99 Vortec 5.7 tuning

Hi All,

I just bought a 1999 tahoe for 1200 bucks. It runs and drives and everything but the oil pressure is pretty bad at the 550 RPM idle in gear. At 650 it picks up a few PSI. I am thinking of licensing it using my HPT and upping the idle. In addition to that I am wondering if there is anything i can do to give it some more oomph. Ive only ever messed with the L67 engines in the wbodies. If i am going to license it i wouldnt mind seeing a bit more power out of it.

A few questions i have For this specific application:


1. Can you tune ignition timing using HPT? Since the truck runs on 87, could advancing the timing with some 93 octane boost performance.
2. Could the truck conceivably be tuned to run on e85? ( i know this isnt neccesarily the forum for it, but would the fuel lines etc handle the ethanol?)
3. is it reasonable to think that i could tune for a cam? When i rebuild the engine next year i want to add a bit more pep.

Quote:

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Originally Posted by 04lss

Hi All,

I just bought a 1999 tahoe for 1200 bucks. It runs and drives and everything but the oil pressure is pretty bad at the 550 RPM idle in gear. At 650 it picks up a few PSI. I am thinking of licensing it using my HPT and upping the idle. In addition to that I am wondering if there is anything i can do to give it some more oomph. Ive only ever messed with the L67 engines in the wbodies. If i am going to license it i wouldnt mind seeing a bit more power out of it.

A few questions i have For this specific application:


1. Can you tune ignition timing using HPT? Since the truck runs on 87, could advancing the timing with some 93 octane boost performance.
2. Could the truck conceivably be tuned to run on e85? ( i know this isnt neccesarily the forum for it, but would the fuel lines etc handle the ethanol?)
3. is it reasonable to think that i could tune for a cam? When i rebuild the engine next year i want to add a bit more pep.

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1. You can look over the tuning options with a stock file from the database
2.Probably but you wont have enought flow flow with stock inectors
3 Yes , depending on #1

I?m fairly certain that pcm isn?t supported, it the black one with 4 connectors? I believe you have to change to the newer express van pcm for that engine that uses two connectors to tune those

98-99 black box pcms are supported. 96-97 black box pcms aren't. Some people will upgrade them to a 0411, not because lack of support, but for other reasons.

Im running a 98 tahoe PCM swaped into a 1997 silverado 5.7L L31 vortec with only upgrade being a ZZ4 cam.

You can pick up ALOT from the stock tune. First thing i always do is disable torque management and get the trans shifting nice then id go after tuning the fuel tables.

Its pretty difficult to tune the mass airflow sensor on these because there is no way to disable dynamic airflow (thats your VE table) so it runs in MAF only. So i would start by getting the open loop speed density fueling right (you will be stuck in the secondary VE table if you fail the MAF but its really no big deal).

After all that go after ignition timing. A typical vortec head 350 with around 9-10:1 compression likes 32 degrees of timing "all in".

My spark table is setup like this from 80 kPa MAP and up.

1600 RPM: 24*
2000 RPM: 26*
2400 RPM: 28*
2800-6000 RPM: 30*

Also AFR advance is set up to add another 2 degrees of timing once im in power enrichment which comes in at 40% throttle.

I should point out im only running 93 octane but ive had no knock retard like this pulling 8,000 pounds of trailer

Quote:

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Originally Posted by 2xLS1

98-99 black box pcms are supported. 96-97 black box pcms aren't. Some people will upgrade them to a 0411, not because lack of support, but for other reasons.

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Is there anything else required to swap to the 0411 PCM? Is it plug and play other than updating the tuen? TIA

Completely repinning the connectors for starters.

I have a 98 stock 4x4 2 door Tahoe (135K miles), should I be able to tune it without updating to a 411 PCM? That would be my preference as I don?t plan on doing in mods other than a less restrictive muffler. I have pulled the tune out and it will let me do some data logging, although it was limited. Does someone have a good data log setup that would be good for this PCM? Thanks in advance. R

Here's a copy of the current tune and a log file.