Truth or Fictional

**Naf** · 05-06-2007, 11:00 AM

Hi all,

I have a serious issue with my Tahoe...I did basic bolt ons, Long headers, 3" collector pipe on stock muffler, Air aid intake pipe, Air hog air filter, taylor wires, Bosche Platinum +4 plugs, earth kit, and Apexi super ground stabilizer...

Now i hit the dyno and i only got 250hp and 300ftlb but my A/f was 12.0 the whole way which i noticed dropped my torque curve...

I would like to know if there is any truth to the LQ9 intake manifold and throttlebody being bigger capacity then the LM7 intake manifold and throttle body?

I will be installin SLP 1.85 rocker arms, but i still need more air supply...

I am tryin to squeeze the most hp on the stock tune...I have the fule, i just need the AIR...

**SeVeReDiStOrTiOn** · 05-09-2007, 10:14 PM

You can change your a/f by getting a tune(which is why it's off)...which you should have with the headers anyway. The lq9 manifold/Tb is the same as the lm7 and flows more then enough for your mods....Shaner also ports the truck TB's if you want to open her up some more http://s2performance.net/

**Wesman** · 05-10-2007, 08:05 AM

Its not the lack of intake air thats making it run rich, its your tune. The tune controls how much fuel is added for the amount of incoming air, if you increase the air coming in, the fuel will increase as well.

What you need to do it get the PCM tuned for the proper A/F ratio. While your at it, ditch those Bosch Platinum +4 plugs. Bosch plugs in general don't work well in Domestic ars for some reason, I've never seen one run quite right with those in it. And the 4 prong ground electrodes don't help performance at all, electricity takes the shortest path, not all 4 paths. So its only actually firing against one of those prongs at a time. Get some AC Delco Iridium or NGK Iridium IX plugs instead (they are the same, NGK makes them for AC Delco). The truck should run better as soon as you put them in.

New plugs and a custom tune should give you a nice bump in power and fix your A/F issues.

**SeVeReDiStOrTiOn** · 05-10-2007, 02:02 PM

^^^

**Black02TA** · 05-11-2007, 06:12 AM

Originally Posted by Wesman

And the 4 prong ground electrodes don't help performance at all, electricity takes the shortest path, not all 4 paths.

path of least resistance is what i am sure you meant... but still doesnt take all 4 paths

**Wesman** · 05-11-2007, 08:52 AM

Originally Posted by Black02TA

path of least resistance is what i am sure you meant... but still doesnt take all 4 paths

Yep, thats what I meant. Like you said, still only one path though.

**Naf** · 05-14-2007, 09:46 AM

Mind you once i installed those bosch plugs, my idle got better, and my fuel economy got much better...and with economy comes power

I found the tank was filled with the wrong fuel...bloody 90 rather then my usual 95...That would trigger the knock which would pull the timin which would lead to rich mixtures...Again i was runnin stock tune with stock block setup...I should be close to lean, not rich...

I am going to upgrade the intake tube to a 4" with a ported 80mm bbk thottle-body, i am also installin a 3" intermediate pipe, new muffler to the stock rear pipes with resonator to keep her quiet...

Should increase my torque, and hp big time...

Your thoughts guys...

**vetteemt** · 05-16-2007, 08:36 AM

From working on my Camaro SS and my 02 Silverado it would really like a tune. The factory computer is setup to adjust to normal changes (air temp, load, air pressure etc..) that the engine will experience in stock form. Once you start changing the airflow through the engine i.e. intake, headers, etc, the factory computer will be able to change enough to allow the vehicle to run, but not at its best of it abilities. Retuning the computer gives it better base maps to start from, so it will not have to adjust that much, it will be right on.

**Naf** · 05-16-2007, 09:28 AM

I agree with your statement, if one was to modify the factory setup, a tune would be in order...

However looking at my run, i am rich, so unless gas is expensive, which it aint for me, a little more fuel aint hurting nuttin...Its keepin the pistons cool, there is not detonation. and the black smoke doesnt start puffin till i hit 4000rpm

Plus i want to finish up all my mods before i tune for numbers...

Will let you all know the outcome once that happens...Parts are in the mail regretfully...

Have new rocker arms with needle bearins, and the previously mentions mods to go...

**SeVeReDiStOrTiOn** · 05-16-2007, 04:19 PM

Originally Posted by Naf

Mind you once i installed those bosch plugs, my idle got better, and my fuel economy got much better...and with economy comes power

I found the tank was filled with the wrong fuel...bloody 90 rather then my usual 95...That would trigger the knock which would pull the timin which would lead to rich mixtures...Again i was runnin stock tune with stock block setup...I should be close to lean, not rich...

I am going to upgrade the intake tube to a 4" with a ported 80mm bbk thottle-body, i am also installin a 3" intermediate pipe, new muffler to the stock rear pipes with resonator to keep her quiet...

Should increase my torque, and hp big time...

Your thoughts guys...

Your idle probably got better because your old plugs were over due for a change...could have also had some fouling. Bosch plugs are junk...

All we have here in cali is 91 octane and i don't have any knock retard on my 5.3...my timing is advanced a good amount also.

Again...you're running rich because of the headers.

Originally Posted by Naf

I agree with your statement, if one was to modify the factory setup, a tune would be in order...

However looking at my run, i am rich, so unless gas is expensive, which it aint for me, a little more fuel aint hurting nuttin...Its keepin the pistons cool, there is not detonation. and the black smoke doesnt start puffin till i hit 4000rpm

Plus i want to finish up all my mods before i tune for numbers...

Will let you all know the outcome once that happens...Parts are in the mail regretfully...

Have new rocker arms with needle bearins, and the previously mentions mods to go...

Running too rich will burn up the cats...if you have cats.

**Naf** · 05-16-2007, 10:11 PM

I stand by the Bosch...I installed them in my now scrapped vehicle, and again the idle smoothed out and the power was felt throughout the rev count...and she barely had 7500kms when i scrapped her...

I had MSD coils and Morosso wires with the Bosch on my LS1..I also added extra earthing which really helped her out too....You will be surprised how much you can make with simple thing like earthing it correctly.

But alas, we are all different with different approached to the same goal...Gettin infront of the opponent. There is no right and wrong, there is just the joy of our acheivements...

Thanx guys for your inputs, and again i will keep you posted to my progress

**RandyW** · 05-18-2007, 03:38 AM

You got good advice, which you asked for, but you aren't listening, why bother? If you are running rich you are losing major horsepower and bearing and ring life. Put a good set of AC plugs in there and get a tune, you will see big h.p. improvements, or keep doing what your doing and complain about the power level.