Loss of power/engine cuts - still there

[herwawan]

Hi peeps!

Here is some update on the long quest to get rid of my engine cuts.

- Previous symptoms lead us to believe the intake leak could most likely be the reason for the engine cuts around 4000 rpm (with nice backfires)
- The AFV setting was also getting very high (over 120%), which corroborated the theory of intake leak
- On a side note, my fuel pump was making some sad noises and it wasn't clear what influence it could have on the engine

I decided to change more parts:

- Intake flanges and seals
- Fuel pump and oil sensor

For information, all parts have been mounted in a shop (I got to be honest, I was traveling for a bit and just wanted the bike to ride when I came back haha), at Bartels' in LA. Throughout the process of putting the new intake flanges and seals, the intake body has been massively cleaned as it was - to be very polite - really dirty and the TPS sensor bolts were also tightened.

Some new parts later, the situation has improved on certain aspects, but not on others.

- The engine "sounds" definitely better than before, but everything isn't perfect still
- As the AFV was now closer to 100 and the intake being cleared of any leak, I updated the ECM with the map adapted to the K&N filter and Jardine exhaust. On this latest, it's a success as after fire totally disappeared.
- The backfire and the engine cuts didn't disappear, but also the engine is lacking power pretty badly. The very weird thing is that it's happening only with the engine warm. Cold, it will rev just great and run into no issues at all.
- With the updated ECM, the AFV setting is now doing the opposite of before, with a setting at 81%. I read on THIS PAGE that this is something known, except that I don't have any after fire, but I indeed have sloppy acceleration and the good old engine cuts around 4000 rpm. On THAT PAGE they mention something interesting about "reports of the ignition coil bracket losing it's electrical bond (ground) to the frame. An easy solution is to run an additional ground wire to one of the coil mounting screws." - any thoughts?
- I then played with the settings as explained in the article to lock the AFV at 100% and seek for improvement. Obviously I got some engine errors (13 - 02 sensor that is either always rich or always lean, makes sense), but the weird loss of power seems to disappear, but not the engine cut which was even worse - acceleration, engine cuts with nothing happening for a full 2 seconds, and then the backfire and the engine kept going.

To add a level of complexity:

- The issue is the same with both Stock and Custom EEPROM
- The issue is the same before and after the new intake flanges and seals (they were truly dead before though), and before and after the new fuel pump
- The issue seems temperature-related, but the temp sensor is fully working and in the log, the temperature never exceeds 200+ celcius, the fan doesn't even start - but maybe that's weird in a hot LA day? Log can be found here
- When I experienced the first engine cut off and backfire after driving it today, the needle of the RPM was going crazy up and down for a second - which ring the "electrical issue" light in my mind
- When the bike starts, the RPM level is perfectly stable around 1000*rpm, but as soon as it's warm and usually after the first engine cuts, it's becoming way higher (between 1200 and 1500)
- The TPS reset was done after the ECM update, and the TPD is currently at 3.7 degrees

At this point, it seems useless to change any more parts just now and I just need to diagnose the correct issue to address it accordingly... but I truly can't tell at this point what goes wrong. I'm calling the gods of Buell that are around this forum and maybe we'll find wtf is wrong with this dear lady!

As a reminder, the detail on the bike and all the parts changed:

- 2005 Buell XB12Scg
- ECMID: BUEIB
- 25,000 miles

New items:

Engine related:
- Oil (20W50) + filter
- Spark plugs (10R12X - I know, not the best but I read the NGK recommendation from Lunatic on a random topic a bit too late)
- Fan (OEM Spal)
- Clutch cover gasket
- Battery (Deka ETX14)
- O2 sensor (OEM)
- Intake flanges and seals (Twin Motorcycle)
- Fuel pump + low level sensor

Chassis related:
- Front isolator
- Turn signal flasher
- Fork seal
- Steering head bearing

As for the previous owner, I have the following information:

- K&N filter installed in 2013
- Jardine exhaust installed in 2013
- Ignition coil & wires installed in 2018 (used, a few weeks before I bought it)

[user_deleted]

