Single Massive Backfire

[weehe]

Good to know on the PC, I thought it was a ecu flash. That is good to know on the fuel pump dying. The first thing I asked was if the tank was replaced because of rust and was told there was no rust. I am guessing it was probably run dry or had really old gas as it sat. Anyway to see if there is a leaking injector? It starts up fine and there are no misfires. Also the plugs all looked uniform.

I will check out the AIs and CO values this week/weekend and let you know what I find. And will see if I can get a video. Then I'll do a TB sync when the carbtune comes in. After that I'll start exploring the more time consuming/expensive options.

Another side question. If I remove the cat and make the stock exhaust freer flowing, would I need a PC to make sure I'm not too lean or can I adjust the CO values. This is for once the problem is fixed lol.

 

[FinalImpact]

Because one thing effects many others its very difficult to pin point specifics at home. Unless you do cylinder power balance and leak down tests, then you can say that mechanically the engine (pump) appears that all four cylinders are capable of doing the same work! That said, most injectors are tested out of the engine for leak, flow rate, and pattern.

Valve lash impacts cylinder filling and compression as well as engine vacuum at the TB. We can correct this!
Engine piston ring sealing effects compression and TB vacuum but is not easily corrected.

Per TB, AFR effects cylinder burn time and crankshaft velocity per firing stroke which impacts TB vacuum. So, all things being equal, compression, valve timing, ignition, if each TB supplies the same AFR we should have equal vacuum at each TB. BUT, not all cylinders burn at exactly the same rate accelerating the crankshaft at an equal velocity. The TB sync adjusts the air to cylinder to balance if all else is equal.

ALL of THAT is why the OEM process is to DO the **action items** we can adjust (correct to match them) before doing TB Sync.

• Clean fuel system
• New Plugs at proper gap
• Adjust Valve lash
• Set idle speed (compare apples to apples)
• Perform TB Sync
  
  As for midpipe mod, it will help the early bikes flow better and improve the throttle response. I'd suggest a FC for best results.

 

[weehe]

Because one thing effects many others its very difficult to pin point specifics at home. Unless you do cylinder power balance and leak down tests, then you can say that mechanically the engine (pump) appears that all four cylinders are capable of doing the same work! That said, most injectors are tested out of the engine for leak, flow rate, and pattern.

Valve lash impacts cylinder filling and compression as well as engine vacuum at the TB. We can correct this!
Engine piston ring sealing effects compression and TB vacuum but is not easily corrected.

Per TB, AFR effects cylinder burn time and crankshaft velocity per firing stroke which impacts TB vacuum. So, all things being equal, compression, valve timing, ignition, if each TB supplies the same AFR we should have equal vacuum at each TB. BUT, not all cylinders burn at exactly the same rate accelerating the crankshaft at an equal velocity. The TB sync adjusts the air to cylinder to balance if all else is equal.

ALL of THAT is why the OEM process is to DO the **action items** we can adjust (correct to match them) before doing TB Sync.

• Clean fuel system
• New Plugs at proper gap
• Adjust Valve lash
• Set idle speed (compare apples to apples)
• Perform TB Sync
  
  As for midpipe mod, it will help the early bikes flow better and improve the throttle response. I'd suggest a FC for best results.

What would you suggest for cleaning the fuel system. Is there an injector cleaner you like to use? I have/can do all but the valve lash easily before I do the TB sync.

 

[FinalImpact]

Chevron Techron (black battle) .... Mix per directions (5Gal fill).

Scott has some other stuff for marine apps but it costs a bit more.

I give all my vehicles a dose 3X a year to remove moisture. The key ones being before winter to reduce moisture and or prevent frozen lines. It can't hurt!

 

[weehe]

Chevron Techron (black battle) .... Mix per directions (5Gal fill).

Scott has some other stuff for marine apps but it costs a bit more.

I give all my vehicles a dose 3X a year to remove moisture. The key ones being before winter to reduce moisture and or prevent frozen lines. It can't hurt!

