Sluggish Acceleration - bad spark plug cap?

My Gen 5 (2001) VFR has sluggish acceleration. It will run to redline but takes a while to get there.

I'm working through a list of checks to identify the cause but today I found something that I think is it.

Wondering if anyone has encountered this and found it to cause poor acceleration

I tested the resistance of the coils primary and secondary (HV) sides.

3 of the coils were 2.8 ohms primary and 18-20 Kohms secondary.

The # 4 cylinder coil was 2.8 ohms primary and 180 Kohms secondary.
I pulled it apart and the coil is 13.8 Kohms which is the same as the other 3.
I took the resistor out of the cap and cleaned up the connections. but the best I can get is 40 Kohms for the assembly.

The resistor is 5 Kohms which is what I would expect but the cap itself without the resistor is 20 Kohms.

I've ordered a new cap and am hoping this is the cause of the poor acceleration. Any thoughts?

I'm going to try driving it with the 40 Kohm secondary and see if it has improved over the 180 Kohm performance but it could very well go back to 180 Kohm as soon as I start the bike.


So far I have checked and confirmed to be good:

• TPS
• Map
• Baro
• Valve clearance.

Still to check.

• Compression. Ran out of time today.

Thanks,

 

Fuel starvation? When was the filter last changed?

 

That's a good question as I just got the bike.
I have a new filter and gasket but just haven't got that far down the 'to do' list yet.

I would have expected it to act more like a good initial acceleration and then taper off as the fuel demand went up if it was a plugged filter.
When I pulled the #4 spark plug (high resistance plug cap) it looked like it had just come out of the box. I've got the resistance down closer to the others now so I think that may be it. Just going to check the wires from the ecm to the coils to verify they are good and then I'll test drive it.

Stay tuned

 

So I verified there was continuity between the ecm and the primary side of the coil +'ve (common to all coils) and trigger (individual to coils).

Then I went for a ride. The bike now has more snap to it. Pulls away from a stop more firmly and responsive to throttle snap from 4K up. Roll on at 100 km/hr (50 mph) is good in 4th and 5th gears. 6th is a bit sluggish but it seems normal.

It looks like the high resistance spark plug boot on #4 was the cause.

The fuel filter will still get changed when I have a free weekend and the tank fuel level is down.

 

I'm having very similar issues with my 99 5th gen, think it's a bad coil, have ordered a set of 2nd hand ones to see if changing one will work,hoping it's that easy.