I want to improve my SL2


Asked by Oct 31, 2011 at 05:25 PM about the 2002 Saturn S-Series 4 Dr SL2 Sedan

Question type: Car Customization

My SL2 is getting up there in mileage and I might soon be relying on it to drive to a
job 4 hours away ever week (and back).  I was wondering if there's things I can do
to help improve it's fuel and power.  I'm a computer guy and I'm used to updating
firmware on phones and computers all the time to get updated features; is there a
way to do this with a car's computer?

Someone once told me I'd get better efficiency with a cold air intake.  Are these
ideas true?  Are there any others?  Thanks in advance!

22 Answers


A cold air intake should improve the fuel economy- the logic behind it is that making it easier for the car to aspirate (both on intake and exhaust) will allow the car to expend less energy on keeping itself running. According to your post your car is a 2002, so it's OBDII- you can purchase a tuner (either a chip that replaces the EPROM, something that plugs into the diagnostic port, or something that completely bypasses the standard ECU) or possibly even reflash the ECU yourself. Obviously the DIY approach will be cheaper and give a more custom fit to the car's exact abilities, but also stands the chance to completely destroy the electronics or engine if you really screw up. There are guides on the internet, but I don't know of any specialized in the S-Series. One more thing that will likely improve your fuel economy, but negatively affect your performance, is to replace your transmission's gearing with the SL1's 5-speed. The gears are significantly taller, but if everything goes well it should be able to bump your interstate fuel economy pretty close to 40 MPG. This probably wouldn't be worth the hassle if your car's an automatic.

1 people found this helpful.

The only intake that will help with fuel economy is a hot air intake positioned over the exhaust manifold. It will kill power as a consequence though. Things you want to do to improve economy and power is just to maintain the car. New plugs and wires, make sure you are running a 195 degree thermostat, the ECTS is a brass one, the tires are aired up to 40psi(cold pressure), the air filter is clean, etc. Josh has no idea what hes talking about. A cold air intake will marginally increase power, but does nothing for fuel economy. It’s a noise maker that will dirty the engine oil faster do to all of the extra dirt and crap its sucking up. And another idiotic thing that Josh suggested, “tuning” and “chips”, yeah, theres no such thing for the S-series unless you go with a full standalone ECU which you shouldn’t do based on your experience and goals for your car, obviously. The only “good” thing Josh mentioned was the SOHC 5th gear. Its an easy enough swap if youre mechanically inclined. Its only possible to do on the manual transaxles though. It would never work on an automatic transaxle because the ECU would detect the incorrect gear ratio and not work in 5th. The only downside of swapping in the 5th gear is you’ll lose cruise control for good.

3 people found this helpful.

youre an idiot. Dont give people advice unless you know what the hell youre talking about

2 people found this helpful.

The cold air intake and high flowing exhaust would help. Also a small low boost turbo would help. It would atomize the air causing a cleaner more effective burn of the fuel. Plus you can turn up the boost pressure if u wanna have some fun!!

1 people found this helpful.

again...Josh has no idea what the hell hes talking about. Boosting a car to increase fuel economy? Are you high? Please go away and read something so that you arent just blurting the first stupid thing that pops into your head

3 people found this helpful.

Wrong Josh. However, forced induction *can* be used to improve an engine's fuel economy if the kit is engineered for the purpose. Jay Leno's Tank Car had a turbokit installed specifically for this purpose, and it went from around 9 to 13 MPG. On a normal car, however, it's unlikely that you will see such a pronounced effect, and there aren't any turbokits designed for the S-Series, so he'd basically have to make it from scratch, making this mod not really worth the effort.


i dont know jack about tank engines or how they are managed. You can improve economy in any prehistoric engine design by adding a computer to run the car. EFI > Carburetor Again, you are wrong. There is a turbo kit made for the S-Series. Alphatuning makes it. Its expensive. Its cheaper to assemble your own setup. Now, can we stop talking about things we know nothing about? and thats to BOTH Joshes....


A tank engine is the same exact thing as a car engine, just bigger. And you said earlier that improving engine management didn't improve fuel economy.


