Ask a tuner...

[P3Auto]

Open thread to discuss tunes, answer questions, and advise.... Anyone?
Bring it on...

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[Brando5185]

Surging boost under 3/4-full throttle. Causes?

[LiLpNoY]

Awesome idea.

I've been reading up on how the injectors being Maxed out? Would it be a good idea to upgrade those before going for a protune? Currently stage two using the ots Cobb tune. I do want to protune but just thinking what to do so I'm not paying for every little part.

[missiceblast]

can we have an Ask a Ninja corner too??

congrats P3!!!

[rack]

I must have missed the announcement, whats P3 Stand for Seth?

[06gtleg]

Originally Posted by LiLpNoY

Awesome idea.

I've been reading up on how the injectors being Maxed out? Would it be a good idea to upgrade those before going for a protune? Currently stage two using the ots Cobb tune. I do want to protune but just thinking what to do so I'm not paying for every little part.

Very good idea. BTW i have my stockers for sale hahaha.

[P3Auto]

Originally Posted by Brando5185

Surging boost under 3/4-full throttle. Causes?

Before I go into too much detail its important to understand that most turbo charged engines with larger high pressure turbos don't like part throttle boosting and control can be a real pain. I'm not saying it cannot be done but let me throw out some of the factors.


MAIN PROBLEM: The gain or duty cycle of the boost control to reach desired boost is usually drastically different at part throttle vs. wide open.

Lets assume were talking about an IWG (internal wastegate) which is what stock Subarus and a lot of bolt on turbos use. The IWG has a WGA (waste gate actuator). The WGA has a spring that is designed to keep the waste gate shut up to a certain pressure load. What ever the WGA spring is set to is what your min. boost will be. In other words if you told your boost controller that you want zero boost you would still get what we call "Spring pressure" which might be 6-11PSI in the case of a Subaru typical turbo setup. So the first problem is you cannot make zero pressure at part throttle or below min at part throttle.

Now lets look at a lot of guys/gals that run manual or added on electronic boost control. Does the boost controller know the difference between part throttle and wide open or even off throttle? A good boost controller will monitor throttle position for this very reason. Does yours?

Part throttle boost control issues can also stem from you point of boost control signal. Where do you pick up a boost signal to control your WGA, are you getting it pre-throttle body or post. When your at part throttle there can be differences between the manifold pressure and the pressure you might read at the turbo outlet nipple for instance. In fact there may be a pressure drop after you intercooler as well, but thats another discussion. So you really should be getting your boost control signal from the manifold post throttle body.

The ultimate setup would be two boost gauges one from the turbo outlet region and one from the manifold, then you could monitor for leaks, blocks, or large pressure drops due to restriction in the intercooler. Cool huh?

There can also be some other strangness like turbulence, compressor stalling, etc which will cause the boost to spike and dip as the controller tries to keep up with the changes. Remember a boost controller (electronic style anyway) is constantly changing the duty cycle that it pulses the signal to the WGA. It has to look at the boost currently and figure out what changes to make to hit the desired levels. Sounds simple but its not considering every change is not instant due to turbo lag, delay from longer pipes, and other factors like what I mentioned above. The boost controller is also only allowed to make so much change at one time. You controller problably isn't allowed to pull enough duty cycle off the WGA to lower the boost where you want it.

There is tons more to this and I suggest some reading on how boost control works in general. I know your running an EBC so check all the hoses and make sure you have it connected the best way. If it has no idea of throttle position then you may not be able to solve this problem. I would need to know more about the EBC to answer better.

I think the best solution would be to go back to using the stock boost control system. It knows throttle position and can control part throttle boost much better than any MBC or most EBC's. Other wise drive with a heavier or lighter foot and stay away from that sweet spot that it spikes at. Also allowing the car to control the boost gives you another failsafe in case of problems the ECU you set you back to spring pressure.

Oh another thought, with Subarus I have noticed the by pass valve or blow off valve will crack open at part throttle boost some times. This can cause all kinds of issues as well and it is due to where it gets its vacum signal from to open and how much pressure it has to keep it shut.

[P3Auto]

Originally Posted by LiLpNoY

Awesome idea.

I've been reading up on how the injectors being Maxed out? Would it be a good idea to upgrade those before going for a protune? Currently stage two using the ots Cobb tune. I do want to protune but just thinking what to do so I'm not paying for every little part.

The best way to tell is by logging injector duty cycle %. Run the car up to redline in 3rd or 2nd and see how high a % you hit. I like to keep it below 90% at redline. The COBB AP should be able to log injector duty cycle. There is a second or even third fuel table your tune will switch to in case of a heavy knock event, its around a 10% or more increase in fuel. You should always maintain this in case of an issue.

Injectors need to be upgraded anytime you increase air flow much beyond stock levels with the Subarus. This might be from more boost, bigger turbo, intake changes, cams, etc. I find that the STI is good to about 18-20PSI on the stock turbo with min mods before you really should size up the injectors.

Due to the fact our octane is low up here we tend to have to run rich which means more fuel then others run. COBB OTS tunes have you covered with a very rich tune typically, good and bad.

[P3Auto]

Originally Posted by rack

I must have missed the announcement, whats P3 Stand for Seth?

http://forums.nasioc.com/forums/show....php?t=1955846

[rack]

Great information, but what does P3 stand for?

