Former G35 Junkie...looking for Mods

[Effin Ponderous]

Hi all,
Former G35 Sedan owner taking the step to AWD. I picked up my 05 Legacy GT new last month (yes I did say my 05 and it was new). Crossed over from Infinitidom and I've gotta say I'm pretty impressed. Fit and finish is as good and some of the interior materials are better. Faster than my stock 03 G, but it may be time to start the modding. Only one issue and not sure if anyone can help on this one...
Once I fill the gas tank, the car will sputter alot at about 1/4 throttle. This goes on for about the 1st 10 minutes after filling. This morning I tried to open it up and the car sputtered and coughed under WOT. I've also noticed that it's a real dog (hesitates and sputters) with the A/C on. Now I understand that the A/C robs alot of power, but this seems to be more than just robbing power. I really have to run in sport mode to get any acceleration. I figured that I should run it back to the dealer, but I expect the "we don't see anything, bring it back when it does it again" thing.

As far as future mods go, is the SPT intake worth it?
Is the Cobb tuning system worth the $600, and can you really get another 45 CHP and 55 lbs of torque?
Can anyone suggest better mods for the buck?

[TSi+WRX]

The filling issue seems somewhat weird - maybe coincidence? Alternatively, maybe heat-soak of the TMIC? Unknown....

The A/C does rob considerable power, but if you're noticing it to be excessive, it truly may be so. Regardless, under WOT, our compressor will cut-out in order to relieve parasitic loss, so I'm not sure what might be the issue here, but this, combined with your previous report, makes me think again of perhaps heat-soak...

What's the temperature/humidity like in your area recently. Have you noticed any significant performance changes due to weather changes? It could be that you're running the vehicle hard enough to note heat-soak, especially after having the vehicle stopped for a while.

Also, the part-throttle hesitation sounds somewhat like the "stutter/studder" that some owners report. Do you notice this happening during any particular point in the rev-band?

[Effin Ponderous]

TSi+WRX= The filling issue seems somewhat weird - maybe coincidence? Alternatively, maybe heat-soak of the TMIC? Unknown....
I fill up at the same spot every time (3 times total). It's 7 miles from home and always after sitting over night. I don't think heat soak is the problem, but is there a big problem overal with it?

The A/C does rob considerable power, but if you're noticing it to be excessive, it truly may be so. Regardless, under WOT, our compressor will cut-out in order to relieve parasitic loss, so I'm not sure what might be the issue here, but this, combined with your previous report, makes me think again of perhaps heat-soak...refer to above

What's the temperature/humidity like in your area recently. Have you noticed any significant performance changes due to weather changes? It could be that you're running the vehicle hard enough to note heat-soak, especially after having the vehicle stopped for a while. Haven't driven it long enough to know yet, but the temp is in the low 70's and humidity is high.

Also, the part-throttle hesitation sounds somewhat like the "stutter/studder" that some owners report. Do you notice this happening during any particular point in the rev-band? Primarily up to 3k rpm, and then it starts to clear up.

[coxx]

As far as future mods go, is the SPT intake worth it?
Is the Cobb tuning system worth the $600, and can you really get another 45 CHP and 55 lbs of torque?
Can anyone suggest better mods for the buck?

The Cobb Accessport is well worth the $650 or whatever it costs. Might want to get it thru TDC tuning. They have some sort of special where you get one of their custom stage 1 maps already loaded on it for like $700 (usually their maps are $150 alone). Their maps are more aggressive than cobb's. As far as the SPT intake goes, it's prob a waste of money.

[TSi+WRX]

Hum....low 70s, less than a 7-mile run that's not too hard (the TMIC isn't like a cat, it doesn't retain heat - nor "remain cool" - for that long...even just a few miles of stop-and-go traffic, with low airflow, at low speeds, will tax its cooling efficiency), it's hard for me to imagine heat-soak, too. Humidity does seem to affect our vehicle a bit in terms of TMIC efficiency, though. But still, that's rather low ambient temps for you to be seeing such trouble.

