
Posts: 8,680
|
Re: Throttle Position Sensor
Throttle position is a good indicator of engine load, as such the TPS is effectively a load sensor, it's connected to the ignition system and the ECU will alter timing slightly to account for load.
Checking its setting is worthwhile if you think throttle transitions are not as smooth as they should be, but in my experience such problems are most commonly carburation.
__________________
If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst" |
16-10-11, 08:23 PM | #4 |
No, I don't lend tools.
Mega Poster
Join Date: Jul 2003
Location: Skunk Works, Nth London
Posts: 8,680
|
Re: Throttle Position Sensor
Do you have setup figures for the sensor?
__________________
If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst" |
17-10-11, 01:14 AM | #5 |
Guest
Posts: n/a
|
Re: Throttle Position Sensor
Nope, only figures I have are from the dyno, runs were done with TPS in situ which as far as I know is in standard trim.
Looking at that thread, I reckon that disconnecting a TPS on a carbed bike would simply leave the ignition at max advance and thus have no negative implications. FI bikes may respond differently to bypassing the sensor since FI and a TPS work hand in hand (in theory). That's why I was surprised to find that carbed SVs employed a TPS in the first place: not many carbed bikes did. It's an interesting one because some carbed SVs are a little unusual in that they can be jumpy when bringing power in, say exiting a bend, and that is something I associate more with FI. Since the fuelling seems to be OK, its probably worth while disconnecting and seeing what happens. Unfortunately the pix in the thread relate to the FI model which presumably is different in the connector department, if anyone has bypassed on a carbed bike, I'd be interested in where you unplugged the thing. |
17-10-11, 07:14 AM | #6 | |||||
No, I don't lend tools.
Mega Poster
Join Date: Jul 2003
Location: Skunk Works, Nth London
Posts: 8,680
|
Re: Throttle Position Sensor
Quote:
Quote:
Quote:
Quote:
Quote:
TPS setup, (from Suzuki's own workshop manual): Looking at the end of the connector you will see it is roughly heart shaped, there are three pins, two next to each other at the wide end, and one at the narrow end, call the the single pin at the narrow end 'A' and the upper left hand one 'B' and the right hand one 'C' Throttle shut - 3.5 - 6.5 K-ohms between 'A' and 'B' Throttle open - Resistance between pins 'A' and 'C' should be 78% of the resistance of the resistance between 'A' and 'B'.
__________________
If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst" |
|||||
17-10-11, 02:42 PM | #7 |
Guest
Posts: n/a
|
Re: Throttle Position Sensor
Cheers for that, especially the last bit, I reckon the only solution is to sse what happens. The old SV - which was an ex minitwins JHS bike - had no throttle position sensor and from memory is what a lot smoother getting on the throttle low down. That's how best to desscribe what I'm feeling, getting on the gas from a closed throttle the bike reminds of a 990 Superduke.... or in fact lots of FI KTMS... all or nothing stylee.
It does seem that the thread on this subject had people reporting similar findings, and remedied by ditching (or by passing) the tps. |
17-10-11, 03:07 PM | #8 |
Member
Mega Poster
Join Date: Jul 2003
Location: Warwickshire
Posts: 2,801
|
Re: Throttle Position Sensor
As said, the TPS on the carbed engine is a part load ignition advance device, just like the vacuum advance capsule on old distributors. My SK1 has it.
The engine needs more ign adv at part load to achieve the best combustion (economy). It's well worth setting it up correctly. There is no advantage in deleting it, it's lose/lose, it won't run as well at light load and will give worse economy. As said, the most likely candidate for poor off idle running is carb adjustment. Balancing the carbs for vacuum is easy, adjusting the idle mixture on a running SV engine is more tricky due to where the adjuster screws are situated. They really need to be set while the engine is running to allow for variations in manufacture (jet sizes etc) There are special angled-drive tools like this example , but they tend to be expensive. I have managed it with a thin thermal glove and a short screwdriver, I can just get my hand through the frame gap but it's tricky and you need to know where the adjusters are by feel because you're working blind. People often find the screws are corroded and won't move, so the carbs need to come off for cleaning anyway. US bikes had anti-tamper plugs fitted to the screws. Also double check the choke cables and plungers are free, stuck plungers will ruin light load running when warm.
__________________
"Artificial Intelligence is no match for natural stupidity" |
17-10-11, 03:27 PM | #9 |
Guest
Posts: n/a
|
Re: Throttle Position Sensor
Interesting.
Are you sure the TPS wasn't emissions related rather than economy related? It could be that coming of idle it needs a tweak, one reason why I thought the problem was TPS related was because members reported this problem and suggested TPS removal as remedy in that thread. Unfortunately dyno runs are buch better at showing you what's happening when you're on the throttle where everything looked good, so the dyno charts don't really help. Ta to both of you for the info. |
17-10-11, 08:05 PM | #10 |
Guest
Posts: n/a
|
Re: Throttle Position Sensor
Done some research. Yup, late 90s carbed bikes did use them like you suspected, and yup - they are strictly emissions related. What they do is retard the ignition at part throttle low down the range , because that is where the emissions legislation was severe.
My other bike (carbed) had a TPS, which was disconnected by the tuner. (The cdi reverts to default, ie an open throttle map = optimum advance throughout.) Since I ended up with 130 brake at the wheel as opposed to 90 I don't think the bike misses it, although obviously there are other mods With FI, the TPS can do more sophisticated stuff, but the TPS on the SV just retards the ignition until revs are out of the emission zone - if its anything like the Kwak K-Trick system. This may be wrong, but looking at bikes of a similar vintage, that does seem to be the story. Proof of pudding will be in eating, but I am bearing in mind that there may be other issues. |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Throttle Position Sensor | hardhat_harry | Mini-Twins | 0 | 08-11-09 09:37 PM |
Gear Position Sensor | Yarodia | SV Talk, Tuning & Tweaking | 33 | 04-05-09 07:19 PM |
throttle position sensor | Bibio | SV Talk, Tuning & Tweaking | 9 | 20-10-08 02:49 AM |
Pointy throttle position sensor | svdemon | Stuff Wanted | 9 | 02-09-08 07:50 PM |
Throttle Position Sensor | tricky | SV Talk, Tuning & Tweaking | 10 | 08-06-06 07:16 PM |