Surging at 3-4k RPM

[Flyingwombat]

Fixed 1601, the engine light lamp had come out of it's connection, easy fix.

[the slow heart]

If after each dismantling you find throttles bit off balance, you might be right to prime suspect worn screws.

When you blow with mouth at iacv, are all three lines equally releasing air? When you continue blowing and finger block orifices at manifold, do you feel pressure block and silence? O ring under the valve should be good.

What about the spark plugs?

[ghulst]

When you cleaned the carbs, did you really push something through all of the needles and thoroughly did the same with all of the other little passageways within the carbs?

I did an ultrasonic cleaning session on the carbs of my Ducati and then I needed to do it again.

[Flyingwombat]

Uploaded the latest map, no difference.

"If after each dismantling you find throttles bit off balance, you might be right to prime suspect worn screws."

Possible but threads look in good condition

"When you blow with mouth at iacv, are all three lines equally releasing air? When you continue blowing and finger block orifices at manifold, do you feel pressure block and silence? O ring under the valve should be good."

Oring appears fine, will blow into IACV to check...

"What about the spark plugs?"

 All new and gapped correctly.

"When you cleaned the carbs, did you really push something through all of the needles and thoroughly did the same with all of the other little passageways within the carbs?"

Used carb cleaner spray from liquimoly to clean throttle body inlets, will be ordering new seals for injectors, will clean the injectors and replace the seals when I do. Also trying to get an EFI relay, and a throttle body housing.

[the slow heart]

If the fuel map is updated and no test/sensor misbehave, the possibility of electrical issue gets less. Is there easy way to check that all three spark plugs fire at required frequency?

And since problem is in lower rpm some air leak still might cause the erratic situation. Injector seals renewal is a good move in that sense. You could think further which seals are exactly broken during your work, and how to check all of them for sure after the problem shows again ( since threads/screws seals are intact ). If you try to reproduce the problem with iacv socked unplugged from the el.looming, what happens?

Good luck!

[Flyingwombat]

So today I addressed a sticky throttle cable, not a cause. Then installed a new IACV housing and more rigid hoses, just in case.

I checked the balancing screws, they were annoyingly loose, I could turn them with my fingers on the heads... So will get some new loctite.

Got some throttle bodies from a broker, the screws were so much stiffer, so will re-balance with the new ones, came with injectors so will be cleaning them and selecting the best. Hopefully this will sort it. Otherwise fuel pump will be coming out, which is a bit of a pain I'd rather not have to work on.

[Lee337]

Big respect for sticking with this, many would have got shot of the bike by now.

Looking forward to seeing you resolve the issues & having a fully functioning bike.

[Flyingwombat]

Thanks, was my dad's bike so it's not just a bike. Also I'm an engineer, so I spend my whole life trying to work out why things are broken.

Today I cleaned the injectors and fuel rail.

Battery needs a charge before it'll start again, so fingers crossed tomorrow.

At this rate it'll be running next January...

[Flyingwombat]

Cleaning injectors did not help...

My long term fuel trim seems to have set itself really weird too, was down at -60, I have tried to reset this, but unfortunately the slider on the TuneECU app is playing up (only for the trim) and if I select any number highlighted it jumps to another random number, ie. -10 jumps to +80 and then 0 to -80 and +10 to +60. Doesn't make sense so have a TuneECU query on this as it seems to be a UI issue on the app.

The engine is quite sporadic now, it's fluctuations have worsened, at idle it will stall or bring itself up to around 3000rpm.

On the plus side I think I'm getting there. The fuel pump is noise when priming is getting worse, a very noticeable squeal now. Considering replacing that, the fuel pressure regulator and the filter. Could do with measuring the fuel pressure really but the Triumph part is extortionate. Does anyone know how to read the pump voltage?

[the slow heart]

Why exactly OEM gauge, you could easily improvise with another pressure gauge reading max at least 5 Bar.

Pump voltage also, the el.socket is not super tight, so two thin wires could be put in the female orifices before plugging the socket, then use these two for your volt meter.

Have to check was there an easy way to clear long term trims.

[Flyingwombat]

Why exactly OEM gauge, you could easily improvise with another pressure gauge reading max at least 5 Bar.

Exactly what I did in the end.

Pump voltage also, the el.socket is not super tight, so two thin wires could be put in the female orifices before plugging the socket, then use these two for your volt meter.

Have to check was there an easy way to clear long term trims.

So the pressure seems good, basically at 3 bar(g) consistently, even when it runs up the revs or stalls.

I have managed to find the number which changes LTFT to 3.0 (slider error still unresolved), much closer to 0 than -60.

So what I am seeing now.
At LTFT around 0 it fails turns over but doesn't rev to idle.
At LTFT around -10 it will remain stable but burning rich and smelly throttle response is slow to opening or closing.
At LTFT around -30 the application of the throttle will cause it to run up through the revs, even when throttle released.

So either burning rich or not at all. The opposite problem of previous lean burning.

I'm starting to think major vacuum leak from somewhere. Partly because if I manually cover the IACV to restrict air flow at idle it's still pulling air in from somewhere... Also looking at the throttle body vacuum it's far lower than it was when I last tried balancing it.

Potentially it's a throttle body gasket? Or maybe something else...

Still to replace injector seals, they arrived today.