SC'd AT GT-S doing something odd...

1393 Views 34 Replies 13 Participants Last post by jlitman, Nov 25, 2006

jlitman

Discussion Starter · Oct 25, 2006 (Edited)

Okay... what the hell is going on here? :scared:

I decided to take a little vid for a 0-60 run (sorry for poor quality, phone vid). The good news is, full tank of gas (100 Octane), 0-60 is just over 6 seconds flat up slight incline (so maybe less with better tires, nigh-empty tank, and perfect straight, yes?).

The bad news is I got some sort of weird shuddering and hesitation in 3rd gear, similar to bouncing off of a rev limiter :faint:

This happened once before recently... the last time this happened I had been running 100 octane -- I had a bad tank of gas, filled it with high octane and a bottle of techron to rememdy the problem, and then switched back to 93. It happened only once and that was it. No CEL and no pending codes, so I assumed it was the ECU adjusting timing due to going from 100 to 93.

I assume it's the same tonight as well, as it had the same symptoms, no CEL or pending codes, and after wards it was fine on a second and thrd series of runs... except I'm back on the 100 octane to tide me over until water injection (coming soon!) and it's below 60 F outside, so why would this happen?

What the hell, man??? :AF:

Could this be the ECU adjusting timing? The techron causing more harm than good? Something else? I know I need to keep my eye on this, but should I be overly worried?

Here's the vid http://media.putfile.com/What-the-86

P.S.
Yes that's me saying "Whoa!?" when the car starts acting crazy :chuckles:

1 - 20 of 35 Posts

zuoom

· #2 · Oct 25, 2006

the "whoa" comes after.. took you like 1 second to react to it. .P must have shocked you.

it sounds like the speed/rev limiter kicking in.

can you replicate it again? otherwise, it's just a one off.
maybe you want to switch the camcon off?

i had something like that when the wiring was not done properly. and it would hang in gear 1.

if it does not happen again, then no need to worry i reckon. in the mean time, i would switch the camcon off. personal case, the car ran smoother for me when off than on.

jlitman

Discussion Starter · #3 · Oct 25, 2006

zuoom said:
the "whoa" comes after.. took you like 1 second to react to it. .P must have shocked you.

it sounds like the speed/rev limiter kicking in.

can you replicate it again? otherwise, it's just a one off.
maybe you want to switch the camcon off?

i had something like that when the wiring was not done properly. and it would hang in gear 1.

if it does not happen again, then no need to worry i reckon. in the mean time, i would switch the camcon off. personal case, the car ran smoother for me when off than on.

I was wondering if it was something screwy with the camcon as well -- someone else mentioned random camcon problems...

I'm reluctant to mess with it. A/F on the emanage was tuned to match the VVTi adjustments so god only knows what might happen if I switch it off. :scared:

I did another series of runs and even had my datalogger to record everything in real time -- no problems. Car just pulled like mad through all gears (maybe very, very slight high RPM backfire at very top of 1st, but that's it).

Maybe it was just the ECU adjusting the timing for the higher octane -- so that's good, right?

On another note, I discovered that my air intake temps (at the MAFS) were within 1-3 degrees F of ambient at cruise! Go super-shielded SRI! :applaud:

zuoom

· #4 · Oct 25, 2006

hmm, today i had my own share of random issue.

did a couple of high rev runs. car felt ok. no CEL no nothing.

on the cruise home, the AF goes uber lean. very light load at that time. came to a stop. AF goes like 19. almost off the scale. engine shakes alittle, trying to get back to 14-15. no go, still 17-18. 400rpm? shakes. had to threw it to N (netural) and step on the throttle to keep it at 15, 2500rpm.

as sudden as it came, it went away. this would be the 3rd time i'm experiencing this since installation in Aug. very random. can't replicate even if i try.

btw, what do you use to datalog?

Boosted2.0

· #5 · Oct 25, 2006

weird - looked like a loss of fuel pressure or some major input problem (MAF signal cutting out)

when you described it I thought it was going to be the trans slipping when going into lockup, but thats not it at all.

NIce 1st and second gears BTW - thats hauling ass for an auto!

jlitman

Discussion Starter · #6 · Oct 25, 2006 (Edited)

zuoom said:
hmm, today i had my own share of random issue.

did a couple of high rev runs. car felt ok. no CEL no nothing.

on the cruise home, the AF goes uber lean. very light load at that time. came to a stop. AF goes like 19. almost off the scale. engine shakes alittle, trying to get back to 14-15. no go, still 17-18. 400rpm? shakes. had to threw it to N (netural) and step on the throttle to keep it at 15, 2500rpm.

as sudden as it came, it went away. this would be the 3rd time i'm experiencing this since installation in Aug. very random. can't replicate even if i try.

btw, what do you use to datalog?

Auterrra scantool for my Palm pilot. Works pretty well. There's a whole thread on it floating around...

