lost power

2005 ISUZU ASCENDER
6 CYL • 2WD • AUTOMATIC
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PAPADC
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2005 isuzu ascender...on long trips on interstate, car would lose some power(still runs, but little power), would be fine after a couple of minutes...now is continual problem...changed air filter but not much help...what should I check next?
Jul 12, 2011 at 12:11 AM
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SATURNTECH9
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I would check for codes and restricted exhaust to start with.
Jul 12, 2011 at 12:18 AM
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RASMATAZ
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Verify the fuel pressure and comeback with the readings-we start here
Jul 12, 2011 at 12:20 AM
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PAPADC
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how much of a chance could it be the catalytic converter?
Jul 12, 2011 at 12:22 AM
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SATURNTECH9
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I dont know odds thats why i said do a back pressure test to check for possible cat issues have it scanned for codes and checking the fuel pressure like rasmatz said wouldnt be a bad idea.
Jul 12, 2011 at 12:26 AM
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PAPADC
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had it scanned last week...only problem shown was some to do with the engine being 21% but should be around 5 or 6 %(or vice-versa)...sound familiar?
Jul 12, 2011 at 12:28 AM
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PAPADC
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old code was something to with something "below threshhold"...had it erased & it hasn't come up again
Jul 12, 2011 at 12:31 AM
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SATURNTECH9
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That really doesnt ring a bell 21 percent of what?throttle postion?Dont really know need more details about that one.How checking the fuel pressure and back pressure?
Jul 12, 2011 at 12:34 AM
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RASMATAZ
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P0420

Check the Catalytic Converter if its clogged-up by doing what Sat9 suggested on backpressure test of the exhaust system-
Jul 12, 2011 at 12:34 AM
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SATURNTECH9
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Would have been helpfull to have known the exact code number it was.
Jul 12, 2011 at 12:35 AM
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PAPADC
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not sure...idles fine, doesn't skip...but when I press gas pedal a little hard, it doesn't want to go...if I ease into the gas it will evenually get to normal speed
Jul 12, 2011 at 12:38 AM
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RASMATAZ
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Disable the EGR valve and see what happens might be opening too soon-don't work have the computer rescanned again -maybe something might just pop up-
Jul 12, 2011 at 12:44 AM
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PAPADC
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pretty sure the code was P0420...was erased last week...engine light not on again
Jul 12, 2011 at 12:45 AM
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SATURNTECH9
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Without doing some testing one can only guess what might be wrong.When you do some testing let us know what you find.
Jul 12, 2011 at 12:51 AM