Horizons Unlimited - The HUBB

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-   -   2008 990 bad idle after altitude change (https://www.horizonsunlimited.com/hubb/ktm-tech/2008-990-bad-idle-after-83018)

MilesofSmiles 26 Oct 2018 00:19

SOLVED! and just in time avoiding catastrophic failure.....

A few years ago I took the bike to a well known mechanic in California to do some throttle body maintenance (sync) among other things. All was well for a couple years until the altitude problem cropped up.

Fast forward to last week

After dumping cash into new fuel pump, 02 sensors, plugs ( I installed) the bike still ran like crap below 4000 feet and 4000 RPM. I then took it to another local KTM mechanic with a good reputation to finally resolve this problem. The gas was old and had clogged the injectors. When I got the bike back it ran fair but I needed to add injector cleaner in the gas and finish dissolving the crud.

After 317 miles, the bike still ran like crap below 4000 feet and 4000 RPM. Actually scary in intersections. So I decided to tear down the bike again and it was a damn good thing I did. The throttle bodies had worked their way out of the intake manifold boots over the past few years. They were angled in the boots so the majority of the gas went down the intake yet they were sucking in air from the sides as well. Upon inspection, the top boot clamps were only hand tight. Had I hit one more sharp bump the throttle bodies would have come completely out spewing gas all over the place and stranding me and possibly starting a fire.

I paid good money to two well known KTM mechanics and in both cases they both completely screwed up. The latest one said he "Cleaned the bodies, checked valves, checked plugs, added coolant and injector cleaner".

The bike is torn down to the heads now and there is no indication that the aforementioned work was done. The throttle bodies are still dirty, the valve covers still have a layer of un-disturbed dust on them and a few other tell tail signs I was ripped off blind. If he had done the work I paid for, he would have caught the loose wobbly throttle bodies and fixed them. This did not happen.

Summary. Do the work yourself and do not rely on any mechanic, no matter how well recommended they are, to work on your bike.

Next week a complete SAS removal and Rottweiller air intake + 02 sensor dongles are going in. The sync vacuum will be in next week and the carbs will be synced in my garage, then the throttle idle will be set to .6V and a 15Min reset will be done. The bike should run like a bat out of hell when I'm done with it.

MilesofSmiles 6 Dec 2018 23:08

I installed the air intake kit and removed the SAS crud and took the bike for a spin. The bike still ran like crap below 4000 rpm. So for a final push to succeed in taming the beast, I took all three MAP sensors off, cleaned them, swapped out the vacuum tubing and cleaned the brass fittings on the sides of the manifold and guess what. IT RUNS FANTASTIC!!!:clap::clap::clap::clap::clap:

Had I known then what I know now, it would have taken me $1.25 and a couple hours work to fix a bike that could not run below 4000RPM or below 40000 feet.

For all you KTM owners: Your Adventure bike has 1 Mass air pressure sensor behind the front headlight and 2 manifold air pressure sensors located on ether side of the throttle bodies. Your manifold vent hose, vents into the airbox depositing little bits of crud down the throttle bodies. This crud then finds it's way into the manifold vacuum holes and clogs the brass fittings that the MAP sensors plug into. Also I found that the vacuum lines themselves were rigid and no longer held a solid vacuum. They slid right off the brass and sensor with ease.

Case closed........


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