utkinpol

I am trying to do a little poll here to figure out if it is worth to try to fix it or just let it go - in case if this is a typical issue.

Synopsis is quite simple - in second gear only, when in between 1000 and 2000 rpm, if i give full throttle car hesitates, engine chokes a bit, jerks and then pulls full throttle. If i reset ecu it goes away but quickly recovers as ecu learns and ajusts timing. I wonder if such behavior is typical for other cars that has 200 cell cats or if mine should be looked at. There are no cels, no misfires detected, maf sensor reading seems to be correct, fuel mixture seems to be about ok too, without maf it seems to behave in a similar way. So from diagnostics standpoint i cannot track it down to anything. Readings frm both o2 sensors also seems to be same.

So it may be then spark plugs, coils, vacuum leak, etc. i can buy new coils and new pre-cat o2 sensor for right bank ( i replaced left one this winter) but kinda not sure if it will do any good or not as above 2k rpm there are no issues at all, no lost torque, car pulls fine. Only issue is in second gear, between 1k and 2k if i give full throttle.

Any ideas?

toper

does it do this in all modes (normal, sport, sport+)?

Captsteve123

My did this when I was not in sport mode, so now I drive it in Sport mode all the time. Plus I like how it feels in that mode anyways.
One observation I made while driving car, not in sport mode, but cruising at 45 mph is if you have your foot on the gas and use your left foot and touch the brake just little, it duplicates that same issue. I have a new brake switch, as someone told me it may hang up while at a stop, but have not changed it just yet.
Good luck!

gpjli2

I seem to remember that you are using gt3 TB. Have you reflashed/upgraded ecu? If not consider it. I have to tell you that sudden full throttle from 1K rpm other than perhaps in first is sure to catch out the motor and to my mind should be avoided unless a semi is about to run you over from behind. Words like "lugging" and "detonation" come to mind. Also, sudden application of full power at low rpms is one of those conditions contributing to heat spike and cylinder problems as per Hartech and others. I have a simple solution for this: (to paraphrase an old joke) "Doctor, it hurts when I do this" Doctor: "Stop doing that". Just sayin.........

mattyf

Just gave it a shot my stock .1C2S. I would not call it a choke, hard to say, maybe slight hesitation, but certainly not as bad as you describe it. Basically the engine just felt like crap floored in 2nd at under 2000 rpm. Major lugging, but no pinging.

Edgy01

Absolutely never.

utkinpol

Interesting responses, thanks guys. Obviously i practically never 'floor' it in this rpm range at 2nd gear, that is why i am reluctant to dig into this too much or start replacing parts left and right. I was mostly curious if this is a comon thing or a sign of some specific problem. For now I just dumped a bottle of techron cleaner into tank and I think I will leave it at that.

Psymon

Here's another post, not sure if it's exactly the same as what you are experiencing. Mine is at post #6, and it's not only 2nd gear.

https://rennlist.com/forums/997-foru...one-place.html

Dadio

Have never been in second gear at 1000-2000 RPM so I can't say whether my car would stumble or not. As I will never be in second gear at those RPM ranges I will never be able to answer that question. With that said, I would love to know why you would you want to be in second at those RPM ranges and fully depress the throttle when you have a perfectly good first gear designed expressly for that purpose ?????

jhbrennan

You shouldn't need a new brake switch...braking while pressing the throttle activates PSM or some other function and will cause the jerkiness you're feeling. I found this out trying to dry the rotors after washing the car while pressing brake and throttle at same time.

wc11

Why 2nd at 1000 rpm is the better question.
Almost sounds like its about to stall.

Buddhamonk

2nd gear sub 2k...you're lucky not to stall but it also depends on how much throttle you are giving.

Jk i know you can't stall in second. Just stay at 5-6k in second like i do

PhilD

FWIW Mine did this with a K&N intake, does not with stock or Fabspeed. So could definitely be related to any intake mods.

utkinpol

I think it is a lack of backpressure plus dirty injectors plus (probably) weak coils.
I am at the middle of the 10gal of gas I put in with techron cleaner and so far is seems like whole 2nd gear pull from 1500 to 3k got way smoother. I think it was simply a clog in the pipeline. it pulls ok now.

for those smartypants who wonder why it is relevant for car to pull from 1500 rpm (I do not do it at 1k, obviously) - it is when you drive in your suburb neighborhood you do not want then conversations with your neighbors why their glass in the cabinet fell off when you car passed by at 6k rpm screaming like a jet plane.

so far it seems one $13 bottle of injector cleaner improved it to the level where it may be forgotten for a while. it probably would not hurt to replace all coils too and refresh o2 sensor but heck with it, it drives just fine as it is. if it will throw any cel, then I will look at it again.

I still wonder what is that condition that puts timing to this area, it would be great to be able to recognize it proactively but it does not seem to be that simple, apparently. especially when you have, like, about of 10% of stock parts left in the pipeline.

utkinpol

that is identifiable - with K&N if that is the conical one inside of engine bay timing goes bananas when it starts to suck in overheated air from engine compartment. those conical filters that are inside of the bay only work well if it is a forced induction car, turbo or supercharger, and all air goes in via intercooler so it does not matter if you have proper CAI or not. for NA cars it is critical to suck in all air from the outside to maintain timing.

I always wondered what was the deal with Porsche and why they did not maintain same body like on turbo and gt2 cars for all models they make. to have those air pickups on the sides would provide excellent air flow under some pressure for NA cars, at good speed it would probably boost it very nicely, almost like a supercharger. but, well, it is what it is.