Extremely High Idle

[rafamartineiz]

Hi there! Sorry for my English as I'm a Brazilian trying to survive with a rather expensive (at least here) cb 650f 2015 in Brazil.
I'll go with the problem that started it all, then the actual (bigger) problem.
At the beginning, the bike had a high idle after warm, oscillating between 2k and 2k rpm. It was odd, but not odd enough for me to deal with while I was working 6 days a week.
This week I had 2 days off so I decided to buy a new injection hose kit to replace it all (some of the hoses were literally split in half) to see if it would fix the issue.

Oh boy, I had no idea what I'd face...

- fairings out
- fuel tank out
- air box out
- injectors out
- throttle body out
- hoses (map sensor, pair sensor, all related to air injection) replaced
- reverse order until the start of death began: bike "idling" at 6k rpm. Turned off, removed tank again, checked for anything loose (sensor connectors, hoses or something like that), nothing in sight. Start again, 6k rpm again.
Turned off. Did steps above thousands of times, every time finding something that could potentially fix the issue, nothing did at the end so here am I asking for help.
I've a Jdiag m100 pro scanner that I've been using to see live data from sensors in these short starts, nothing unusual seen. No current faults also, just some weird stored short to ground error from map, injector 1 and tp sensor. I tried to erase them but it seems that they come back whenever I turn off and turn on the bike again. These faults were already stored before this maintenance I started. I checked with the service manual the wiring for each sensor and the expected results for voltage and continuity were found.
My next step is to assemble the air box with the rubber seal better positioned (3d printer to the the work) as it was inside the channel without any function - one of the photos shows how it was before. Or it is supposed to be that way and I'm messing it even more?

I can upload photos, videos or anything that may be relevant upon request.

Again, any help is appreciated.

 

[Brammers]

Your tps could need recalibrated. Those seals also need to be replaced. They should be in the groove and will likely cause an air leak.

Also check the boots for leaks (as you've had the injector body off).

Any air leak will cause idle issues.

J

 

[rafamartineiz]

After taking absolute care for the boots, air box tubes, air box gasket and reassemble everything, I got progress, then I didn't (yeah, frustrating). At the first start, the bike was reving at 1k rpm for like 5 or so minutes, I thought "nice, probably the problem is fixed". I assembled the tank, added the fairings, and when I started again, it was fluctuating between 2 and 3k rpm. Any guidance from now?

 

[rafamartineiz]

Here are some photos of the readings from the scanner (I took 3 or 4 pictures of the same screen to show the rpm fluctuating)

 

[Brammers]

I want to say that's a map sensor problem. Possibly a kinked hose on reassembly?

Or a vacuum leak.

 

[rafamartineiz]

Considering all possibilities:
- Kinked/folded hose: wouldn't it happen even before fixing the 3 bolts from the tank as it was already in the bike? That's pretty much all that changed from the time it was running ok (idle steady at ~1100 rpm) to the time it wasn't (idle fluctuating from 2 to 3k rpm every second).
- map sensor: I tried to blow and suck it with the scanner to see the voltage and kpa fluctuations and it indeed happens, also, when idling, the sensor also fluctuates (should it do so if everything else was ok? I guess not, but how am I supposed to check it without replacing it 😕). But is it enough to rule the map sensor out/in? If there's indeed a vacuum leak, the sensor would be simply doing its job measuring the pressure bouncing up and down inside the engine due to more/less air than expected inside the throttle body.
- vacuum leak: yeah, that's one major option and I think that's the root cause, I'll have to get my smoke machine to see if I can catch this leaking spot (or any other ideas that may help me get to the bottom of this).

The bike revs flawlessly over 3k RPM, but as soon as it comes back to this 2 ~ 3k rpm range, if I'm driving it and it's geared, it starts stuttering, making it extremely hard and dangerous to guide on urban routes (I took it to a ride to see how it would behave).
Regarding TPS reset, it shows 0,5v at idle speed and 4,5 or so volts when fully opened. I've tried to reset it through my scanner but I don't know if it indeed happened. Maybe not.

 

[Brammers]

Three tank bolts? Mine only has two, unless you removed the hinge bolt too.

That last one could have moved down and pinched anything.

You don't need to remove the tank for this work, just tilt it up and prop it there.

J

 

[rafamartineiz]

I've taken the tank out for this, I knew it could be done without removing it, but at the end I decided to take it out. I also took it to a reliable garage as I was running out of options and without proper time (maybe tools and knowledge too) to fix it. I'll let you know what was the outcome when I get it back, ok?

Thank you all for the attention anyway.

 

[Brammers]

Looking forward to hearing the outcome!

J

 

[rafamartineiz]

Hey y'all

Final update:
The garage suffered a lot (according to them) but found the problem and delivered the bike fixed to me yesterday. I took it for a quick ride and it is apparently fixed as it's no longer idling at 2k even when the engine is warm (that was the initial issue which started months ago). Needless to say that the 5 ~ 6k rpm when starting the engine is no longer happening too.
Here's what they did to find the error and fix it:
- nozzle cleaning
- nozzle replacement
- error check (no error related to that recognized on mine neither on their scanner, weird)
- sensor test/replacement (apparently they tried the good and old switch and test method).
Until they found that the IACV was causing all the trouble. During my tests, the actuator was working fine (the rubber was moving up & down while holding its base) outside its slot when the key was turned on, the resistance of the IACV motor was within the parameters and the electrical circuit had nothing different of what the manual says.

Anyway, I hope this post can help someone in the future and also thank you all from this forum that promptly supported me somehow.