03 gmc 2500hd 6.0l gas eng eng loss power, eng lite flashes , random multiple misfire under load.at idle runs ok
Country: United StatesMake: GMCModel: 2500hdYear: 2003Engine: 6.0l gas Already Tried: fuel pump,filter, plugs, wires,and started to cut exaust off before cats, it will barlely go down the road
Hi,welcome to Just Answer.I will be happy to assist you with this question today.I will try and assist you as best as possible from here,feel free to ask any follow up questions to my info provided here.Did you remove the catalytic converters or open up the exhaust on one or both sides to see if it operates normally?Has spark been tested at all on all of the cylinders?Do you know what cylinders are misfiring?Let me know so we can continue,thanks Pete!peterpete19041038.9053435185
Hi,welcome to Just Answer.I will be happy to assist you with this question today.I will try and assist you as best as possible from here,feel free to ask any follow up questions to my info provided here.Did you remove the catalytic converters or open up the exhaust on one or both sides to see if it operates normally?Has spark been tested at all on all of the cylinders?Do you know what cylinders are misfiring?Let me know so we can continue,thanks Pete!
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I have open up the exuast before the cats ===no change
while eng is runing i individualy unpluged each coil and the eng would respond to the loss of spark
the code that comes up is random multible misfire
Are you using an after market or K & N air filter at all?
no
It may be possible the mass air flow sensor is causing this fault here as I have seen and have had to replace before.Locate this sensor near the air filter box and unplug it with the key off,then start the engine and see if it runs properly at idle or when revved up.If it does then the sensor either needs cleaned or replaced.It sounds like you have good spark and your fuel pump has been replaced so this shouldnt be a fault so this leads me to believe air flow or air flow sensor may be at fault causing this.Let me know if you need anything else with this question asked here.Thanks Pete!
no difference
Was anything done on the vehicle before this fault occured?Did this fault occur after fuel was added to the fuel tank?
no it has gradualy been getting worse since january and the truck has been a daily driver
i first notice when i would have the boat behind it
O.k.,I would do a compression test and see if any cylinders have low compression as I have seen some valve issues on this engine before.If compression is o.k. then next I would have the fuel injectors tested to make sure none are atomizing/spraying to much fuel compared to the rest,I have had to replace injectors on this engine as well.If possible get a hold of a scan tool that can read misfire data to see if you can locate one or more specific cylinders misfiring this way you can tell which cylinders are causing this fault.
Experience: GM training and dealer tech for 14+ years. Diagnostics
Hi Mike,I'm just following up with you to see how everything is going. Did my answer help?Let me know,Pete