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martinkeller1

Excursion Diesel Runs Lean

I'm writing to ask about a potential issue with my 2003 Ford Excursion, diesel engine. At 74475 kilometers, the engine seems to be running excessively lean. Symptoms include reduced engine power, check engine light, rough running, and jerking during acceleration. I suspect a defective injection valve or injector. Any insights before I get professional diagnostics?

4 comment(s)

leonshadow1

Lean running on a diesel Excursion is no joke, especially with those symptoms! Have you checked the mass air flow (MAF) sensor? A faulty MAF sensor can definitely throw off the air-fuel ratio and cause a lean condition. Also, any signs of catalytic converter issues? A clogged cat can indirectly cause similar problems, messing with the air flow. It is also possible that you have vacuum leaks, causing the engine to run lean. Have you checked for those?

martinkeller1 (Author)

Thanks for the quick reply. Regarding the mass air flow sensor, is there a recommended way to test it, or is replacement better? Also, for the catalytic converter, what specific things should I look for besides the current symptoms? How do you usually find vacuum leaks?

leonshadow1

Testing the MAF sensor usually involves checking its output voltage with a multimeter while the engine is running. You'd need the correct specs for your Excursion, though. As for the cat, a noticeable sulfur smell (like rotten eggs) or excessive heat radiating from underneath the vehicle could point to a blockage. Vacuum leaks are tricky - a mechanic usually uses a smoke machine to find them. Honestly, with those symptoms and your suspicion of fuel injectors, a shop with the right diagnostic tools is probably your best bet to avoid chasing ghosts.

martinkeller1 (Author)

I appreciate your expertise. I took the Excursion to a reputable shop, as you recommended. They confirmed a faulty fuel injector, and replacement was needed. The total cost was 515€, including parts and labor. Thanks again for your time and help.

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