New Member & i hope someone has some other ideas

[xavier]

Greetings guys

Been using this forum 4ever but I decided to join

tons of info and it really helped me out so I am hoping someone might have some ideas on solving a problem I currently have.

My dad gave me a 1999 yukon that had a blown bottom end and was sitting for a couple of years

I took it and put in a rebuilt engine and tranny

Engine

4 bolt main not 2 bolt
forged Steel crank
Bored out
Everything else is stock

Complete exhaust system front to back including headers

Tranny
Rebuilt ..but tranfer case was old but cleaned

So I started to have this problem with no low end power RPM 1000-3000

Brand new and I can not even smoke the tires and going up hill she has zero power

I had a check engine light telling me she is running lean but I fixed that with the MPFI conversion no check engine light but still no power

recently i did

AEM intake
change to MPFI
change the MAF sensor
check fuel pressure 54 running 61 w key on

brand new cap rotor and wires

After doing all of this she still isnt running her best.

I put her on the dyno and the guy told me 197hp including all the mods I just talked about

here is the video

http://www.facebook.com/profile.php...137&ref=name#!/video/video.php?v=389671949599

Anyways

Is there anything I forgot to check or change ?
Am I just crazy and no one can burn out there 99 yukon ??

trying to understand what to do next

Thanks

 

[95TwinTT]

Still have all the Cat's and O2 sensor's?


Do you know what caused the original engine to fail?

 

[xavier]

Universal Cats and **** it was a custom job

O2 sensor are old off the existing exhaust system

THe original engines bottom end blow out of it ..

there was a hole in the oil pan so I assume the rod shoot out of it

The block was a right off so it is new block re built

 

[crmzendrgone]

What engine are we talking about here?

A little better descriptions of the symptoms please.

Spuddering, bogging down on accel, these types of things?

 

[95TwinTT]

Couple of things to verify…

Any chance the O2 sensors got mixed up while doing the new exhaust?

There are four O2’s, Bank One = Tan with white and Purple with white

Bank two = Tan and Purple

All four use pink and black for +12 and ground.

The schematic shows both the pre Cat and post Cat O2’s with the same color wires

Maybe the wiring harness is short enough that there is no confusion. Mixing up either pre and post or bank one and bank two could cause a lean scenario.

What determined the size of the universal Cat's?

Could be you need a custom tune to make all the non stock items run together in harmony.

A wide band O2 sniffer and a good scan tool could probably narrow it down quickly.

 

[xavier]

It is a 5.7 vortec

it starts and idels great

it is really just when i step on the gas it hesitates for a sec and goes but doesnt seem to have full power

Justin and I have been emailing back and fourth and i am going to get the truck wired up and see if I can figure out what the problem is but I am going to also take a look at the O2 sensors as well ..the guy who did the ehxuast said they where a bit lazy but didnt think they needed to be changed .. but i think EFI live can help

 

[95TwinTT]

Assuming all is correct mechanically and all sensors are good, you are down to fuel map and timing tables.

I’m sure Justin can make it right. Good luck…….

Oh, and welcome to the forum…….

 

[xavier]

So my buddy took my truck for a drive today and came back and said he thinks it is the torque converter.

Anyone else have this problem of no low end power and when u step on the gas it takes a couple of seconds for it to kick in

 

[steamroller]

Bored out
Complete exhaust system front to back with headers
AEM intake


I put her on the dyno and the guy told me 197hp including all the mods I just talked about

Sounds pretty close hp wise to me, they only made 255 to the crank, then you have to take into account drivetrain losses, 15-20%

A bigger bore, exhaust and intake MIGHT equal 20 hp, unless your MPFI upgrade is something other than the upgraded injector set I think it's about right, I have no idea on the hesitation problem

 

[95TwinTT]

I can't imagine how a torque converter could cause your problem.

What did Justin suggest?