Triumph Rat Motorcycle Forums banner

Where do I start with misfires

5K views 13 replies 6 participants last post by  TT140 
#1 ·
I need help. I have a 2012 Efi bonneville. Bought from new with Tors installed. Not long after I fitted the TTP breathe bell mouth, DNA filter and TTP tune 1. Everything was good. I then fitted Lossa stubbies and everything was still good but a lot louder. After a year or so I started having bother with the right cylinder mis firing. Trip to dealer and new plugs fitted and everything was fine again. 500 miles later and I started having the bother again. Rough idle, hard starting , spluttering when revved to about 3-4000 revs and popping from the exhaust. Pulls hard over 4500 tho. Plugs are black and sooty and it smells rich. Contacted Mike at TTP and he advised it could the stubbies playing hell. So TORs back on , new plugs in and she still isn't running well. What could be wrong? Are the plugs sooting up because it's running rich leading to misfires as the plugs foul. If so why is it now running that rich? The map was fine before. Are the plugs sooting up because of the misfires and I have a ignition/ combustion problem. Can someone point a technical noob in the right direction and how I go about diagnosing what it is. Dealer isn't an option at the mo as the local one went bust and the next nearest is 100 mile away so I'd like to try and sort this myself. If possible. Thanks in advance.
 
#2 ·
#5 ·
1. Check compression = one cylinder is in question so this eliminates other fuel/spark issues.
2. Air cleaner = where is this soot coming from if the compression pans out as equal across the board. Clogged pleats means stutter issues.
3. Snorkel mods = all was good a year ago so no, not some air intake difference 1 year later was the same exact intake sucked, right?
4. Stubbies = with the year later is you install it and the right side dies, the plug soots, not some year later it occurs; this too is not it.
5. TTP tune 1 = I have to go back to a stock map and see if this tune 1 is stumbling at this rpm range, cleans up after this rpm range is to eliminate the map before you swap good known parts that will be exchanged for good know parts and out of pocket was no change.

Recap:
That air cleaner lets in lots of air without restrictions, meaning, has a wider pleat fiber to let in larger scratching type contamination to the rings and cylinder wall finishes = Compression test so no tail is chased in the diagnose... singed~noltt.
The TTP tune is a big stumble/cleans up kind of mapping. No factory map stumbles up the linear rpm range but some aftmk map in the way of a driveability issue. So, the aftmket map variable has to be weeded out so out it goes... singed~noltt.
The 500 mile window of that plug signing off sure sounds like low compression rather than a coil or coil wire needing replacing with a spark unit thrown in too was to eliminate the hard parts being swapped out, right?

Make sense in the diagnostic steps more or less?
 
#8 ·
1. Check compression = one cylinder is in question so this eliminates other fuel/spark issues.

2. Air cleaner = where is this soot coming from if the compression pans out as equal across the board. Clogged pleats means stutter issues.

3. Snorkel mods = all was good a year ago so no, not some air intake difference 1 year later was the same exact intake sucked, right?

4. Stubbies = with the year later is you install it and the right side dies, the plug soots, not some year later it occurs; this too is not it.

5. TTP tune 1 = I have to go back to a stock map and see if this tune 1 is stumbling at this rpm range, cleans up after this rpm range is to eliminate the map before you swap good known parts that will be exchanged for good know parts and out of pocket was no change.



Recap:

That air cleaner lets in lots of air without restrictions, meaning, has a wider pleat fiber to let in larger scratching type contamination to the rings and cylinder wall finishes = Compression test so no tail is chased in the diagnose... singed~noltt.

The TTP tune is a big stumble/cleans up kind of mapping. No factory map stumbles up the linear rpm range but some aftmk map in the way of a driveability issue. So, the aftmket map variable has to be weeded out so out it goes... singed~noltt.

The 500 mile window of that plug signing off sure sounds like low compression rather than a coil or coil wire needing replacing with a spark unit thrown in too was to eliminate the hard parts being swapped out, right?



Make sense in the diagnostic steps more or less?

Tried a number of maps and the stumble is still there but it is still intermittent. Sometimes it runs without a hic five minutes later it's there and then five mins later runs fine. Multi tester is on the way to try and rule out or in electrical gremlins.

Is a compression test doable at home??
 
#9 ·
Yes, Sears might have a hand held compression tester. Pull both plugs, bungee cord the throttle open, ground the spark plugs back into the wires and ground them away from the spark plug hole, that or see how easy it is to remove one wire off the coil or spark unit? Because you'll have to use the starter and watch the needle stop pumping and that's where the number is.

Tried a number of maps and the stumble is still there but it is still intermittent.
This new info changes things. Intermittent wasn't mentioned.


Sometimes it runs without a hic five minutes later it's there and then five mins later runs fine. Multi tester is on the way to try and rule out or in electrical gremlins.
I am not about to keep diagnose bleeding about aftemrk crap in the loop being played over and over. I think I mentioned go back to the stock map, not this one variable in the loop kind of why I sign off like I do.
 
#11 ·
Stock map is exactly the same misfire
Thanks, that helped a lot with more out of the way. I'm not liking the slow deterioration of the plug @ 500 miles. That leaves the possibility of narrowing down the compression being a variable. You need that out of the way first thing, I can't emphasize that enough. Remember, I'm here on this side of the problem and I would not chase any further but getting that comp number(s) out of the way.

You don't want me to walk out the scenario if I think like this. That injector staying open or leaking when closed? That's a lot of pressure to keep pushing that leak in and more hydraulic the cylinder; my mind would imagine. What do you think? Plus the fuel pump to get you there to redline, the ign box/one side of the ECU connector for spark(if applies), the coil(s), or spark sticks getting you up to redline, etc, sure are not looking like those jobbers. They seem to be working fine.

And then I'd think, come on compression, I don't want to think corrupt ECU with a stock map back in it. So that means to swap the ECU and see if that knocks out the fueling issue if not a compression issue.

Someone had a bad ECU that would stumble @ 3,200 rpm. He mailed it to me, sure enough, that was one sad running brick.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top