'99 Swift bad fuel economy mystery...
 

Hey there,

About 8 months ago I bought an automatic '99 Swift to replace my automatic '96 Metro. I purchased a scangauge a few months ago, and I've confirmed its accuracy using the odometer and set it up properly etc.

The problem I'm having is that I'm getting about 8 LHK on the highway and about 12 LHK city average! This is despite no hard accelaration, not driving agressively, etc. I've been practicing my eco-friendly driving techniques that I've read about on the internet.

I have tried a few things to try to get better economy out of it; their was a bad gasket seal on the transmission that got fixed for about $150 and the exhaust system rotted out a bit and was noisy so I replace the exhaust for about $300. Not bad for a car I bought for $1000. It has 134000 KM on it (Im in Canada)... also replaced spark plugs.

Do I need to do something else here? Transmission flush?

Whats up with this car? My Geo got WAY better economy than this, and from what I've read I should be getting more like 6 LHK hwy, and 8 city...

??? I bought this sucker thinking I was getting basically the same as my '96 and its really messing with my fuel cost plans...

I would start with the cheapest things first.

1) Check or replace the thermostat and PCV valve.
2)Try coasting down a hill that you know how fast your older Metro sped up. Maybe you have a bad wheel bearing or brake pad/shoe dragging.
3)Try cleaning the injectors.

Just a few ideas, maybe other folks here know of more reasons for bad FE.

Another issue I have had lately is the Ethanol in the fuel. Sometimes it drops my FE by 25%!! And the number of gas stations that sell pure gasoline is decreasing every month.

I suspect the oil companies are adding more than 10% ethanol in the fuel. Who knows? I really don't trust Mobil/Exxon to tell us the truth.

Did you check out the mechanics of the car? Brakes not dragging, compression up to spec, wheel alignment, fluids good, tire pressures at spec, O2 sensors good...

I'm not a mechanic... so...no? I've asked my mechanic whats wrong and they seem to think the car is in good shape.

These are some good suggestions to get me started in asking the right questions.

Anything else?

You have a scan gauge, so put it to use.
Make sure that your engine is getting up to temp, 192F
Make sure that your engine is going in to closed loop.
Make sure that the rest of the info on the scan gauge looks correct.

After that, do a tune up on the car, transmission flush, spark plugs (compare them to each other), air cleaner, pcv valve, check your timing, check brakes and wheel bearings.

Is your new Geo a 3 or 4 cylinder engine? hatch back or sedan?

4 cylinder hatch back Suzuki Swift. How does one go about checking the engine temperature? Can the scangauge do that? Is it FWT for the temp? How long should it take for the engine to reach optimal temperature?

How do I ensure that the engine is going into a closed loop? What does that even mean, and why is it important?

Also wanted to mention that I very rarely get the infinate fuel reading of 0.0 LHK; even when coasting down a hill I'm often still at 2.0-3.5 LHK. Related?

I have two engine codes that pop up now and again but I cleared them recently (the mechanic said they were not important issues). I remember I think that one of them is P0036 "Heater Resistance Out Of Limits" according to engine-codes.com

Wow just read your mpg thats a slight issue for that car. I'd check to see if your trans is shifty properly and try to get your injectors cleaned out. Your sparkplugs may be shot as well. Check your airfilter to see if it is clean or not. If your engine is choking for air you are not buring fuel properly and your engine has to work harder to get going.

Plugs were checked last week as was transmission & air filter replaced 3 months ago. Could be injectors but I have no way of checking.

Yes, FWT is coolant temp in Fahrenheit, CWT is coolant temp in Celsius.
That is going to depend on how much load the engine is under, in the winter 2-3 miles/5K and it should be warm.

Closed loop means that the computer is not running a preset program but that it is instead choosing how much fuel is being burned based off of the oxygen content of the exhaust, based off what the o2 sensor is reading, your p0036 engine code says that you have a bad heater on your down stream o2 sensor, not sure if this would keep it from going in to close loop or not, your scan gauge has the option of telling you when you are in closed loop, it should go in to closed loop once it is warmed up unless you are at full throttle.

Was that mechanic worried about your mileage or just about you not being stranded?
Do you have your scan gauge operators booklet? if so I recommend that you finish reading it as it will better help you use the tool you have.

How about the ignition wires or the distributor the plugs may be fin but they might not be getting enough power to perform properly.