Throttle Position Sensor Issues (Are you Experiencing Poor Idle/Mileage, or Stalls?)

[Motogiro]

2D1-85885-01-00 & 2D1-85885-00-00 TPS are used across many yamaha bikes, including some years of FZ6, R7, R1 etc. So it should still apply. But thanks for reference.

What issue are you experiencing?

 

[labanina]

What issue are you experiencing?

TPS on my bike only goes up to 90 in diag menu. But smoothly so, without any dead spots or drops. More generally, I'm trying to nail down reason for violent vibrations after ~4K RPM. Just noticed the TPS thing in the process.

 

[TownsendsFJR1300]

TPS on my bike only goes up to 90 in diag menu. But smoothly so, without any dead spots or drops. More generally, I'm trying to nail down reason for violent vibrations after ~4K RPM. Just noticed the TPS thing in the process.

I wouldn't expect the TPS to make the engine run so bad above 4K, (running violently)..

Back to basic's, how do the spark plugs look? Any arcing going up the porcelain?
Have you replaced spark plugs?

What's the compression on each cylinder?

A Leak Down Test certainly wouldn't hurt.

Sounds like a dead cylinder above 4K, which needs to be looked into...



Also, from AI for EXACTLY your bike: (take with a grain of salt):

The throttle position sensor (TPS) range for the 2011 Yamaha FZ6R typically operates between 0% and 100%. In diagnostic mode, it is common for the TPS to max out at around 87% when the throttle is fully open, which may indicate a factory limitation rather than a need for adjustment
.


.

 

[labanina]

how do the spark plugs look?

Old ones looked fine (picrelated), I recently replaced them with iridium ones.

What's the compression on each cylinder?

200 200 200 195 Psi.

Spoiler: cyl 4 video

https://imgur.com/mvy44ap

A Leak Down Test

I'll look into it. If I understand procedure correctly you TDC the cylinder, pump air through spark plug hole and see how much pressure escapes, correct?

Sounds like a dead cylinder above 4K

Would it show on intake vacuum lines? I've got the gauge kit I used for TBS, but I never revved engine very high with those connected. If one cylinder is falling behind, vacuum should drop on it on high revs, no? I synchronized cylinders on idle (1300rpm), per spec 21-22 cmHG.

max out at around 87%

Fair enough, the info on values is contradictory on the internet.

 

[TownsendsFJR1300]

Did you do or check the throttle body sync?
Also, what SHOULDN'T BE ADJUSTED, (it may have been) is a screw between
the two TB's (2 barrel each, if you would). That sets the mechanical sync FOR THE BUTTERFLYS
THEMSELVES... IE, so their both at the same angle, one's not opening more than the other
causing a large imbalance:


Re the Leak Down test.

You'll need the tool and an air compressor..

Get the cylinder your testing to TDC, COMPRESSION STROKE.
Put in 90-100 PSI and measure the leakage. 15% leak down is about the limit you can go.

With the compression you have, I suspect you'll pass the leak down test.

Re vacuum, once you get into the higher RPM's, the vacuum at the TB's really doesn't help.
I sync at idle AND 4K RPMs. You can get them pretty close at 4 K and that does, IME, help with the vibs.

As you describe your issue, so intense, I'd be suspecting an ignition failure at the higher RPM's

*If you had a lazer temp gun, shooting at the header, next to the head, right after a high RPM run, MAY
show a lower temp, IF that cylinder wasn't contributing.. This is usually used at lower RPM's where the
contribution is easier to detect...

IE, an old 2 stroke Chain saw, with my tool, FAILING miserably:

 

[labanina]

Did you do or check the throttle body sync?

I did the throttle sync. Not the final result on the pic as a ended up moving it a bit closer to 20 across all cylinders, but looking at the manual now it's 238mmHG so maybe I should up it a bit. I knew not to mess with center screw but I didn't find it anyway on my bike. Syncing was done at idle (1300rpm), I couldn't do it for 4k it's like a whackamole you try to sync at 4k - cylinders go out of sync at idle and vice versa. At idle I was able to get cylinders within 1 cmHG, at 4K that would have to be within 5 or so.

