engine misfire

[dcstrom]

I have a miss or stutter or something now most noticible going through 2500-3500 rpm. Seems to be getting worse and power is flat... now if I hold steady at 3000 you can definately feel the miss. It´s getting pretty annoying. I think my fuel economy is going south as well.

I first noticed this after I had a valve check and TB sync. It was barely noticible though and went away shortly after. But then it came back...

I had the CCT changed and valves adjusted by Yamaha France, and it´s still there (so doubtful that it was a faulty reassembly by the tech in the UK). it´s intermittant and had gone away wso techs in Paris were unable to check it out. Typical. Now about to head into the Czech Republic and it´s back worse than ever.

Bike is at 77,000 miles.

Anyone experienced this or something similar?

 

[tubebender]

Hey Trevor!

Based on the work you had done I'd start with the coils and plugs. Is it more pronounced after wet weather?
If the plug wells don't drain you may get an intermittent short. How many miles on the plugs?
Check the hose between the left throttle body and in the intake air pressure sensor.

That's all I got at the moment.

 

[~TABASCO~]

I was just about to say the same. Check coil #2 for water. I've seen #2 with water dammage on many customers bikes.

 

[dcstrom]

Thanks guys, looks like this is fixed - combination of a few things, not least my stupidity...

I had valves adjusted recently, and I had a new set of spark plugs ready for the occasion. The current ones had 24000 miles on them. Went to get the plugs to give to the tech, and couldn't find them. Not wanting to buy another set of plugs (at UK prices) I asked the tech to just reinstall the old ones, and I would fit the new ones myself (when I found them).

Not long after the service I starting noticing a little miss at lower revs under load - seemed to be too much of a coincidence not to have something to do with the service, but the miss went away soon after so not much to be done about it.

I found the new plugs the next day.

A few weeks later and now the miss is worse, something needs to be done. Didn't think it would be plugs but I had some and replacing them within the scope of work that I could do myself. This is what I found...

First thing I noticed was that this reservoir in the throttle body side of the air filter box was nearly coming of - I guess by pressure from one of the minor burps the engine had started having.

Then one of the drain holes in the front of the airbox was blocked with bugs and crap, so some water was sitting there...

The number one coil had a lot of corrosion.

And the number one plug was white - as though the engine was running lean - but the number two plug, same cylinder, is a nice color. Can't explain that one. Also a lot of corrosion on the plug.

The plugs were pretty worn too - I'd assumed that when the tech put them back in at the valve adjust, he would have at least gapped them, but no.

The other coils had some corrosion too, but not as bad as number 1. None of the spark plug wells appeared to have any water in them.

End result, new plugs seem to have fixed my problem! I'm wondering if the miss was a result of a few things - water/corrosion in the coil/old plugs, and that the new plugs are just covering other issues for now... might have to see about getting replacement coils somewhere down the road.

 

[kjetil4455]

I have a miss or stutter or something now most noticible going through 2500-3500 rpm. Seems to be getting worse and power is flat... now if I hold steady at 3000 you can definately feel the miss. It´s getting pretty annoying. I think my fuel economy is going south as well.

I first noticed this after I had a valve check and TB sync. It was barely noticible though and went away shortly after. But then it came back...

I had the CCT changed and valves adjusted by Yamaha France, and it´s still there (so doubtful that it was a faulty reassembly by the tech in the UK). it´s intermittant and had gone away wso techs in Paris were unable to check it out. Typical. Now about to head into the Czech Republic and it´s back worse than ever.

Bike is at 77,000 miles.

Anyone experienced this or something similar?

Sorry to revive an old thread, but this is now happening to me, quite similarly.

The moto did not have stuttering initially, just weak and somewhat erratic idling. We found some corrosion of 2.5 out of the 4 coils, and changed 4 spark plugs. We just did some maintenance on the coils (This was before syncing the TB). The dominant (white) bleeding screw was almost completely closed, so we turned this to 3/4 as recommended by several people on this forum. This improved the weak idling (the moto would easily choke and turn off when letting out the clutch), but didn't fix it. So we did TB sync. The TB pressure was way off, and the left cylinder's bleeding screw was dysfunctional causing a major drop in vaccum. We were able to fix this and normalize and calibrate the vacuum in both cylinders. All seemingly good. A week or so later I raised the CO2 settings to +10 on both cylinders. Seemingly good. Then I was advised to maintain the factory difference (C02 +0 and C01 +6), and after this the problem seemingly started. I tried changing it back to +10 though, and it didn't fix the misfiring.

