Recent drop in engine idle

[RickV]

Any idea what would make the idle on my `99 Girly all of a sudden drop from the usual 1000 rpm to around 500 (or less)?  I bought this bike a couple months back.  It's now got 45K miles on it.  Runs great.  I recently pulled the K&N filter, cleaned & re-oiled it.  I've riden at least 300 miles since I did that.  Just noticed the idle steadily dropping while riding home from work today.  Is there a vent hose or something that I had to reconnect to the tank that might have an effect on the idle (leaking or cracked)?  How about the seal around the filter housing, where the filter slides in.  I noticed the previous owner had some kind of sealant around the flange.  I didn't put anything on the crack.  I wouldn't think a little air slipping in around the filter housing would matter.

Thanks,
RickV

[2004Tiger]

In cars, often when a user re-oils a K&N, the excess oil travels downstream and covers the Mass Air Sensor. This causes the computer to get erroneous signals.

[RickV]

I just read in my Haynes shop manual that there is an intake air pressure sensor that has an effect on the ECM as it measures barametric pressure within the airbox and combines that info with that of other sensors to adjust fuel delivery.  I guess I need to pull the tank & put a little sealant around the housing where the filter slides in.

I started using mid-grade gas in the last two tanks (89 octane).  The previous owner always used high octane.  I doubt if that would affect idle speed.

RickV

[RickV]

Still haven't gotten the idle back up.  The only thing I haven't tried is synchronizing the throddle bodies.  Need to get some gauges to do that.  If that doesn't do it, I'll have to take it in to a dealer.  Any other ideas?

[Bruincounselor]

Still haven't gotten the idle back up.  The only thing I haven't tried is synchronizing the throddle bodies.  Need to get some gauges to do that.  If that doesn't do it, I'll have to take it in to a dealer.  Any other ideas?

Have you acquired a vacuum leak? It's easy to disturb the factory tubing pulling the tank and airbox off. Perhaps your tubes are brittle and cracked?

$ .02

[iansoady]

I'd have thought that would increase the idle speed as the IACV (stepper valve) lets in more air when the idle speed drops. It could be a problem with the IACV itself - these can stick on some vehicles but I'm not aware of it happening on the Tiger.

Tuneboy has an IACV test function.......

[RickV]

This did develop after I pulled the tank, so it could be related to a vaccum leak.  I did notice the crankcase vent line was off the airbox.  I don't think that happened when I pulled the tank, but was probably like that when I bought the bike.  BTW.  This bike has 45K miles on it & I doubt any of these lines have ever been changed.

[swamper650]

After 25k miles my 02 developed a drop in idle speed. After a bit of searching about, discovered I needed to adjust the throttle cable at the throttle itself. A little fiddling and all is good.

[Bruincounselor]

I'd have thought that would increase the idle speed as the IACV (stepper valve) lets in more air when the idle speed drops. It could be a problem with the IACV itself - these can stick on some vehicles but I'm not aware of it happening on the Tiger.

Tuneboy has an IACV test function.......

Perhaps. When I was installing my cruise a vacuum leak kept my bike from running at idle.

[iansoady]

After 25k miles my 02 developed a drop in idle speed. After a bit of searching about, discovered I needed to adjust the throttle cable at the throttle itself. A little fiddling and all is good.

But the throttle cable shouldn't be tight on idle - you should always have a little bit (2mm or so) of slack. So I can't see how this would work.

[RickV]

Nope.  Throddle cable won't do it.  Suppose to be slight slack in the cable when completely released.

[swamper650]

Did not say I took the slack out of the cable...as posted  I adjusted the cable.........Idleing great now  no further issues..................

[Bixxer Bob]

I've been doing a bit of reading on this, but it's hard to narrow it down on what you've said so far - so here are a few questions:

Girlies have fuel injection ergo the idle speed is not manually adjustable (stating the **** obvious):

Is the drop really gradual, or do you just notice it when you stop somewhere on your journey?

If it is gradual,  what distance are we talking about before it starts to drop and how long after starting from cold?

Does your Girly have an oxygen sensor in the exhaust?  (Or does it have a catalytic converter?  the two go hand in hand)...

I'm trying to work through all the sensors that change the mixture as conditions change,  but one thing you could check - have you disturbed the pipes from the idle air valve to the cylinder bodies?  If you have that shouldn't cause a gradual change, it would be the same all the time, but you never know...  

In fact, if it's just a small leak, the sensors could be coping with it when the engine is cold but can't when it warms up.  Only my two penn'th  

[RickV]

I've been doing a bit of reading on this, but it's hard to narrow it down on what you've said so far - so here are a few questions:

Girlies have fuel injection ergo the idle speed is not manually adjustable (stating the **** obvious): correct

Is the drop really gradual, or do you just notice it when you stop somewhere on your journey?  I did two things before the ride that I notice the "sudden" drop.  I pulled the air filter (K&N) cleaned & oiled it.  It wasn't very dirty, but did show signs of wear.  The previous owner always ran premium gas.  I tried a tank of midgrade, but have since gone back to premium.  I don't think it really matters that much.  I put a little RXP in the tank to clean the injectors.  Didn't help, didn't hurt.

If it is gradual, what distance are we talking about before it starts to drop and how long after starting from cold? When started cold, it idles around 2K for about 20 seconds, then drops to 1200-1500 for another 30 seconds or so.  It then gradually drops to 800-900 rpm until it starts to warm up.  Once fully up to normal operating temperature, it drops to about 500 rpm.  

Does your Girly have an oxygen sensor in the exhaust? (Or does it have a catalytic converter? the two go hand in hand)...  I don't think so.  I will have to check the Haynes manual.

I'm trying to work through all the sensors that change the mixture as conditions change, but one thing you could check - have you disturbed the pipes from the idle air valve to the cylinder bodies? NO. If you have that shouldn't cause a gradual change, it would be the same all the time, but you never know...

In fact, if it's just a small leak, the sensors could be coping with it when the engine is cold but can't when it warms up. Only my two penn'th

[RickV]

Based on what you're saying, it sounds like it could be a vacuum leak.  The only hoses I've messed with are the hoses connected to the gas tank.  I had to disconnect all of them when I removed the tank to get to the air filter.  Maybe I need to go back & check connections.