On THAT PAGE they mention something interesting about "reports of the ignition coil bracket losing it's electrical bond (ground) to the frame. An easy solution is to run an additional ground wire to one of the coil mounting screws." - any thoughts?

all XB coils are dual-fire models and are NOT grounded in any way, shape or form. they work precisely the same as all old school automotive coils which were NEVER grounded either. this style coil is ball point pen simple. primary windings receive constant voltage....secondary windings receive a "trigger signal" which collapses the windings sending a high voltage spark out the tower to either a spark plug as in the buell case....or to a distributor cap as in the automotive case.
i'll also note THAT PAGE plagiarized the info directly from me. the dedicated wire mentioned does NOT ground the coil. it merely uses the rear hex cap coil mounting bolt to tie the left frame rail or negative battery cable directly to the motor as an additional ground source for the motor components only.
i know very little to nothing about ecm programming....afv values....and the like but i do know this: you have a serious electrical problem and it's all inter-related. note this: the coil is triggered and signaled by the ecm.....so is the fan....so is the dash assembly. are you absolutely certain all your grounds are pristine and your ecm is a known good unit? have you tried another ecm? have you performed the warm motor "ecm and harness wiggle test"? this has the flavor and essence of both bad grounds and some sort of terminal fault within your ecm.
know where all your grounds are located? if not let me know.

[herwawan]

i'll also note THAT PAGE plagiarized the info directly from me. the dedicated wire mentioned does NOT ground the coil. it merely uses the rear hex cap coil mounting bolt to tie the left frame rail or negative battery cable directly to the motor as an additional ground source for the motor components only.

i know very little to nothing about ecm programming....afv values....and the like but i do know this: you have a serious electrical problem and it's all inter-related. note this: the coil is triggered and signaled by the ecm.....so is the fan....so is the dash assembly. are you absolutely certain all your grounds are pristine and your ecm is a known good unit? have you tried another ecm? have you performed the warm motor "ecm and harness wiggle test"? this has the flavor and essence of both bad grounds and some sort of terminal fault within your ecm.
know where all your grounds are located? if not let me know.

- Noted for the coil - interesting and glad to get the correct information, thanks. I'll leave that aside then.

- Very clear for the electrical issue. I am not certain all grounds are pristine, and neither do I know if my ECM unit is good. I haven't tried another unit and I did not perform the testing procedure you're mentioning yet! Basically with warm engine, I wiggle the ECM cables and see what happen? What am I supposed to look for?

- First thing I can do is cleaning the grounds. I have located in the user manual two grounds under the seat on each side of the frame and one below the airbox plate. It makes 3 in total, correct?

- I also found your thread about wire grounds. I get a bit confused about the information here as it looks like you are referring to another ground, in the front area? But depending on the year, it looks like sometimes it's located in a different area "either bottom triple clamp or front of frame/head-stock". I see what the triple clamp is, but a bit unsure about the frame/head-stock.

[Cooter]

It's hard to read some of that info. The way I read it, it's conflicting itself But thank you for the detail info!!

I concur it's an electrical issue, at least that needs to be fixed first. I say that from the 'RPM needle jumping' clue you gave. Also because there isn't much tuning-wise that will make a bike die for 2 full seconds and restart itself.
Check for continuity through the ignition circuit, while wiggling the key switch, run switch, and ignition relay. The most common would be corrosion in the red run switch. The second would be corrosion in the ignition relay socket. You can also swap the ignition relay with another one while it's out.

Get a good copy of the wiring diagram and print it out as big as you can, you'll need it.

[herwawan]

It's hard to read some of that info. The way I read it, it's conflicting itself But thank you for the detail info!!

I concur it's an electrical issue, at least that needs to be fixed first. I say that from the 'RPM needle jumping' clue you gave. Also because there isn't much tuning-wise that will make a bike die for 2 full seconds and restart itself.
Check for continuity through the ignition circuit, while wiggling the key switch, run switch, and ignition relay. The most common would be corrosion in the red run switch. The second would be corrosion in the ignition relay socket. You can also swap the ignition relay with another one while it's out.

Get a good copy of the wiring diagram and print it out as big as you can, you'll need it.

