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Losing power

7K views 44 replies 14 participants last post by  Corey Thrasher 
#1 ·
A couple times recently I've noticed my 2016 Street Twin briefly loses power.

First time, I was accelerating onto the highway, in 4th or 5th gear with the throttle about half open. I gave it a little more gas and nothing happened.

It's happened a couple times since then. Sometimes when accelerating but sometimes I can be cruising along and the power just drops briefly. So far it's only happened on the highway.

It acts like it's not getting enough gas or is only firing on one cylinder. It only lasts a second or two. Then goes back to normal.

Anyone else experience anything like this?
 
#2 ·
I had a similar experience. One day I started having a slight hesitation when giving it more gas. It occurred a few times. The next day it happened again but with increased hesitation and frequency. About 30 miles from home the MIL came on.

I hooked up my Dealertool software and I had a “#2 ignition coil” fault. A few months prior I had performed my own 10K maintenance and remembered disconnecting the coils in order to remove the cam cover. So I checked the wiring and spaded terminals to the coil and found the terminals slightly loose. I squeezed down a little on the female terminal and reconnected. The hesitation immediately ceased and has been fine since. My theory is the coil was getting insufficient primary voltage “in” and was producing insufficient secondary voltage “out”. There wasn’t enough fire to burn the mixture fully. I could be wrong on this, but ultimately I was able to fix it sans dealer.
 
#3 ·
Hmmm... I don't have any way to read the codes and the nearest Triumph dealer is a little over an hour away, so it's not super easy to just drop it off. But it might be worth swinging it by a local shop to see if they can check for error codes.

I bought this bike used with only 300 miles on it from a guy who lived about two hours from me. On the way home from buying the bike it got REALLY sluggish. In fifth gear with the throttle wide open I was barely doing 60mph. I pulled over and could see the spark on one side jumping through the spark plug cap to the engine block. The cap had a hairline crack and it was only running on one cylinder. The original owner was great. Towed it to his dealer, they fixed it and he delivered the bike to me a couple weeks later.

This issue feels a little like that, only MUCH less pronounced. Because it's intermittent, I can't check to see if the spark is jumping again. It's a little hard to see the plug while I'm trying to merge into traffic on the interstate ;) But I'm wondering if it's related. Or wondering if maybe his dealer didn't quite button things up properly like what tahtye describes.
 
#4 ·
If your MIL (Malfunction Indicator Light) is on, you can check for the specific DTC (Diagnostic Trouble Code) or codes that caused it to lite up by doing the following,
Press and hold the i button, turn ignition on, wait until you see dtc in the speedo display and release the i button. Make note of the code(s). A proper code begins with a “P” followed by four digits. P0000 = no faults. FYI - My MIL didn’t come on immediately after I noticed the issue.

Or you could pull the bolt on the tank, pull tank back a little, raise and support the rear of tank enough to get your hand under it, follow the spark plug wires to the coils mounted on the main top frame tube and check for bad wires or terminal connections. Hell, tighten everything up, can’t hurt. Not hard to do and who knows? Caution, if your tank is full don’t tilt it up too far or you’ll get fuel out of the overflow and out through the EVAP canister.

Just thinking out loud, When it was ‘really’ sluggish we know you were losing spark energy, a lot of it by your description. So it makes sense to me by losing less spark might mean less sluggishness because of more/better burn.. for the record I’m not a mechanic by trade but spent my working life troubleshooting and repairing light to heavy mechanical/electrical equipment.
 
#9 ·
Great, no DTC’s! Since your MIL was off that should’ve been expected. But as I stated twice already, I had symptoms before my MIL lit up. My guess is that some DTC’s aren’t tripped immediately in order to avoid nuisance faults.

I believe you have 3 choices,

Do nothing more and hope your issue goes away magically on its own. Possible but..

Or, Take it to your dealer or bike repair shop.

Or, Try what I did to fix mine. It may not fix it, but it won’t cost you anything to try! I’m trying to lead you to water but I can’t make you drink it, lol.

Good luck and hope you get it resolved soon.
 
#10 ·
If you have any mechanical knowledge the plugs are easy to pull now. You could lay them grounded on the head connected and spin it over. You should see a solid arc from both. Other than that it could be a lot of things fuel or ignition connected. You can at the same time view the colour of the pig and evaluate it which will tell you if the feeling is ok. Hope you get it sorted, Nothing worse than having a new bike that doesn't run right.
 
