Poor Gas Mileage in my 300zx

[ob8matt]

I'm not getting the best gas mileage that I can. I just had a new fuel rail installed because of a leak but they told me I had a great deal of carbon buildup in the car. I called another place and they informed me of the Chevron products that clean the car just as well as cleaning them themselves with their machine. Any other suggestions as to what I can do to the car in order to get the best fuel mileage possible?

[LAKE ERIE Z32]

ride a bike?

lol sorry i just felt like being a smart arsegood luck

[EQwhipD]

Bad gas mileage could be due to alot of different scenarios. My brother was getting crappy mileage and he swapped out his MAF and got markedly better gas mileage. It also could be due to bad O2 sensors, and if it were the knock sensor...your rpm's would be jumping up and down. You might want to pull the codes on it to see what's wrong.

[ob8matt]

I just had new Bosch Oxygen sensors put in. I think it could be the fuel injectors. I also had the tests run and the knock sensor did code but my rpms haven't been jumping. MAF? Mass Air Flow sensor, is that the abbreviation?

[EQwhipD]

You are correct sir...MAF is just Mass Air Flow abbreviation.

[ob8matt]

Do you think that the plugs that connect to the fuel injectors may also be playing a role?

[AZNiNjARaVeR]

highly doubt it, even though those are probably quite oxidized. Do you have an estimated MPG currently?

[Zwicked]

You say new fuel rail installed. Was it a replacement stock one? What injectors?

[ob8matt]

The fuel rail was a stock part that was replaced. It was purchased straight from Nissan by my mechanic. The fuel injectors haven't been replaced but I was told that they need to be cleaned. Another mechanic encouraged me to get the Chevron Techron in my gas tank before I went ahead and spent the money to have all the carbon buildup removed. The Techron is suppose to do the job.

[Zwicked]

It's not often these injectors plug up.Poor gas mileage can be a result of many things, and to track it down we need to start at the beginning.

A couple questions:

1. Why were the rails replaced?2. How did it run before the rails were replaced?2. What else did they do to the engine when they did that?3. Is you mechanic a competent Z mechanic with experience on this vehicle?

[ob8matt]

The fuel rail was replaced because of a crack which the mechanic did show me and I could see the hole. Other than that I had new O2 sensors installed as well the #2 cylinder wasn't firing and a new coil was put in. He isn't a strictly Z mechanic.

[GoodfellaFD3S]

I havent seen it posted here, how many miles are on your spark plugs and wires? also, what do you consider poor gas mileage?

[ob8matt]

The slugs and wires are new as of 5,000 miles and I think I'm getting about 12-13 miles to the gallon. In my opinion I should be averaging about 18-20.

[Q45tech]

Knock sensors will definitely decrease MPG because the ignition advance is retarded to a fail safe number, lowering conbustion efficiency.

[ob8matt]

Do you think that the replacement of a knock sensor will be noticeable right away? Thanks.