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Lack of acceleration


Alpha628

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Hello sirs

I bought a 2007 chevy trailblazer with 29k miles last year from an older gentlemen who seemed to have had it parked for a while. 3 months in the fuel pump failed. My mechanic changed the fuel pump but never cleaned the fuel tank. My acceleration has never been restored. When I press on the gas peddle very lightly it seems to move fine but when I give it gas it doesn't do anything unless I go so far down that it downshifts and even then it sortve roars for no reason not picking up as much speed as it should, but then as I ease my foot off the gas peddle it accelerate faster lol. Almost like the power was being held back by a clogged fuel filter. Never had to climb revs like that to accelerate. Can it be that a dirty fuel tank is clogging my fuel pumps filter again? I got the fuel pump changed last summer. I also changed the spark plugs. Does it matter if it's platinum or iridium? Would that be the cause? Please help I have no check engine light and some misfire codes in memory.

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Im not sure how well it would work, but a few years ago our boat was misfiring and running poorly. We went and bought a can of Sea Foam and it helped. Maybe give that a try.

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Revs smooth as silk hits 6k hard

 

It used to accelerate like pressing the gas peddle when it's on neutral lol. I wish I knew what was wrong. Cold start ups can be rough too car jolts and exhaust starts poppin white smoke for 20 seconds while the car shakes a little until it comes out smooth and steady.

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Generally, if this happens all the time then you should look into exhaust system being restricted somewhere, like catalytic converter or muffler. Have you asked the previous owner about the history of this truck? Was it doing this when the old guy stopped driving it? Was the truck parked in a garage or barn when he stopped driving it? I have seen mouse nests plug a muffler up near completely while the car was parked for the winter.

 

Plugged exhaust will show up as low to no power on wide open throttle, If you slowly lift off the gas pedal it will appear like it is connected in reverse. As you lift, the engine actually begins to pull again. Press back down on throttle, engine slows down (this is done at speeds over 30mph). I have seen a catalytic converter break the honeycomb apart inside, but not appear to be plugged all the time. On a 30 minute drive it would appear to be plugged while leaving a green light, then at the next light be completely normal. You could also hear it rattling around inside the cat at idle. If you can, drop the exhaust after the cat first to make sure the muffler is not plugged,

 

I am surprised you are not getting a code being set. This should be screwing with Oxygen Sensor output voltage and then setting a code. If possible, try holding the gas pedal down as long as you can while driving to see if you force it to set a code. Also, take a good look at the intake side of things too. Air box, pipe from air box to intake, and the air filter.

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I do not know if the fuel filter is only in the fuel tank or not, but, if changing the pump last summer did not fix the symptoms you are speaking of at the time, then it will not likely be the fuel filter in the tank(it is part of the pump assembly and should be new). The filter cannot plug that fast, and still be able to drive the truck.

 

You may have a blocked exhaust. You may also want to take a good look into the air filter assembly. If the truck was parked for months in a rural environment it is not uncommon for mice to nest in various automobile "tunnels". Once had a car towed in that was stored in a barn over the winter, mice had taken up residence in the exhaust system, apparently finding the muffler a nice multi-tenant environment. Could not clean the muffler out, had to replace it. The catalytic converter may be plugged as well, not from animals, but from usage. If the converter or exhaust is causing this, you may be able to verify by seeing if the engine will rev in park when you floor it. Obviously do not hold it down, just see if you can duplicate the loss of power under heavy throttle.

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Every time after leaving it parked for a while when I start it it does this. For 30 seconds and goes away.

 

 

http://youtu.be/quL85mVtsE4

And this is on the highway. My revs climb but not much happens until I put excessive force on the gas peddle in the end. Finally crawled up 3 or 4 mph.

 

 

http://youtu.be/2JW4I7eOL_0

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Yes sir I ended up replacing the fuel pump because my gauge was also acting up. My acceleration is kindve restored but still only under heavy throttle. I have no codes none even in memory car has a fuel air ratio of 1. When I come to a stop The car jolts no change in revs or nothing it jolts and when I realize the brake pedal to move again it jolts again. When I'm coming to a stop I can hear my transmission downshift thru all the gears and when I'm driving it feels like my car is in a higher gear I have to squeeze the revs out of it to get the same acceleration I used to get when I would just think about touching the pedal lol. I literally didn't even have to apply pressure as soon as I touch it it moves and I'm going as fast as I want all under 2k rpm. Can this be my differential?

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