Ok so I've got an 02 z06. It's got American racing long tubes, Vararam cold air intake, XS power exhaust, polished throttle body and an RPM 3 cam that was installed and tuned by Race Proven Motorsports.

I've had this little issue with my Vette now for a while, but now it's getting much worse now that it is cammed. My car seems to be consuming fuel at an unusually high rate, and the gauge will quickly change the amount of fuel it shows. It did it when it was bone stock and with each mod has gotten a tad worse. The gauge is reading accurately - when I fill up the correct amount of gas goes in to get it to full.

Last night for instance. I put $35 in the tank at 1/4 of a tank and was 1/8th of a tank below full. Drove home about 5 miles and parked it. This morning it showed that it was completely full. I ran a few errands today (about 10 miles) and it had went from full back down to 1/16th below full. Went from Target out to get dinner (3 miles) and I was down to 3/4 of a tank.

Last week I was at a hair over half a tank, drove 28~ miles and ended up being about 1/8th above empty. Roughly 30 miles and 25 minutes. All highway. As I was driving I was just watching the gauge slowly drop down. I was able to put about $50 into the tank and get back up to full so the fuel WAS used. However, these numbers seem very, very wrong to me. I'm not seeing any sort of fuel leak anywhere, the car is running very strong.

Anyone have any ideas? I've searched and the only thing I've come up with is when people's gauge reads empty when they're actually full. Haven't come across anyone with my issue. I will say that I drive like a grandma most of the time and don't really get on it very often (I live in a high traffic area, there aren't many opportunities to get on it safely). There are also no codes being thrown. I've checked in the DIC and there are no current codes, or history codes. Can't see any type of leak at all, and I don't smell gas coming from anywhere. Thanks in advance!

 

Also forgot to mention this. As I was coming back today I ripped on it a little. 15mph roll in 1st gear, and went through to the top of second. Let of the gas and put it in neutral and the engine stayed at around 2300rpm, and didn't drop down until I turned onto my street and put it into 2nd gear. Not sure if that's related or not.

 

The gas gauge can have its own problems. I would first manually calculate your MPG over a full tank of fuel and give us a number. I'm not sure what $35 here and $50 there really is.

 

Who tuned your PCM and how was it tuned?? Sounds like it isnt tuned properly.

Who did the work?

Bill

 

You should first determine if in fact you have an excess consumption problem. Attempting to determine fuel consumption by reading an inconsistent fuel level gage is useless. Fill the tank, operate the vehicle for at least 100 miles, re-fill the vehicle, and then calculate the milage. Adding Techron to the gas tank has been known to correct erractic fuel gage readings for many.

 

If I'm reading this correctly. it looks like you burned up a tank of gas driving 76 miles.

 

Roshan at Race Proven Motorsports. He's definitely got it tuned right. I can also say that when the car was bone stock it did this.

Not quite. I burned up 1/4 of a tank driving 13 miles yesterday. Last week I burned up over 1/4 of a tank driving 30ish miles.

I will do this and update the thread once I've done it. Thanks!!!

 

It is important to note that it normally takes multiple treatments with Techron to correct the problem, IF that does turn out to be the root cause.

 

I've added twin turbos to my 2004 C5/T6 and have noted that around town my fuel consumption has gone up. Well I guess that should not be a suprise in that I tend to run higher RPM's for shift points now. On the flip side every one beside and behind me enjoys the sound.

Reset your avg fuel consumption calculator on the DIC when you fuel up that should tell you what you are consuming. If the tune was not correct and you were running rich you should be throwing a check engine light or it would show up in one or more of the codes if that is not happening check your foot!

One other thing check the fourm for gas tank recall. I remember there was a recall on some of these cars for problems with cracking between the tank cross over, although if it were that you should be either seeing or smelling fuel.

Good luck

 

When you add bigger injectors, your fuel milage calculator will NO LONGER READ CORRECTLY!! You can use EFI Live and readjust the calculation parameters to make it read the correct mileage.

If you truely are burning that much fuel, something is making it run rich. What are your LONG TERM FUEL TRIMS reading?? If there very high, the tune is not correct.

Data log the PCM and check the values for the following sensors:

O2 Sensor switching output: Should be switching between 02 millivoilts to 900 millivolts

Coolant Temp sensor: Should rise and fall with coolant temp and read close to the actual coolant temp

Map Sensor output: Make sure that your Map is working correctly on the vacuum side and the boost side.

Bill

 

Ya, like others have posted do some full tank to full tank fuel calculations and determine your true mpg. Come back in about 1000 miles or after 2 to 3 tanks of fuel once you have some usable numbers.

 

Hmmmmmmm......... Some issues here for sure.....