Problem with my 99

My '99 800 suddenly began starting very hard and having no midrange or top end power. I am not getting an FI fault light ( yes, the FI light works when you first turn the key on). I have had the tank and airbox off and can find no loose vacuum lines or wires anywhere. It has a PC 4usb which I disconnected to elminate it from being defective, it runs worse with PC disconnected. PC is now re-connected. The bike wont take throttle unless you give it gently, then it will rev. A good friend of mine (Master Toyota mechanic) helped troubleshoot it. After much discussion and trying different things, he tried clamping the vacuum line going into the MAP sensor and the bike revs like it should, on the stand. I replaced the MAP sensor with no change. The bike is very clean and has been well taken care of. Upgraded R&R, brand new battery 14,500 miles, K&N filter, PC4usb and TBR slipon exhaust. Any help on this issue will be greatly appreciated.

 

If you short out the diagnostic connector (two wires going into an unconnected plug on the LHS of the rear sub-frame), you can count the long and short flashes: long flashes for the number of tens, and short flashes for the number of units. Eg: two long, three short is 23 (I can't recall if there's a code 23, but you get my point). There's also a procedure for clearing codes, and be aware that there are some codes that absolutely will not clear by themselves, even though the Honda manual says that they will.

Also bear in mind that your injector nozzles could be coated with varnishes and gums from the fuel, which could easily cause the symptoms you're experiencing.

 

Tink & Danny - he said he's NOT getting any FI codes.

 

Not like I was much help. I was just pointing out your erroneous ways.

 

Tink......You're fired lol

 

Guys, you need to read it again... He said that he didn't have the FI fault light. There are codes that can be set without getting the FI fault light while not in diagnostic mode (I had one on my previous 5th gen that would never clear, but I didn't have the FI fault light when not in diagnostic mode).

You're all fired!

 

Thanks, guys.. I am taking it to one of the best Honda techs I know. I'll keep you informed.

 

ok.. My tech guys says to replace the TPS or Fuel pressure regulator. Im thinking TPS. he says the TPS can be bad and still not throw a FI fault code.. It looks like Hoinda doesn't sell a TPS, just the ENTIRE Throttle body FI system. WTH?

 

I've got an extra '99 TB sitting on my workbench, let me know what you need.

http://www.partsfish.com/oemparts/a/hon/5053e920f870021c54be364a/throttle-body-assy

 

Hey, thanks for the offer Capn. Right before I saw your reply, I purchased a throttle body assy from eBay. Last night I replaced the TPS and fuel press. reg. No difference. Disconnected the Power Commander again, just for the heck of it. Makes it harder to start.
What next?

 

It sounds like it's fuel limited (lean condition) but that doesn't explain why it will rev when you pinch the MAP sense line. If anything, pinching that line at idle (high vacuum) would keep the mixture leaner as you open the throttle bodies and let air in but it's really going to come down to what the ECU is seeing in terms of signals from the sensors and how is it responding to these signals. I would test each input to verify that at the very least the ECU is getting good data. If it is still running poor, and you can't find the reason, like a plugged fuel filter or a mud wasp nest in the exhaust, then it's looking like an ECU issue.

So what's the message?
Go back to the basics and try not to make assumptions. Can air get in Y/N, Can air get out Y/N, Fuel is available Y/N, Ignition is good and advancing properly Y/N, of and of course cylinder compression.

 

Good answer, Jethro. This evening I am starting out with a new set of plugs, then I'll check for fuel pressure.... I know there is no obstruction in the intake tract, exhaust should be clear too. I think I will try to set the power commander to full rich as well. I will be looking to pick up an ECU if anyone has that sitting around (not likely).

Thanks to everyone for the help.

 

what is the voltage at the battery when the bike is running? do you have access to a scope, if so check for excessive ripple at battery when running

 

Not sure about the voltage at the battery. I will check it tonight. No access to a scope, just a decent multi-meter.

 

ok measure neg bat term to frame ground when running. incorrect voltage will toss the inj system out to lunch

 

I got a CA spec ECU sitting around. But I don't think that's the problem, probably wouldn't run if the ECU had fried.

 

Hey VFRCapn, What would you take to let me try that Ca spec ECU? I'm willing to try that next.