Misfires/hesitation under load K1100

[Kevin1100]

Hello everyone, I am new here and just introduced myself on the introduction page.

To get right to it, my K1100 with ABSII and motronic 2.2 rides great except for one thing. Sometimes when I accelerate hard it will hesitate/misfire. Sometimes it feels like a classic misfire (just a tiny buck and then it will go) and sometimes it's a full 1-2 seconds of full on delay before actually pulling. The engine doesn't die or anything, it's just like it's not getting spark or fuel for a bit, and then it does and it's all good.

I already replaced the fuel pump and filter and spark plugs. Today I took some resistance readings to rule out ignition issues and got the following:
lead #1 5.77k ohm
lead #2 5.9k
lead #3 5.64k
lead #4 5.87k
coil pack 1&4 primary resistance 2.9ohm, secondary resistance 12.38k
coil pack 2&3 primary resistance 2.4ohm, secondary resistance 12.36k

These numbers seem right enough to me but I just wanted to double check here.
Any pointers on what I can do next? I tried diagnosing the TPS by grounding pin 1 of the diagnosing plug but had no luck with an LED (it turns on but when pulling the throttle it will just stay on, even with WOT). Can I use my multimeter to read out values, resistance or continuity instead of using an LED? I feel like I'm better with my multimeter than with LEDs.

The bike has sat for a few years so I might get some injector cleaner in the tank as well just for the heck of it. I rode about 500 km since changing out the whole fuel pump assembly, lines and always use the best fuel so I thought it wouldn't be necessary but it's cheap enough to give it a shot.

Thanks in advance!

[Scott_]

Where to begin...... in no particular order
Fuel spray pattern of the injectors
valve clearances
exhaust CO mix
vacuum leaks
fuel pressure

[Laitch]

During these momentary power interruptions of one or two seconds, do any instrument bulbs light or does the tachometer plunge to zero and rebound immediately?

[Kevin1100]

No weird electrical gremlins otherwise. The tacho drops (which makes sense because the RPMs drop too) and then picks up as the engine picks up again. Everything else on the dash keeps working as usual. I'm guessing you're implying a possible issue with the battery but judging from this I think the battery is fine. The PO said he bought it brand new right before he sold it to me and it also looks brand new, I have cleaned and checked all ground connections so I think the battery side of things are ok.

[Laitch]

I'm implying a fault in the ignition switch that is common in old Bricks could be occurring regardless of the battery's state of charge.

The contacts within it become corroded and need cleaning and lubrication, similar to distributor points in the relics that taught some of us early on. It starts out with an occasional miss and often ends up with a prolonged spell of roadside cursing in the middle of nowhere. When the fault occurs it acts like the switch has been turned off for a moment—the alternator bulb lights, the tach needle drops like a stone and then, PRESTO, everything is normal.

[Kevin1100]

Ahh gotcha. Meant no disrespect with my implication of your implication! Seems that that's not the issue for me (luckily). Although good to keep in mind as I actually have some experience with the relics of the past as you say. My mk2 golf left me stranded and wouldn't start for 7 months, went to 3 garages but no one could find the fault and all told me to scrap the car. That was my introduction to wrenching, and after 7 long months I found out about the distributor points, replaced them in 5 minutes for the massive cost of €7,49 and the car ran like a dream and has never left me stranded in the next 5 years dailying it (still use it every day).

While inspecting I actually found a tear in c4's intake hose. A new one should be coming tomorrow so hopefully that will fix it. I have some experience with lean bogs on my carburetted car but nothing this bad, but who knows.

[Laitch]

. . . the massive cost of €7,49 and the car ran like a dream and has never left me stranded in the next 5 years dailying it (still use it every day).

GoFundMe saves the day again!