Hi everyone this is my first post in here.

I have a 2008 Chevy Avalanche with 5.3 and I was happy with it till the day it decided to blow(2019).

I was looking for more power so I purchased a 6.0 L engine taken from 2013 Caprice. Engine has compression issues so I did a rebuild my self and installed an aftermarket camshaft (BTR stage 3) and don’t ask me why I chose this one because I really don’t know . Pushrods (7.400” x 080 WALL), double springs, chain and timing gear, high performance oil pump, Air intake, Ls3 intake manifold and injectors and Y pipe (It’s illegal to modify exhaust in my country) this is almost it.

Since the first start of the engine till today (September 2019 - now), everyday I hate the car more, even though it was the best thing in my life.

I didn’t gain any power, not even factory power, engine has a lot of problems. It will not start immediately and sometimes it will not start at all (cranks like it has low voltage). It will drive normally but when I’m flooring it will struggle and stall (backfires through intake manifold I think) but if I was gentle it would struggle less but still backfires. I can’t do an acceleration from zero (means no burnout)

Bad brakes (hard pedal)/ traction - stability warning

Smells like unburnd fuel

I have 3 codes ( P0336 P0335 P0300)

Changed crankshaft position sensor twice, then looked for wiring issues and found out that camshaft sensor wires were naked , after fixing the problem I didn’t get any codes except P0300 but all the symptoms are still happening all the time)

Fuel pressure checked

Checked for vacuum leaks

Checked compression (140 - 170 psi)

Changed sparks plugs ans wires

All my local mechanics don’t know what’s wrong. At this point the last engine has more power than this one , If anyone can help please let me know what should I do.

Thanks

 

The obvious first question is why you have not listed how it was tuned for the new engine. The next question would be why you have not listed verifying that the cam is installed correctly. Way too much missing info to give you any real answers yet.

 

I’m not the one who tuned it + I know nothing about tuning

2# I mean what could go wrong when installing the cam?

 

1) If it's not tuned for that cam, it's not going to run correctly at all. It sounds like you installed a cam without having it tuned. That is absolutely NOT going to work. 2) Camshafts can sometimes be manufactured incorrectly. 9 times out of 10, you can install it dot to dot and it will be fine, but then there's that 1 time the cam was ground wrong and installing it dot to dot will screw everything up.

 

It’s tuned for the cam for sure.
what do you suggest to do?
change the cam? no other suggestions?

 

Can’t possibly be tuned correctly,(engine hasn’t ran correctly) Brakes aren’t going to work correctly because you have lost most of the vacuum your engine can produce,By installing the BTR stage 3 cam. Exhaust is going to limit your engine. Post up the rest of your combination injectors, throttle body, valve springs, lifters. Did you measure the pushrod length to determine you needed the length you selected.

 

You need to verify that the cam is installed correctly according to the can card, and is not a tooth off. I suspect the cam timing is off. If the car was tuned for an incorrectly installed cam, that means it was tuned incorrectly. The fact that it cranks slow is one indication valve timing is off, the strong smell of fuel is another, and backfiring thru the intake is another. Are your headers/exhaust manifolds hotter than normal? It's been my experience that when an engine has a cam installed incorrectly, power will be way down. Best of luck....

 

First... if its backfiring.... its NOT tuned.... CORRECTLY..... no way....

Second... which BTR stage 3 cam are you talking about?? the truck stage 3? or the normal stage 3? BIG difference..
If you have decided to put the standard BTR stage 3 in a 7000 lb truck.... then you will never be happy with it.....
Even the Truck stage 3 is kinda big with stock stall converter with a 4L60E in my opinon..

Third..... it sounds like your timing is off like others have said.....

 

You need to post the tune and a data log as a start.

There are so many different things that can cause these problems, without more information and what has been checked. Everyone will just be guess, which is what most people do anyway.

 

First of all, thank you all
I’m sure that the tuner tuned it for this cam because I told him all needed informations (unless he don’t know what to do)
I contacted with BTR to make sure and they said it must be dot to dot. But it could be one or two teeth off (everything is possible due to installation)
I didn’t measure the length of pushrods (it was tunner suggestion)
my plan was to upgrade TB and Headers but I must fix the problem first.
I’m waiting for the tunner to send the chart

 

Tune must be way off and the could be a laundry list of small issues creating a massive problem with how it runs. You said you did all the work yourself? How does the car sound mechanically while running. Is the valvetrain very loud with ticking noises? Slow cranking like it has low voltage with a known good battery, bad ground to the heads/block or the ignition timing is fighting itself. Id check for clean grounds as an easy fix which can also attribute to the crank sensor codes.

The compression from 140-170 is a bit wide of a swing, which cylinders were low and which ones were higher? They should be pretty close to each other, unless you left this untouched prior to doing the cam swap knowing it had compression issues from the start..you should've addressed this 1st before doing all else and expecting a healthy running engine.

My last question is the tuner himself. Usually anytime a car comes in for a tune and the tuner asks you about the setup and they perform a tune. If the motor doesn't respond well..usually the tuner would point out various things of concern as to why he cant tune it, the tune isn't complete..its just patched enough to get you home and he would give you a list of things to look into and then bring it back for a reflash. Or the tuner just plugged in basic changes for a typical cam swap and sent you on your way regardless and said nothing then I wouldn't be going back to the same tuner.

Id say check the other easy things you can,especially anything you did yourself that might've been missed or slightly off. Cam timing off a tooth, rockers not fully seated or too tight, bad injectors or o-rings on the injectors, plug wires not fully on or bad coil/wiring. Check everything you touched. Usually its a stupid mistake that causes the most grief.

 

1# 155 psi
2# 150
3# 155
4# 150
5# 140
6# 155
7# 170
8# 155
I hear noises coming from valves/ valve springs but not tapping noises
If you want to hear add me on insta: 3mmar_kha