SES gas mileage

[cep39]

I recently installed headers and high flow cat on my 99 camaro, and I have the expected SES light. But ever since the light has been on I have been getting terrible gas mileage, to the tune of only about 330 miles to the full tank. I think there is a small leak around the flange, but it doesnt seem too serious. Anyone have any idea why this is happening?

[CDNFB]

Re: SES gas mileage

Your going to have to be more definitive in regards to your terrible gas milage.

Your getting 330 miles now, but what were you getting before?

There are some guys on here that would love to get 330 miles to a tank in the city. Now if we're talking about highway milage, then you might have something to complain about.

Have you actually read what the SES code is, or are you assuming its the Post Cat 02 code? Maybe your Pre Cat O2(s) is/are shot?

But here's a thought as well; I have seen it many times after putting on a set of headers and a high performance exhaust system, the guys will complain about getting worse milage. What usually happens is the car is driven harder than it was before because is sounds better, and feels better, and the person likes to hear and feel the performance. Maybe your just driving it harder?

[Smoke Panther]

Re: SES gas mileage

What usually happens is the car is driven harder than it was before because is sounds better, and feels better, and the person likes to hear and feel the performance. Maybe your just driving it harder?

with an opening post as vague as that, I'm willing to bet that's exactly the case. The harder you drive your car, the worse gas mileage you're gonna get, performance parts or no.

[blackRS]

Re: SES gas mileage

Your getting 330 miles now, but what were you getting before?

man, i would love to get that right now:cry:

[96greenmachine]

Re: SES gas mileage

i used to...but not lately, maybe im just driving to hard hah :)

[cep39]

Re: SES gas mileage

Sorry about the vagueness originally, but I very rarely fill the tank all the way but I expected to get more miles out of a full tank, especially when half of it was highway cruising. In fact a trip to the beach and back which normally used to only take just about a quarter tank took a full half tank a few weeks ago. And ever since the header install I have not been driving it hard, I have actaully been sort of babying it trying to get good mileage haha. And yes I am assuming its the post O2 sensor code, but is there any way to know?

[96greenmachine]

Re: SES gas mileage

have autozone check ur codes...thats a way to know

[blackRS]

Re: SES gas mileage

why put headers on and then baby it? think you have the timing backwards;)

[zymose]

Re: SES gas mileage

From what I understand, the Post Cat 02 sensor doesn't effect how the engine runs. I thought that the code just showed that you had a problem, but that it doesn't change anything with your performance. Atleast that's what I've read on here several times.

As far as the leaking flange, I would check to make sure that it isn't blowing hot air on anything. We had a Bonneville that developed a leak and melted one of the wire harnesses. It was a nightmare trying to splice all of the wires that got shorted out.

[camaro9407]

Re: SES gas mileage

you are right. i am in course 4 at uti and thats fuel and ignition driveability, the post cat o2 sensor is just used in emission testing, it has nothing to do with your a/f ratio