You'll need the tool and an air compressor..

Thanks, I will look into this.

I'd be suspecting an ignition failure at the higher RPM's

Yeah, that's one of suspicious points to me too. With how dumb Yamaha did ht leads into the caps contact, it's entirely possible one shakes loose under high RPM despite my reinforcement efforts. One thing I noticed is that headers are different color, but it could just be that the outer ones (cyl1 & cyl4) are getting better cooling. I'll get the thermometer and see if there's any difference, thanks for advice!

 

[Gary in NJ]

I typically perform a leak-down test if one or more cylinders fail the compression test. If the compression passes, the leak-down test doesn’t really reveal anything.

 

[TownsendsFJR1300]

Don't worry about the total vacuum Yamaha posts. I live at sea level and can't get it to their spec's.

The MAIN thing when syncing is just getting all cylinders within the 10 MMs Yamaha requires.

As for the 4K syncing, you SHOULD be able to achieve that AND get a good sync at idle.
Yes it takes some fine tuning, I put a large fan in front of the bike when doing so as the
engine will be kicking fans on.

If yours is way out at 4K, and no way to get it any where's close, that may lead to your issue,
IE a cylinder not pulling the same as the others, etc.

Pic of my last sync at 1,300 RPMs, but at 4k, still within 10 mms (after valve adjustment , 26,600 miles):


.

 

[grcamna7]

Subscribed

 

[labanina]

*If you had a lazer temp gun, shooting at the header, next to the head, right after a high RPM run, MAY
show a lower temp, IF that cylinder wasn't contributing.. This is usually used at lower RPM's where the
contribution is easier to detect...

So I bought a lazer temp gun and took it to exhaust header temps. Roughly 5cm down from engine block, collected about 20-30 datapoints for each cylinder, below are averages.
Outer cylinder 1 & 4 headers are ~40% cooler than inner cylinder 2 & 3 headers. And difference persists when revving bike stationary or from cold start, so wind and fan cooling are not factors.
After 10m ride at 8-10K RPM:

• Cyl 4: 135°C
• Cyl 3: 246
• Cyl 2: 285
• Cyl 1: 150

Then I switched coils from left to right, and naturally caps too, and went for another test ride. Nothing changed for temps:

• Cyl4: 127
• Cyl3 233
• Cyl2 257
• Cyl1 170

At idle ~1300 RPM, from cold start within 1 minute:

• Cyl4: 75-100
• Cyl3: 150-180
• Cyl2: 160-190
• Cyl1: 80-110

My first idea was maybe Cyl1 & 4 mixture is somehow lean. So I increased C1 value in diag menu which I know supposed to work from exhaust test this year.
Used to be: C1=20, C2 = 20.
Tested new: C1= 60, C2 = 6.
Nothing changed for temp, so fuel mixture appears not to be at fault. Dropping C2 lower also didn't do a thing except making bike run even worse.

This makes me think something electrical, like the wires going to the left coil are bad, or it's ground is bad.
XJ6/FZ6R is wasted spark ignition system, there are only 2 coils, each works with 2 cylinders.
Left coil goes to Cyl 1 & 4, right coil goes to Cyl 2 & 3. I swapped coils left to right and replugged caps into spark plug wells. But the wires that go into terminals of coils remained the same. The left double power connector still goes to the left coil that works with cyl 1 & 4. It's just a different coil now.

 

[TownsendsFJR1300]

Lean would run hotter.... Your #'s don't lie...

With moving the coils around and getting NO CHANGE on the outer cylinders,
I'd suspect a bad ground / wiring issue...

Their not contributing fully....

.

 

[Gary in NJ]

Lean would run hotter.... Your #'s don't lie...

With moving the coils around and getting NO CHANGE on the outer cylinders,
I'd suspect a bad ground / wiring issue...

Their not contributing fully....

.

I agree…the center temperatures look as I suspect, the outer cylinders are cold.

 

[labanina]

I'd suspect a bad ground / wiring issue...

So I have tested terminals that feed into coils from harness with multimeter:

• Ignition ON
• Black probe to BAT -
• Red probe to Orange-Black terminal Left Coil and Red-Black Right coil terminal

This returned 12V properly. Then I connected the coils and put red multimiter probe on a tiny exposed piece of coils connectors that go into terminals, to ensure coils do get power from the system.

