2004 Tahoe 5.3L Losing Power

[Headrush]

Hello,

I have a 2004 Tahoe 5.3L with 85,000 miles on it and recently it feels like I am losing power when towing light loads (1,000 or slightly more). I added a Volant CAI and larger tires, 285x75x17 on stock rims.

When recently towing on a flat surface it wouldn't hold at 70 mph, I was hauling a single place snowmobile trailer with a sled on it and it kept downshifting, very annoying and hard on the tranny. When using tow/haul it didn't make any difference.

I'm stumped, any ideas.....

 

[XXL]

Depending on how much bigger your tires are you are probably going faster than 70 mph, and you changed your gear ratio. maybe try to borrow a set of stock size tires and see with a gps or something.

 

[Headrush]

I ran it with a GPS so the MPH's are about 2-3 higher at 70 mph.

 

[locknload]

I would check your fuel filter and maybe even fuel pressure. If thats ok make sure that your mass air flow sensor is clean, if not you can buy maf cleaner at any auto parts store. If everything checks out ok reinstall your factory air intake, some times the cold air systems just make them run too lean at part throttle. Hope this helps!

 

[Headrush]

^^^

Thanks! I will check and see on the fuel pressure and pump. When we drove out west, hauling an aluminum FLOE 14" enclosed going about 65 mph, I was getting 7 mpg, something just doesn't seem right....

 

[hilinerider]

fuel and air i would look at

 

[M.M. 700]

like stated above, change fuel filter and cleand the MAF.

When I tow with my 04 tahoe with 85,000(or any 1/2 ton truck) miles on it. I put it 3rd (or drive) and put the tow/haul. I Never pull using OverDrive... unless it is a light load on flat ground.

You added bigger tires, so it changed the gear ratio higher. Even without the taller tires they will hunt for gears pulling in over drive and will heat up the tranny.

 

[gonehuntnpowder]

Make sure there isn't a air leak around the air tube into the throttle body on the volant air box. They have a problem with leakage a both sides of that pipe. I have seen lots of problems with the volant box. The pipe doesn't fit well at the throttle body. Is the SES lamp on?

 

[MORSNO]

I had similar symptoms when my fuel pump was dying (01 5.3L). The truck ran great empty, but as soon as it had a load it would loose power. When my mechanic tested the fuel pressure, there was just enough for the engine to run. He said it was amazing that the injectors were still operating on all cylinders.

 

[Headrush]

Thanks guys. I took off the CAI tonight and am going to drive it on a business road trip tomorrow and see how it does. I looked at the filter from the CAI and it seemed really clean for having it on for 7 months.

Maybe the fit wasn't right as suggested above. Also, no error codes have kicked out.

I assume the fuel pump isn't a cheap or easy replacement - any ideas on how much?

 

[MORSNO]

I assume the fuel pump isn't a cheap or easy replacement - any ideas on how much?

I had it done by a local mechanic for half of what the dealer quoted (around $400).

 

[97exc]

I have an 01 5.3 Tahoe, changing the fuel filter after 100,000 miles (should be done every 30k or so) helped a bit on mine. Do you notice any longer cranking times or difficulty starting when lower on fuel? Could be signs of fuel pump/pressure issue. Also agree with towing in 3rd, reduces the hunting and constant shift changes.

Another possibility: I had similar loss of power symptoms when my alternator was failing. I first noticed my lights dimming when it would downshift uphill. Progressively got worse until it finally quit about 6 months later. Not sure why alternator would affect engine power (spark output maybe??) but it sure drove better with the new one.

 

[Headrush]

I drove it today with the stock intake on and it made a huge difference. I was not towing anything, but it didn't downshift as it did with the CAI and the MPG's seemed a little better (+1).

I need to hook up the trailer and see, but it feels like it has some power back - I haven't done an alternator yet as it doesn't seem like it needs it, but I am sure it's coming with 85k on it.

 

[Insaneboltrounder/sjohns]

Ive heard the valves in the gm are garbage and go bad fast

 

[M.M. 700]

I drove it today with the stock intake on and it made a huge difference. I was not towing anything, but it didn't downshift as it did with the CAI and the MPG's seemed a little better (+1).

I need to hook up the trailer and see, but it feels like it has some power back - I haven't done an alternator yet as it doesn't seem like it needs it, but I am sure it's coming with 85k on it.

If you call a chevy dealer and ask how much a new alternator cost's, make sure you are on the chitter or wearing a diaper cuz you will chit yourself....I did just a lil bit.

 

[Headrush]

Well, the drama continues. I woke up this morning and went to work and the garage stunk like gas really bad - I checked the gas cans and sled and no gas odor over there, but it was strong by the passenger side of the tahoe.

Any ideas......

 

[snengineer]

Blocked fuel filter....I had similar symptoms on my gmc truck, took the filter off and I could not even blow compressed air through it. Darn near ruined my fuel pump....change the fuel filter or at least check to see if its plugged up.

 

[Headrush]

^^

Thank you - is there an easy way to do that?

 

[locknload]

As far as your fuel smell if you dont see any specific leaks under the vehicle check the fuel pressure regulator, this is on the fuel rail on top of the motor. Unplug the vacuum hose from the regulator and see if any gas comes out of the hose or the regulator, if it does then the regulator is leaking and you need to replace it- very simple procedure. Some times I have had to start the vehicle and let it run with the vac hose off and wait a few minutes before it started to leak. Hope this helps. Also make sure your fuel cap is on tight!

 

[prairie poo]

^^

Thank you - is there an easy way to do that?

Yep, seek professional help!