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No power towing up hills


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I'm towing about 9k lb and truck slows down to 35-40 mph going up 6% grades. I went up the same hills in October at 55-60 mph with power to spare. Then I didn't drive it until March. I installed a new heater core (which has no bearing on this problem), a new crankshaft sensor, and a Fuel Boss pump with a new Airtex pump as a backup. I also washed my AME air filter. After doing all of this I did a test run towing a car on a flatbed trailer from Ontario, CA to San Diego with no problems, 60 mph all the way. My fuel pressure is 18-19 lbs @ idle and 20-21lbs @ 1800 rpm and above. my boost pressure is 26 psi @ 2800rpm and drops as the rpms go down. Any thoughts?

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If you have a lack of power and no smoke the only thing that would cause it is lack of fuel. How long has it been since the fuel filter was changed?

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Fuel filter was changed on 9-18-11 at 69,444 mi. It now has 74,523 mi. The boost PSI is the same as when it runs good and I checked the clamps not to long ago. There is no check engine light on but I just put my Matco Tool code reader on and it showed p0336, crankshaft position sensor range/performance, pending. In March I replaced that sensor due to a complet failure. The engine would start,back out of the driveway, check engine light came on and the engine stops. The code then was for a bad crank sensor. I replaced the sensor, cleared the code and have driven over 1k mi so the monitors would have reset if there were no more problems. I think that either it's a bad sensor from Nappa, or a wire/connector problem. I'll try to get to it this week. I'll clear the pending code, drive it for a while and see what pops up. Thanks for the help. I wouldn't have put the code reader on with no check engine light.:doh:

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  • 2 months later...
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UP DATE: I still don't have full power. I checked the connection for the crank sensor, and it's OK. I found the data link connector for the Edge EZ unplugged and the grounds at both batteries a little loose. I took it out on a short camping/fishing trip this weekend and no power going up hills. The peddle is to the floor and barely over 60 mph. I think the air filter may be bad, being it's washable and it has been wash twice. I read some were that the element can brake down after being washed and restrict the air volume. I'm going to put the stock air filter back on and see how it goes. One more thing, there are no new codes. l

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If your reader can see live data from the engine drive it and see what your MAP sensor is showing. If the MAP sensor has stuck or not working correctly it may not cause a fault but not be seeing the boost pressure, if the MAP sensor doesn't see it the ECM won't give the engine any more fuel.

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I changed the fuel filter the day before I went camping, 8-8-2013. My code reader does read live data and I have live data read out from 3 years ago that I can compare.

That would be where I would start. With your fuel pressure being good and no excessive smoke and good boost pressure its the only thing I can think of to cause it. Sent from my DROID BIONIC using Tapatalk 2
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Thanks for the feed back guys. MAP pressure is 14.65 psi @ idle and 31.47 psi on a hill wide open and not towing. I opened the EZ box and it was as clean as new. The exhaust is 4" and straight through and I don't think the turbo would spool up if it was blocked. The only time I notice the lack of power is when I'm towing. The truck runs great when empty. :banghead:

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Thanks for the feed back guys. MAP pressure is 14.65 psi @ idle and 31.47 psi on a hill wide open and not towing. I opened the EZ box and it was as clean as new. The exhaust is 4" and straight through and I don't think the turbo would spool up if it was blocked. The only time I notice the lack of power is when I'm towing. The truck runs great when empty. :banghead:

14psi at idle...? HOLY SHIPWRECK BATMAN!!!!!! i idle at 0 and on setting 5 can bump 30psi before defuel kicks in... i think your map sensor is jacked? (unless you put a typo in?) this makes sense that you have poor towing power, when hitched up the ecm is already seeing high psi so it thinks its fueling properly but in reality it isnt and thus no towing power.
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No typo. This is live data. the boost gauge on the A post reads 0 at idle and 26-28 wot. The live data only comes in metric so I have to convert it. The data came in at 101 kPa (14.65 psi) engine off or at idle, this is close to atmospheric pressure and the same base reading I had 3 years ago. Now that said, the wot reading of 217 kPa (31.37psi) is higher than the base reading of 200 kPa (29.0 psi) so it looks like my boost gauge is of by at lest 3psi. At what pressure does defueling take place? NOTE: As the rpms go down so does the boost pressure and still no power so would the defueling problem correct itself until the next over boost?

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I would get a new sensor. Especially since it doesn't match the gauge. Unless the EZ is jacked... I think the EZ plugs into the map sensor. I would either try a new map sensor or unplug the EZ and see if there is any change.

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That's what I'm starting to think all so. If I unplug the EZ the check engine light will come on setting a code P0234 engine over boost condition? The description of the MAP sensor on page 14-103 states "Engine protection is used to derate (drop power off) the engine if turbocharger pressure becomes to high." I can't find at what psi is to high. I might have to take out the boost elbow, be fore it was put in max boost was 18psi.

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Since I removed my banks tuner I have a similar issue. The best way I can get any power is to roll into the throttle. If I hammer it over boosts and the power is weak. I have a banks waste gate actuator and it opens at near 33 or 34 pounds. If I roll into it and keep the boost down, I have better power. Since my gauges went with the Banks I am just guessing at boost pressures.

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