makoshark

iTrader: (3)

I have a 99 5.3 xcab Z71 truck with about 112,000 miles on it and it seems to be getting tired. I am losing power and gas mileage. I have no interest in buying a new truck, so I thought I would do some changes to my truck. I searched in here and found a few tips, but still haven`t answered all my questions though. This is my daily driver and it`s not a performance truck nor do I offroad in it. I just need some more lowend grunt, not highend horsepower. I also don`t want to do FI. Do I rebuild the 5.3 to get more power out of it or do I put a 6.0 in it? I just purchased a set of 05 LQ9 heads cheap. If I do the 6.0 install, then what can I use from my 5.3 to complete the 6.0. I don`t plan on buying a complete 6.0. Just block, crank and rods and then a new LS6 ported oilpump, timing chain, lifters, cam, arp bolts, eutectic pistons. "042" 200/208 .500/.500 115. That`s the Vinci cam I was looking at. I don`t drive my truck hard, but do a little towing with it. It has 3.73`s in it now, but I need some power. I have a 67 and 69 camaro that I am restoring and I also have a 01 ws.6 trans am that I play with, so money is a concern on this build up. What is your input on my delimna? TIA

therock

iTrader: (2)

Try cleaning your MAF sensor elements and resetting your PCM. Is your air filter new or OK? Have you done a compression check?

makoshark

iTrader: (3)

I just cleaned my K&N filter the other day and cleaned the carbon off the throttle body blade. I have not cleaned the maf though. Truck runs good oil pressure is strong, so I doubt it`s losing compression. I increased my tire size to 285 a while back and that is mainly what killed my power and gas mileage, but it`s starting to drop even more now. I am also experiencing vapor lock as well. Think it needs a new fuel pump. I hate to go through the expense and time of building and installing a new motor, but I NEED more power. The truck never had enough power for me anyway. If there are alternatives to not putting a new motor in, them let`s hear em. I`m all ears at this point.

JERRY2500

Clean the maf, especially after oiling the K&N filter. Cats may be cloged, so you may want to remove or replace them. If your going with a 6.0l your going to need to replace the injectors. 99's have 19# injectors and 2000 and up have 24# injectors. I have a set if you need them. And last but not lease replace the 99 pcm with an 02 pcm and get a custom tune from Nelson Performance or one of the other sponsors.

therock

iTrader: (2)

I agree with the above plus the 02 pcm and Nelson tune.
112k is lots of miles on the cats. I would replace them.

makoshark

iTrader: (3)

What`s the difference between the 99 and the 02 PCM? Are you saying to put that on my 99 with the 5.3 in it?

1slow01Z71

iTrader: (36)

The 02 pcm is just alot better plus a custom tune will help alot. Replace the o2 sensors and cats and you should feel a big difference in performance and mileage.

screamingjimmy

You talked about Vapor-Lock, It would be a good idea to replace your fuel filter which usually causes those symptoms. If that don't do it, you might even be looking at a fuel pump.

TURBHOE

iTrader: (4)

here is some info on the 02 pcm

makoshark

iTrader: (3)

Ok, so I get an 02 computer and have it tuned. I throw the cat in the garbage and fire up my welder and build a dual exhaust. No emissions check in my state. Put something like the air raid intake setup and port the throttle body. Put new O2 sensers on. Already have put a fuel filter on and have already made plans to put a new fuel pump in. Put 24lb injectors on. I don`t really want to deal with headers. I hate them. What about the LQ9 heads I have? Mill them and bolt them to my 5.3 or put them on my T/A or put them on my 69 LS1 camaro? Do I have too many miles to put a cam in?