Has my c5 been "tuned"?
09-02-2014, 10:15 AM
#1
Has my c5 been "tuned"?
Hi guys,
Forgive me, but I have several questions here, and I want to learn something.
I recently purchased my c5 and have been reading up on all the 'tuning' (some) guys do to their vettes. I will be the first to admit that I don't know exactly what that is, but I have some idea. You can tune 'em up for more horsepower/less fuel economy?, but I was wondering if it is possible to do the reverse (from stock)?, i.e. slowing the pace of fuel injection. I drove the car home and coming home I got about 27 MPG on the highway (interstate), and was wondering if that is normal, assuming the car has NOT been tuned 'down' sort-of-speech, from the stock settings. I ran 93 octane. It is a '99, automatic, with 62K on the clock, and it DOES have a carbon fiber intake, and a different exhaust than stock, but right now I'm not exactly sure what kind it is-----After the cats, 2 "mufflers" (if you want to call 'em that, lol)(look like 2 big Tylenols), right underneath the seats, about 18-24 in. in length, and then a straight shot all the way to the back.
I assume that "tuning" could also include some tweaking with the computer systems to produce MORE or LESS hspwr and fuel economy? and if a car has been tuned "down" (meaning less power/more MPG), would it cause the acc. pedal to feel a little 'soft' compared to one that hasn't? and if that has been done in the past, can it always be reversed back to "stock" settings if that's what you want, sometime in the future?
I'm really not complaining either way, I love my c5.... (navy blue met./black leather)
Just wondering......................
Forgive me, but I have several questions here, and I want to learn something.
I recently purchased my c5 and have been reading up on all the 'tuning' (some) guys do to their vettes. I will be the first to admit that I don't know exactly what that is, but I have some idea. You can tune 'em up for more horsepower/less fuel economy?, but I was wondering if it is possible to do the reverse (from stock)?, i.e. slowing the pace of fuel injection. I drove the car home and coming home I got about 27 MPG on the highway (interstate), and was wondering if that is normal, assuming the car has NOT been tuned 'down' sort-of-speech, from the stock settings. I ran 93 octane. It is a '99, automatic, with 62K on the clock, and it DOES have a carbon fiber intake, and a different exhaust than stock, but right now I'm not exactly sure what kind it is-----After the cats, 2 "mufflers" (if you want to call 'em that, lol)(look like 2 big Tylenols), right underneath the seats, about 18-24 in. in length, and then a straight shot all the way to the back.
I assume that "tuning" could also include some tweaking with the computer systems to produce MORE or LESS hspwr and fuel economy? and if a car has been tuned "down" (meaning less power/more MPG), would it cause the acc. pedal to feel a little 'soft' compared to one that hasn't? and if that has been done in the past, can it always be reversed back to "stock" settings if that's what you want, sometime in the future?
I'm really not complaining either way, I love my c5.... (navy blue met./black leather)
Just wondering......................
Last edited by JayTee72; 09-02-2014 at 10:20 AM.
09-02-2014, 10:31 AM
#2
Oh, and just FYI, I did this:
On a 35mph road here I put it on cruise at 32 mph, and the DIC showed "inst. mpg" hovering between 30-32 mpg. Is this normal ? Is this right? or is the DIC reading off some....? or has she possibly been tuned "down"?
On a 35mph road here I put it on cruise at 32 mph, and the DIC showed "inst. mpg" hovering between 30-32 mpg. Is this normal ? Is this right? or is the DIC reading off some....? or has she possibly been tuned "down"?
09-03-2014, 04:04 AM
#3
Le Mans Master
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St. Jude Donor '13-'14-'15
Tuning a stockish engine without major mods as yours will always result in more HP and better mileage due to the engine running more efficiently--- There is no trade off of HP vs mileage---Only when you do heads cams gears stall converter etc the mileage may go down but not much----27 MPG is average maybe a tiny bit low even---32 MPG in high gear at a low speed is normal---
09-20-2014, 04:36 PM
#4
Melting Slicks
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St. Jude Donor '14,'18
Congrats on your purchase. I bought a 02 in 08 and love it. I was directed to a Corvette speed shop where for $250 they hooked up a laptop, changed the shift points (auto) and removed the throttle delay that's built into the motor to reduce emission (I noticed the delay when punching it on the interstate to move around the packs, they scare me!). He said I wouldn't recognize the car and was he ever right.
