LS1 upgraded - programmed? how?
Thread Starter
Launching!
Joined: May 2010
Posts: 228
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From: MS
LS1 upgraded - programmed? how? I bought a 2002 SS with a FAST intake, 90mm throttle body, and long-tube headers installed. The cats were also removed. I live in Mississippi, and the car is from New Mexico. I don't know if the car has been tuned since these additions.
Besides the air/fuel mixture, could there be anything else that needs to be tuned? Could a programmer change the a/f mixture and fix any other problems there might be?
Thanks
Besides the air/fuel mixture, could there be anything else that needs to be tuned? Could a programmer change the a/f mixture and fix any other problems there might be?
Thanks
Staging Lane
Joined: Jan 2009
Posts: 59
Likes: 0
From: Bella Vista, AR
PCM Tuning is Essential With the type of mods it is essential that you tune the Fuel Air Multiplier table (stable cold starts) and volumetric efficiency table (desired air fuel ratio at all combinations of manifold pressure and RPM levels). You will only achieve a small fraction of the benefit from the mods without changing the VE table. Tweaking timing advance and Power Enrichment verses RPM is are also necessary to obtain peak TQ and HP from your engine, even if you do not perform any mods because factory settings are performed with an eye on pollution control instead of all out performance.
Staging Lane
Joined: Jan 2009
Posts: 59
Likes: 0
From: Bella Vista, AR
Fyi Proper tuning will solve any performance problem you have unless there is a damaged component or sensor. All sensors must be working properly; even an engine coolant temperature sensor that is not working will ruin performance. Using the PCM to "dial in" you tune unleases amazing performance in the LS series motors.
Did the previous owner install an aftermarket CAM and heads? One would think so given the other aftermarket components you have mentioned. below 1000 RPM it is easy to experience a 15% or higher decrease in volumetric efficiency (if PCM is not adjusted for this idle will be way too rich) and similarly your VE will increase by 15% or more at 4800 to 5200 RPM (not adjusting for this will result in AFR being too lean).
Power enrichment setting of 1.1 at WOT will give you near optimal performance - these motors like 13.1 AF ratio. A very common mistake is using an aftermarket mass air flow sensor that is poorly calibrated, or modifying a stock one which is nearly impossible to recalibrate properly. Look the the Pro-M racing MAF sensors; no need to go with a diameter larger than stock because this is not the component that restricts air flow, and larger diameter results in reduced resolution (MAF sensor cannot measure air flow as accurately). The larger throttle body you have is okay, but 85mm is probably more than sufficient to extract optimal peformance out of your motor and it will have better performance at idle and tipping in when accelerating from stops and the area just above idle. Let me know if I can help you; I have about 400 hours tuning experience on the LS1 and LS6 engines.
Did the previous owner install an aftermarket CAM and heads? One would think so given the other aftermarket components you have mentioned. below 1000 RPM it is easy to experience a 15% or higher decrease in volumetric efficiency (if PCM is not adjusted for this idle will be way too rich) and similarly your VE will increase by 15% or more at 4800 to 5200 RPM (not adjusting for this will result in AFR being too lean).
Power enrichment setting of 1.1 at WOT will give you near optimal performance - these motors like 13.1 AF ratio. A very common mistake is using an aftermarket mass air flow sensor that is poorly calibrated, or modifying a stock one which is nearly impossible to recalibrate properly. Look the the Pro-M racing MAF sensors; no need to go with a diameter larger than stock because this is not the component that restricts air flow, and larger diameter results in reduced resolution (MAF sensor cannot measure air flow as accurately). The larger throttle body you have is okay, but 85mm is probably more than sufficient to extract optimal peformance out of your motor and it will have better performance at idle and tipping in when accelerating from stops and the area just above idle. Let me know if I can help you; I have about 400 hours tuning experience on the LS1 and LS6 engines.
Thread Starter
Launching!
Joined: May 2010
Posts: 228
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From: MS
Thanks Everyone: Thank you for the info.
James: It does not a performance cam or heads on it. Those are near-future upgrades though. I'm stuck between the MS3 and the Futral F14 cam...
Back to the subject, I will probably end up taking my car to a local shop and let someone that knows what they're doing work with it. I appreciate the offer, but I'm very meticulous about my car. I would much rather be there watching the whole operation go down.
James: It does not a performance cam or heads on it. Those are near-future upgrades though. I'm stuck between the MS3 and the Futral F14 cam...
Back to the subject, I will probably end up taking my car to a local shop and let someone that knows what they're doing work with it. I appreciate the offer, but I'm very meticulous about my car. I would much rather be there watching the whole operation go down.
400 hours? Hmm.
With the few mods that you have it is probably rare that it is essential to tune the open loop fueling table. A lot of cars with big cams probably are running with this table stock and are having little trouble with cold starts.
Also as long as you're running the MAF, tuning the VE tables won't do much of anything. Not to mention that for his few bolt ons the VE table probably isn't that far off anyway.
Modified MAF and aftermarket MAFs are about equal in there ability to be dialed in. It's not usually as easy as a completely unmodified stock one, but as long as it is in good working order can be dialed in pretty close relatively easy. A stock unmodified will do nothing to hurt performance on a bolt on car. With heads and cam it could cause a slight restriction but not that much, but at that point if you want every last horsepower you'll need something besides stock. And any change to the MAF directly affects the tune.
To answer your questions though, it's not imperative that you get it tuned right away (unless you have to get it inspected or something) if those are all the mods that you have. You will be giving up a few horsepower but not likely enough to be worth the price of getting a tune. Save your money for heads, cam, etc,.. and tune it then when it really needs it.
And I wouldn't mess with a programmer. If you must do something, then get a mail order tune from a reputable shop (Frost). You'll be saving money and getting more.
With the few mods that you have it is probably rare that it is essential to tune the open loop fueling table. A lot of cars with big cams probably are running with this table stock and are having little trouble with cold starts.
Also as long as you're running the MAF, tuning the VE tables won't do much of anything. Not to mention that for his few bolt ons the VE table probably isn't that far off anyway.
Modified MAF and aftermarket MAFs are about equal in there ability to be dialed in. It's not usually as easy as a completely unmodified stock one, but as long as it is in good working order can be dialed in pretty close relatively easy. A stock unmodified will do nothing to hurt performance on a bolt on car. With heads and cam it could cause a slight restriction but not that much, but at that point if you want every last horsepower you'll need something besides stock. And any change to the MAF directly affects the tune.
To answer your questions though, it's not imperative that you get it tuned right away (unless you have to get it inspected or something) if those are all the mods that you have. You will be giving up a few horsepower but not likely enough to be worth the price of getting a tune. Save your money for heads, cam, etc,.. and tune it then when it really needs it.
And I wouldn't mess with a programmer. If you must do something, then get a mail order tune from a reputable shop (Frost). You'll be saving money and getting more.
You are fine on a stock tune with your mods - like Jon said, not getting everything out of it if it isn't tuned, but save your money till you get the cam or heads/cam done. Then find a good tuner in your area - that is the hardest part! There are alot of people/shops out there that "say" they know LS engines... find the modified LS cars in your area and talk to them about thier driveability and reliability and you will find out who the good tuners are.
