Ask the Tuner (Tuning Alliance)

[Tuning Alliance]

Hey everyone,

 

I haven't been on here in a while. Brittany has been taking care of this forum for TA(and doing a great job), but I wanted to make myself available here for technical questions. So if you have power goals, reliability questions, or general tuning thoughts please feel free.

 

Without further delay. Fire away folks.

 

~Mike

[Th3Franz]

Speed density tuning vs maf ... what are common mistakes?

[robburns201]

^^^^^ and differences of them for Noobs like me!

[utc_pyro]

1) Do you consider the OEM MAF scaling or injector scaling closer to real?

2) What is your preferred way to dial in injector scaling?

3) How should one adjust injector firing angle when upgrading injectors?

[wbrawley]

What gauges to have up while logging for a tune? DAM, IDC, Boost, FKL, etc?

[sshole]

Do you have a preference for injectors? I have DW 850cc top feed injectors to go with 18G turbo and a local shop is saying they don't want to tune my car because they don't like how finicky the injectors can be (i.e. getting the car to idle smoothly).

[Tuning Alliance]

Speed density tuning vs maf ... what are common mistakes?

 

Improper injector scaling, latency, and tip-in. Things can be a bit easy if you have a good reference like known injectors, known maf calibration, etc. Then you can create a rough VE table by logging various pressure and engine speeds to begin to tune with.

Also I've seen many bumpy tables, in my experience this is the difference between an okay tune and a great tune. Smoothing is key.

There is also a delicate balance with the fuel learning system. So if latency is off the base load calcs are off and then it snowballs skewing the VE table. A heavy amount of fuel post tip can also often trigger learning when it sees a regular spike in corrections.

 

^^^^^ and differences of them for Noobs like me!

 

Speed density is using your MAP (pressure sensor and a charged air temp which requires relocating the air temp sensor) to provide the main calculation for fueling. It has several advantages:

 

1. Provides more physical data for the ecu to look up using a 3d chart with 484 cells of data vs a mafs 54. Which also better compensates for variation in engine load.

2. Engine will still run with a hose popped off or leak with SD, and miscalculations with due to intake/boost leaks with a maf system are eliminated.

3. Engine will not have any issues with vent to atmosphere blow off valves (provided it works correctly and proper spring rate).

 

 

Disadvantages

1. More tuning work.

2. Some believe MAFs are smoother but this depends on the MAF, housing, and airflow. A properly tuned SD car will run extremely well. I have done enough hybrid configurations as well, but overall I'd go with full SD.

 

1) Do you consider the OEM MAF scaling or injector scaling closer to real?

2) What is your preferred way to dial in injector scaling?

3) How should one adjust injector firing angle when upgrading injectors?

 

1. I'm not entirely sure what you mean, but the stock maf curve is okay. Cars are off in both directions all the time (sometimes rich, sometimes lean). Scaling is not something id change on stock injectors, latency can be off a little.

2. Injector scale is really a fixed number to me, based on the flow rate so I simply input it. Latency and tip-in are what I'm tuning, I most if not all maf curves in my library of calibrations, and would calculate based off of the ID in custom cases(this also would need refining). Latency is a combination of fuel trims, tip-in, and feel. I typically start with a default tip-in value, and play with latency until it trims reasonably throughout the range if rpms in conjunction with maf or ve tuning. Then I will actually adjust the tip in as i know the timing of deliver is correct.

3. The firing angle generally doesn't need to be altered unless in extreme cases in my opinion. This is how the fuel is delivered in relation to engine position, if latency is correct it should be firing nearly at the correct time. Not to say improvements cant be made, but I would expect in situations where the injectors are physically further away like in the cases of methanol systems for better atomization you would need to adjust this.

 

What gauges to have up while logging for a tune? DAM, IDC, Boost, FKL, etc?

 

Boost, A/f senor 1, fine knock corr, feedback knock corr., a/f learning #1, intake temp.

 

Do you have a preference for injectors? I have DW 850cc top feed injectors to go with 18G turbo and a local shop is saying they don't want to tune my car because they don't like how finicky the injectors can be (i.e. getting the car to idle smoothly).

 

Most tuners complain about side feed injectors as they can be tricky. I tune up to 850cc sidefeed, above that just dont tune that well. Above that any top feed from 420cc to 1300cc i have no issues with DW and ID I have done tons of. 850cc DW top feed are fairly straight forward in my opinion.

[Max Capacity]

Nice to see you back on the Forum. I do drive past your house every now and then and notice all the Subaru's in the driveway.

[covertrussian]

1) Do you consider the OEM MAF scaling or injector scaling closer to real?

 

I looked at the MAF scales of different year Legacies & WRX's and they all had different scales. I'm not sure even Subaru knows the answer to this .

 

Though there are other changes in between legacy years, like VF40 vs VF46, side fed vs top fed, compression, etc.

[solidxsnake]

I looked at the MAF scales of different year Legacies & WRX's and they all had different scales. I'm not sure even Subaru knows the answer to this .

 

Though there are other changes in between legacy years, like VF40 vs VF46, side fed vs top fed, compression, etc.

 

I wouldn't be surprised if they have an automated routine to throw a specific car (i.e. whichever one is being used for testing a specific tune) onto a dyno, run though some tests and gather data from logs to use to extract MAF scaling, MAP scaling, O2 sensor scaling, etc. If the changes are minimal between different years with otherwise the same equipment, that's what I'd expect, along with the typical refinements you'd see roll out it subsequent years.

