losing power

[98z-28]

I have a 01 silverado 2500 h/d 6lt 4x4 with auto trans.This truck loses power when under strain like going up a hill not towing or hauling.I have replaced the T.P.S sensor,mass airflow sensor fuel pump&regulator all filters,All o/2 sensors.Everything me and my friends could possibly think of we have tryed.I am at wits end as i need this truck to work.Please help if possible.By the way i have had two mechanics tell me they could not fix it.

[j cAT]

Originally Posted by 98z-28

I have a 01 silverado 2500 h/d 6lt 4x4 with auto trans.This truck loses power when under strain like going up a hill not towing or hauling.I have replaced the T.P.S sensor,mass airflow sensor fuel pump&regulator all filters,All o/2 sensors.Everything me and my friends could possibly think of we have tryed.I am at wits end as i need this truck to work.Please help if possible.By the way i have had two mechanics tell me they could not fix it.

remove the upstream O2 sensors then go for a test drive...with the sensors removed from the exhaust the problem is gone or better then the cat converter/s are plugged....or muffler etc...

[chevy393]

i just recently fixed a similar problem in my 00 5.3L silverado, if i gave it 100% throttle or going up a hill it barely moved but at normal accelerate ( 1/3 throttle) didnt seem bad or anythign was wrong, well it ended up being my knock sensors, i replaced both of them, boom 100% back to normal, not saying this is ur problem but it was my power loss problem, do u have check engine light on at all or no? and im not sayin go do huge ass burnouts but like start powerbraking ur truck and see if u still notice the power loss, thats were i noticed mine the most, i couldnt turn bald 29in tires over in the mud, put new knock sensors in and i turned my 35x12.50s over on dry pavement in a sec, so theres my 2 cents weather it helps or not idk lol, well good luck man

[dal69]

I have a 2001 2500HD 4x4 w/95k. I had a problem when towing a 8k trailer up a 6% grade. Truck did not seem to respond to acceleration after about 1/3 throttle. I changed plugs (ac-delco) and inline fuel filter both helped a bit but truck still doesn't seem to have the power it should. Did you have an opportunity or plan to replace knock sensors as suggested by poster? If so how did it work out?

[j cAT]

Originally Posted by dal69

I have a 2001 2500HD 4x4 w/95k. I had a problem when towing a 8k trailer up a 6% grade. Truck did not seem to respond to acceleration after about 1/3 throttle. I changed plugs (ac-delco) and inline fuel filter both helped a bit but truck still doesn't seem to have the power it should. Did you have an opportunity or plan to replace knock sensors as suggested by poster? If so how did it work out?

what gear and what speed ???
8k Lbs is a lot of load, and 6% is a steep grade...how does the vehicle run with no loads ?

usually engine washing destroys these Knock sensors,,,the front of engine has a seal that is supposed to keep water.road chemicals out of the sensor area,,,this was not very well installed at factory,,if you wash your engine..and it is not running properly you should get a dtc that will reveal improper ks feedback/signal...as the sensor connections corrode ....

[dal69]

Originally Posted by j cAT

what gear and what speed ???
8k Lbs is a lot of load, and 6% is a steep grade...how does the vehicle run with no loads ?

usually engine washing destroys these Knock sensors,,,the front of engine has a seal that is supposed to keep water.road chemicals out of the sensor area,,,this was not very well installed at factory,,if you wash your engine..and it is not running properly you should get a dtc that will reveal improper ks feedback/signal...as the sensor connections corrode ....

Managed to pull grade @ around 40 mph, truck shifted between 2nd and 3rd. Not near enough power in 3rd and 2nd running close to 4k rpms.

without load truck seems to run fine, I have only driven the truck 8 or 9 times since purchase and only have an 05 Silverado 2 wheel drive to compare.

Is it true that I would get a check engine if sensor was to malfunction?