Immediately after properly balancing the TBs and increasing the bleeding screw opening (the white one), although no other symptoms manifested, I think the engine sound is a little rougher. Like it sounds when running with the clutch in the friction zone (but in neutral), ie. as if the engine is not getting enough fuel. But I am not sure. There have also been some incidences of backfiring that I didn't hear before.

Now, two three weeks later, I started noticing gradual onset and also worsening of engine misfiring when cold, around 2-3000 RPM. It would go away when the engine is warm.

I am not sure if this is because we:
1. Significantly increased the bleeding screw (dominant), which the manual says not to do
2. Didn't change (just did maintenance) of the coils. Although there was no misfiring after this for another month
3. The ECU is not flashed. Could turning the screw 3/4 have caused a high air influx that is not balanced by the ECU?
4. Improper CO2 settings (initially they were 0 cyl two and 6 on cyl 1).
5. Big increase in vaccum pressure after TB balancing and fixing the defect left screw. Right cyl had about 22-24cm Hg and left about 18cm Hg. Now both are at 25cm HG (close to spec and should be acceptable).
6. anything else?
7. we also changed the CCT. Not sure if that has anything to do with it.
8. bike has 40 000 Km on it. Haven't done the valves yet. Maybe do this first?

Thanks for reading

 

[Squibb]

You have a 2012 Gen1 I understand, with 40k Km or c 25k miles - what is the service & warranty history here?

First you need to check for codes, available though the dash. Just post anything suspicious, along with D:61 & D:62 figures.

Then just a few initial thoughts: -

- What were the resistance readings when you checked the coils? You mention corrosion, hence historic witness of water ingress.

- Has the wiring harness been updated? You may need to check the VIN with your Yamaha dealer.

- When changing the CCT, did you check to see whether the chain had slipped a tooth during the process. Something you can revisit when checking the valve clearances maybe?

 

[kjetil4455]

You have a 2012 Gen1 I understand, with 40k Km or c 25k miles - what is the service & warranty history here?

First you need to check for codes, available though the dash. Just post anything suspicious, along with D:61 & D:62 figures.

Then just a few initial thoughts: -

- What were the resistance readings when you checked the coils? You mention corrosion, hence historic witness of water ingress.

- Has the wiring harness been updated? You may need to check the VIN with your Yamaha dealer.

- When changing the CCT, did you check to see whether the chain had slipped a tooth during the process. Something you can revisit when checking the valve clearances maybe?

Thanks so much!

We stripped the chain when doing the CCT so I am pretty sure it didn't slip.
Regarding the wiring harness, no idea what it is, forgive my ignorance.
Resistance readings, we didn't do this.
Service history --> I live in Colombia. There are no service histories here

I did some googling and was left with the impression that valves or coils are the main suspicions with this problem.

Thanks again.

 

[jbrown]

If the wiring harness recall fix has not been done, you can see a wide variety of issues from misfires to won't run at all.
The recall fixed a failure prone wire splice in the wiring harness. If wiggling wires around changes the symptoms, the bad splice could be the problem. You *should* be able to find out from Yamaha if the recall was done on your bike by giving them your VIN.

 

[kjetil4455]

If the wiring harness recall fix has not been done, you can see a wide variety of issues from misfires to won't run at all.
The recall fixed a failure prone wire splice in the wiring harness. If wiggling wires around changes the symptoms, the bad splice could be the problem. You *should* be able to find out from Yamaha if the recall was done on your bike by giving them your VIN.

Thanks!!!

 

[Squibb]

Enquiries here should elicit an answer regarding the wiring harness, which @jbrown has explained: -

.......... https://www-incolmotos--yamaha-com-co.translate.goog/servicios-yamaha/?_x_tr_sl=es&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc

Then tell us the codes, as requested. Please don't clear any codes at this stage.

When you do the valve clearance & timing check, please take the time to post the primary & secondary coil resistance readings. Failing coils are notoriously difficult to isolate, but plug colour sometimes helps. Remind me, were all the plugs renewed?

Backfiring suggests a lean burn condition, so you need to check the balance port cap isn't leaking. Are the exhaust & headers in good condition, with no leaks evident?

 

[kjetil4455]

Enquiries here should elicit an answer regarding the wiring harness, which @jbrown has explained: -

.......... https://www-incolmotos--yamaha-com-co.translate.goog/servicios-yamaha/?_x_tr_sl=es&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc

Then tell us the codes, as requested. Please don't clear any codes at this stage.

When you do the valve clearance & timing check, please take the time to post the primary & secondary coil resistance readings. Failing coils are notoriously difficult to isolate, but plug colour sometimes helps. Remind me, were all the plugs renewed?

