Herky Jerky Throttle

[ionbeam]

I read your symptoms as classic light throttle, light load surging.

The correct fix for this is a PCIII which electronically smooths the rate of change in the fuel injector’s fuel delivery.

I’m no big fan of the blind Barbarian CO hack, but there is a real chance it will help in this situation. When you fatten up the FI shot a tad you will be inducing a very mild, over rich ‘bogging’ condition. The misadjusted combustion ratio will mask light surging. Up to a point, the richer you can run the engine at small throttle openings the smoother and slower it will respond to the throttle (along with poor performance and reduced gas mileage).

Edited to add: Hmmm, warm engine, steady speed, stable load = the engine running in the closed loop mode using the O2 sensor for ECU feedback. What happens to your situation when the O2 sensor is temporarily disconnected?

 

[rushes]

I did the barbarian jumper mod and noticed much smoother light throttle response.

Best of all it's free! :thumbsup:

You can always change your settings back if you don't like it.

 

[Harald]

But I got a Mac and therefore can only use the stock map provided with the PCIII.
Thx

Scott

I have all the maps loaded on my laptop at SEATAC airport. I'd be glad to load whatever map you wanted. Just PM me.

 

[C&C]

Okay, I didn't want to start a new thread (paranoid, I know; I have Iggy lamented diffuse anxiety ) so here goes. For those that are having the herky/jerky throttle response while at steady throttle, I have found this to help me:

I was doing a TBS (because the engine was very uneven when going steady state) and when I pulled the throttle body caps I noticed that the rubber (although looking in good condition) had some cracks in them. Well, two out of the four wouldn't hold a vacuum (sucked on the end, with my tongue and wouldn't stick) so I figured I was experiencing a small vacuum leak in two of my throttle bodies. Anyway, long story short, after making some throttle body caps and re-installing them on the engine, drivability was vastly improved. (Note; I have an '04, so the caps have been removed and re-installed multiple times and were subjected to age as well; and had cracked.) So at least take that into consideration if you are having similar driveability problems.

Hope this helps. Chuck

 

[CHRIS_D]

Okay, I didn't want to start a new thread (paranoid, I know; I have Iggy lamented diffuse anxiety ) so here goes. For those that are having the herky/jerky throttle response while at steady throttle, I have found this to help me:
I was doing a TBS (because the engine was very uneven when going steady state) and when I pulled the throttle body caps I noticed that the rubber (although looking in good condition) had some cracks in them. Well, two out of the four wouldn't hold a vacuum (sucked on the end, with my tongue and wouldn't stick) so I figured I was experiencing a small vacuum leak in two of my throttle bodies. Anyway, long story short, after making some throttle body caps and re-installing them on the engine, drivability was vastly improved. (Note; I have an '04, so the caps have been removed and re-installed multiple times and were subjected to age as well; and had cracked.) So at least take that into consideration if you are having similar driveability problems.

Hope this helps. Chuck

I know this should be common sense (It should of been for me but I think it was being lazy :blink: ) but dont' use needle nose pliers to remove the caps. It will crack them and the cracks are hard to see.

 

[SkooterG]

Okay, I didn't want to start a new thread (paranoid, I know; I have Iggy lamented diffuse anxiety ) so here goes. For those that are having the herky/jerky throttle response while at steady throttle, I have found this to help me:
I was doing a TBS (because the engine was very uneven when going steady state) and when I pulled the throttle body caps I noticed that the rubber (although looking in good condition) had some cracks in them. Well, two out of the four wouldn't hold a vacuum (sucked on the end, with my tongue and wouldn't stick) so I figured I was experiencing a small vacuum leak in two of my throttle bodies. Anyway, long story short, after making some throttle body caps and re-installing them on the engine, drivability was vastly improved. (Note; I have an '04, so the caps have been removed and re-installed multiple times and were subjected to age as well; and had cracked.) So at least take that into consideration if you are having similar driveability problems.

Hope this helps. Chuck

On my last spark plug change I also noticed these caps on my 04 FJR were cracking. I ordered new ones and replaced a few weeks ago. Don't think I noticed any difference in performance however. Still, I agree this issue is worth looking at as the FJR ages.

 

[BuilderBob]

Power Commander.

End of discussion.

That was the solution for me as well. I also noticed that my whites are whiter and my colors are brighter since switching to the PCIII.

 

[Jon]

I did the write-up on the BJM on Gen II bikes. On my '07, I found these four things greatly smoothed out throttle response:

1. Throttle body syn (TBS).

2. Take out the slack in the throttle cable(s).

3. Unwind the throttle return spring one turn.

4. Do the BJM and CO readjustment.

As an alternative to #4, leave the stock CO adjustments and buy a Power Commander. The choice is yours. While I believe the PC is the better way to go, the BJM is a lot cheaper.

 

[zenwhipper]

Good to see this topic still has some legs. I still have the issue with the bike. My proposed solution will be to try a Power Commander. I'm just waiting for the smacks to pay for the thing. Ahhh, winter is coming, I'll likely do it then.

Scott

 

[zenwhipper]

Ok I did get a PCIII a while back it definitely is a vast improvement . After doing a few seasons on the bike with the PCIII - I noticed that there is a consistent flat spot in the throttle at about 3K to 3.3K RPM. Me no likee. Is there a PCIII map out there that addresses this? Not sure others have noticed this issue with the PCIII. Can one adjust their PC in a sense making their own map? Maybe all I need is a bit more fuel in this RPM.

My ride:

2008 FJR, no CA model

PCIII, w/ O2 sensor unplugged

all else stock

Thanks Mates.

Scott