New GT4 Owner Intro
11-05-2017 | 10:56 PM
#18
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From: Santa Cruz
11-05-2017 | 11:03 PM
#19
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From: Santa Cruz
Glad you are digging the car, John.
Very perceptive on your part. The engine in my GT4 felt a bit soft from 3500-5500 rpm to me, something I didn't notice in the GT4s at the European press launch in Portugal. I wrote about the same sensation here on RL. Felt like the ECU pulling the ignition timing back, but that was just a guess. So I tried some high test fuel from Sonoma, which seemed like it helped but it was one of those "am I really feeling that, or am I feeling that because I want to be feeling that?" I spoke with Sonnen and Porsche of Fremont, and had my car reflashed at the latter. It did seem to get better, but then went back to its old self. Then a friend with a GT4 here in Marin did the same thing, with the same results. He said his car felt sharper right after the flash, then went back to being a bit soft in the midrange within a week. I think that points to the engine management being reset and then (re)learning that it doesn't like CA 91. My theory, and it's only that: Porsche didn't get enough miles in with the 3.8 in the 981 chassis in CA to get the ECU maps right with our crappy fuel. I've only seen two photos of a 981 3.8 prototype in CA, both being of the same 981 Spyder and both taken at the same intersection in Santa Barbara—when we usually see scores of spy shots whenever Porsche is testing a new car in CA. Again, it's just a guess.
So I don't think anything is "wrong" with your GT4, and I guess a silver lining is that 5500 rpm is always a bigger rush than expected here in CA.
pete
Very perceptive on your part. The engine in my GT4 felt a bit soft from 3500-5500 rpm to me, something I didn't notice in the GT4s at the European press launch in Portugal. I wrote about the same sensation here on RL. Felt like the ECU pulling the ignition timing back, but that was just a guess. So I tried some high test fuel from Sonoma, which seemed like it helped but it was one of those "am I really feeling that, or am I feeling that because I want to be feeling that?" I spoke with Sonnen and Porsche of Fremont, and had my car reflashed at the latter. It did seem to get better, but then went back to its old self. Then a friend with a GT4 here in Marin did the same thing, with the same results. He said his car felt sharper right after the flash, then went back to being a bit soft in the midrange within a week. I think that points to the engine management being reset and then (re)learning that it doesn't like CA 91. My theory, and it's only that: Porsche didn't get enough miles in with the 3.8 in the 981 chassis in CA to get the ECU maps right with our crappy fuel. I've only seen two photos of a 981 3.8 prototype in CA, both being of the same 981 Spyder and both taken at the same intersection in Santa Barbara—when we usually see scores of spy shots whenever Porsche is testing a new car in CA. Again, it's just a guess.
So I don't think anything is "wrong" with your GT4, and I guess a silver lining is that 5500 rpm is always a bigger rush than expected here in CA.
pete
Glad to hear it’s not just me. I poked around this forum and didn’t see anything else about it, but I could be guilty of trying a few search terms and giving up before getting the right one.
BTW, I was very happy to submit my renewal form for 000. Looking forward to another year!
Best,
11-06-2017 | 01:15 PM
#20
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From: ^ The Bay Bridge
Hey Pete - thanks for the response. Interesting, I didn’t think about it being an ECU / CA fuel thing. I only noticed it on WOT, but the engine felt sort of dead (where the GTS 3.8 never does) in mid range and then, right, it kicked back in above 5k.
Glad to hear it’s not just me. I poked around this forum and didn’t see anything else about it, but I could be guilty of trying a few search terms and giving up before getting the right one.
BTW, I was very happy to submit my renewal form for 000. Looking forward to another year!
Best,
Glad to hear it’s not just me. I poked around this forum and didn’t see anything else about it, but I could be guilty of trying a few search terms and giving up before getting the right one.
BTW, I was very happy to submit my renewal form for 000. Looking forward to another year!
Best,
But it's not just you. Both zellamsee and I have felt it—but there are a lot of other GT4 owners in CA who probably have the same thing and aren't bothered by it.
Thanks for renewing!! I'm excited about what's coming in 2018...
pete
11-06-2017 | 01:20 PM
#22
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From: ^ The Bay Bridge
Oddly enough, only a few of its 14,000 miles were logged in another state—Nevada—and the drive home from that tankful was over a glorious mountain pass. I was too consumed by the scenery and the empty road (along with a lot of high rpm running) to take much notice of the mid-range soft spot (which is pretty minor...kinda like finding something to pick on). Also, as with mixing 96 or 100 in at Sears Point, which I did a few times, I am not sure the ECU will let its guard down after part of a tank of higher octane fuel. I think it learns that it doesn't like 5,000 miles on 91 and adjusts accordingly. Run it on 93+ long enough, and I am sure it can adjust itself accordingly, but I am just not sure how long is "long enough." And mixing fuel to get higher octane is a pain unless it's close by. So far, no cool gas stations in the swing of normal life nearby—though there are places in the South Bay and also down in LA that sell race gas in regular pumps. Why stations waste one of three pumps with mid-grade, I do not know. I mean, does anyone buy the mid grade stuff?