• Performance times 3?
• Peter Paul and Pat?
• Parking lot 3?

[TurboSetch]

P3 name up to speculation and imagination...lol

[P3Auto]

Yes it is...Wait a second...Multiple personality disorder kicking in again...BTW I am or was Turbosetch for those who missed that part.

[AKSTIDAD]

Originally Posted by rack

Great information, but what does P3 stand for?

• Performance times 3?
• Peter Paul and Pat?
• Parking lot 3?

Its a secret
He said that maybe someday, when his silent partners want to be known he will then give us the info at that time

[rack]

Originally Posted by AKSTIDAD

Its a secret
He said that maybe someday, when his silent partners want to be known he will then give us the info at that time

Ah, gotcha, I must have skimmed over that looking for a 3 word Acronym with all P's

[f1speeder]

I have Cobb Ap on my 06 WRX and tuned by CBRD.

Every 4mths my car starts to bog at 5k to 6k so I have to uninstall the CBRD map then reinstall the factory map then reinstall the CBRD map. Then the car is back to 100%.
It's like it looses tune at about 4mths and I have to re-tune it with the map.

[AKSTIDAD]

Originally Posted by f1speeder

I have Cobb Ap on my 06 WRX and tuned by CBRD.

Every 4mths my car starts to bog at 5k to 6k so I have to uninstall the CBRD map then reinstall the factory map then reinstall the CBRD map. Then the car is back to 100%.
It's like it looses tune at about 4mths and I have to re-tune it with the map.

Do you do the basic maintance ?? ie oil change and filter change at the time of the bog?
I noticed I had a slight decline in perforamance a few weeks ago ( ongoing slightly) and i did my last oil change and looked at my airfilter ... What a winter breakup will do!
Just a suggestion.

[f1speeder]

Yes, I do my oil and filter change at 2800 miles and air filter at 8 mths.

I don't notice anything different after I do these.

[P3Auto]

Originally Posted by f1speeder

I have Cobb Ap on my 06 WRX and tuned by CBRD.

Every 4mths my car starts to bog at 5k to 6k so I have to uninstall the CBRD map then reinstall the factory map then reinstall the CBRD map. Then the car is back to 100%.
It's like it looses tune at about 4mths and I have to re-tune it with the map.

The tune does not change no matter what unless Cobb is doing something bad to the code but its very doubtful. Now that being said your car can learn or make adjustments on the fly or over time.

I would suggest the next time you have the issue take a look at the IAM or DAM what ever Cobb calls it on the AP. It should be a 16 and not below an 8 for an early WRX. If this number falls below an 8 your car will start to go into a limp mode. Different fuel maps, timing retarded, etc. Your car can also learn long term fuel trims and apply them to the open loop portion of the map as well.

The problem with what you describe and the ECU learning is that it does not take four months to figure it out. A day or less of different driving and the car pretty much has it down. Out side temp or altitude changes as well as poor fuel will cause the ECU to make adjustments but nothing should be "corrupting" the tune. I feel the problem may not be related to time but rather an intermittent issue that may hit once in a while which then causes the car to fall into a limp mode.

The next time you have the issue let me know and we can gather some data. I would also suggest you try an ECU reset which would clear all the learned tables and set the IAM/DAM back to default. If an ECU reset doesn't clear up the issue and it absolutely requires a re-tune then I would contact Cobb since it could be a bad AP perhaps or a known bug.

[f1speeder]

Thanks I'll keep you posted.

[rack]

1999 Subaru legacy Outback SUS Limited 30th Anniversary Addition.

When I used to drive my wifes car, if I drove it too rough directly after starting it, the car would seem like it want to lurch forward still, RPM's would be very high, then all of a sudden the car would just die.

Would could cause that?

[NikFu S.]

Is this thread going to focus primarily on engine management issues or do you feel up to takin' a whack at a couple very unique problems with my SVX?

[P3Auto]

Originally Posted by NikFu S.

Is this thread going to focus primarily on engine management issues or do you feel up to takin' a whack at a couple very unique problems with my SVX?

Its not really a supposed to be for major diagnostics on a specific problem. I intended to make it more of a Q&A for people that are tuned or wondering about tuning for adding power or mods. If you want to bring the car to the shop or send me some PM's I might be able to help.

[P3Auto]

Originally Posted by rack

1999 Subaru legacy Outback SUS Limited 30th Anniversary Addition.

When I used to drive my wifes car, if I drove it too rough directly after starting it, the car would seem like it want to lurch forward still, RPM's would be very high, then all of a sudden the car would just die.

Would could cause that?

This could be a lot of things. I would really need to see this happen and be able to log the ECU at the time or look for other signs. I want to say a vacum leak is quite possible or part of the emmisions system is messing up when the system is cold. Dozens of possibles. Bring the car over some time or get with me via PM or phone and we can talk more about it.

[Marlons101]

why is my cel on for missfire but no codes show? why does it flassh atl low rpms but not at high rpms?

I have changed plugs, fuel filter, checked lines, cleaned MAF, ....what else should i do? car runs normal just this flashing cel? my gas mileage is **** so does that point to my front O2 sensor?

[MrDubb]

Originally Posted by f1speeder

Thanks I'll keep you posted.

Hit Chad up since he tuned it, he should be able to tell you.