Boosted2.0 said:
weird - looked like a loss of fuel pressure or some major input problem (MAF signal cutting out)

when you described it I thought it was going to be the trans slipping when going into lockup, but thats not it at all.

NIce 1st and second gears BTW - thats hauling ass for an auto!

Thanks! Should get better after WA/I, retune, and better tires (mine are shot!). Speaking of tuning, I can't wait until you have a PFC solution for us AT guys

So... uh... about the weird car behavior... should I be worried? This has happened twice now. Once immediately following an octane change; once 100 --> 93 and then last night 93 --> 100. Both times, it only happens once, no CEL or pending codes, and no other obvious problems in how it runs or sounds

It couldn't be from the bottle of concentrated techron, could it??? :wtf: Isn't that the same stuff in Chevron, which is the fuel I typically use. Could the fuel pump be on it's way out?

Boosted2.0

· #7 · Oct 25, 2006

Could be fuel pump on the way out or some other odd foible of the stock ECU. I wouldn't be too worried about it if it only happens when you first change fuels. And no - techron will not do that - its awsome stuff.

It could also be a bad couple of load cells in your map on the e-manage - would be interesting to see the burble on a log.

drewd

· #8 · Oct 25, 2006

That video was horrible and it gets to 40 about as quick as my manual GT :wtf:

r1kde

· #9 · Oct 25, 2006

looked like a fuel issue, that seamed pretty normal for starvation

Boosted2.0

· #10 · Oct 25, 2006

drewd said:
That video was horrible and it gets to 40 about as quick as my manual GT :wtf:

yeah - thats smoking fast for an auto GTS - seriously

drewd

· #11 · Oct 25, 2006

Boosted2.0 said:
yeah - thats smoking fast for an auto GTS - seriously

Good god. I'm glad the dealership only had manual or I'd be kicking myself more than I am for getting a GT :sadpace:

jlitman

Discussion Starter · #12 · Oct 25, 2006

Boosted2.0 said:
Could be fuel pump on the way out or some other odd foible of the stock ECU. I wouldn't be too worried about it if it only happens when you first change fuels. And no - techron will not do that - its awsome stuff.

It could also be a bad couple of load cells in your map on the e-manage - would be interesting to see the burble on a log.

Okay -- thanks -- I'm relieved!

drewd said:
That video was horrible and it gets to 40 about as quick as my manual GT :wtf:

Good god. I'm glad the dealership only had manual or I'd be kicking myself more than I am for getting a GT

I said the vid was poor quality :shrugs: If you start the count when the car actually gets moving it hits 60 MPH at about 6.3 seconds and I'm not on a perfect straight. If your GT can do that then fair enough, but I'd love to see the vid.

Anyway, you are realy starting to sound like fingernails on a chalkboard with all this irrelevant negative commentary, my friend.

zuoom

· #13 · Nov 11, 2006

something odd's happening to me.

after hours plus of hard driving, if i come to a hard stop. the engine would kind of splutter , idle rough/low rpm.. and once for the first time last nite, it shut down.

* this is after tuning.

you ever encounter something like this?

jlitman

Discussion Starter · #14 · Nov 11, 2006

zuoom said:
something odd's happening to me.

after hours plus of hard driving, if i come to a hard stop. the engine would kind of splutter , idle rough/low rpm.. and once for the first time last nite, it shut down.

* this is after tuning.

you ever encounter something like this?

That might be the IACV :shrugs:

zuoom

· #15 · Nov 11, 2006

hmm, it idles just fine when cool/hot though..

?? got no CEL to work with.. maybe will get a mastertech obd reader and see what gives.

Boosted2.0

· #16 · Nov 11, 2006

zuoom said:
something odd's happening to me.

after hours plus of hard driving, if i come to a hard stop. the engine would kind of splutter , idle rough/low rpm.. and once for the first time last nite, it shut down.

* this is after tuning.

you ever encounter something like this?

did this happen soon after you filled the gas tank?

silver21

· #17 · Nov 11, 2006

yea you really need a Pfc lol... pulls sooo much better in lift.... but I have no idea with the problem?? ECU/Camcom problem I'd guess....

zuoom

· #18 · Nov 11, 2006

hmm, i can't say it's soon after. but the tank was full from an earlier day top up.

LightningRod

· #19 · Nov 11, 2006

drewd said:
That video was horrible and it gets to 40 about as quick as my manual GT :wtf:

Umm ... his 0-40 is faster than yours ...

He said his 0-60 is about 6 seconds flat; stock 6-speeds can't even do that.

FITGT

· #20 · Nov 11, 2006

zuoom said:
something odd's happening to me.

after hours plus of hard driving, if i come to a hard stop. the engine would kind of splutter , idle rough/low rpm.. and once for the first time last nite, it shut down.

* this is after tuning.

you ever encounter something like this?

My stock GT does that now and then, I think the ecu is just adjusting? I know when I drive on the highway for a few hours, when get off and stop. It boggs about 2-3 times, then it starts to level out.

1 - 20 of 35 Posts

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