4.8 to 5.3 swap expert help needed..

I have a 1999 silverado shortbed extended cab 4x4 with the stock 4.8, i want to swap in a 5.3 as PAINLESS as possible, meaning, without buying anymore than i have to for the swap besides the 5.3 engine. ok, being a 1999 model truck, do i need to find a 1999 model 5.3 or what all year 5.3's will go right in with no trouble? I know the newest 5.3's is out because they have the active fuel management, so what year 5.3 do i need to look for and does it matter if it is in a tahoe or whatever or does it need to come from a truck also? Next, what other things will i need from the donor truck besides the 5.3 engine? Can i just get the engine computer from any 5.3 truck or does it need to have come with the identical options my truck has?
Thanks all!

99-06 5.3s will work fine. No computer is needed. You'll have to get your PCM tuned to work with it.

cool, can i just get the 5.3 pcm so i dont have to mess with tuning my 4.8 pcm? also, does the 5.3 have to come from a 4x4 also or can it be any 5.3?

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Originally Posted by mopower440

cool, can i just get the 5.3 pcm so i dont have to mess with tuning my 4.8 pcm?

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You'll have to have one tuned either way. With the 5.3 and your 4.8 PCM, it won't run great. With the 5.3 PCM and your truck, you'll need VATS turned off in the computer.

*cough* 6.0 *cough*

what is VATS? how easy is it to have my PCM tuned for the 5.3 ? It isnt going to be one of those deals where i swap in the new engine and then cant get the pcm straightened out for it and then screwed is it? Is this a pretty common and easy swap?

Vehicle Anti Theft System. And it is very easy. Pick up the phone and call any reputable tuner. Nelson, Blackbear, Wheatly... They can send you a PCM in the mail that will work for you. It is literally a unplug, pull out, put in, plug in swap.

cool, so anything else needed besides the complete engine? will my 4.8 accesories work like the alt, ac compressor and all that? will any 5.3 work or does it have to also come from a 4 wheel drive?

Take all your acessories, intake and other parts and swap them to the new engine. Check the PN on the fuel injectors and if they are the same keep the ones that came from your 4.8L on the intake otherwise put the new engine's injectors on your intake. Be sure to give the PN of the injector to the tuner so he can adjust your tune accordingly. Swap all your engine sensors to the new one since you know the history of them.

5.3 is to 4.8 as 350 is to 305. Drop in replacement.

so all i need is the 5.3 engine? I can use my wiring harness and all accesories and all, ? also, again, the truck is a 1999 and your positive any 5.3 from 1999-07 is fine? Just wondering cause the junkyards around here list them as year specific.Thanks again all

Correct. Any from 99-06. Half of the 07s are Gen IV and require more work. You can tell by the heads and intake.

ok thanks, now, i see that HP and torque went up through the years from 1999-06, was that in the engine designs or the fuel injection? if it was changes in the engine, what year 5.3 should i look for to get more HP and torque?

I haven't seen drastic changes other than the heads changed from Casteks to 862s at some point. 862 heads are what you want.

The power differences came from the tuning.

if the crank sensor behind the starter is light grey then it is a gen4 and will not work with your PCM without buying a pulse converter box, a couple hundred more dollars added to the swap.

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Originally Posted by RedHeartbeat

if the crank sensor behind the starter is light grey then it is a gen4 and will not work with your PCM without buying a pulse converter box, a couple hundred more dollars added to the swap.

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Or if it has a 4bolt TB, or if it has 243 or 799 heads.

If you were to get the PCM from a 99-02 5.3, you don't have to have the VATS turned off. You just need to do the security relearn procedure.
Not a good chance that the PCM will have all the exact options you need like gear ratio, tire size, etc. though. So you will need a retune anyway. Best bet is to send your existing PCM in and get it swapped to 5.3 config.

also, make sure to reuse your cable throttle body.




ps - this topic's been covered eleventybillion times on here. just click around with the search box & you should be able to find just about every question you've asked so far

ok, after reading about the crank sensor and heads and all, let me ask it a different way, in order to drop in a 5.3 without anything else besides a pcm retune, what year model 5.3's will work, meaning i dont have to worry about checking head numbers or crank sensor colors or any of that..1999 only or? Truck is a 1999

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Originally Posted by mopower440

ok, after reading about the crank sensor and heads and all, let me ask it a different way, in order to drop in a 5.3 without anything else besides a pcm retune, what year model 5.3's will work, meaning i dont have to worry about checking head numbers or crank sensor colors or any of that..1999 only or? Truck is a 1999

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Any from 99-06... like stated.

so you mean that 1999-06 wont require the convertor for the crank sensor or different throttle body or any of the mess mentioned above?

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Originally Posted by mopower440

so you mean that 1999-06 wont require the convertor for the crank sensor or different throttle body or any of the mess mentioned above?

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Yes... For the third time. There is no other way to answer this question, regardless of how you ask it.

Another child left behind. Honestly if you don't have the brains to figure it out, take your truck to someone that does.

now now... we can't hurt peoples' feelings. everybody has to have an equal opportunity


















...to fall on their face

man, sorry all, i sure didnt mean to make anyone mad, was just confused because first was said any 99-06 is a direct swap, then someone chimed in saying i needed to check head numbers and the TB and crank sensor, so i didnt know, again, sorry, did not intend to make anyone mad.

07 is when the stuff youre worried about started changing

any 4.8 or 5.3 from 99-06 is directly interchangeable

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Originally Posted by mopower440

man, sorry all, i sure didnt mean to make anyone mad, was just confused because first was said any 99-06 is a direct swap, then someone chimed in saying i needed to check head numbers and the TB and crank sensor, so i didnt know, again, sorry, did not intend to make anyone mad.

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The thing is, all this information has been posted over and over and over and over again. Sometimes new ppl come on here and ask these types of questions when 30 seconds of searching will answer all your questions. In fact, there are special threads called stickies that are "stuck" to the top of forum sections for these exact situations. Dont get offended by some of our members, patience is not their best quality.