• Ignition ON
• Black probe to BAT -
• Red probe to contact points on coils, going into terminals

This returned 12v on both contacts, both coils. I guess when power is connected they switch and both contacts get power? I have also compared V when putting black probe to BAT - and to engine block itself, and it was the same 12V so there appears to be no grounding issues on coils. I've cleaned terminals, bent them to be a bit tighter and sprayed a smidge of electric lube on them.

I have also tried to test injectors:

• Ignition ON
• Red probe to 10A EFI fuse right contact
• Black probe to injector power connector contacts

On all 4 injectors, one contact was 12V the other 6V. Injectors won't probe properly from battery, I guess there is a relay somewhere between battery and fuse that only turns on during engine operation? Testing injectors with diag codes 36 & 37 they all click properly (in pairs), I've put a screwdriver to my ear to hear it better.

I have also took out and examined ECU, labeled Mitsubishi FUA0030 20S-00 F8T84671 1111
But I'm not sure how to test anything from it. AI doesn't give good instructions on how to test anything out of the ECU connector. It has 34 pins, 17 per row.



I'm not sure what to do next. The coils seem to be getting power properly, so do injectors, the coils ground isn't bad. Fuel comes to injectors from one common rail, so there can't be fuel pressure problems with injector 1 & 4 but not 2 & 3. Exhaust headers for cyl1-4 don't leak, at least I don't see anything like that. I don't see anything wrong with throttle bodies visually, they open and close simultaneously without any visible gap remaining and I was able to sync them. Compression on cyl 1-4 is same as cyl 2-3.

Lean would run hotter

I've tried making Cyl1-4 leaner and Cyl 2-3 richer, by dropping C1 and upping C2 in diag menu, didn't change anything.

Tomorrow I'll try doing TBS on higher RPM, 4-5K and see if all cylinders pull vacuum equally.

 

[Gary in NJ]

You said you can hear the injectors clicking, but that doesn’t mean they are delivering fuel. I would get a visual inspection on all 4 injectors.

 

[labanina]

You said you can hear the injectors clicking, but that doesn’t mean they are delivering fuel. I would get a visual inspection on all 4 injectors.

I did that today through diag menu. All injectors spray fuel properly. I don't know how well it can be seen from the video though.

Spoiler: Injectors test

https://imgur.com/QaD5ai1

While I was in there, I did spark plug test too, all spark plugs work but there is a BUT

Spoiler: Spark plugs test

https://imgur.com/2InHgmY

The BUT is that Cyl1 & 4 spark plugs are all crapped up, barely can see white porcelain in the middle.
Those spark plugs are barely 2 months old.
So Cyl1 & 4 run rich (cold) and Cyl 2 & 3 run lean (hot), for whatever reason.
I'll try dropping O2 sensor and see how it goes without it.


I have also checked TBS at idle & 4-5K RPM. All cylinders pull roughly equal vacuum.

Spoiler: TBS video

https://imgur.com/Kpk4d0X

Inspected the cam chain down right at the window, and it is much more loose at exhaust side than it was a month ago before valve lash adjustment job.
I can fit entire finger under it.
Will check if shop installed CTT correctly and if so, will order new cam chain.

 

[tuning-forks]

None of the videos in that post are showing for me.
Did this problem exist before the valve-adjust job? I don't recall you mentioning that before, but I may have missed it.

 

[labanina]

None of the videos in that post are showing for me.
Did this problem exist before the valve-adjust job? I don't recall you mentioning that before, but I may have missed it.

I spoilered vids to avoid spamming one post with 3 videos, but only links to imgur show up that way.

Picrelated are spark plugs in June, before I changed them and before other manipulations with bike. They looked even and fine, nice white porcelain isolator down the middle.


Valve job was far end of July. I changed bunch of stuff around the bike before that, during July, hoping to fix vibration: like changing injectors to Chinese ones, cleaning fuel filter, spark plugs, TBS etc. After all that I also had troubles passing CO exhaust test so mixture difference started before valve job. Suggestion to use temp gun to measure temps of headers last week - was the first time I did that.. Months ago I did note their color difference and tested that water evaporated equally fast from all 4, but that's not a really meaningful test.

