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Discussion Starter · #1 ·
My G20 is getting around 13-15mpg. This is really low even though I don't expect it to be 1-2mpg less during the winter here.

I put like 7 miles a day on average to get to classes and home (2 stop lights and thruway). I fixed the EGR and had a tune up. The car got 28mpg on the same route. After a tank of gas it was back to 13-15mpg. I have been checking on my tire pressure regularly almost every morning and the car is working fine. I need some ideas on what to do now. Is an engine compression test needed?

I have read from a few threads that said bosch plugs arent good. The mechanic installed those for my car. Should I change the plugs again? What is MAF?

Thanks everyone.
 

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Bosch plugs should not cause that big of a difference. It could be any number of things, start by checking to see if your ECU is throwing any codes.
 

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Discussion Starter · #6 ·
kaiseiken said:
Bosch plugs should not cause that big of a difference. It could be any number of things, start by checking to see if your ECU is throwing any codes.
I have fixed the check engine light. Will the ECU throw out codes even if the check engine light is off?
 

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CEL = check engine light. I think what Mattb is saying is that it may not turn on the check engine light, but WILL throw a code meaning you can go to a local autozone and have them read the codes off your car and see if the knock sensor is there.

I would definitely check your MAF ground, thought it's wierd you reverted back to crappy mileage after one tank
 

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A cold air intake increases gas mileage a bit..
 

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merlin said:
CEL = check engine light. I think what Mattb is saying is that it may not turn on the check engine light, but WILL throw a code meaning you can go to a local autozone and have them read the codes off your car and see if the knock sensor is there.
That is correct. Just before I traded my P10 in it started throwing the KS code but there was no check engine light, I only found out about it because I was playing around with an OBD2 code reader at work. That being said my gas mileage was still around 24mpg in mixed driving for the last tank I put through the P10.

Your driving habits can also cause bad gas mileage, if I do nothing but short 1-2 mile trips in my I30 I'll get around 17mpg. But 15 out of a G20 is horrible, there's definately something wrong.
 

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Ways to improve gas milege, especially on older G20's

1) Replace the 02 Sensor....this is important cuz after many years of driving and accumulated milege, your 02 sensor will get dirty etc... and eventually poop out on you. replace this part for ~$60 or so

2) Inflate your tires to proper pressures. I run 35 PSI in my tires all around
3) Make sure your wheels are balanced and that the alignment is within factory spec.
4) Drive gently, no hard stops or acceleration
5) Make sure your fuel, air filters and all are clean. Keep your car properly tuned up and maintained.
 

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I guess I'll state the somewhat obvious - brakes dragging or calipers sticking or even e-brake cables that have seized can cause poor fuel mileage. Fuel this time of year will kill at least a couple of miles per tankful, as winter blend is in full season. Cold weather as well.
 

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Ya that's way too low man. Yesterday when I filled up my P10 I got 25.5 mpg, using winter gas, and mostly city driving. Something is definitely up.
 

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I got 300 miles to the tankful this past weekend. 60% highway 40% city driving
 

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"wut is MAF?" i asked the same thing around 60 something post ago.
 
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