Sounds good, will get it in the next fill up. I don't really have to worry about winter storage as I'm in Texas and ride more in the winter than summer lol.

 

[TownsendsFJR1300]

Yamaha make a product called "RingFree".; Available on-line or at your local Yamaha marine dealer

https://www.shopyamaha.com/product/details/ring-free-plus?b=Search&d=34

It's extremely popular in the marine world, recommended for use in most (possibly all) Yamaha outboard engines.(per the owners manual)

Its not cheap, but 1 oz treats 10 gallons so its considerably MORE concentrated than Seaform/Techtron, etc.

I've run it at 3x the recommended amount for badly (not completely clogged) clogged carbs, FI'ed engines. It won't hurt anything running it heavy, then lighten up and just regularly. besides being a fuel system cleaner, it also cleans the top end of the engine, rings valves, etc from carbon etc.

I run it in EVERY GAS ENGINE (cage included) I own.


Highly recommended, extremely effective IME..

 

[TownsendsFJR1300]

Another thought,

Also, as FI noted previously, a leaky injector (NOT sealing fully, especially under heavy de-cel-HIGH VACUUM) could be throwing excess fuel into the engine causing the back fire..

This is confirmed with your statement, that when the throttle was open just slightly, NO BACKFIRE HAPPENS (less vacuum). That's why your plugs look good, but still have a backfire issue

A small piece of crap, just worn injector could be the issue. You can them cleaned/tested. IMO, I would run the Ringfree 3x the recommended amount, it may help that particular injector. If it doesn't, pulling them and getting them tested would be the next step..



***Just as a side note, my '01, Toyota Four Runner, (16,000 miles) slowly developed a higher than normal idle (maybe 200 higher) over time. The fuel system has NEVER been serviced. After a tank or two (and NOTHING ELSE), using a heavy dose of Ringfree ALONE, the idle eventually dropped back to normal. 600 RPM W/O the A/C on, 650 with the air on it was around 800-850... It DOES WORK...

 

[weehe]

Sounds good, il look into the RingFree. Says I can't buy it online in the link. I'll look at our one motorcycle shop in town lol. Hopefully they will have it, but I'll look online more if they don't.

 

[FinalImpact]

Most of the mixing ratios are there to preserve CATs and O2 sensors... Using excess can damage them.
I gave my son the old Camry. Car is gonna make 300,000 miles with the only engine work being valve adjustment and timing belt every 90,000... Die hard V6!
Great little engine the 1MZ-FE...

Original cats, although all of the O2 sensors have been replaced at one time...

Techron kept it humming although that Gen is rock solid. Maybe it didnt need it.

I do the fuel treatments when the big fuel storage tanks are subjected to extreme weather changes as they can condensate and that can make in into our tanks as end users...

 

[TownsendsFJR1300]

Sounds good, il look into the RingFree. Says I can't buy it online in the link. I'll look at our one motorcycle shop in town lol. Hopefully they will have it, but I'll look online more if they don't.

The MC shop likely won't have it..

From Amazon; Amazon.com: ringfree yamaha

West Marine; YAMALUBE Ring-Free Fuel Additive | West Marine

Just type in "Ringfree".

Read the reviews as well...

 

[weehe]

Just checked my CO values, C01 = -15, CO2 = 2. Seems like a large difference to me. I know they should be different, but by 17? I should have the Freering and Carbtune by next weekend.

 

[TownsendsFJR1300]

Its not unusual... Save those #'s somewhere permanently, just in case..

 

[weehe]

Its not unusual... Save those #'s somewhere permanently, just in case..

Since they are not super rich, probably safe to assume they are not the problem. I am going to experiment anyways and see if it changes the backfire.

 

[weehe]

Well adjusting in either direction didn't change the backfire. However, +5 to both drastically increased throttle response and power (according to butt dyno)

 

[weehe]

http://vid903.photobucket.com/albums/ac240/weehe/20150920_1336261.mp4

Here is a video of the backfire. You can even hear it when I'm turning around at the end of the street.

