help,no power and poor mpg in my k2500?
 

Any help would be appreciated. Bought this truck from a farmer friend who owned it for the last 16 yrs. It is a 1995 K2500 4x4 with the 5.7 and 4l80 trans. the truck was ordered with 4.10 gears.

now on to the problem..... this truck had a bad miss, no power and poor fuel mileage(8.9 mpg). I took it to two different shops they ran diagnostics and couldnt find the problem at either place, no engine light or stored codes at this time.

I have replaced the following- plugs wires cap and rotor, air filter, fuel filter, fuel pump, pick up coil in the distributor, also checked the gear on the distributor. this got rid of my misfire problem and seemed to help the engine start easier and run smoother. I then removed the cat. converter and installed a thrush welded muffler with new pipe to the factory exit. o2 sensor tested ok. still no power and bad mpg so I replaced the ecm, still no improvement.

I have tried swapping out the egr valve as well as the injectors, I tested the iac valve on the throttle body and cleaned it as well. coolant temp sensor is reading ok under diagnostics at the shop. so I am at a loss on this one. The truck just has no low end power at all and is still getting 9.5 mpg after all the work i have done thus far. I have owned this style truck in the past and theyt always ran well and got decent fuel mileage but this thing is a slug and eating me alive in fuel. any ideas??????

---------- Post added at 01:30 PM ---------- Previous post was at 01:27 PM ----------

Almost forgot I did find a caliper hanging up up front recently and thought I had found my power and mileage issue but I replaced the calipers, rotors, and pads a couple of weeks ago and although it no longer feels like I am towing a trailer it still has no low end and gets 9.5 mpg!!

What size wheels/tires on this beast? You haven't got it all Kiddy-Kared up do ya?

Allan

just a set of mud and snow 265/75/16 tires, talked to the original owner and he says the truck always had plenty of power and averaged 14-16 mpg so at least I know the truck was capable of running right at one time just dont know what to do with it next other than put a for sale sign in the window.

Just some ideas thrown out in the wind for you to chew on.<O:p</O:p
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Check to make darned sure the Electronic Spark bypass wire didn't get left unhooked somewhere along the line. Also, the knock sensor. Without those two, the engine runs at base timing (which by the way, I like to run at 2° instead of 0°) with absolutely no advance, which just kills fuel mileage.<O:p</O:p
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When you replaced the ECM, you did do it by referencing your VIN? Ya can't just throw another ECM in the truck; they are calibrated for 'that particular' truck.<O:p</O:p
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Is this guy throwing any more codes at all?


Is the front lower air dam in place? Truck isn't 'lifted' is it?


Mudders and the 4:10 are gonna be somewhat of a hurdle, but I think you ought to see upwards of 12 for sure.
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Allan<O:p</O:p
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spark wire is hooked up but haven"t checked the knock sensor, is that something I can do or does it have to be tested by a dealer?

no lift on the truck.

I could live with the less than average mpg if the darn thing had any nuts but this thing will barely break a tire loose on snowy roads and forget about it on wet pavement or dry, have never owned a 350 as gutless as this pig!

thanks for your help by the way:)

ecm was ordered by the number on the original unit, and no it still isnt throwing any codes at all, thanks again for the reply any other ideas?

Say, Just had another thought.<O:p</O:p
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Have someone goose the engine while in neutral. Stand back by the exhaust and listen for a restriction.<O:p</O:p
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Maybe we've got a collapsed double-walled pipe somewhere in the mix?<O:p</O:p
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Allan<O:p</O:p
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You need to take the truck to someone that has a 4 or 5 gas analyzer so they can look at emissions. It will show the fuel mixture and how efficient or not efficient it is running.

thanks for the help, I will see who in town might be capable of running the exhaust check for me. but so that I understand, does this help them pinpoint the issue or just verify a rich or lean condition?

Im havein the same pronlem with my 454 im thinkin its runnin super rich