Hey everyone. My 1994 Camaro Z28 is getting horrible gas mileage and I'm not sure why. So far the best I've been able to get out of it is 17 mpg but it will go as low as 10 mpg. It has a rebuilt engine bored over to 355. The rebuilt engine has around 1000 miles. I changed the oil filter and oil, fuel filter, and put a K&N Cold Air Intake on it. I also ran fuel injector cleaner through it. I always use cruise control when I drive it. Any advice would be appreciated. Thanks!!

 

Are we talking city or highway mileage? 17 in the city is pretty good. I think I get about 15 and I have 120k miles. Highway I'm usually around the 20-22 area if I keep the lead foot in the trunk. O2 sensors, spark plugs/wires, opti can all lead to poor mileage. M6 or A4? If this is highway mileage, then there is defiantly a problem.

 

I get 18-19 in mixed city/highway driving.

 

scan or have the computer scanned for trouble codes. test the evap system, https://camaroforums.com/forum/lt1-l...-system-51219/ you may have gotten oil from the filter on your maf which will cause it to fail and can effect fuel mpg, check fuel pressure, high or low fuel pressure can cause a rich condition.

 

Thanks for the advice. It is a 6 speed manual. That is a mixture of city/highway but mainly highway. It got new spark plug/spark plug wires when the engine was rebuilt so they should still be good. I also see on the receipt that it got a new Air Flow Sensor. I'll change the O2 sensors and go from there. And no codes show up when we test it.

 

Many times new engines will take some time to break in and youre just at the 1000 mile break in period. During the break in period gas mileage will suffer as well as fluctuate. Check everything out and if it looks good, Id run it another 500 miles then make an assesment on your fuel mileage. Since you have obtained 17mpg, I would think its close to normal.

 

Since he does more highway, he should be doing better than 17, especially with a 6 speed. Unless it's being driven in 4th the whole time. But that double over drive should be helping quite a bit.

 

i you added the k&n filter after the new maf was installed it can still be failing. if the oil from the new filter is not drained off it will get on the maf and cause it to fail. pull the cai lose and see if there is any indication of the filter oil getting up there.