 

[TownsendsFJR1300]

I'm sorry, but OMG, literally LOL!!

Sounds like a rubber band breaking!!

 

[FinalImpact]

At a glance this is nothing "normal" at all. Does it do this when its just started/when engine is cool or when the exhaust is still below operating temp? Abstract, but lets say something in the exhaust is being heated and is so thin it gloes. Add some unburned fuel and walla - it burns. So perhaps remove and inspect exhaust. How long has this been an issue? Ever since you obtained it?

Have you ever pulled the sparkplug caps and inspected the wire to cap junction? Even tho they run great, it can cause strange anomalies. While out, remove and inspect the ceramic resistor in the cap.

 

[weehe]

At a glance this is nothing "normal" at all. Does it do this when its just started/when engine is cool or when the exhaust is still below operating temp? Abstract, but lets say something in the exhaust is being heated and is so thin it gloes. Add some unburned fuel and walla - it burns. So perhaps remove and inspect exhaust. How long has this been an issue? Ever since you obtained it?

Have you ever pulled the sparkplug caps and inspected the wire to cap junction? Even tho they run great, it can cause strange anomalies. While out, remove and inspect the ceramic resistor in the cap.

It does it all the time, warm and cold. When warm it takes a longer decel to pop though. I can also force it sooner if I brake while decel. It only happens in gear with 0 throttle while decel. I just replaced the spark plugs and ensured the wires to caps were not loose. This has always been since I bought it. A coworker mentioned timing might be off as a backfire like this happened on older cars when timing was off. I plan to take the exhaust off to check out the cat, but not really sure it will be useful as I'm not sure what I'd see.

 

[FinalImpact]

It does it all the time, warm and cold. When warm it takes a longer decel to pop though. I can also force it sooner if I brake while decel. It only happens in gear with 0 throttle while decel. I just replaced the spark plugs and ensured the wires to caps were not loose. This has always been since I bought it. A coworker mentioned timing might be off as a backfire like this happened on older cars when timing was off. I plan to take the exhaust off to check out the cat, but not really sure it will be useful as I'm not sure what I'd see.

Olden days folks would roll down the road at speed, turn the ignition off (we are talking points and condenser), pump the gas (Cage Carbs have accelerator pumps), and then turn the key on. All of burning gas from the engine would hit the unburned gas which made it into the exhaust and "CRACK" one big massive backfire. If excessive, mufflers were defigured and/or blown apart!


Hot or cold doesn't matter, it runs great otherwise, yet does the boom thing. While in diagnostic mode did you notice the TPS lower value?


EDIT:
I really don't think this is the smoking gun (something in the exhaust) and still want to know that there are ZERO exhaust leaks and that the AIS valve is working (AND IS LEAK FREE!!!). HINT: PLUG the air box VENT to the AIS. It may be easier than testing it for flow. The valve is Normally Opened and is closed by the ECU. If it has failed and is always open or unplugged, it could be the item that gets this in motion. WHAT EVER YOU USE TO PLUG IT, MAKE CERTAIN it can NOT come out and stick in your throttle plates!

To your point, not much to see other than shining a light into the mid-pipe cat and seeing if the material is melting or obstructed or something is in there that glows hot when exhaust passes it. Use a small lamp that you can lower in from the elbow side should do the trick (Pipe in hand), lighting up the whole area and looking it over. Shake the muffler listening for something inside. You might even fire the bike off WITH the mid-pipe removed and make sure nothing flies out of the header. Its not that loud until you rev it!

Inside of S2 CAT....


Unplug this from the air box and either blow into it while the engine is running or plug the large hose on the right and ride it.
More pictures here: AIS Block off plate installation

 

[weehe]

Hot or cold doesn't matter, it runs great otherwise, yet does the boom thing. While in diagnostic mode did you notice the TPS lower value?

Yeah it runs fine otherwise. Just scares the crap out of people. I will check the TPS value but last time I checked I thought it said 16.