minimum hp gains from gmpp headers/A.I./catback?

[matt55]

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[playhard67]

so which is it??? Is a tune permanent? Or does it default to stock with a power failure (disconnect battery etc)??

if you just do a performance tune and nothing else...won't that also void warranty?

[Mblock66]

Originally Posted by CamaroSpike23

define minimal. 5ph? 10hp? 15? 35? while the gains will be improved upon by a tune, freeing/smoothing up the intake air will give you gains out the door. exhaust becomes tricky as you can mess up the backpressure with the motor and hurt your performance over helping it. but the MAF's that GM uses are some of the best. the only thing with a CAI that could hurt is if the diameter of the tubing is not setup properly and impedes the flow of air rather than helps it, which would lead to lost power.

which brings me to a question... you say you lost 7 hp on a subaru, do you have the 3 dyno sheets from stock, CAI, tuned to show? I dont doubt you in the least that you lost hp, but I would like to see the overall power curve rather than just peak numbers. also did it lower your torque values at all? did it bump the power band up or down in the rpm range at all? jw.

Oh no it lost 7 hp through the entire range. Sorry I didn't mean peak. The intake screwed up the g/s and MAF readings so bad that they entire curve moved down. Once it was tuned (as best as we could) it got like 3 hp which almost makes it not worth it at all. Why spend $200 on the intake and $300 on a dyno tune to get 3 hp. So buyer beware is all I am saying. Don't believe everything you read on dyno charts. They are usually totally overstated. KN intakes never make the 22 hp they claim but that is marketing for you.....

On the Subaru cars we have two tunes. One is called a realtime and the other is a base tune. When you lose power source you lose the realtime map but the base map will stay.

So for example if you are running a stage II 19 psi boost map on 93 octane as your base but you want to flash a valet realtime over it so the car will not go over 1500 rpms you can do that on the fly without needing a full base flash. But if the valet is smart enough to disconnect your battery and reconnect, it will wipe out the realtime and he can go for his joyride on your performance mapped car.

I am not sure how HP tuners works on the GM cars as I was not the primary tuner in the shop. So i am not sure if there are base and reatime applications like in the street tuner / pro tuner software for subaru ecus. I would think not. It is probably a base flash and that is it. So that means if you lose power the tune will stay

[Speedy1975]

Originally Posted by Dom

GM doesn't give it performance tune. It comes with a reliability tune.

I would definitely re-tune after every mod. Why wouldn't you? Connect a tuner, make some WOT runs, record, check O2s and so on. It's not that hard. Every car reacts differently.

Firstly, cars from the factory are tuned to EPA standards which is usually quite lean.

Secondly, tuning after every mod, while giving you the most out of the mod, is not very cost effective. It's best to install all the mods you plan, and do the tune as the final step to maximize all the mods as a system. This will provide the most bang for the buck.

Originally Posted by playhard67

so which is it??? Is a tune permanent? Or does it default to stock with a power failure (disconnect battery etc)??

if you just do a performance tune and nothing else...won't that also void warranty?

I've never heard of a tune being lost if the battery disconnects. The chips in ECMs are EPROMS which hold their data after power is removed.

I have no idea on the tune vs. warranty deal. If GM has a way to know you've changed the program, I'd assume they have some wriggle room on the warranty.

[1_2Many]

Sorry if I sound ignorant here, but I was under the impression most modern cars are able to learn how to best use their power regardless of modifications.

Couldn't you just reset your ECU (i.e. unplug battery for a few hours) and have the system learn how to deal with the new intake, exhaust, cam, etc.?

[PsyDoc]

Originally Posted by Speedy1975

I've never heard of a tune being lost if the battery disconnects. The chips in ECMs are EPROMS which hold their data after power is removed.

I have no idea on the tune vs. warranty deal. If GM has a way to know you've changed the program, I'd assume they have some wriggle room on the warranty.

Perhaps I misread or wrongly inferred some reports over in one of the Mustang forums about an issue some owners, who had put mods on their cars, have with the stereo system (Shaker 500 and 1000, I believe) draining the battery. Because the guys did not drive the car that often (2-3x a month or so), they reported that once they got it fired up and took it out, it did not run like before. They went home, reloaded the tune, and it ran like it should.

