2008 990 bad idle after altitude change
 

Here's a problem I have been experiencing.

I will ride from 900 Ft to 8,000 then back down. When I get off the highway and come into the traffic lights, the bike won't idle and just dies. After I struggle to get trough the gauntlet of stop signs, I get home turn off the engine, let it sit for a few, then all is fine again upon restart.

Almost like the ECU can't handle the altitude change.

Once this happened on a slippery surface and the back end spun around so fast it smashed me to the ground before I even knew what happened :thumbdown:

Any thoughts.

SOLVED SOLVED SOLVED AND JUST IN TIME. See my last post for details.

Could it be a malfunctioning barometric pressure sensor input to the ECU?

I have had exactly that on numerous trips to the Alps on my 2008 ST1300 Pan European - it can run really badly after a significant change in altitude. Switching off and back on sorts it out. I looked into this a few years ago and came upon an explanation that fits, but I have no evidence if it is correct.

I was told that when the bike is first switched on the ECU takes a base line pressure reading and selects the best fuelling map based on that pressure measurement. However, the particular map selected can only accomodate a limited range of pressure changes either way. In 'normal' use (the UK for me) the altitude changes I see are fairly insignificant and I never have an issue. When I go to the Alps however, I can change altitude by many thousands of feet very quickly without stopping the engine. Eventually it will start to run badly. Shutting off the bike and then re-starting allows the ECU to take a new base line pressure reading and select a different fuelling map. All is then well again. I have really only noticed the problem when descending, which is when it would get much more air at the lower altitudes and therefore be running weaker on a 'high altitude' fuel map. Can't say I have noticed any issues going up the hills, but I suppose it could run rich?

Now, this might all be a load of rubbish, but it sounds plausible and it fits the symptoms.

Anyone else had a similar experience? Any fuel injection gurus out there care to comment?

Auto reset after 5 min idling
 

I understand that most KTM are designed to automatically self reset mapping when started and left idling without touching the handle for 5 minutes. I'm doing it on my 990R every now and then here in Switzerland, riding the Alps all the time, but never letting it to reset while in altitude. No problem thus far. Nothing like calling a nearby authorized dealership to get the right info, usually.

2008 990 bad idle after altitude change
 

The ECU reset is the famous 15 minute (exactly and without touching the throttle) reset procedure and would be my first trouble shooting step

Thank you for this, I never had problem with the ECU luckily, very useful to know!

I wonder if any message appear on the bike display when the reset is completed, or if it can be taken for granted after 15 min exactly?

My 990 had the same idling sympton after a fuel stop.

My best advise for reset procedure is:

Engine should be cold, use main stand.
Air temperature should be low, early morning/late evening.
Idling should be 15 minutes without touching the throttle.
Stop engine afterwards using key.

If the engine dies during the set-up, restart it without touching ingnition key and throttle. Idling time does not start at zero again.

As long as the FI lamp is not on, the idle reset should do the job.

That should do it. I have never heard of the temperature component but all worth trying. I replace my fuel pump filters every two years for preventative maintenance, and wow do they get dirty.

I've done the 15 minute idle trick several times now, but now the problem persists.

I took a ride up to 7000 feet in the rain. Bike sat in the rain as I watched the doodah parade in Fawnskin, then I rode back down. When I got off the frwy it was running like total crap. I let it sit for a week and tried starting it and it wont even idle. Almost like water in the gas. I noticed that both gas caps were closed but not clicked in place. Could rain have gotten in the gas with both caps closed but not snapped in place? I guess so so I will test the fuel. The fuel pump has less than 500 miles on a rebuild kit if that's worth anything. If the fuel is clean (no water) then a tear down would be in order.

I'm a little taken back with KTM because I spent my whole morning today trying to diagnose why my license plate is skewed to one side on my 2014 690 Enduro R. See post today about this

It's clear the 15 minute reset won't work in this case as the problem is that it runs fine at or near sea level (and possibly even OK once over 8K ft.?) but once back to sea level, it's screwed up. So it's the transitions from LOW to HIGH and back to LOW that the ECU is having trouble following. ... at least that's how I read the OP's description. A 15 minute reset would only get the bike running at the current altitude and once you ride UP and DOWN again, likely same problem will occur.

Usually turning off ignition, wait 30 seconds, then back on, will allow ECU to reset to current conditions or go back to default setting, so that's the quick and dirty temp fix.

But could well be a bad sensor somewhere or bad ECU ($$$$$) or moisture in there somewhere. I'm sure the dealer will happily sell you one ... but may be easier or cheaper fix? Their diagnostic computers should pick this up and they can read error codes too which should point to problem. Good luck!

Water certainly could have got into tank on unsealed fuel caps. Simply run something like Sea Foam or one of the moisture removing products to help. Can also help with Ethanol in the fuel. On KTM's it seems Ethanol can destroy fuel pump.

I run Sea Foam preventatively through all my bikes every few thousand miles.
Good luck, hope it's an easy and FREE fix!
bier

I'll drain both tanks and check for water. Sea Foam is good stuff and I run it all the time.

I recently went into a Shell Station and asked if they were serving E85 fuel so I wouldn't wreck my new 25cc leaf blower. The answer was no, but, she did have the latest water test results from her storage containers. It seems the regular octane 87 had 1 gallon of water mixed in with the gas while the 97 octane had 0.

In certain Yamahas this was corrected by turning throttle MORE than 1/8 of a turn.
This could be difficult in a windy road that required some finnese...



It let to a recall and the software was changed so that the computer read the ambient pressure after a throttle turn of only 1/25 . Turning ignition off and on also reset system.

Lets fast forward with this problem. Since my last posts, the bike has a new fuel pump, Lambda sensors, plugs, sycned carbs, de-tarnished carbs and injectors.

So, after 2 years of on/off working on it, I go back up to 8000 feet and it runs like a champ. Showroom quality, powerful and no snachy or jumpy throttle. I come back down to sea level and it runs like crap again between idle and 4000 rpm.

The bike does not know it returned to sea level. Even after resting a couple days it still runs like crap. So now I need to look into all the SAS BS and mass air flow solenoid. yes the 15min idle reset has been done with no positive results.

Al lot of money has been spent. I need to resolve this on the cheap.

Any thoughts?

get rid off lambda sensor and tune engine then (tps/idle).

Tested TPS/Idle and everything is fine. 02 sensors are brand new and tested fine. Charcoal canister dump tested fine.

It's actually scary to ride in the city. Every stop is a butt clencher. Once up the hill, it's showroom quality.