rawb Posted October 9, 2010 Share Posted October 9, 2010 so , I have bin gifted with a 6.o litre , lack of power , intermintent, only when he hauls a 40 foot trailer on a blue moon.... everything i check out is mint.. exaust back pressure is 49 maxed , fuel pressure is 55 psi , E G R is a pass . I took down the exaust to check CAT.. looks great, clean Turbo and new ring installed, I took egr out and cleaned it and passages, curious for answers, thanks in advance Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 9, 2010 Share Posted October 9, 2010 exhaust back pressure is 49 maxed Your EP reading is too high. Specification is no more than 35 PSI @ 3800 RPM. Excessive back pressure will cause low boost most noticeable under high load conditions. I see that you checked the exhaust and turbo... (I would inspect the exhaust for damage, VISUALLY inspect the catalytic converter for plugged or broken substrate and perform the VVT test.) Did you drop drop the exhaust and drive it while monitoring EP to see if it was lower? Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted October 9, 2010 Share Posted October 9, 2010 When you do the VVT test, pay close attention to the "shoulders" of the steps.... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 9, 2010 Share Posted October 9, 2010 Still thinking here... we had a 5.4L truck with low power that had a bad muffler causing high back pressure. I don't remember hearing if anything was in it though. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted October 9, 2010 Share Posted October 9, 2010 One of the key things going on is the intermittent nature of the concern. If there is something moving around inside the cat or the muffler, I would expect a rattle when I caress it with a rubber mallet. Now... Are these readings being captured when the "concern" is present or when things "appear" to be running good. At face value, this would be an ideal situation for the VDR. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 9, 2010 Share Posted October 9, 2010 One of the key things going on is the intermittent nature of the concern. If there is something moving around inside the cat or the muffler, I would expect a rattle when I caress it with a rubber mallet. Funny thing about loose substrate that is turned around sideways and wedged in the housing blocking the outlet or little bits of substrate that are stuck in the holes on the muffler, there won't be much sound other than the mallet hitting the steel. Been there, been screwed by both situations... once. None the less a good suggestion. This brings up another idea. Is there any history of a cat failure? It may have a good cat in it now however a previously failed cat could have left behind some "litter." (Shameless pun intended) Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted October 9, 2010 Share Posted October 9, 2010 Sadly, you are correct about the "wedged" part. And, considering the alternator thread, where do we draw the line with diagnosis? Do we have the right to make expensive guesses to avoid a diagnosis that has a better than even chance of being the same as our guess? What I see as something that drives us.... Cambodian Tire - whoops, I really meant "Canadian Tire".. Pep Boys... all the big box creatures practice something so close to "bait and switch" that it clouds the line. They quote low, get the wheels off your car and drop the hammer. The SA that phones the customer is under pressure that you and I cannot imagine. The consummate salesweasel, he will quote fantastic warranty offerings on brake pads.... spark plugs... ball joints.... all manner of parts. The labour will NOT be covered. In the case of brake pads, you will need rotors, hoses, a brake flush, an ABS service and hardware. None of this is covered under the warranty. Fuck... people are sheep... Dealerships quote high. It is driven into us that we need to "fix it right the first time". The only way to do that is to replace parts that are even remotely suspect. Big box stores operate on the "Barnum and Bailey" principal.... "There's one born every minute". Big box stores get to blame you and me for their inability to repair your car... (research "right to repair" stuff). Fuck... did I digress again? Sad old men with opinionated old lives.... Who needs 'em when you have someone like me? Quote Link to comment Share on other sites More sharing options...
rawb Posted October 10, 2010 Author Share Posted October 10, 2010 thanks for all the input guys , I did drop the cat and actually inserted a long tool inside to see if substrate was loose, however it was solid, no noise either with the love of a rubber hammer, sitting in neutral at 3800 rpm , ebp is about 32 - 34 psi, replaced map hose and cleaned fitting, performed vvt test and it looked good as well.the reading of 49 psi was on road test fully loaded up hill, ebpa, this thing drives great all the time for me...customer needed vehicle back , i guess if i have to i will road test with trailer on... duplicate customers concern first.... Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted October 10, 2010 Share Posted October 10, 2010 thanks for all the input guys , I did drop the cat and actually inserted a long tool inside to see if substrate was loose, however it was solid, no noise either with the love of a rubber hammer, sitting in neutral at 3800 rpm , ebp is about 32 - 34 psi, replaced map hose and cleaned fitting, performed vvt test and it looked good as well.the reading of 49 psi was on road test fully loaded up hill, ebpa, this thing drives great all the time for me...customer needed vehicle back , i guess if i have to i will road test with trailer on... duplicate customers concern first.... What year is this thing? Quote Link to comment Share on other sites More sharing options...
rawb Posted October 10, 2010 Author Share Posted October 10, 2010 06 f350 Quote Link to comment Share on other sites More sharing options...
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