On Monday I filled up my tank. First time in awhile; I usually do half a tank at a time, or enough to get me through the week.

As of right now, I'm down to less than half a tank already. My odometer is at 122 miles (reset when I filled it up), so that means I'll get around 240 miles out of 15 gallons of gas. If my math is correct (more than likely it's NOT), that's 16MPG.

Has anyone had their cold air intakes reduce MPG? I've read over and over that they are supposed to do the opposite, but usually a full tank of gas will last me 3-5 weeks. A lot of my driving is at 40MPH, and there's a lot of stop-and-go which can reduce it a lot. But I've never had a tank run down this quickly.

I also seafoamed my car that day as well. Put it in the gas tank, brake booster line and the oil. Could that have had a negative effect on it?

 

Go back and read the first page of this thread.

Fact, a CAI cannot in any way improve fuel economy on a modern fuel injected engine; it is a physically impossible.

 

What about it? I can post it another place; I just wasn't sure where exactly it would fit.

Ever heard of a warm air intake? Basically I just added .0000001HP to my car and a whole lot of noise for nothing... sweet.

 

Sure. Modern carbureted cars all had intakes that pulled heated air off of a heat stove on the exhaust manifold. Thermostatically controlled, it switched over to cold air above a certain temp.

Did the mileage drop coincide with the CIA installation? If so then switch it back. If not then you might want to take a look at the usual suspects: Secondary ignition components in good shape/fairly new? Ditto with the O2 sensor.

 

Ohh, gotcha. Learn something new everyday!

I'm honestly not sure if the two are related, I've had my intake in for a few weeks, but the fuel just now started to drop drastically. That I noticed, anyways. I may switch it back to stock since I now know it does absolutely no good. I'll have to check my maintenance book (wrote all the repairs ever done down in a comp. book), but I think some ignition parts were replaced a few years back. Cat convertor and all of the O2 sensors were replaced in November because of my [first] accident, so those should still be in tact.

So can I completely rule out that running seafoam through the car isn't a cause?

 

The Seafoam most likely didn't help or hurt; it just made for a lot of smoke.

 

Seafoam can help some things, maybe break up some carbon deposits in the combustion chambers. But it won't fix everything, and it's not a cure-it-all.

CAI won't help MPG, but I don't see where it would hurt that much either. What about the previous fillup being short? Keep recording MPG over a span of several CONSECUTIVE tankfulls. And don't stress about what you think the fuel gauge is telling you.

 

It can hurt depending on the cat. Whats your set up and car? A change in intake temp from stock can change fuel readings. Im gonna revert back to stock intake and see if my issuesgo away. Surprisigly the IAR in the accords helps with power and mpgs.

 

Good plan; I'll keep track of it for the next month or so and see how it goes.

Robinson, I have a 99 Accord LX with a stock cat/exhaust for now. If the tank keeps draining like this, I'm gonna switch back too.

 

You will want to change your oil now.

Seafoam is a solvent mix designed to dissolve sludge; it also dramatically reduces the film strength of oil.

If I recall instructions for similar products were to add it, idle the engine for 10 minutes and immediately change oil/filter -
and specifically to not drive it (run the engine above idle) with the solvent in the oil.

Luck.