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Can I get better mileage for my car?

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Dona A. Roberts
New User

Aug 25, 2014, 11:29 PM

Post #1 of 4 (890 views)
Can I get better mileage for my car? Sign In

For past two weeks I have a trouble in setting out my car. It always starts up the first time, however the second time it fails to set out. So, I went over my.............
link deleted ............. and they first cracked the engine codes and get as P0422 and C1225. They found the issue is with vacuum hose leak and that was cleaned and corrected. They also found a little leakage in the self test system and that was also fixed. Right now, I have a concern over mileage of my car, should it be the same as before or is there any opportunity for betterment.

(This post was edited by Hammer Time on Aug 26, 2014, 2:07 AM)

Hammer Time
Ultimate Carjunky / Moderator
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Aug 26, 2014, 2:08 AM

Post #2 of 4 (871 views)
Re: Can I get better mileage for my car? Sign In

Any attempt to slip advertising in here will not be tolerated.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 26, 2014, 3:32 AM

Post #3 of 4 (866 views)
Re: Can I get better mileage for my car? Sign In

Dona - I don't think you are long for this place but can't help it.

You want better mileage for your car? Easy. Just a couple things to do.

1. Plan your trip such that you travel downhill both ways. I'm sure Google Earth has an 'app' for that.

2. Only travel with a strong tail wind both ways as well.

Remarkable how much better MPG you can get, LMAOROF..........


Ultimate Carjunky / Moderator
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Aug 26, 2014, 4:36 AM

Post #4 of 4 (859 views)
Re: Can I get better mileage for my car? Sign In

Would be nice to know what year, make, model, and engine size you have.

If you have a vacuum leak, that means that unmetered air is going to enter the intake manifold and raise the manifold pressure when the throttle is closed. On a MAF system, this will cause the MAF to read less air than what is actually going through it, so it will cause lessen injector pulse width and the engine will run lean. The oxygen sensor will detect this and the computer will add fuel to compensate balancing out the leak.

If this is speed density, it will cause the MAP sensor voltage to rise. The computer will think the engine is under load and will add more fuel. This will cause the engine to run rich. Once again the 02 sensor will pick up on this and the computer will trim by adding less fuel to compensate.

If the fuel trim system can compensate for the changes made by the vacuum leak, you won't notice any reduction of fuel mileage. If it can't compensate and the trims are at limits, you will probably notice a reduction on fuel mileage, but you will have some sort of drive-ability issue in the form of a rough running engine at idle and or idle surging.

Also note that vacuum leaks don't play a major role in how the engine runs when the engine is above idle speeds.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 26, 2014, 4:40 AM)

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