Just bought a used 2008 G35X, deal seemed great but I've noticed a few flaws as I've examined the car closer.

I noticed on the carfax that this car consistently fails emissions inspection, didn't think much of it I'm hoping you guys can tell me if this is related or not.

Close to where the exhaust comes from the engine you can see this: (attached image)

Not sure which part of the exhaust this is but there is 4 on each side. So 8 between the two exhausts.

Any help with why anyone would do this to their exhaust... Thanks.

 

just seems like the heat shield on the cats that is rusting out a bit

 

Yes, that is just the heat shield on the cats....it has no effect whatsoever on your emissions.

You should have the previous owner tell you why it kept failing emissions. (Possibly that the exhaust was modified or SES light, etc....)

It all depends on what the previous owner tells you. If your SES light isn't on, then you shouldn't have any problems with your emissions.

 

Problem is I got it from a dealership so they don't know much about anything.

It's harder to see in the picture but it is not just rust there are significant slits in the middle of each rust spot and they are on each side each one of the heat shields.

They are symmetrical so they look like someone either cut them or by design but I doubt it.

Also my MPG reading on the computer is ready approx 10 MPG... not sure if that is related.

 

From what I remember before I took the heatshields off since they were completely rusted, they did have slits in them to ventilate the air out from the catalytic converter. The heat shields were only there to prevent grass fires if you park a car in tall grass. Otherwise, there isn't really a reason for those heat shields.

As for your 10mpg, that does sound a bit fishy, because most cars get about 14 mpg-18mpg in the city, and 23-28mpg in the highway from what I've read.

Unless you drive your car extremely hard, 10mpg is out of the norm. You actually may have an emissions problem. You can ask the dealer to look at the car for you. Do you have a SES light in your dashboard?

The whole car just sounds fishy to me if it has failed emissions, especially if it is only 5 years old. I would think someone modified the engine/exhaust which is illegal in most states which causes the emissions to fail. It is possible that the previous owner then put back OEM parts when he decided to sell it/trade it in back to dealer. If you have no SES light on currently, that would be my guess. The dealership has no prior service records for that car?

 

Those are on all HR catalytic converters. They are not cuts, they are cooling vents in the heat shield with some rust on them.

Here is a pic of some not so rusted.

 

yes not "slits"...that's how they are supposed to be

 

I am going to guess the previous owner had an aftermarket exhaust and that is why he failed. He probably returned the car to stock before trading it in.

If you dont have an SES light right now, you are probably fine. The low MPG is probably because it was driven hard on acouple test drives. Rest it and see if it goes back to normal.

 

Most emissions test are just OBDII checks nowadays so if you don't have a code, I would imagine it passes now.

The 10mpg is disturbing. I can't imagine getting that low no matter how I drive the car! I think you should look into that. Does the car idle fine and is otherwise running fine?

 

thank you for your help guys.


The computer is what is telling me 10 mpg I'm going to manually calculate it on my next fill up to see what the deal really is. I do not drive the car hard I stay under 3k rpms 90% of the time.

The computer drops my MPG reading down to >10 MPG anytime I accelerate whatsoever.

No ses light on.

 

MPG will always read <10 when you accelerate, because under acceleration you are getting <10 mpg.

 

Just refilled the tank its telling me I have 235 miles to empty... does this sound right?

I have reset the MPG multiple times.

 

235 per tank is a little low. Most people shoot for about 300 miles per tank. But it is calculated on previous MPG. Drive it normally for about 15-20 miles and it should go up.

 

If you are looking at the active MPG view then that will change anytime you press the gas pedal.

Also if you are using the low grade gasoline, you are going to experience lower MPG.

I would suggest getting a fuel injector cleaner such as Lucas Oil to run through on a few tanks of gas. You don't know how it was driven before you. Also, an oil change and a spark plug change would not be a bad idea, you don't know the last time that was done.

Also, have you looked at the air filters? You never know how the vehicle was maintained prior to you purchasing the vehicle.