#11 · (Edited)
As suggested, I pulled the tank back and checked the plug wires and bolts holding the coils as best as I could. Everything seemed pretty tight.

Thinking back, I think this might have started after I replaced the stock Triumph battery with an aftermarket battery. But that couldn't cause this problem could it?

A few weeks back, heading out for a ride I noticed the bike was a little slow to start, but didn't worry much about it. Stopped a couple miles from home and when I got back on, the bike wouldn't start. Pulled the battery, took it to the local auto parts store. They tested it, said the result was "inconclusive." It was a 3-year old battery on a bike with only 1800 miles, but I figured it couldn't hurt to replace it. They pulled one (a regular old lead/acid battery) off the shelf. I installed it and the bike started right up.

I honestly can't remember if I'd noticed this losing power symptom before then. If I had, I was still in the "maybe I'm imagining things" stage. But it's clear it's a real issue now. It happens at least once every time I take the bike out. I'm grasping at straws here, the battery couldn't cause something like this right?
 
#14 ·
Update: the battery failed the test and the store replaced it with a new one which they tested before sending it out with me. Unfortunately that didn't fix the problem.

I'm having a really hard time finding time to make the trip to the dealer. They're an hour away and getting a lift home so I can leave the bike is turning out to be surprisingly hard to coordinate.

So I'm considering replacing the throttle/grip assembly. Costs about $100 and should be simple to do.

What do you all think? Would you likely start there or somewhere else?

Recap: bike randomly loses power above 50mph. It acts like the throttle was closed when I'm holding it steady or sometimes under hard acceleration. When it happens, if I actually do close and reopen the throttle the problem goes away and the bike accelerates normally.
 
#15 ·
I’d bring to the dealer at this point, especially if it still under warranty. My dealer is an hour away as well. I usually get a loaner and ride while they’re working on it. Always get it back same day. See if they can do that, although, with the nature of your issue, they might need to keep it for a bit.
 
#16 · (Edited)
Took the bike to the dealer about a month ago. They've had a hard time figuring out what's wrong. It took them a couple weeks just to reproduce the issue on a test ride. They've submitted a ticket to Triumph to ask for advice and so far it sounds like the only response they've gotten is to check for a vapor lock (which they're doing today).

They did finally find a couple things wrong. But nothing that's a "smoking gun" and I want to get this group's thoughts on what they found.

Like I mentioned earlier (https://www.triumphrat.net/water-cooled-twins-technical-talk/950726-losing-power.html#post2003913358) the bike had an issue with a cracked plug cap when I bought it. That meant it ended up running on just the left cylinder for about 15-20 minutes on the highway while I was panicking, trying to figure out what was wrong, and finally finding a safe shady place to pull over.

The dealer now thinks that the RH side of the catalytic converter got damaged in that episode. They say the RH pipe after the cat is blued, the RH fuel trim was set way high (making the RH cylinder lean), and with the lower part of the pipe off they think they can see some damage (a hole) in the cat medium on the right side.

They think a bunch of unburnt fuel got dumped into the RH side of the CAT when it was running on just the LH cylinder and that fuel damaged the cat medium (possibly igniting inside the CAT). They think the cat medium could be collapsed causing the RH side to be overly restricted, which is why the ECU is responding by cranking the fuel trim on the RH side.

Triumph has apparently told them there's no way a damaged CAT could cause the intermittent power loss I'm experiencing. And the dealer is being careful to say they're not sure the two things are related. But they're pretty confident the CAT is damaged.

I'm going to have them replace the CAT. It's broken, and whether or not it's causing my issue, it needs to be fixed. But I'm troubled that Triumph doesn't think that could be the problem. I don't want to go through all this and pick the bike up just to have to take it back. (The nearest dealer is an hour from my house.)

So what do you think? Does it seems like something like this COULD occasionally make one cylinder cut out?

The power loss has happened in two different scenarios. The most common is when I'm cruising at a steady speed/steady throttle position on the highway for 5-6 miles. The other time it's happened is under hard acceleration (merging onto the highway). In both cases, if I close and reopen the throttle, the bike goes back to normal.
 
#17 · (Edited)
There is no left and right hand side to the cat.
The exhausts are merged as they enter the cat and not in a nice clean, aerodynamic way.
It gives a new meaning to the word ‘agricultural’.

It is possible that the cat has been damaged but I don’t think this has anything to do with the cutting out issue.
 