Sorry if it looks confusing sometimes, maybe it is in the words I used. I will try to define more specifically one thing that I think can be confusing:

"engine cuts": I really translated the same words as I would use in French and maybe it is incorrect. What I mean by that, is that with the throttle open to the same position, the engine will stop accelerating and "caugh".

I have the full service manual printed already, but I just realized the wiring diagrams are not printed correctly (I guess the page format wasn't A4 - I guess you call that letter here). From what I read on the different pages, there are only 3 different grounds.

Electricity really isn't my thing, it's going to be intense. One of my dear friend who's color blinded used to help me with electrical wire in my old cars, that should tell you how bad (= scared) I get with this topic hahaha He would read the wire diagrams, I would tell him the color of the cables he would cut or plug Good thing we never had to diffuse a bomb!

[Cooter]

"Good thing we never had to diffuse a bomb!" That's funny Max.

Should be easy to check, I'm packed the next couple weeks but would like to help you out if I can.

[herwawan]

Yeah, I ended up in the ER (thankfully it wasn’t a big deal at all) one day because of a massive shock. I was working much younger on the kitchen with my dad and as I was wiring the electric stove, for some reason the electric switch was on. Touched half a second the wrong cables - 220v and 32A later, I'm since really scared of electricity haha I did it another time with a extension cord that was in a bad condition haha you never learn the first time!

Anyways, I did the grounds under the seat today and also cleaned up the battery connectors. I also replaced the battery tender cables as I was around - the old ones were really dirty on the battery side and weren't compatible with my battery tender.

Next stop is the big one under the air box backplate a bit later.

[njloco]

I put a smidge of roller chain spray lube ( has an anti corrosive in it ) on the connections of both battery connection after cleaning, + and -, I also put a little on the grounds after a good cleaning. ( no matter how clean they look ) this seems to me, to keep them from building up any residue for a longer period of time.

[herwawan]

Good call njloco! Thanks Once I've figure this all out, I'll definitely do a second pass with the right lube on the right screws/bolts to make sure everything is perfect.

Now, I just finished with the big engine ground. I cleaned the hell of that thing, and the big chunk of wire is in okay condition (see picture below). As I was dismantling the airbox and backplate thing, I realized my back head cylinder is a bit covered with oil, nothing bad. But as I removed the back-plate, I also spotted the crankcase breather of the rear cylinder is loose. The poor thing is moving around like there's no tomorrow (see picture below). Not that it can explain my cuts, but that's something to add on the list and which probably explain the oil on the head cylinder down hill.

So what about the engine cuts? Well to make sure we compare apples to apples I stopped trying to fix 1420482 things at the same time and I put my stock eeprom back on, did a good TPS reset, and went for a ride. The result is... troubling.

First, as I let the bike warm up to adjust my TPS, the engine stopped around 150.C. No hard time, nothing but just a simple "Imma stop right there". I fired it back without any issue and the idle is even more stable than ever. It never happened again since.

I went for a ride, well it rides very well when it does, no loss of power, just brute force and I can tell the engine works fine. I've been able to go all away before the redline, the engine sounded really good... until it "caugh" again at 4000 rpm (backfired once, just the first time). After that it's almost like I can "feel" something is different with the engine, in the way it vibrates. But, this time with a trick. I thought it was temperature related, only happening when the engine warm... Well, at some point the fan started (good sign, it works too) as I was sitting in a short traffic. Then I decided to head back and I ran into no issues at all. Ran perfectly well all the way up the redline. And randomly a bit later, it did it again, just a couple times.

So it's even more random than before, but at least, there's improvement.

- The idle is now rock steady in all conditions (starting cold, warm, when it rides well or after the "caughing")
- The cuts and backfires are not happening all the time after the engine is warm
- The AFV is now more normal, chilling at 105% after a 30 min run
- The TPS degree is at 5.3

I'm still in the dark, though, because I have no idea where to look now haha

IMG_5969.jpg

IMG_8704.jpg

[Cooter]

OK try this. With the bike warm and idling, wiggle the key and wiggle the Kill switch, take the seat off and wiggle the relays by the fuse box too.