OK. I have decided to install headers. I have bought cool socks for my boots and wires, I have an Elite Engineering Thermal Abs etc. I live in Wyoming. I have found a competent mechanic here that I feel comfortable letting do the install which isn't rocket science I just don't want to do it on jackstands!! Nevertheless my question is about the tune. I already have the Vararam and I am sure I will need a tune after the headers. Does a Chevrolet dealer have to do it or can it be done with aftermarket equipment? I am confused? Also there is a Corvette only center in Denver CO about 5 hours away. They can tune it but should I drive that far before the tune? I know there are some mail order tunes but I really don't want to be without my car for that long. What exactly does the tune entail and require? Any input and suggestions would be greatly appreciated!!

 

Just my opinion, but with a VaraRam and Headers, I would not pay the price for a tune. The car's PCM is capable of adjusting the fuel and spark maps within the parameters for these mods and the car will run fine. It will take 100 or so miles and several start cycles for it to fully make the changes, but the car will run fine. Don't get me wrong, with a competent tune, you might pick up a (very) few horsepower, but, for my experience, the money for the tune could be spent wiser. Good luck.

 

Get a tune without a doubt, I added a Callaway honker and LG LTs and lost about 3 HP, the PCM was overcompensating for the increased air flow and dumping too much fuel into the intake causing it to run rich. I got it tuned and picked up around 60 Hp from 330rwhp to 393 rwhp. You need the tune.

 

IMHO, a tune is beneficial even without any mods. If nothing else, modifying Torque Management and adjusting the fan settings is worth it.

Not every car with headers and/or a CAI will lose power without a tune, but almost every car with mods will benefit greatly. Perhaps you won't gain 60 HP, but you will gain power, and probably get better gas mileage as well.

A mail order tune is not that intrusive, can be done within a few days if you FedEx the ECM both ways. See the Corvettes of Westchester threads on this subject. Other tuners, such as Texas Speed, also offer this service.

 

This is not correct. A header car will be lean closed loop and rich on the tables so a tune should be done to correct the mixture regardless of whether the car is throwing codes.

There are a lot of threads on mail order versus the live tune. My own opinion is that a good (<---- notice key word, good) live tune is better than the canned version. Driving to the tuner shouldn't be a problem, just remember your lean part throttle so try and stay out of it till you get tuned.

 

If you are doing headers and a CAI then you need a tune. 99% of us get a CEL for the O2 sensors that can only be permanently removed with a tune. The throttle response will drastically improve with a tune and you will have the benefit of having your car tuned to your mods instead of the Chevy Generic tune for 91 Octane and any altitude.

The COW tune is great, if you send your ECM to Chuck check the shipping prices. The United States Postal Service was HALF the price of United Parcel Service for the same overnight delivery. If you send a Dyno sheet to Chuck with your ECM be sure and let him know if it was a Wide Band O2 or a tailpipe sniffer for A/F ratio. I didn't and had to get it re-tuned.

 

I have headers only.....NO CAI yet. I have been driving 25 miles/week for almost 4 months with no problems w/o tune. I haven't tuned yet because I plan on cam install in a couple of months. Are we saying that headers w/o tune can damage a car?

 

OK. So I get that the majority says get a tune. I planned on that. Figure with the money I am spending on the mods I don't want to leave HP on the table and also want the improved throttle response. So if I am not giving the car WOT is it ok to drive it 300 miles to the nearest tuner? Also if there are any tuners reading this what is the turn around time to send my computer in? Do I have to have a dyno sheet? I am not sure if there is a dyno here for cars? I know there is one for bikes but not sure about cars? I hate to sound naive but I am really new to this and want to do this right without a big hassle or possible damage to engine. Thanks for all the help....Craig

 

Hey Craig.... No worries about driving the car with headers and no tune...The worst that happens is a check engine light fort the cats and o2's. But, don't wait to long.

DO NOT drive a cam / heads / Fi car with no tune....You won't get very far!

If you send your pcm to me, it will be back to you same or next day after I recieve it. REALLY QUICK.

Call me with any other questions you might have....914-332-0049 anytime!