Backfiring suggests a lean burn condition, so you need to check the balance port cap isn't leaking. Are the exhaust & headers in good condition, with no leaks evident?

Dear friend, thank you for your help.

So we just cleaned all the coils today. We also measured the resistance of the Coils: 2x had 9.83k Ohms and two had 9.63k Ohms (the most corroded ones), and I presume that's the main problem. I have ordered 4 new ones. Either way, we cleaned them well and installed one good and one bad per cylinder, to avoid having both bad ones at the same place. All plugs looked fine, but we changed one that looked ALMOST fine, mainly because we had already changed the 3 others adn wanted to eliminate all doubts possible.

The engine POWER and throttle response increased A LOT after cleaning the coils, but the gentle misfiring was still there. As I mentioned earlier, the misfiring started after playing around with the CO2 settings, so I took it back to shop and we tried to change the CO2 settings. We tried 18 / 12 (Cyl1 & 2) first, but this made the misfiring worse. Then Did the opposite, ie. 12 and 18, which made it better (There was a +6 difference between the two cyls from the factory, but Icouldn't remember which), and this made it clearly better. I guess this problem occurred as I wrongly remembered the CO2 calibration order.

Will take it out tonight and see how much better it is. It still remains to change the 4 coils, and as I said, I have ordered them. But I didn't have this misfiring problem before even when the coils were super corroded.

I suppose it can also be that, as we increased the bleeding screw to 3/4 (this is not spec) on the throttle body, greater fuel intake is needed to balance it and that could fit with the CO2 settings at a raised level helping the moto, as you also suggested as it might be running lean (after raising the bleeding screw opening). However, the misfiring problem developed about two weeks after balancing the TB, not immediately after, which at least at a glance speaks away from this as being the cause. IDK.

The valves are unchecked for now. The harness stuff, I haven't gotten a response yet. They know very little about the super tenere down here at the yamaha shop because so few people in this country have a moto greater than 200cc.

Question, and excuse my ignorance: Balance port cap? what is that? Google didn't help me find the answer. Also, exhaust leaks, I don't think so, but I am not confident. How would I know? There is no obvious leakage. HEADER LEAK, not sure what this is neither. How would I know? Thank you for your patience.

 

[Squibb]

The coil resistance readings should be within these ranges: -

Primary range spec: 1.19-1.61 ohms
Secondary range spec 8.5-11.5 k-ohms

The TB cap, is part #15 here ........ https://www.fowlersparts.co.uk/parts/5944966/xt1200z-super-tenere/intake-2
You will have removed this to balance the TBs. Sometimes they perish with age, crack & admit air randomly, usually worst when the engine is cold, the cracks can heal once warm. Indeed all the inlet connections between the TB & inlet ports should be checked for the same reason.

There are various crafty ways to check for air leaks without disassembly, but most are dangerous in an enclosed space, so I leave you to try some research on google if you wish to try a short cut.

 

[kjetil4455]

The coil resistance readings should be within these ranges: -

Primary range spec: 1.19-1.61 ohms
Secondary range spec 8.5-11.5 k-ohms

The TB cap, is part #15 here ........ https://www.fowlersparts.co.uk/parts/5944966/xt1200z-super-tenere/intake-2
You will have removed this to balance the TBs. Sometimes they perish with age, crack & admit air randomly, usually worst when the engine is cold, the cracks can heal once warm. Indeed all the inlet connections between the TB & inlet ports should be checked for the same reason.

There are various crafty ways to check for air leaks without disassembly, but most are dangerous in an enclosed space, so I leave you to try some research on google if you wish to try a short cut.

Ah, the white-screw-side cap. Yes, we have already balanced the TB and although the cap wasn't leaking, it was slightly porous with initial surface deterioration. We used a silicone-adhesive material to seal / prevent it from future hiccups. There are no vacuum leaks.

Ohmage: Ok, so then, as expected, I had two good and two bad ones. I guess this is what is causing the problems, because we cleaned the ones I have and placed one good and one bad per cylinder. This REDUCED the KNOCKING significantly, virtually eliminated (I guess one cyl had both of the bad ones initially, not sure) and greatly improved throttle response (power restore), as stated, but it did not eliminate the misfiring, although it is not more gentle due to the absence of knocking. I have ordered four new coils and will replace them all.

Thank you sir

 

[kjetil4455]

In case someone reads this I just wanted to update and say that we have resolved it. I wrote the solution here, to avoid double posting: https://yamahasupertenere.com/index.php?threads/airscrew-adjustment-to-fix-off-idle-stumble-and-throttle-body-sync-w-pigtails.1973/page-27