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#19 ·
Triumph has decided my intermittent loss of power is related to the damaged cat after all. They're fixing it under warranty even though I'm outside the formal 2 year warranty period. Fingers crossed that they're right.
 
#21 ·
Triumph may be playing it safe since the cat is part of the emission system which is covered under a separate warranty from the vehicle under federal law. That law covers emission system components in one section, and failure of emissions tests in another. I'd suspect that the pipe that turned blue is actually the header pipe where it enters the cat.
 
#22 ·
Any update? I'm taking my 2017 in on Friday for the same issues. It's done it to me three separate times now.

All three times I left my house, immediately jumped on the highway, drove for 45min at highway speeds and the bog down/loss of power issue came up after getting off the highway. When it was at it's worse, quickly opening up the throttle in any gear would cause it to loose power. If I gave it gas very slowly it would be ok.

The last time it happened I heard a very distinct arcing sound coming from the right hand side at the ignition coil. I got the bike home and let it sit hoping to see If I could see the arching later that night. But I didn't hear or see anything. I put my OBDII Reader on and it didn't give me any codes.

I've had two short rides since with no issue so this is frustrating. Hopefully it will do the same thing when I take it to the shop. I'm a month from my warranty expiring.
 
#23 ·
No news here yet. Honestly I think there's maybe a 50% chance my issue is caused by the catalytic converter. Just crossing my fingers.

You sure the arcing you heard was from the coil? The other posts I've seen all mention arcing from the plug cap, either through the cap or around the bottom rubber seal. And that's where mine was arcing originally (through a cracked cap).
 
#25 ·
The switch plate had to come off of the clutch lever housing when I installed the cruise control kit on my T120. You don't want to look in there, or inside the switches on the brake lever side. The switches are not weather proofed in any way. I guess this is why there's a suggestion in the owner's handbook that the switches be covered while washing the bike. This won't help in a heavy downpour.
 
#28 ·
The only loss of power I have had was when I first rode my DB9.

There was a charging issue (faulty/loose) connection and the bike just lost power when the voltage dropped.

But if your battery terminals show about 14 volts when the bike is running then this is not the problem unless there is an issue under load at the plug coils as you have said.
 
#29 ·
Luckily it was hot and my plug cap was arcing away as I pulled up to the dealer. I went in, grabbed the mechanic and he confirmed it. I’m lumping my annual maintenance in on this visit so they’ll check to see if anything else is a miss. I’ll let you guys know if anything else comes up. The caps are covered under the regular two year warranty term.
 
#42 ·
How's the bike running now? My 2017 Street Scrambler exhibits exactly the same issues as yours. I'm pretty sure its not the battery as I replaced it 3 months ago with an identical OEM Yuasa. Before I read these threads I felt the fault was electrical and not fuel so plugs and coils seem to be starting point. My bike has done 3000 miles, 1500 of those with the Street Twin Scrambler exhaust, K&N air flilter and Triumph dealer remap although no idea what the map is. I would say my issues have gradually got worse in the last 300 miles and a coldish ride out yesterday ( 8 Deg C) included 3 or 4 instances of bogging down.
 
#30 ·
Picked the bike up a couple days ago. They replaced the cat and a discolored section of pipe. I had them also replace plug caps for my peace of mind.

On the way home I experienced a moment of hesitant acceleration that *may* have been the same issue I've been having or may not. But other than that, so far so good.

I'm going to try and do lots of riding over the next week to try and test things out.
 
#31 ·
Well, it wasn't the catalytic converter that's been causing my problem. I lost power on the highway again riding today. I'm not upset over the dealer replacing the cat. It was damaged and needed to be fixed. It cost me some time, but no $$.

But I sure wish I knew what was causing this.

The tech at the dealership said the only other thing that Triumph corporate suggested was that it could be the gel battery I installed. They said these bikes really like traditional lead acid batteries and that gel batteries sometimes produce some quirky behaviors.

I DID replace the battery around the time this bug popped up. I honestly don't remember whether the issue started before I replaced the battery or after. It's intermittent and the first couple times it happened I thought maybe I'd imagined it, or closed the throttle a little, or was in the wrong gear when I tried to accelerate... It took it happening a few times for me to be sure something was wrong.

When I replaced the battery, I just got whatever was on the shelf at the local auto parts store that fit.

So, back to the auto parts store... I got a regular lead acid battery. It's filled and I'll trickle charge it overnight, then install it and cross my fingers that the problem goes away.
 
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