STAY TUNED!
Chuck CoW

 

Craig, Where are you in Wyoming? I'm in Wheatland and did similar mods. I had COW do my tune by mail order. I can feel the difference but I felt I really needed it because of surging a very light throttle in lower gears. Chuck really helped this but I still feel a little surging. The throttle responce is much better after the tune. I don't have any dyno figures though. Bill

 

You might want to try the diablo sport predator tuner. it is easy to use , and you will get 25 rwhp. this is what i used and i love it. however you must have access to 93 octaine fuel.

 

We can only get 91 out out here, because of the altitude, I think.

 

I did Callaway intake and Melrose LT headers without a tune and drove it for a few hundred miles. Then had a tune. It made a BIG differance. I'm lucky to have a great shop a half hour away, but a great tune is well worth the drive.

Just my 2 cents.

 

Who did you use?

 

Yes with our altitude the highest octane I have seen is 91 unless you add booster? It would be nice to live close to a "good" tuner but it sounds like mail order tune does a pretty good job. Question about the diablo predator tuner. What does that entail? Is there present programs? I have never used a tuner and have absolutely no idea what it entails? Do alot of you do your own tunes or is this different?

 

Gee, then I guess your cars don't run when the outside temp is -10*, or 110*, HUH? Not saying the car won't pick up a horsepower or two, but the CAI,..... BS. All it does is collect COLD AIR!!! What's the difference in driving in the winter, when the intake supply is much colder and denser, and driving in the summer heat? The car's PCM compensates. Leaner because of headers. Will your car not run 1200' above sea level? The pcm in these cars is designed to run the engine in a wide parameter of conditions. If you wish to throw away $600 for a dyno tune on a car with minor mods, then knock yourself out.

 

I dont like having to fork out 500 bucks either considering the marginal gains but that doesnt chage the facts. The car will be lean closed loop and rich on the tables in all conditions. The ECM cannot adapt properly to headers. I went almost a 1000 miles before I was able to get my car tuned and guess what. My car was lean closed loop and rich full throttle. There are no exceptions, this is what happens when you install headers.

If your comfortable with this thats fine.

 

The diablo is easy to use. you just plug it in to the diagnostic port, and it downloads a pre set tune into the pcm. i actually called diablo sport and asked them how they get the paramaters, and they said that they use a hp tuner, to get the most hp and torque. then program it into the diablo, which you in turn download into your pcm. you can also tune every thing yourself if you want to.

 

One of the main benefits of computerized engine controls is the ability to compensate for different conditions. There are sensors which tell the computer the air temperature (IAT), the mass air flow (MAF), absolute manifold pressure (MAP), throttle position (load demand), O2 concentration (burn efficiency) etc. The computer uses these readings to point to different parts of a set of tables to tell it how to set the fuel and spark for these particular conditions. The computer also learns, trimming the values in the tables by up to 20% based on closed loop feedback. So it actually self-tunes as you drive.

But Chevy made some assumptions about the car, and the way it would be driven, that can leave some horsepower on the table. A tuner can use dyno and live road logging information to alter the factory's choices in ways that can pick up more power, remove some nanny protections, improve part throttle response, etc.

(Note that a proper tune requires access to actual data from the actual car. Canned tunes may not be safe, or may leave power on the table in a particular car operated in particular locations, or in a particular manner. Any performance tune takes you closer to the edge of the safety envelope, so you want to make darn sure the tune doesn't cross the line in a particular car/situation.)

Generally, the factory tune is conservative and safe, even with mild mods like different air cleaner housings or headers and exhaust system changes. (Radical changes like wild head/cam packages, turbo or supercharge setups, etc are a different story.) So you won't damage anything by not tuning the car for most common mods, but you may be leaving some power on the table, some fuel economy on the table, or some driveability on the table.

If you are into performance mods, I think you should own a copy of HP Tuner software so you can live log the car and tune it. If you don't want to do a tune yourself (and the learning curve to do it right is steep), at least the software will allow you to document your car before and after mods for a tuner who can then make up and send you a custom tune to meet your particular objectives in your particular driving situation that you can then download into the car. (Some tuners won't work this way, some will, find one who will.)

 

Hey man.. Please call me.... If your car was surging before....and is still surging after the tune...I think something else is wrong with your car.... Please call me monday and tell me about it..... It's not suposed to do that.....

Chuck CoW