'99 Swift bad fuel economy mystery...

[brucepick]

Definitely note down any codes that come up. As Ryland suggested, a mechanic may not be thinking towards exactly the same goal as you.

You can google the codes to find out what they mean - include the year and model of car with the code when you do.

[orange4boy]

A bad O2 sensor can cause high FE and your car is due at 135000km. The fact that the O2 sensor heater is gone is a warning sign that the sensor may be malfunctioning too. Already, without the heater it will put you car in open loop for longer than normal: uses more fuel.

An O2 sensor can be bad and not through a code. Mine was working in reverse a
while back and caused all kinds of strange behaviour including poor mileage so that would be my first suggestion: replace O2 sensors. You can get $ generic ones installed. don't need to get $$$ dealer parts.

The O2 sensors are bolted to your exhaust pipes in front of and behind the catalytic converter. Do em both.

[bandit86]

Check your front wheel alignment, make sure they both poi t straight. Try to have some one sit in your car when you check. I got an alignment and starts wearing the insides of the tires. Anyways, I usuall use bungee cords to secure 4 foot levels to the rim, and measure behind and in front of the tir. Make sureyou are getting a true reading, tryto stayoff of raised lettering. There should be a 1/16 to 1/8 smaller reading in frot of the tire comparedto behind

another one might be that the car was in an accident and is dogtracking, and it ispushing air with it's side as it goes down the road. If you have bedrails you can check that too, secure them to the rear wheel facing the front and see how far he back to front wheel alignment is off. Or you canget a 4 wheel alignment, but I don't think there is anything adjustable on the back so shops may not check it

[orange4boy]

Ha. That's exactly what I did a week ago, Bandit.

Originally Posted by bandit86

There should be a 1/16 to 1/8 smaller reading in frot of the tire comparedto behind

For FE it's better to have 0 toe in. Some people claim cars track better with some toe in but I have not found this to be true with radial tires on my cars. If you want rock steady tracking put on an air dam and kill that front end lift. Plus gain some FE.

[acropora1981]

ok... Sorry for the delayed response; not abandoning the thread at all, just moved in with my gf and we've been painting/cleaning/moving/going to jays home opener.

So my car is running @ ~90 C (194F) which seems about right, and it gets to that temp within a few minutes of driving.

Closed/open loop seems ok, but it is doing one thing weird. If I'm accelerating hard it is open, but it is also open in another circumstance. Lets say I'm on the hwy going 100kph and I take my foot off the accelorater and coast. It opens when my car coasts.

The codes have yet to return...

Thanks for more info I'll look into all these avenues, starting with sensors.

[acropora1981]

Alright so another code poped up - P0136 which is apparently P0136 - O2 Sensor Circuit Malfunction (Bank 1 Sensor 2) according. Is this the upstream or downstream sensor?

edit: now it appears to have dissapeared again...weird.

[acropora1981]

sorry for multiples in one day... looks like that code is for the downstream O2 sensor.

Can someone point me to a decent generic (cheap) pair of O2 sensors that I can replace mine with and and online dealer? Keeping in mind that I am not a mechanic...I need something that will fit my 99 Swift without and kind of modification...

[mekanic]

If i remember right the swift and metro were quite different cars. swift was a 4 cyl car and the metro (3 cyl) was specificly made as an economy car. I bet the tuneing was for econ on the metro and much more performance on the swift.