[j cAT]

Originally Posted by dal69

Managed to pull grade @ around 40 mph, truck shifted between 2nd and 3rd. Not near enough power in 3rd and 2nd running close to 4k rpms.

without load truck seems to run fine, I have only driven the truck 8 or 9 times since purchase and only have an 05 Silverado 2 wheel drive to compare.

Is it true that I would get a check engine if sensor was to malfunction?

the load is quite high ,,,also the air temp makes a big difference..hot air you loose power...also a tranny cooler keeps the engine cooler more power when towing large loads...

if the engine temp increases you will get pinging and the ks will cause the timing to get retarded..

best when towing up these steep grades is to manually down shift to second and keep the rpm's at 3700rpm....

keep an eye on the temp gauge,,,when is rises its time to down shift....

I'm sure you are aware no 4th gear at any time....use tow mode also...

[dal69]

Originally Posted by j cAT

the load is quite high ,,,also the air temp makes a big difference..hot air you loose power...also a tranny cooler keeps the engine cooler more power when towing large loads...

if the engine temp increases you will get pinging and the ks will cause the timing to get retarded..

best when towing up these steep grades is to manually down shift to second and keep the rpm's at 3700rpm....

keep an eye on the temp gauge,,,when is rises its time to down shift....

I'm sure you are aware no 4th gear at any time....use tow mode also...

Ambient temp at time of towing was below 75 degrees motor temp stayed around 210 although tranny temp gauge did register around 230 at 1 point.

Do you know if this truck comes equiped with a tranny cooler.

Another suggestion was to install a HD clutch fan. Would this help in the cooling you referred to.

How about the K&N air supply? Pros/Cons

[jyount]

Originally Posted by dal69

Ambient temp at time of towing was below 75 degrees motor temp stayed around 210 although tranny temp gauge did register around 230 at 1 point.

Do you know if this truck comes equiped with a tranny cooler.

Another suggestion was to install a HD clutch fan. Would this help in the cooling you referred to.

How about the K&N air supply? Pros/Cons

The factory air cleaner is good to more hps than you have, all the k and n will do is sound like a ricer.

you have the tranny cooler in the radiator I think, I don't think it has an external, follow your lines and see..

I think that an add on electric as a pusher in the front would be cheaper than the hd fan clutch and it won't take hp away.
autozone is a dirty word to me, but you can get an electric fan and thermostat setup there for around 75 bucks if I remember right, put one on my s10 so I could take the fan off, that was years ago, so don't remeber for sure now...

If you fan clutch is working it should be fine, make sure it is though.

[j cAT]

Originally Posted by dal69

Ambient temp at time of towing was below 75 degrees motor temp stayed around 210 although tranny temp gauge did register around 230 at 1 point.

Do you know if this truck comes equiped with a tranny cooler.

Another suggestion was to install a HD clutch fan. Would this help in the cooling you referred to.

How about the K&N air supply? Pros/Cons

I believe your vehicle has a cooler,,this tranny cooler though is not that large...get the largest that will fit..it is no that hard to install with the correct fittings/hoses..mount in front of the condenser..this will keep the tranny and engine cooler..then the engine will have more power..

K&N filters are very good and will save money if you keep this vehicle..I have used these for many years on vehicles with well over 100,000mi...my 1996 still has the 1998 K&N in it..these filters are better than paper because they filter air of a higher quantity, over a longer time period...paper is good under normal driving for about 5,ooomi..then the air gets restricted,,,lost power...because the computer will reduce fuel to keep emissions down...

improper maintenence has given these filters a bad reputation,,,properly cleaned every 15-20k mi..they are of value..

your vehicle may have a bad fan clutch this is possible..I would replace with the proper one..not with the heavy duty,,but what was there,should be suffecient..

electric fans are a problem....these can damage your electrical system,,unless you installed a high powered alternator..

also fans are not used at hwy speeds and only come on when a over temp condition occurs..

if the fans are always on ,,they might last about a year..