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2006 STS4 4.6L
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602 Posts
Discussion Starter #1
I'm currently looking into a few things for my 4.6

-Timmy's ported throttle body $400
-Ported intake manifold $200-$400
-Ported heads $2k roughly
-Custom headers (maybe, somewhat cost prohibitive) $2k-3k at least.

I'll be topping these off and bringing it all together with a tune, ideally a dyno tune from N* performance as they should be ready pretty soon (hopefully). I haven't been able to get a hold of them on the phone yet, though. Unsure if they do TCM tuning for ours but I would be surprised if they don't.

I'm also looking into some light(er)weight wheels right now, but the factory alloy wheels aren't exactly heavy.
Also looking at a custom aluminum driveshaft but that will most likely be quite the project and not sure if it would be worth it.

Any opinion on if I am going too nuts with any of these? I reckon I'll be one of the first (if only) ones to ever step into this territory with the LH2.
Cost isn't really a figure for me, I love my car enough to invest a good amount of cash in it.

For anyone who would suggest buying a V, don't. I prefer the AWD NA V8 over the supercharged RWD.
 

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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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153 Posts
I don't know of any Northstar specialists, but I am sure there are some. I would think the biggest gains would be with the cylinder head work and some long tube headers. Then get it dyno tuned.
 

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2006 STS V8 AWD, '95 Ford Ranger
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28,957 Posts
Cat converters are part of the exhaust manifolds so it would be messing with federal law to delete the CATs.
 

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2006 STS4 4.6L
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602 Posts
Discussion Starter #4
Short tube headers would probably be the way to go, there are a couple companies who build decent aftermarket cats.
 

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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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I did a lot of research on shorties for my Trans Am. There was no gain from those, only long tube headers. I imagine it would be the same for our Northstar. I live in an area where I do not have emission checks.
 

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2006 STS4 4.6L
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602 Posts
Discussion Starter #6
It would appear that the long tube headers are going to be more beneficial in most situations, but I honestly do not believe that there is any way to fit a set of long tubes in the space available with the AWD 4.6. I think I will be lucky to fit a pair of shorties comfortably, in my opinion.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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2,047 Posts
You sure you have the E67 ECM and not that Siemens/GM one that I'm stuck with on my 05? I thought the breakpoint was mid-MY06.
 

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2006 STS4 4.6L
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602 Posts
Discussion Starter #8
I've got the e22 ECM same as you. PCM performance does tuning for it and Northstar Performance should be rolling theirs out pretty soon, from what I understand.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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04-06​

RWD Cadillac SRS/STS/XLR 4.6 LH2 (E22 ECM)

$475​
No friggen way! I thought all hope was lost. I wonder what software they use. That is pricey but is at the very least a path to get rid of my nuisance P0430. And maybe pick up a few ponies? Any idea how much there is on the table with a bone stock LH2? I always thought they were conservative on low/mid range spark advance, perhaps after some driveline lash complaints on the launch 04 SRX. Of course there are two sides to that coin. It would figure that the responsiveness would unmask the fact that my driveline bushings have all aged. But this is all very interesting. I guess I haven't been paying attention.

Hopefully we can figure out which is the best option, at least when NorthStar Performance actually releases theirs. Not that we'll have dyno comparisons (would be nice). Is it an ECM exchange? Seems like that's the only way.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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Sent inquiries to both PCM Performance and NP. I am too excited to just wait for this thread to develop. Here is what I sent to NP (and something similar to PCM Performance):
I am interested in your tune services for my 05 STS AWD Northstar, with the lovely Siemens/GM E22 ECM. I have come to understand that you are about to release support for this ECM. To that end, I have a couple of questions which shouldn’t be too difficult:
  • Do you have any dyno results or ANY empirical results for the LH2 w/ E22? Talking power, drivability, MPG, anything I can sink my teeth into.
  • Can you disable DTCs? I need to turn off P0430 and I guess I would also turn off P0420 just for completeness. I assume this is possible, but let me know.
  • Can you say what software you are using to actually modify the E22 calibration? In-house? Just curious.
  • Does any of this include TCM stuff or is TCM tuning even necessary? Thinking about torque management type stuff here.
I have a vague feeling we're not supposed to talk about DTCs these days so I'll edit posts if it's really that hush-hush.
 

