Camry intake vacuum reading (video included)

[dave255]

1995 Camry; 5sfe; 247,000 miles

Over the past 5 years or so I have noticed a very gradual decrease in my car's fuel efficiency. I am currently getting about 24-25mpg on average, whereas about 5 years ago I was getting about 29-30.

This afternoon I hooked up a vacuum gauge to the intake manifold for the first time in the life of my vehicle to see if the results would give me any clues.

I have never done this test before, but from what I can tell, my car's performance seems spot on. Though since this is the 1st time I have done this, I thought I'd post a video of the gauge as I ran the test to get feedback from more experienced members of the forum. In the video, you will see the vacuum gauge with my car at a steady idle. I also threw in a few short bursts to 2500rpm and then back down.

Any thoughts, comments, concerns would be greatly appreciated. Thanks in advance!

You Tube

You Tube

[N/A Camry Sleeper]

My first guess for the dropping fuel economy is your 02 sensor. I had 265K on mine when I replaced both of them and gained close to 3MPG highway. Secondly a good thorough decarbonization of the throttle body and intake will allow more air to get to the cylinders. Finally, the EGR could be clogged or resticted which could affect MPG as well...

[chronoti]

also all this mixing fuel with ethanol will loose you a few points, try to find a gas station that sells unblended fuel

[JohnGD]

There is some fluctuation of the needle. When was the car tuned up last? Valve clearances checked?

[fenixus]

I believe that slight fluctuation on the needle might indicate a leaky gasket (e.g. valve cover or distributor plug), that would account for a tiny slight vacuum leak I think?

[Stillrunning]

Originally Posted by dave255

Over the past 5 years or so I have noticed a very gradual decrease in my car's fuel efficiency. This afternoon I hooked up a vacuum gauge to the intake manifold for the first time in the life of my vehicle

Did you do a compression test 5 years ago? Doing tests early to establish base numbers for comparison is a good idea. The gauge readings are within spec - 17 - 21 at idle and 2 - 25 on accel/decel. Mileage drop may not be just engine wear so I'd look at what's been suggested, O2 sensor, ethanol, etc. which are things you can actually fix.

Oh, and look for poorer fuel mileage as our illustrious government has decreed that there can be up 15% ethanol in gas.

[Mike Gerber]

In addition to what has already been posted, make sure you are not comparing Winter fuel mileage to Summer fuel mileage. Winter fuel mileage will decrease as the engine is taking a lot longer to reach operating temperature. During this warm-up period you are running a richer fuel mixture.

In addition I think you are geting excellent fuel mileage. I have a 94 Camry 4 cylinder 5SFE engine that I have owned since new. The car was rated at 21 city and 28 highway. Your 95 should be the same. I get around 20 MPG city in extended around town driving and around 29 on the highway. In Winter the mileage for city driving drops to around 18-19.

Mike

[JohnGD]

Possibly. Your leak made the needle tick like clockwork however.

Originally Posted by fenixus

I believe that slight fluctuation on the needle might indicate a leaky gasket (e.g. valve cover or distributor plug), that would account for a tiny slight vacuum leak I think?

[fenixus]

yeah, it was slightly different. I will check again before and after resealing with RTV the distributor plug (leaking now), hopefully it smooths out a bit.

Originally Posted by JohnGD

Possibly. Your leak made the needle tick like clockwork however.