Have you tried either holding your hand up over the TMIC or actually putting your hand on it to see if it is heat-soaked (it'll be "slightly uncomfortable" to the touch, but not outright "hot"), right before you pull-out of the gas station?

Do you have the means to datalog your vehicle?

What you report with the part-throttle hesitation does sound a little like "stutter/studder." This is a known issue, which exists to varying degrees of severity, on some '05s and even '06s.

I hate to refer you over to "the other site," but this issue is addressed thoroughly there. :)

If you're looking for some "starting-out" mods, actually, the AccessPORT is probably the best "bang-for-your-buck" purchase you can make. Even with no hardware changes (i.e. "Stage I" reflash), you'll still gain a good bit of driveability improvements, and although by no means a definitive cure (some have had their stutter/studder recur), there are a percentage of AP owners who have reported either complete resolution or minimizing of their stuttering/studdering issues either using the off-the-shelf Cobb maps or through use of custom or semi-custom maps.

Combined with your current concerns, this may not be a bad investment for you at this point, particularly in light of the fact that the AccessPORT will serve as the engine-management tuning base for your vehicle well into more aggressive modification "stages."

With the SPT intake, there exists some current debate about its efficacy as well as "safety." I would be tempted to take a pass on this modification at this point, particularly as you are looking at the AccessPORT as a potential first-line modification and as Cobb specifically recommends against running any aftermarket intake with their off-the-shelf maps. Additionally, with our Scoobys, an intake change nets really very little true "power" gain - it is only upon more drastic hardware changes (many will keep the stock intake tract until they at least upgrade to a bigger turbocharger) that the true limitations of our stock intakes are reached. At the lower "stages" of tune, particularly if you're only utilizing off-the-shelf maps, an intake is more an aural improvement/modification than anything else.

[Effin Ponderous]

WOW, guys...truly excellent info and fast! This looks to be a relatively new site (I've been looking for a couple of weeks), but I am not familiar with the "other site" that you mentioned and no need to for now. I am truly an F/I DIOT. I was borne and raised on GM small blocks from the old days, and up until my last G35S, hadn't gone under the hood in over 15 years. I definately gained knowledge on the G, but this F/I thing is a little scary right now. It seems I have alot to learn here.
My last ride...

[TSi+WRX]

^ Beautiful car! I really like the G35s - their engines truly purr.

---

Don't worry about the FI stuff - you'll get the hang of it in no time. And I'm working "in-reverse" of you, bro. I have a good musclecar buddy, who has slowly but surely started to convince me that "a car without a computer" is perhaps the best car of all. :lol: But more seriously, like you, I'm learning a lot from him on a daily basis, and it truly is like learning a whole new language....

"The Other Site" is LegacyGT.com - it's a bit more "restrictive" in terms of the partying that can go on, but overall, it's still an awesome techinical resource and still ranks (by my standards) as one of the more friendly on-line communities (especially when it comes to cars) that I've frequented.

:)

[Effin Ponderous]

I was an advisor on my last G-Site. We were in the process of putting together a mod list for everyone. We included dyno'd hp/tq increases, as well as manufacturers rated, cost of the mod, and even by ease of installation. Is there anything over here for us FIdiots?

[TSi+WRX]

I think that the proprietor of "The Other Site" is trying to get something similar started:

http://www.subiwiki.com/wiki/index.php/Main_Page

However, I'm not sure how far the project has progressed along....it's quite new.

The old "stickies" from the top of the .com sub-Forums are all being moved there, and I see that a good portion of the information has been added already! :D

The Legacy "BL" version is what you'll be interested in. :)

[Effin Ponderous]

The Legacy "BL" version is what you'll be interested in. :)
Please forgive my suba-newbi-ism...
The BL version is?

[Bu11dogg2]

Welcome!!

get the AP, UP/DP and you will be more than happy!!

[TSi+WRX]

Please forgive my suba-newbi-ism...
The BL version is?

No need to apologize! :) The "BL" is our current chassis designation, year 2005+. "BP" designates the wagon.