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To tune or not to tune...


Scruit
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Current status:

 

 

- 2005 LGT Limited 5MT

- 178k miles, 33k since #YNASB

- Oil pressure is 14psi at idle, 76 psi freeway cruise when hot.

- Stock intake with K&N

- Stock TMIC with bulletproof kit

- Stock injectors. 3 have been replaced over the years.

- BNR 16g turbo. Will hit 16psi on the boost guage

- Inidia catless UP

- CNT catted DP

- Stock exhaust

 

 

I worked with Dave at Cryotune 2-3 years ago and got partway through an off-the-shelf tune, but unrelated issues on my side got in the way and I wasn't able to finish the tuning. I have a safe tune on it right now, not a fast tune.

 

 

 

- Tuning via ecuflash / romraider and leaningview

- Learning view shows no timing corrections and <5 a/f correction.

- No knock during 2nd gear pulls

- IAM is always 1.000

 

Problem:

It feels slow. :spin:

 

 

Where to go from here??

 

I have a few options:

 

1 - Leave it as is.

2 - Tune as-is

3 - Warm it over a little but more, then tune

 

So obviously I'm going with option 3, but what can I do?

 

- 740cc injectors

- Exhaust

- Better TMIC

 

 

I'm working with a $1k budget. Leaning towards a stage 2 or 3 tune with Cryotune, figuring it'll cost me around $350 for the tune, so $650 for parts. Installs will be done by me, so no labor cost.

 

 

Thoughts? I'm leaning towards injectors and tune.

Edited by Scruit
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What are your long term goals? Do you plan to get a bigger turbo? EVERYTHING stems from the turbo!

 

If those were my choices I would get a TMIC, 3 port EBCS(boost controller, Cobb and Grimmspeed both make one) and fuel pump(Aem 50-1215). Stock TMIC goes to about 18psi, which doesn't really warrant an exhaust or injectors at that point, but if you want more boost, then you will need a TMIC. IMO the tmic is the first bottleneck after the downpipe! This is how i break down my priority order, turbo->Downpipe->tmic->turbo->fuel pump->injectors->exhaust->shortblock! The turbo goes twice because you can start off with the bigger turbo, or start from stock then go to a bigger turbo.

 

If you plan to do more mods in the future, mainly getting a bigger turbo. I wouldn't buy anything and just get a tune now, save up and then get it all done at once. Otherwise your going to tune a bunch of times for minimal gains.

 

If your staying with a 16g then I would get tmic, EBCS and fuel pump first then an exhaust.

 

If you plan to go with a bigger turbo, then I would still get a tmic/fmic, EBCS and fuel pump first, but injectors next. Don't leave out the fuel pump, if you get bigger injectors you will need a pump, the pump is more critical than the injectors.

 

Basically what you do now should be determined by what you want and plan to do in the future. You don't want to start replacing parts and doing mods twice because you didn't plan ahead.

 

Hopefully your already familiar with this thread

 

https://legacygt.com/forums/showthread.php/turboi-wiki-twist-178684.html

 

tons of info.

Edited by Tehnation
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What are your long term goals? Do you plan to get a bigger turbo? EVERYTHING stems from the turbo!

 

 

 

 

No plans to change the turbo any more.

 

 

 

 

 

If those were my choices I would get a TMIC, 3 port EBCS(boost controller, Cobb and Grimmspeed both make one) and fuel pump(Aem 50-1215).

 

 

Let me take a look at those. Thank you!

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The issue I’m having is that there seems to be a specific performance problem that means the engine is running like garbage right now. I don’t think it’s physical or mechanical because sometimes the performance is there, sometimes not. I don’t see anything in knock or misfire data so I believe that it’s timing but I don’t think it’s pulling timing based upon anything in learning view.

 

Next thing to do for me is to check prior 2nd gear pull logs from a couple of years ago and see how current pull logs compare.

 

For now I don’t want to add a tmic on top of this problem, nor replace injectors.

 

I’m going to look more closely at plugs/coils etc, bug as nothing is showing up in logs or codes I don’t think it’s a dead coil/injector.

 

The other thing it is doing is stumbling off idle if I blip the throttle in neutral. And just today I noticed the rpms drop to 500 and the oil pressure drops to 7 or 8psi when releasing the throttle when fully hot, the slowly creeps back to 850rpm over about 4 seconds.

 

I have cleaned the iat and maf sensors and put a new paper filter in. No help.

