[Z06] 2003 vs. 2004 Z06 Difference?
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
The shocks were the biggest change. I installed them on my 03, there is a difference.
It's hard to prove but owner reports seem to indicate the 04's are a little stronger. It appears some of the fat that GM built into the LSX series of motors was taken out yielding slightly more HP. Many 04 owner's report getting "lean" codes when they install any low restriction intake like Blackwing etc. Where as, on almost every other LSX motor even after installing an intake the AFR's are still rich. If I had to guess this factory tweaking (if true) may have yielded another 5 HP or so. But every little bit helps. Again there is no official confirmation by GM on this, just anecdotal evidence based on what 04 owners report on the forum.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
Tom
It's hard to prove but owner reports seem to indicate the 04's are a little stronger. It appears some of the fat that GM built into the LSX series of motors was taken out yielding slightly more HP. Many 04 owner's report getting "lean" codes when they install any low restriction intake like Blackwing etc. Where as, on almost every other LSX motor even after installing an intake the AFR's are still rich. If I had to guess this factory tweaking (if true) may have yielded another 5 HP or so. But every little bit helps. Again there is no official confirmation by GM on this, just anecdotal evidence based on what 04 owners report on the forum.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
Tom
Last edited by AFVETTE; May 24, 2005 at 07:42 AM.
Advanced
Joined: Oct 2001
Posts: 62
Likes: 0
Originally Posted by Shylor
2004's didn't get an owners video. GM removed an accessory plug under the console. 2004's got better tuned shocks. I can't think of anything else off hand besides the Z16 option.
Melting Slicks
Joined: Apr 2003
Posts: 2,285
Likes: 16
From: Nashville TN
[QUOTE=Craig99SVT]Can you give a little more detail around this plug? Where exactly was it located and what was its function?[/QUOTE
Do you mean the accessory plug located inside the center console? Or the plug in the plug in the footwell near the fuse box?
Do you mean the accessory plug located inside the center console? Or the plug in the plug in the footwell near the fuse box?
Team Owner
Joined: Apr 2001
Posts: 26,794
Likes: 614
From: Elmhurst, IL (West Suburb of Chicago) & Home of MEGA Horsepower
St. Jude Donor '06
I have also heard for a lil tiny extra bit of performance the 04 Zs run slightly leaner from the factory vs 02 and 03 Zs (for a slight if not negligible extra edge in performance)!! 
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Le Mans Master
Joined: Nov 2001
Posts: 6,984
Likes: 0
From: Central Coast CA
I believe the 04 got an updated fuel injection system that it shares with the C6, though it wasn't supposed to provide any more power.
Or the plug in the plug in the footwell near the fuse box?
Le Mans Master
Joined: Feb 1999
Posts: 7,121
Likes: 0
From: Vilano Beach FL
Howdy!
That's the FFS fuel system - it actually started in the mid '03 model year - mine Z is an '03, built in April '03 and it had it.
The downside is the slight revision to the pump and lines (I believe the regulator is _in_ the tank integrated with the pump and no return) means that there's a lower upper limit to fuel delivery with big mods (particularly FI setups).
Though it's not a huge deal to drop the tank and completely redo it (some people use a 97 fuel system, with return, rail mounted FPR, big pump, etc.) Not a hgue expensive relative to everything when you get to those 600+rwhp level though
That's the FFS fuel system - it actually started in the mid '03 model year - mine Z is an '03, built in April '03 and it had it.
The downside is the slight revision to the pump and lines (I believe the regulator is _in_ the tank integrated with the pump and no return) means that there's a lower upper limit to fuel delivery with big mods (particularly FI setups).
Though it's not a huge deal to drop the tank and completely redo it (some people use a 97 fuel system, with return, rail mounted FPR, big pump, etc.) Not a hgue expensive relative to everything when you get to those 600+rwhp level though
Originally Posted by diverdan
I believe the 04 got an updated fuel injection system that it shares with the C6, though it wasn't supposed to provide any more power.
Le Mans Master
Joined: Feb 1999
Posts: 7,121
Likes: 0
From: Vilano Beach FL
The item (that I'm aware of) that was removed for '04, is a switched power accessory block, that's under the passenger side kick panel.
That's where I hardwired my V1 - I remember posts of '04 owners trying to follow the forum hardwire guides, they were confused that the accessory block wasn't there!
DT
That's where I hardwired my V1 - I remember posts of '04 owners trying to follow the forum hardwire guides, they were confused that the accessory block wasn't there!
DT
Originally Posted by sandmanusd
by plug in the console, do you mean the "cigarette" plug, for c-phones and the like? That was in my 97...
Burning Brakes
Joined: Jun 2004
Posts: 884
Likes: 1
From: McKinney TX
Originally Posted by DT
The item (that I'm aware of) that was removed for '04, is a switched power accessory block, that's under the passenger side kick panel.
That's where I hardwired my V1 - I remember posts of '04 owners trying to follow the forum hardwire guides, they were confused that the accessory block wasn't there!
DT
That's where I hardwired my V1 - I remember posts of '04 owners trying to follow the forum hardwire guides, they were confused that the accessory block wasn't there!
DT
Le Mans Master
Joined: Jun 2001
Posts: 7,331
Likes: 518
From: Admit Nothing, Deny Everything, Make Counter Accusations.
Originally Posted by AFVETTE
Many 04 owner's report getting "lean" codes when they install any low restriction intake like Blackwing etc. Where as, on almost every other LSX motor even after installing an intake the AFR's are still rich.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
A 2004 car that sets a closed loop lean code will also run rich when going WOT open loop. The car runs rich when at WOT to save the cats and the motor.
Last edited by RussBt; May 25, 2005 at 02:18 PM.
Le Mans Master
Joined: Jun 2001
Posts: 7,331
Likes: 518
From: Admit Nothing, Deny Everything, Make Counter Accusations.
Originally Posted by AFVETTE
Many 04 owner's report getting "lean" codes when they install any low restriction intake like Blackwing etc. Where as, on almost every other LSX motor even after installing an intake the AFR's are still rich.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
Hopefully some 04 owners will respond with their opinions as well as dyno numbers and if any of them experienced the "lean codes" after installing an intake.
A 2004 car that sets a closed loop lean code will also run rich when going WOT open loop. The car runs rich when at WOT to save the cats and the motor.