 

On-topic: I noticed you raised the redline from factory in my tune Mike (and I'm sure this is a normal thing for you as well). Besides the obvious benefit of having more headroom to rev the car, is there any justification that the motor can safely handle the extra revs? If I remember correctly, the EJ257 STis have a 7k redline, and that's justification enough, but would like to hear your thoughts (and since I know you tune safe, your word is more than enough to appease me ). For what it's worth, the extra 500RPM has definitely been useful for autocross.

[Tuning Alliance]

I wouldn't be surprised if they have an automated routine to throw a specific car (i.e. whichever one is being used for testing a specific tune) onto a dyno, run though some tests and gather data from logs to use to extract MAF scaling, MAP scaling, O2 sensor scaling, etc. If the changes are minimal between different years with otherwise the same equipment, that's what I'd expect, along with the typical refinements you'd see roll out it subsequent years.

 

On-topic: I noticed you raised the redline from factory in my tune Mike (and I'm sure this is a normal thing for you as well). Besides the obvious benefit of having more headroom to rev the car, is there any justification that the motor can safely handle the extra revs? If I remember correctly, the EJ257 STis have a 7k redline, and that's justification enough, but would like to hear your thoughts (and since I know you tune safe, your word is more than enough to appease me ). For what it's worth, the extra 500RPM has definitely been useful for autocross.

 

That is correct I do raise them a bit on manuals, autos are a bit different in trying to get them to shift quickly. The engine is certainly safe to operate to 7200, so I usually keep them to <7000 on most OEM sized turbos. Yes, power is going down above 6k especially on a vf40/46, but its usable and sometimes helpful (like what you mentioned in autox). On larger turbos with factory heads I will often go to 7200, to best utilize the powerband. I also often opt to use a soft throttle based cut, below the factory fuel cut. This reduces throttle angle above 6900 or so rpm, gently keeping the motor under 7000.

 

~mike

[Jarrettgoose]

I have a 1994 Subaru legacy with the EJ22T when I put the gas pedal to the floor RPMs go up but I’m getting very little acceleration the last owner of the vehicle put in different feel injectors this problem be because of not getting tuned after new injectors ?

[Max Capacity]

Normally rpm's going up and car not going faster as you say, is a slipping clutch.

[Th3Franz]

Good info mike, thanks

[Dishwasher]

You've tuned my Stage 2 Legacy GT and it's awesome. When we began the tuning process you recommended an EBCS, and I turned you down. I'm still not clear on what an EBCS would get me that the factory boost control system does not. Can you clarify? Should I pick one up?

 

Would you as a tuner get more benefit from an EBCS or from a wideband AFR?

[Max Capacity]

FWIW, tuningalliance@gmail.com

 

Mikes a busy guy.

 

DW, I'm guessing a wideband as that's what is used on the dyno.

 

Also I did have Mike install a EBCS on my 09 Spec B. The wagon is still on the stock set up.

[Dishwasher]

Thanks Max, is the Spec.B on a vf40 or is it also on the vf52?

[Eric_H]

Hi Mike,

I'm getting ready for a protune, and was reading around in the tuning threads. I think you mentioned getting a DP, wastegate actuator, EBCS to make the most of the protune in a previous thread. I am not looking to overly stress my stock internals on an EJ255 w/ vf46. That being said, are there any certain mods (internal or not) you would recommend to maintain the longevity and replace inefficient OEM parts?

Thanks!

[Eric_H]

Hey Dishwasher,

This is what I found when researching for mine....https://cobbtuning.zendesk.com/hc/en-us/articles/200025244-OEM-Subaru-Turbochargers

[Max Capacity]

Thanks Max, is the Spec.B on a vf40 or is it also on the vf52?

 

My 09 Spec B has the stock turbo.

[Max Capacity]

Hi Mike,

I'm getting ready for a protune, and was reading around in the tuning threads. I think you mentioned getting a DP, wastegate actuator, EBCS to make the most of the protune in a previous thread. I am not looking to overly stress my stock internals on an EJ255 w/ vf46. That being said, are there any certain mods (internal or not) you would recommend to maintain the longevity and replace inefficient OEM parts?

Thanks!

 

email Mike at tuningalliance@gmail.com

 

His tune will not over stress the stock internals. He's been doing this for a long time and has it figured out well.

[Eric_H]

Thx Max Capacity! I will shoot him an email.

[robburns201]

Mike at tuningalliance@gmail.com is E-tuning my car now and it keeps getting better and better with every revision...plus I have a 5eat and his knowledge of these transmissions is awesome....Also if you're not getting a response you can email brittanys@tuningalliance.com and Will most deff get back to you...Mike is the only tuning guy there so he needs help with emails...Good Luck!

 

Sent from my 0PJA2 using Tapatalk

[wbrawley]

Mike at TA is e-tuning mine currently as well. Only on 2nd revision so far, hope to have it dialed in soon but 1st tune was way better than Cobb OTS.

[Eric_H]

Thanks for the second email address. I will try that one as well. How do you guys feel about an e tune vs a road or dyno one? Sounds like you are pretty happy with the TA etune. I’m also moving away from a COBB ots map, and am looking at a local dyno tune (SLC area).