Help! I got my timing belt changed and I'm getting like 10mpg less now!!!

[85_305]

Ahhhh gotcha. Now thats interesting. As the car DOES kinda have a gassy smell on the outside if you give it throttle.

Wouldn't this trip a CEL though??

[85_305]

Well I just went and looked, and the o2 sensor was plugged in tight and there didn't appear to be any vacuum hoses that were missing or disconnected or rotted etc. WTF

[85_305]

I'm wondering if my primary o2 sensor is shot. Those dont always throw codes right?

[quicksilverdon]

Originally Posted by 85_305

Ahhhh gotcha. Now thats interesting. As the car DOES kinda have a gassy smell on the outside if you give it throttle.

Wouldn't this trip a CEL though??

You need to track down that smell...

[85_305]

It's ever so slight.. I just have a keen nose for things like this. Think it could be a bad o2?

[Carl48]

A bad upstream O2 sensor should at least set a trouble code if not turn on the MIL ("check engine light") if it is bad, that is the whole purpose of OBD II. However, an O2 sensor doesn't always suddenly go bad. They get "lazy" before they go totally bad. Don't know exactly how bad they have to be before the light comes on.

You might want to check around for that gas odor you notice, a leak would certainly cause poor mileage.

This seems to have happened after the timing belt was changed. Haven't done a timing belt on a 2.4 myself (yet) but it is possible to get any belt on improperly. The belt could be on a tooth off and this would upset the timing and cause poor mileage. After the belt is installed, the engine must be turned over by hand at least a couple of full revolutions and checked that the timing marks on the camshaft and crankshaft gears still line up per the instructions in the repair manual.

Other fuel economy killers are worn fuel injectors, dragging brakes, low tire pressure.

[85_305]

^That would make sense because since I got the car back, if you read my first posts my mileage has beeng going from like 19's, to 17's, 15's, to where I'm at now in the 10's.

The dealership did the t belt install

Brakes aren't dragging and tire pressures are great. I dont know about injectors.. thats not exactly common on these is it??

[Carl48]

That gas odor you mentioned could be a leaky injector if you can't find visible evidence of any other fuel leaks. Your senses are your best troubleshooting tools, look around and sniff around. However, after a certain point on a problem like this, without diagnostic equipment, you are limited to guessing and random parts replacement.

[85_305]

Hmm. Interesting. I'm not seeing any leaks on the car ANYWHERE.. I'm really wondering if it's the o2 sensor. Thats seeming more like a possibility to me.

[85_305]

Here is a quick update. So the PT has been sitting a few weeks. It's pissed me and my wife off, so it isn't driven any more.

Well the past few days, my wife's decided to drive it. The tank was bone dry, and put six gallons in. She's already up to near 120 miles and still has near a quarter tank left.

The ONLY factors that have changed are SHE is driving it, and the ac isn't cranked as it's been decent out lately.

I'm pretty good at milking gas mileage out of cars and she is lead footed. I'm gonna be pissed if SHE is the factor thats determining gas mileage lol.