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2006 STS4 4.6L
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Discussion Starter #11
I wouldn't worry about it too much.
Any discussion of modifications to emissions or emissions monitoring system(s) in this thread is for educational purposes only; said modifications are for off-road use only.
I believe I read about PCM performance's tuning and it seems to involve soldering and editing lines of code (don't quote me) but that method might not be used for this. Dyno tuning through Northstar Performance would be useful to really prove how beneficial or pointless any "upgrades" to the STS are (exhaust, intake work, head work, etc).
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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Ideally they would have dyno tested and tuned several LH2s before releasing a mail order tune for stock vehicles. Seems like NP is more likely to get that kind of quality?
 

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2006 STS4 4.6L
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Discussion Starter #13
I think Northstar Performance overall has messed with the Northstar engine a lot more than anyone else ever, and I think they would most likely offer a better (more specific) tune. I think PCM performance has tuned quite a few more vehicles just in general, though; and their tune would probably be well worth the money as well. PCM performance tunes are mail order only, N* performance should be doing both mail order or dyno tuning.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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Does mail order mean an ECM exchange for both? Which would mean either trade or send in to be flashed/modified and returned.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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That was fast. Sounds like it will be a while yet.

Hi Kevin, we are working on it, just not up to the E22 yet. Got two others to get completed first. Hopefully this year sometime we will have that one sorted out as well.

Thank you,

-Jake
------------
Jake Wiebe
President & Founder
Northstar Performance
1-888-800-9470
Visit us on Facebook and Youtube!
 

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2006 STS4 4.6L
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Discussion Starter #17
Rats. Was hoping it would be sooner than that, it would seem by their website that they should have it out sooner but I reckon I would take a personally typed email over much else. I might have to get in touch with PCM performance and see what they can do. I really don't want to go through the process of getting work done on the heads and all that if it won't bear any fruit for at least a while.
I remember when 1BadCadSTS got his ECM & TCM tuning via MadTuner he said the TCM tuning was really where it was at between the two; although I don't recall him having the other modifications I have talked about, either. An ECM tune wouldn't be quite as fruitful seeing as the factory programming is pretty solid for the stock (or mostly stock) vehicle.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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Well didn't NP claim 40 hp and 4 mpg with their tune on a 97 Northstar? I don't know if the margin decreases with the LH2 because of the VVT but I could totally see something being left on the table. I would expect some power and mpg to be left in the tune. I think the trans tuning is pretty solid. Unless someone figured out that it was safe to wind out to 7,000, and I could see that being beneficial since the hp peaks at 6,400.

In your case, I wouldn't bother with any of those hard modifications. I would save up for an STS-V. The tune alone and maybe an exhaust for sound seems like about as far as I think it is worth going on these. I am about to embark on another round of mechanical refreshing on mine (front LCAs, engine mounts namely), and the tune seems like the icing on the cake to get a few more years out of the car (152k now). It would address a bunch of things theoretically like:
  • Continued safe operation on 93 octane. That's all I use anyway. But I don't want it on the hairy edge of knock or something.
  • Fix the lazy throttle tip-on off the line. I am finicky about this and it's not satisfying stock. My wife's 08 SRX is superior, and I also drove an 04 SRX with the original calibration (not the soggy update to soften the lash) and it was also better.
  • If enough WOT power could be added to close the gap with a 100 mph trap speed, that would really be something. Like 98-99 maybe?
  • A few extra MPG would be wonderful
  • Most importantly, turn off P0430 and P0420. I could leave P0420 on because I think that cat is fine but what's the point?
I still have a desire to upgrade to the STS-V down the road. Yes that would lose the AWD.
 

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2006 STS4 4.6L
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Discussion Starter #19
I'm not ditching the AWD or the NA engine, living in Colorado I want to keep my vehicle which can perform in any weather, and it does.
I'll buy other vehicles as well, but for this one I want to see what can be done (safely and reasonably).
The VVT was definitely a game changer when it came to performance, for sure. I definitely think there are improvements to be had, but not quite so drastic as with the older Northstars.
 

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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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So I went to the track with my car, after I installed my 3.23 gears and a local guy had HP Tuners (I think?). He had a wide band O2 sensor to help, got rid of my emission codes (P0420/430) fixed the speedometer, upped the speed limiter to 200 MPH (lol). It was a hot day and my best was a 14.49 @ 99.x MPH. I'm happy with that. Bettie Lou has Gibson mufflers for a nice rumble and cool 4" chrome tips. I believe I can trap at 100 or better on a cooler day. As big and heavy as this is (and roomy!) I'm alright with that. Yeah, a STS-V would be great, but my faster car is the WS6. I have long tube headers, mail order tune 6 spd manual and she recently did 13.2 at 108 MPH. And, that car reliably still gets 26-28 MPH highway. The Caddy was 22.5 MPG on a recent trip from Indy to New Orleans and back.
 
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