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Discussion Starter · #1 ·
Thankfully it was caught on camera. The car is mostly stock save for intake and coilovers. The car seemed to shudder in a tight turn, at high load and Low RPM. It was a fairly warm day ~84F.

Is there a way I can diagnose and get rid of this? Thanks.
 

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Thankfully it was caught on camera. The car is mostly stock save for intake and coilovers. The car seemed to shudder in a tight turn, at high load and Low RPM. It was a fairly warm day ~84F.

Is there a way I can diagnose and get rid of this? Thanks.
Don't autocross.
 

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How low of an RPM are you talking about? Ive always been leery of having an engine trying to pull out of a turn in a racing situation at low RPM if it is at all avoidable. The piston is just moving too slow for comfort while you're also dumping a lot of heat into the cylinder in my opinion. Id qualify anything below probably 3500 RPMs as my floor for trying to pull out of turn on a track and that would be as a compromise to try and stretch out a gear for the follow up segment.

EDIT:: Went back and watched the video closer, it looks like youre pulling out of the turn at 1800 - maybe 2000 RPM. AutoX is a tough one because it is such low speed that you would end up bouncing between 1st and 2nd gear a bunch which would cost you a lot of time. The big things I would verify is pulling the plugs and looking over the plug wires closely, double check engine mount integrity, and ground bolts for cleanliness and tightness. Basically making sure nothing is moving and putting tension on a connector and the ignition system is in top condition. From there, I don't have anything else specific to offer without being able to feel what it is doing in which scenarios and how reproducible it is.
 

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Discussion Starter · #5 ·
How low of an RPM are you talking about? Ive always been leery of having an engine trying to pull out of a turn in a racing situation at low RPM if it is at all avoidable. The piston is just moving too slow for comfort while you're also dumping a lot of heat into the cylinder in my opinion. Id qualify anything below probably 3500 RPMs as my floor for trying to pull out of turn on a track and that would be as a compromise to try and stretch out a gear for the follow up segment.

EDIT:: Went back and watched the video closer, it looks like youre pulling out of the turn at 1800 - maybe 2000 RPM. AutoX is a tough one because it is such low speed that you would end up bouncing between 1st and 2nd gear a bunch which would cost you a lot of time. The big things I would verify is pulling the plugs and looking over the plug wires closely, double check engine mount integrity, and ground bolts for cleanliness and tightness. Basically making sure nothing is moving and putting tension on a connector and the ignition system is in top condition. From there, I don't have anything else specific to offer without being able to feel what it is doing in which scenarios and how reproducible it is.
Thanks I will check plugs and ground strap. The car only has ~21000 miles and has been garage kept, also feel I would have noticed the engine rocking if it was motor mounts, I am not saying it is out of the question but unlikely so I will check other things first. I am pretty sure it felt like a loss in power, I am guessing it is misfiring and possibly tune related but it is a stock tune so I am a bit surprised. Maybe intake temps where too high or maybe its spark/wires like you mention. I was kind of hoping for a CEL to point me in the right direction but no CEL which I found weird. I may pick up HPTuners software+OBDII thing to datalog stuff if I can't make any headway on the plugs and wires.
 

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I’d say if you’re going to make it your regular AutoX car, HPTuners even just for datalogging would be a great investment!


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Here's a guess. The tune has a ramp rate built in to determine when to bring in the fuel for boost. There's an rpm setting there too in that table. Super low rpm mixed with WOT boost can cause some bogging if the tune is not spot on. I would try to keep the rpm up by grabbing the next gear and see if that helps. If it continues then it's something else.
 

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Discussion Starter · #9 ·
Took the car out for a spin and turned TC off (like at AutoX) pulled a high load, low RPM, Left turn but no bogging. I am starting to think it was just because the car was hot from idling behind the other cars between AutoX runs. I have OBD Link MX+ and before today my datalogging setup was not correct. I will take the car out for another spin soon to see if the logs show anything. Aug 7 should be my next AutoX I will try to data log runs then now that I have logging setup correctly.
 

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Do you just turn off TC? Or are you putting the car in Competition mode with both TC and AH disabled? Lots of tight cornering, tires get gooey, AH is going to step in at some point. Might feel like loss of power.
 

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I can't tell much from the video and without logs we're all guessing anyway without pics of your instructor- she sounds cute!

You definitely need data logging, competition mode, and quality gasoline.

But I'd wager it is pig rich in factory form and it's simply too much fuel under load in areas that the ECM hasn't had much time to adjust for (ie LTFT). You will definitely feel it more there as the engine has less mechanical leverage with less RPM.

Tune that bitch- I can't imagine there is any useful warranty to worry about now, right?

Just be really conservative with timing at low RPM / high load. It makes me nervous with boost under 3500 RPM.

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The piston is moving super slow which allows for more opportunity for preignition. Especially if IAT2 is already high before the run.

If I was doing any form of Motorsport but wanted to stay stock power, I’d do at least a better HX pump and a Track Attack style HX. A reinforced brick wouldn’t hurt either.


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Discussion Starter · #13 ·
I was able to get successful logging yesterday, tried to reproduce issue but was fine at high load and low RPM. I agree on the cooling issue, one reason I am learning the car stock is I believe the heat exchangers on the car will be better suited to the factory power before I go making more power and heat. I am leaning toward a trunk tank rather than a bigger front mount HX but I might get that too. Right now I like to AutoX and I am learning to drift too, both low speed high load and sitting in grid with the engine running doesn't leave much airflow over the HX. I think I will throw in some octane booster next AutoX along with data logging. I am logging ignition advance for cyl1 and now that I have data to compare that to with it working I should be able to see if this is the case. I drive with the TC completely off since I am learning to drift too, I want to learn the limits of the car and controlled power on oversteer is what you buy a RWD car for right?
 

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The main reason I suggested the track attack style HX is that it fits the same as the stock piece so the fans will pull air through it at low speed.

There’s no trade off or downside to just improving the HX cooling loop. The engine will thank you though.


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Discussion Starter · #15 ·
I found this interesting
this guy has a pretty good channel in my opinion. He also had another video talking about how the heat soak is delayed and most likely happening after my high load run sitting in the grid for the next run:
I am remembering that heat transfer is a slow process so this makes sense. Anyone have any tips on how to keep the car cool sitting in grid traffic?

0710211405a.jpg
 

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Add a switch to turn on the cooling fans at max. I think that's about your only option short of removing the hood.
 

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The shudder was a warning that your airbags were getting ready to deploy. :p

Seriously, do some searching on here about airbag & autocross if you haven’t already.
 
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