Feels like I introduced too many variables in a hurry to fix bike for summer. Vibration might be one problem and mixture/temp difference the other. Or the same underlying problem just got way worse after I started to drive bike more in summer.

I'm going to undo all the changes that I can: put old injectors in, old spark plugs, O2 sensor, swap coils back and also replace old fuel filter with new one that arrived. The manual CCT is arriving soon too, that would hopefully take more slack out of cam chain. If that's not going to fix anything - I'll try pulling cap boots one by one on idling engine to see if cyl1-4 even contribute to RPM, order new cam chain and try having another shop take a look at the bike.

Yesterday I took a ride after disconnecting O2 sensor and cyl4 header pipe was so cold I could touch it, barely 75°C. Cyl2-3 was like 260-320°C and cyl4 100°C. So it seems to have made cyl1-4 mixture even richer, which makes sense. The engine also sounds like it is sputtering at higher RPM
engine sound

TL;DR: I'm going to undo the stuff I did to the bike because it doesn't seem to be helping (at best).

 

[tuning-forks]

I spoilered vids to avoid spamming one post with 3 videos, but only links to imgur show up that way.

I hope someone else will comment whether they can see the links. When I click the 'spoiler' button, there is just a blank line opens, no link is showing.

 

[TownsendsFJR1300]

None of the "spoilers" do anything.

.

 

[labanina]

I'll try dumping media openly then. I think after first 4 they stop embedding and just show up as a link.

Injector test, since then I swapped to old ones that came with bike, and tested them too. They work just as fine.

https://imgur.com/QaD5ai1

Spark plug test.

https://imgur.com/2InHgmY

Interesting that I stopped riding bike since Monday and only tested it on idle and spark plugs look much better than they did few days ago after intense riding, pic of spark plugs today.



TBS video.
Within ~10mm on idle and ~4K RPM

https://imgur.com/Kpk4d0X

Overall, I returned old injectors, old O2 sensor, swapped coils back around to their original config. Pulled caps one by one on running engine, the sound & rpm drop was the same for all 4 cylinders.

https://imgur.com/GXjUw0G

I have also dropped exhaust to see its state from inside with USB endoscope and it was fine, no obstructions, honeycomb-like cat mesh looks nice down in the muffler. Managed not to break off anything. Tightened header nuts back to spec.

Another thing is that I cracked valve cover lid open from the right side and checked that mechanics did indeed align all the marks.



Don't have any other immediate ideas to test so going to put bike back together and give it a ride on weekends.

Tentatively suspicious:

• Camshaft Position Sensor. If it's going bad, it can ruin firing timing. Resistance measures to spec 285 Ohm (248-372). I can't test it further myself, so it would have to be a replacement.
  
  
• Cam Chain. CCT is doing its job for now, but replacement of chain is due soon.
  
  
• Vacuum leaks. I've tested with brake cleaner spray around intake manifold, but maybe there are some other weird hoses going somewhere that leak, or a gasket. I might buy a vape and see if smoke gets sucked in anywhere.
  
  
• ECU. It doesn't have diag port and I'm not sure custom harnesses exist, I wasn't able to test it manually. Needs to be looked into.

UPD: spray-tested old injectors and their pattern was bad (two lines, clogged), so using new Jesben (CN) injectors now: they spray in a nice even cone. Also fuel pump filter arrived so I've replaced it. Kept battery disconnected overnight to reset ECU, if it even does learn anything. Feels like bike runs the worst now: rode 40 minutes round-trip, hands and crotch are completely numb. Will try doing 200km something ride on weekends to see if ECU would pick up on updates in fueling. On-spec upper engine mount bolts are arriving soon, so I'll drop exhaust, remove frame sliders and try propping engine up on a jack before mounting it in a more "free" position. New manual CCT is arriving, will order cam chain too and have it replaced. Before all of that, I'll try rotating TPS since it only goes up to 90 currently. Then idk what to do, if all of that doesn't help - probably selling the bike.