 

I get a few fish bites on idle but off idle it is smooth. Drives smoothly, just underpowered.

 

Turbo does hit 16 psi, which is why I think it’s timing. Needs to be further advanced, but I don’t know why it’s not. Would external temp make that much difference? It’s been mid 90s here, we are used to about 80.

 

The last weird observation is that when I was pressing the gas pedal very, very slowly the rpm jumped from 850 to 1500 suddenly then back down. Did this a couple of times as I continued to press the gas pedal. I need to chart the throttle input and make sure there’s no dead spots on the pedal potentiometer.

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Did some logging tonight.

 

 

4 observations:

 

 

- AFR pegs out at 11 during the 2nd gear pull

- Ignition total timing is 11 throughout the pull, but no knock of feedback knock correction. Prior pulls wee 16-20 degrees

- ECU says the turbo only got to 13.6 psi but my turbo gauge said 16.

- The MAF g/s at 5k rpm WOT is about 180 right now. Prior logs from years past put that number at 196 5k rpm WOT. Bad maf? Plugged exhaust/cat?

Edited by Scruit
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Dave,

 

 

Appreciated. I will be back to start the tune over once I've figured out this sluggishness.

 

 

Really looking hard at the MAF and MAP right now. Boost gauge shows 16psi but pull log didn't go over 13-ish, so I need to figure out which is correct. Maybe the MAP is under-reading the boost. MAF readings changes when I cleaned it and the car got a lot better, so I'm going a step further an getting a new OEM MAF. I've been running a KN for ever and I'm worried the oil finally got to the maf.

 

 

I'm 99% sure it's a sensor problem and the result is not enough timing. We'll see.

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Did some logging tonight.

 

 

4 observations:

 

 

- AFR pegs out at 11 during the 2nd gear pull

- Ignition total timing is 11 throughout the pull, but no knock of feedback knock correction. Prior pulls wee 16-20 degrees

- ECU says the turbo only got to 13.6 psi but my turbo gauge said 16.

- The MAF g/s at 5k rpm WOT is about 180 right now. Prior logs from years past put that number at 196 5k rpm WOT. Bad maf? Plugged exhaust/cat?

 

What AFR sensor are you using? The stock one will never read lower than 11.1 or 11.2 or so, even if the actual AFR is richer. Which means that if it's reading 11.1 you really have no idea how rich it is.

 

The stock sensor also needs to be moved out of the exhaust manifold and into the downpipe if you want accurate readings. I ran my 05 like that for a couple years with no issue.

 

And I ran my 09 like that for about a year and the sensor died - which makes me wonder if there's something different about the post-facelift 4th gen cars. Or maybe it's just coincidence, I dunno.

 

Anyway, if you don't have a WBO2, I suggest getting one.... or relocate the stock sensor to the downpipe, and tune for an AFR of 11.5. It might leave a little bit of power on the table vs 11.0 but probably not enough to be noticeable. That's what I was planning to do on my 09, but between the sensor failing and random major life events, I never got around to it.

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After seeing some improvement by cleaning the MAF I put a new Denso MAF sensor in.

 

 

Pre and post replacement values are about the same at idle:

 

 

 

4g/s MAF at 850rpm

injector pulse 2.05ms

AFR went from 14.01 to 14.36

 

AF correction went from 4% to 3%

 

 

 

 

Dirty MAF showed 170g/s at 5krpm

Cleaned MAF showed 180g/s

New MAF shows 195g/s, just like the last time I was power tuning. New MAF appears to have made a difference...

 

 

I'm hitting 15.5psi according to the MAP sensor, and that is consistent with the boost gauge.

 

 

IAM is always 1.000, no knock learning in LV, and my A/F correction numbers in LV are 2.7, 7.2, 0.0 and -3.0

 

 

 

 

My 2nd gear pull from 2krpm to 6krpm takes 5.5 seconds. Not much faster than before, but I've noticed is that the 2nd gear hesitation is gone.

 

 

How does 5.5 seconds sound? Normal? Slow?

 

 

 

 

Considering logging is all looking good now, no knock or wild AF corrections, and the engine is running smooth... I think I'm good to work with Dave on the tune. I would just wonder about one last thing first... The injector duty cycle is 80% at 16psi boost at 5500-6000 rpm. Sounds like I might run into fuelling issues if we push the power too far and I'm wondering if I should consider bigger injectors first...

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