Engine idles only when the grip is WOT

[butcher bergs]

2002 CBR600 F4i

All cylinders are firing however the engine only goes to 1100 RPM when the twist grip is held wide open. It then dies when twist grip is closed more than half way.

HELPFUL suggestions please as I am at a total loss.

UPDATED:

My bike is fucked.


Thank you.

[Chippertheripper]

push-pull cables reversed? i got nothing, really, and i don't take you for somebody that'd make that mistake...

[butcher bergs]

Cables are good.

I repeated the issue once again and let a few minutes pass with the throttle WOT. The FI light DOES come on so the computer is seeing an error of some kind. I'll have to figure out the code when I get back home from Tricky's with my tire.

[Doc]

FI error.






Edit: Sorry, Didn't read the whole thread.

[FireboltEric_MA]

I may be stating the obvious & you may have already checked this...BUT From what you said I would look into the Injectors or the fuel pump, Maybe even the filter. MAybe a MAP sensor? I am guessing here.

OR

Read the code and fix it.

[butcher bergs]

Did not get a code using a spare ECU. I'm starting to think that the code I saw with the original ECU in place was a result of low engine RPM.....maybe it was sensing the voltage dropping off or something.

There isn't a spec'd test from Honda for the TPS (that I know of) but in the interest of discovery I poked around a bit at the TPS and noticed my meter showing a momentary open when reading in the area of 3.8 ohms at the TPS while the throttle is moved quickly to wide open however if the throttle is steadily moved from closed to WOT the momentary open does not occur.

For reference, throttle closed shows .9 ohms and throttle wide open shows 5 ohms.

I just thought that the momentary open was peculiar.

All other connections, as far as I can tell, are correct.

Can't keep run-testing at this hour so I'm packing it in. Still open to any suggestions or input based on similar experiences. Gotta see about that possible FI error in the AM.


Derek - You wish it was reversed coils!!

[butcher bergs]

No FI codes. No pinched vacuum lines or fuel lines and all connections are accounted for and in place.

Condition still exists.

Any input at this point, helpful or not, is more than welcome.

[slammp]

keep in mind that I consider myself to know way less than you in this area.

Are the throttle bodies opening properly - could this just be a mechanical failure of a spring or wire right at that point?

Or secondly is the cable inside the throttle grip area ok?

[wiggeywackyo]

Bergs,

Do you have manual? I don't have one handy right now but if you shoot me the code, I can take a look see and maybe you can narrow it down to a particular area.

It sounds like there is a short in the harness somewhere. Vacuum lines in the wrong place maybe?

[6 Fingered Man]

I just had a very similar issue after i replaced the head on my f4i, turned out i was off a tooth on the front cam. I went through all the stuff you are, swapped ECU, injectors, map sensor.. But turned out i was just an idiot while putting the cams in.

[butcher bergs]

The amount of one's knowledge is nothing in the face of a different perspective. Even prior to the thread being posted, I have been fearing a TPS yet I am not fully convinced of that...just don't want to overthink my concerns with the TPS and end up missing something else.

The butterflies are functioning correctly as are the cables to and from the grip.

[6 Fingered Man]

If you want to check the TPS i have a spare set of injectors (you cant remove the TPS from the injectors) . But with a bad tps it should run much better than you are describing.

[butcher bergs]

I just had a very similar issue after i replaced the head on my f4i, turned out i was off a tooth on the front cam. I went through all the stuff you are, swapped ECU, injectors, map sensor.. But turned out i was just an idiot while putting the cams in.

Only thing I've swapped so far was the ECU and I'm certain the cam timing is correct however I will pull the valve cover to ensure this. Too bad it's gonna be 2 days before I can jump back into fixing this thing. Gotta start packing.

[FireboltEric_MA]

Bring it with ya at the track. I am sure we could tear it down to molester it while bench racing at night...

[butcher bergs]

I'd rather not bring a broken bike to a trackday for the sole purpose of wrenching on it at the end of the day. I envision myself stealing people's bikes during the day. At the end of the day I see myself sitting, relaxing, beer in one hand something tasty in the other and not thinking about this bike.

[ZX-12R]

While I know little about CBRs, a 0.9-5Ω TPS sounds suspect to me. On other bikes, I'm used to seeing idle values around 500Ω that increase with throttle position. If you can scrounge up more info on the TPS or have someone with a known good one check it out for you, it may be worth looking in to.

Are you running a power commander and if so, have you had it disconnected lately?

[FireboltEric_MA]

I'd rather not bring a broken bike to a trackday for the sole purpose of wrenching on it at the end of the day. I envision myself stealing people's bikes during the day. At the end of the day I see myself sitting, relaxing, beer in one hand something tasty in the other and not thinking about this bike.

Oh Good, I did not feel like digging into a project.

I'm with you for after hours!Beer & budz..

[butcher bergs]

While I know little about CBRs, a 0.9-5Ω TPS sounds suspect to me. On other bikes, I'm used to seeing idle values around 500Ω that increase with throttle position. If you can scrounge up more info on the TPS or have someone with a known good one check it out for you, it may be worth looking in to.

Are you running a power commander and if so, have you had it disconnected lately?

The TPS readings are something I'll have to dig deeper on.

No Power Commander.

Eric - Sounds good!

[yesterdayze]

Yeah, I would check the TPS too.

Second thing to check is fuel pressure - specifically in regards to is your pump pumping correctly. I've had that problem on stuff I've worked on. Full throttle the pump would be working hard enough to kinda run....

[butcher bergs]

I started thinking about the fuel pump as well and thought even though it primes when the key is turned, maybe it's not running or pumping enough to sustain engine speed.

Got a couple days to mull things over at any rate.

[butcher bergs]

Maybe it's time to do what the mortals do and spray some ether at it.

[DuncanMoto]

Not than anyone would ever be dumb enough to do this, but are the pistons installed the right direction?

[The Magician]

try just disconnecting the TPS and see what it does. I've heard of this remedy on some other bikes as it will run the bike in a safe range instead of optimizing based on TP.

[qqac]

I didn't see whether you did any recent work to the bike, but assuming not, I think the likeliest thing to crap out on its own is the fuel pump, so I second that idea. The Honda FI system takes like 50 psi, and if your pump is dying, your injectors will be pissing like an 80 year old man.

[butcher bergs]

Not than anyone would ever be dumb enough to do this, but are the pistons installed the right direction?

That was funny but not that funny. You get one smilie.

try just disconnecting the TPS and see what it does. I've heard of this remedy on some other bikes as it will run the bike in a safe range instead of optimizing based on TP.

I'll have to try that. Thank you.

I didn't see whether you did any recent work to the bike, but assuming not, I think the likeliest thing to crap out on its own is the fuel pump, so I second that idea. The Honda FI system takes like 50 psi, and if your pump is dying, your injectors will be pissing like an 80 year old man.

90% of the bike was disassembled. Among a list of other things, I'll have to manually run the fuel pump and see what happens. The difficulty is trying to figure out which failing part would cause this issue yet not set off an error code.

Thank you all,except Doc, so far for the help and suggestions.