The motor is computer operated to run at max efficiency. Your mileage is determined mostly by how you drive - considering it's tuned and I don't plan on changing plugs until 100k. 27 mpg hwy is great. I even run the car for a year on regular and it ran fine but I did then start to notice some pinging and stay on hi octane. By watching your mpg you'll know when your motor needs attention.
The motor is computer operated to run at max efficiency. Your mileage is determined mostly by how you drive - considering it's tuned and I don't plan on changing plugs until 100k. 27 mpg hwy is great. I even run the car for a year on regular and it ran fine but I did then start to notice some pinging and stay on hi octane. By watching your mpg you'll know when your motor needs attention.
10-13-2014, 08:47 AM
#5
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St. Jude Donor '10
Congrats on your purchase. I bought a 02 in 08 and love it. I was directed to a Corvette speed shop where for $250 they hooked up a laptop, changed the shift points (auto) and removed the throttle delay that's built into the motor to reduce emission (I noticed the delay when punching it on the interstate to move around the packs, they scare me!). He said I wouldn't recognize the car and was he ever right.
The motor is computer operated to run at max efficiency. Your mileage is determined mostly by how you drive - considering it's tuned and I don't plan on changing plugs until 100k. 27 mpg hwy is great. I even run the car for a year on regular and it ran fine but I did then start to notice some pinging and stay on hi octane. By watching your mpg you'll know when your motor needs attention.
The motor is computer operated to run at max efficiency. Your mileage is determined mostly by how you drive - considering it's tuned and I don't plan on changing plugs until 100k. 27 mpg hwy is great. I even run the car for a year on regular and it ran fine but I did then start to notice some pinging and stay on hi octane. By watching your mpg you'll know when your motor needs attention.
I have an 04 350/350 automatic and wondered the same thing as the OP. My mpg on the highway (usually 65-75 mph) results in 27 or slightly better. Also, I only put 91+ octane and non-ethanol gas in it.
Re "removing the throttle delay", will that cause a problem with emissions testing, i.e., dirtier exhaust? I live in NY state.
Shalom,
Bob
10-13-2014, 03:12 PM
#6
Melting Slicks
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St. Jude Donor '14,'18
Rabbi,
I have an 04 350/350 automatic and wondered the same thing as the OP. My mpg on the highway (usually 65-75 mph) results in 27 or slightly better. Also, I only put 91+ octane and non-ethanol gas in it.
Re "removing the throttle delay", will that cause a problem with emissions testing, i.e., dirtier exhaust? I live in NY state.
Shalom,
Bob
I have an 04 350/350 automatic and wondered the same thing as the OP. My mpg on the highway (usually 65-75 mph) results in 27 or slightly better. Also, I only put 91+ octane and non-ethanol gas in it.
Re "removing the throttle delay", will that cause a problem with emissions testing, i.e., dirtier exhaust? I live in NY state.
Shalom,
Bob
10-31-2014, 08:51 AM
#8
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For a manual its actually easier than an auto to see if someone has messed with the tune. In Manuals, the first thing they do is shut off the CAGS (Skip 1-4 shift). By the way, this is one of the most aggravating features GM has ever introduced :-)
For both auto and manual, monitor your Engine temp from a cold start and verify when the fan(s) kick on. If like 198+, odds are it has not been tuned. If 180-185 I would say it has been tuned.
Also look to see if headers or a cold air intake has been installed. This too is a good indication that the PCM has been modified.
Hope this helps
Ed M
PS -- Almost forgot, congrats on the vette, you will love it
For both auto and manual, monitor your Engine temp from a cold start and verify when the fan(s) kick on. If like 198+, odds are it has not been tuned. If 180-185 I would say it has been tuned.
Also look to see if headers or a cold air intake has been installed. This too is a good indication that the PCM has been modified.
Hope this helps
Ed M
PS -- Almost forgot, congrats on the vette, you will love it