11-06-2017 | 02:26 PM
#23
Race Car
Joined: Sep 2016
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From: California
There is a high octane gas station in Sunol, right off 680 called Sunol Super Stop:
https://www.yelp.com/biz/sunol-super-gasoline-sunol
94, 96, 98, and 101
11-06-2017 | 04:52 PM
#24
Drifting
Joined: Feb 2011
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From: Midtown Atlanta
Oddly enough, only a few of its 14,000 miles were logged in another state—Nevada—and the drive home from that tankful was over a glorious mountain pass. I was too consumed by the scenery and the empty road (along with a lot of high rpm running) to take much notice of the mid-range soft spot (which is pretty minor...kinda like finding something to pick on). Also, as with mixing 96 or 100 in at Sears Point, which I did a few times, I am not sure the ECU will let its guard down after part of a tank of higher octane fuel. I think it learns that it doesn't like 5,000 miles on 91 and adjusts accordingly. Run it on 93+ long enough, and I am sure it can adjust itself accordingly, but I am just not sure how long is "long enough." And mixing fuel to get higher octane is a pain unless it's close by. So far, no cool gas stations in the swing of normal life nearby—though there are places in the South Bay and also down in LA that sell race gas in regular pumps. Why stations waste one of three pumps with mid-grade, I do not know. I mean, does anyone buy the mid grade stuff?
Well, if you're in Atlanta anytime in the near future (by which I mean soon enough to have a strong memory of what your GT4 feels like) I'd love to have you test mine and see if it's doing it or not. It's had an exclusive diet of 93 from birth.
11-06-2017 | 05:01 PM
#25
Quit Smokin'
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From: Columbus, Ohio
Check out the GT4 dyno thread:
https://rennlist.com/forums/gt4/1033337-gt4-dyno.html
There is a not so subtle torque dip in the part of the rev band that you guys are complaining about.
When I looked at the chart I assumed that there is a resonance flap in the intake, or a shift in cam phasing there, but someone that knows these engines more intimately may have a better handle on the cause. The Subaru / Scion FRS BRZ has a similar torque dip, slightly lower in the power, and it is exasperatingly noticeable in traffic. In the Subaru world I believe the dip can be corrected with headers and a tune. I would suspect that headers and a tune could go a long way to smoothing out that dip on these cars as well.
https://rennlist.com/forums/gt4/1033337-gt4-dyno.html
There is a not so subtle torque dip in the part of the rev band that you guys are complaining about.
When I looked at the chart I assumed that there is a resonance flap in the intake, or a shift in cam phasing there, but someone that knows these engines more intimately may have a better handle on the cause. The Subaru / Scion FRS BRZ has a similar torque dip, slightly lower in the power, and it is exasperatingly noticeable in traffic. In the Subaru world I believe the dip can be corrected with headers and a tune. I would suspect that headers and a tune could go a long way to smoothing out that dip on these cars as well.
11-06-2017 | 05:49 PM
#26
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From: Santa Cruz
11-06-2017 | 05:57 PM
#27
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From: Santa Cruz
If you’re on my side of the Bay with your car and fancy a drive, let me know. Would be good to see if it feels the same in both cars. Plus, big spender that I am, It’s on me if the destination is Alice’s or Brother’s Mexican in Pescadero. All you if you’d prefer the Ritz in HMB.
I’m excited to see what’s up your sleeve in 2018!
11-06-2017 | 07:01 PM
#28
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From: ^ The Bay Bridge
Man, GT4s look good in Guards Red—and I don't normally like Guards Red. It's like Henna on an E30 M3. Just works for some reason. Planned on Agate with silver wheels (like the John's new ride) but went with Guards Red in the end. Sure gonna miss it…
11-06-2017 | 07:21 PM
#29
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From: Midtown Atlanta
Actually, it's Carmine -- flourescent lights in the garage are oranging it up. I'd have been happy with Guards, for sure, (every Porsche I've ever had was silver before this one!) but in Jan 2015 I saw my first Carmine 991 GTS coupe, at JW Marriott Palm Desert, still sporting the Beverly Hills Porsche plates, and I knew I had to have wunna dem. I chickened out and ordered my GTS the next month in GT Silver, but the GT4 had to be Carmine. 
Easy to run down to the airport from where I live.
Easy to run down to the airport from where I live.