[Speedy1975]

Originally Posted by 1_2Many

Sorry if I sound ignorant here, but I was under the impression most modern cars are able to learn how to best use their power regardless of modifications.

Couldn't you just reset your ECU (i.e. unplug battery for a few hours) and have the system learn how to deal with the new intake, exhaust, cam, etc.?

Modern ECMs have some "learning" capability, but the range of adjustment is limited. Typically modifications like CAIs and Catbacks push this adjustment outside of it's window.

The adjustments built in to a stock ECM are designed to deal with changes in temperature and elevation. Not the addition of hop up parts.

I learned this directly when supercharging my 4Runner. I hooked up a computer and monitored timing adjustments the computer made before and after forced induction. After the SC was installed it was well outside of the range the computer could deal with. In my case I had to solder in a piggy back ECM to the stock ECM and program it with a laptop to get the timing back to where it needed to be.

[CWI]

Originally Posted by playhard67

so which is it??? Is a tune permanent? Or does it default to stock with a power failure (disconnect battery etc)??

if you just do a performance tune and nothing else...won't that also void warranty?

There is only one answer to that question and you can probably get a few different answers here.

I have been told by the service manager at my dealer that disconnecting the battery WILL reset the ECM to the default settings and that the ECM in my Colorado does have limited learning capability. Any codes will remain until they are erased by external computer.

If you want the answer for a particular vehicle, asking a service dept. They work on them all the time, they would be my choice for accurate info.

[383ss]

Originally Posted by CWIweldace

There is only one answer to that question and you can probably get a few different answers here.

I have been told by the service manager at my dealer that disconnecting the battery WILL reset the ECM to the default settings and that the ECM in my Colorado does have limited learning capability. Any codes will remain until they are erased by external computer.

If you want the answer for a particular vehicle, asking a service dept. They work on them all the time, they would be my choice for accurate info.

then he's a freaking idiot like most people that work at dealerships.

[matt55]

Do stock ECU's need to be re-programed after you dis-con the batt ?

When a ECU is RE-flashed the stock program is written over to new values , still acts stock but with just new values .

The only way to remove it is Re-flash it back over it .

[BeermanSS]

Yes sir. Once your re-write the vcm the only way to get it back is to write the stock tune back in.

[Dom]

Originally Posted by Speedy1975

Firstly, cars from the factory are tuned to EPA standards which is usually quite lean.

Secondly, tuning after every mod, while giving you the most out of the mod, is not very cost effective. It's best to install all the mods you plan, and do the tune as the final step to maximize all the mods as a system. This will provide the most bang for the buck.


I've never heard of a tune being lost if the battery disconnects. The chips in ECMs are EPROMS which hold their data after power is removed.

I have no idea on the tune vs. warranty deal. If GM has a way to know you've changed the program, I'd assume they have some wriggle room on the warranty.

It is cost effective if you buy a programmer and do it yourself every time. I tuned my car at the track after every mod. Taking it to a tuner will get expensive. I don't like dyno tunes anyway. Real world WOT is much more accurate.

Out of the factory cars run rich not lean. Rich is safe, lean is dangerous. I got noticeable boost in power when I leaned out my rich running car. I went from rich to right where it should be. I could have gone lean but it's not safe to run the car lean.

[Dom]

Originally Posted by BeermanSS

Yes sir. Once your re-write the vcm the only way to get it back is to write the stock tune back in.

Exactly. The first thing I do is make a couple of copies of the stock program to revert back. I keep a history of every tune after every mod so I can backtrack if I need to.

I know with the import crowd, they don't have tuners, rather chips. Thats just a cookie cutter tune on that chip and is not nearly as good as a real tune.

[swifttal]

Originally Posted by Dom

It is cost effective if you buy a programmer and do it yourself every time. I tuned my car at the track after every mod. Taking it to a tuner will get expensive. I don't like dyno tunes anyway. Real world WOT is much more accurate.

Out of the factory cars run rich not lean. Rich is safe, lean is dangerous. I got noticeable boost in power when I leaned out my rich running car. I went from rich to right where it should be. I could have gone lean but it's not safe to run the car lean.

Do you have a link/company you'd recommend for programmers?