Did I say that? or is it that you cant read AND dont know anything about standalone engine management. I dont understand why youre still responding on this thread

1 people found this helpful.

my problem is asshats like you guys give out bad and wrong information to people who dont know better. Then you get butt hurt when someone calls you out on it. Let me reiterate what ive been saying. Ahem...get bent. Thank you

2 people found this helpful.

"tuning” and “chips”, yeah, theres no such thing for the S-series unless you go with a full standalone ECU which you shouldn’t do" A standalone ECU is a waste of money on an OBD-II car for this purpose. One of the most important parts of the fuel economy is the fuel map, which just so happens to be located on a single chip inside the ECU. Replacing this chip with one that has been tweaked to match the exact engine's state will decrease the amount of intervention in pulsewidths during closed-circuit operation, thus improving efficiency better than anything you can buy off-the-shelf. The best part with this approach is that while the initial investment can be a bit steep, it's cheaper than a complete system, and the methodology will translate to any OBD-II car for the price of a visit to a TV shop and a hobby store.


Thats fine and dandy. Go ahead and find this chip that'll work on the S-series. Oh wait! I forgot...you cant modify the S-series OBD-II PCM...guess you didnt know that either.


Spoken like someone who's never used a soldering iron. ALL electronics can be modified with patience, cars are no exception. You don't find the chip, you make it.


There have been people, much brighter than you that have tried to hack into the OBDII pcm. No one has succeeded. There have been a few that have used the OBDI pcms, but thats it.


Wow am gone with alex on all of this. I have owned 2 s-series.all so when you do a turbo this cars(any car) your gas mileage will drop. Because It as to drop more gas in to the motor to make it run right. When you put a turbo on a car that is not made for one. You are gone send more time and money then anything. Cool air intake are for looks and noise. So do some math more air = what? Answer MORE GAS. Why because you air and gas has to have the right mix or it will run like shut. Aka it will miss or die on you. THEY DO NOT MAKE CHIPS FOR THIS CAR. Only thing they real do is make a car burn more gas and BYpass shut off on the car if it has one.

2 people found this helpful.

man u guys r stupid tuning is adjusting the ecu.. u can re-map for performance or for efficency. and as far as the turbo low boost for efffency is a plus. until u raise the psi and start mashing the throttle. oh yea and i have a turbo on my 98 sl2 and upgraded fuel system 550cc injectors upgrded fuel pump and fuel regulator w/ re-mapped ecu. runs like a monster 20 psi is my sweet spot

1 people found this helpful.

Prove it.


maximizing fuel ecconomy. clean air filter, fresh plugs (ac delcos) for your saturn, proper tire inflation (what the door tag says maybe a 3 psi bump, overinflating will minimaize traction and increase tire wear. 40 psi is too much) make sure brakes are not seized and draging. remove roof mounted accessories. that is your best choice for not creating other drivabilty issues. turbos, chips, pcm/ecu tunes, trans modifications can maybe aid in fuel ecconmy if done right but it isnt worth the money or hassel.

2 people found this helpful.

Apologies guys for my comment above I wrote most of it and walked away, came back and my son messed with it. Sorry if that offended anyone in here although I don't think it will likely. Have a good one.


No entiendo.


Ah, Alex is so right about so many things, even from so many years ago. First off, Jay Leno came to my unit to scavenge spare parts for his Tank Car, which runs a AVDS- 1790 series engine. My tank retriever ran the 8CR version of that, which goes back to WWII. Those engines are entirely mechanical and they run on no electronic fuel management whatsoever. Those engines could handle detonation, because they are 1790ci displacement...your Saturn isn’t even as large as a 1790, it weighs in at a paltry 3,000lb compared to its 10,000lb. It’s pistons are the size of dinner plates...and it’s packing 12 to your measly 4. You boost an engine, as long as you stay out of boost, you will run efficiently. The second you step into boost, you either cool with fuel or you spend money on an expensive intercooler, preferably both. Go ahead and run lean...watch what happens to your econobuild...you’ll go econobroke real quick. You can do the intake exhaust easy, you start messing with fuel maps based off some idiot’s “chip” and don’t know what you’re doing, well, that’s gonna be real expensive, real quick. Just some dumb Marine waxing philosophical engine Zen tho.

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