Hi All!

First time poster here needing some advice. I've got a 2007 2.4L Camry and it used to get about 20-21 MPG city until one day, my dad took the car in for a service and they did some adjustment (not sure what they did, but I believe it to be a timing chain adjustment) and now I'm getting 15 MPGs city. I've done everything from injector cleaner to fresh service (fresh oil, air filters,etc), increased tire pressure, used an octane booster, replaced O2 sensor (dash board lit up). They garage tried undoing what they did but to no avail.

Driving habit: I drive with a pretty light foot and commute about 6 miles to and from work (12 miles total) in light traffic and I'm not in one place for more than a minute or two at the occasional 4 way traffic lights.

Fuel variations: I pump 95 octane. I've tried 92 octane but MPGs went down even further. MPGs went up a little bit when I used 95 octane with a Wurth octane booster. All mileage tests were done by emptying tank, topping it up with fuel and driving as usual and recording mileage driven until next top up.

Any advice on what the issue might be or what I need to be on the look out for? I've read possible EGR issue or mass air flow issue? Could it be that they replaced the wrong type of spark plug?

TIA

 

Start by finding out exactly what the shop did. The chain is not adjustable.

 

I've tried but even I never get a clear cut answer. Since I bought the car used, they did an engine service and re-tune and that's when the trouble started. So I'm not certain what a re-tune consists off, but they did hook it up to their some system of sorts, as far as I was told.

Is there any particular questions that you recommend I ask other than "what did you do?", since it's all I've been doing for the past couple of months now and just getting tired of going back to them. I plan on taking the car to another garage that's out of the way from me but well reputed, and wanted to take a possible checklist for them to run through to try and figure this out.

 

Where is your dad in this issue? Is this your car or his? You are now working third hand at this issue.

For what specific reason did your dad take the car to the shop? Did the car have a problem or was this just part of say an oil change?

The shop must have billed your father based on a listing of any services they did and parts changed. Do you have this it invoice?

If the MPG went from 20-21 to 15 right after the service, then would be looking at what happened at the shop.

You state the dash board lit up and you replaced the O2 sensor. What "lit up" the check engine light? Did you replace the sensor or a shop? A bad sensor can cause MPG issues and replacing it with the wrong sensor can also.

You should be able to use the octane rating as recommended in the owner's manual.

Check the engine for any unplugged wires or vacuum hoses.

 

Dad works overseas in roughly 3-4month spans with a month break in between, so he loaned me his car which I use and maintain. The service was pretty much the first service about a month later after buying the car.

Invoices are kept for records but unfortunately all the billing history is at my dad's place and well...he's currently overseas.

The dashboard slit a check engine light soon after we bought it, and the garage hooked up a diagnostics unit and said it was a failed O2 sensor. Since sensors are expensive (heavy taxation) where we live, and since my dad was overseas when the problem was identified, he bought the original Toyota sensor so garage merely removed the old sensor and fitted the new one when by dad came back.

Owners manual says 87 and above, and fuel stations here only sell 91 and 95 octane.

I'll probably take it in to re-check for unplugged components but it's not likely as we asked them to go over it a couple of times since the incident. The only thing I'm uncertain of is the if the new spark plugs installed we're the right ones or not. Could that have a significant effect on fuel economy?

 

The check light is now off?

Are you handy with tools?

Suggest you look at the replaced 02 sensor to find the part number. Then search the internet to determine if it was the correct part for your car. For plugs remove a plug, check part number and do the same.

How does the engine idle and perform? If not for the low MPG would you know there is a problem?

 

The check light is now off. Unfortunately I don't have a spark plug socket to pull one out so I'll be borrowing a friend's sometime this week to check on the part number. The O2 sensor is the correct part as it was bought at a Toyota spare parts store. The engine seems to idle just fine and acceleration isn't an issue. With the exception of mileage, I wouldn't actually be able to tell if there was an issue as far as I'm aware.

I did increase my tire pressure from 32 to 35 psi and that helped a bit (as expected), and so did running fuel injection cleaner (marginally). Other than that I can't think of anything else I can do to help improve the fuel economy.

Would a proper re-tune at an authorized Toyota dealership help? What does a re-tune normally consist of?

 

Is the car using much engine oil or having the need to add engine coolant?

There is not much to tune up but plugs. There is no distributor or rotor anymore.

If the check light is now off then assume the 02 sensor was the correct one.

Tire pressure might be cause for a small change in MPG but not down to 15 MPG.

Other things to check are a bad IAC sensor (tells computer coolant temp).

Any change in the gas your using such as having more ethanol percentage?


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