car has bad acceleration, fuel consumption

I suspect that my SVX has some problems. It is a 1994 model, front wheel drive. We had it repaired a while back, but since then, I've noticed that the acceleration isn't as good as it used to be, and the fuel consumption is pretty bad. On a full fillup of 13 gallons, I'm getting about 200 miles, and this is in the city and I'm not a very wasteful driver. Especially coming from stops, sometimes the rpms will just go out of control, going up to 4k, but the acceleration will be pretty lousy. We have a toyota previa van, 4 cylinder, and I think that it has better acceleration than my SVX 6 cylinder. Acceleration is fine once the car gets up to speed, but coming from stops it's pretty lousy. So, in short, it's acting like a 4 cylinder car and it's consuming fuel like a 6 cylinder. Any idea what it might be?

[n00b on demand]

I think you may have transmission problems....

[ensteele]

Welcome to the site. It sounds like you may have some issues with the transmission.

[Chiketkd]

Originally Posted by guynoir

I suspect that my SVX has some problems. It is a 1994 model, front wheel drive. We had it repaired a while back, but since then, I've noticed that the acceleration isn't as good as it used to be, and the fuel consumption is pretty bad. On a full fillup of 13 gallons, I'm getting about 200 miles, and this is in the city and I'm not a very wasteful driver. Especially coming from stops, sometimes the rpms will just go out of control, going up to 4k, but the acceleration will be pretty lousy. We have a toyota previa van, 4 cylinder, and I think that it has better acceleration than my SVX 6 cylinder. Acceleration is fine once the car gets up to speed, but coming from stops it's pretty lousy. So, in short, it's acting like a 4 cylinder car and it's consuming fuel like a 6 cylinder. Any idea what it might be?

Sounds like at least two things are going on with your car:

1) Transmission is flaring and is on the way out. Do you still have all four gears?

2) Your O2 sesnors need to be replaced. When they go bad, the afr runs extremely rich (safe mode) to prevent detonation, which in turn reduces gas mileage and performance.

One silly question - do you run premium or regular gas in your car?

-Chike

I use 89

could you elaborate on the transmission and the o2 sensor? How should I get this repaired? Last time we went to an independent mechanic, I don't think they did a very good job.

[SubaSteevo]

Originally Posted by guynoir

I use 89

I'm guessing that's your problem. The SVX is designed to use 91 or better.

[Chiketkd]

Originally Posted by guynoir

I use 89

could you explain the O2 sensor thing?

How long have you been using 89? You do know that on your fuel gauge and on the inside of the fuel door it clearly states to use premium unleaded only in this car.

The O2 sensors typically last between 60-100K miles on a car. If you haven't changed them on yours then it's probably time that you do. They are used in closed-loop operation to keep the air fuel ratio (afr) at the Stoichiometric ratio (i.e. 14.7:1). When they go bad, the afr in safe mode can richen to as much as 10:1.

-Chike

[Electrophil]

I second the O2 sensors. The differences in smoothness and gas consumption were amazing upon replacing both sensors.

I've only been using 89 for the past few weeks due to the huge difference in the cost between 93 and 89 (alot of pumps in my area don't sell 91).

The problems were evident before that, and I think that things actually improved a little bit when I was using 89.

Thanks, where would be a good place to get new o2 sensors? Is there anywhere online that will instruct on how to replace them?

[Chiketkd]

Originally Posted by guynoir

I've only been using 89 for the past few weeks due to the huge difference in the cost between 93 and 89 (alot of pumps in my area don't sell 91).

The problems were evident before that, and I think that things actually improved a little bit when I was using 89.

Thanks, where would be a good place to get new o2 sensors? Is there anywhere online that will instruct on how to replace them?

You need to ONLY use 93 in this car. The dual knock sensors in this car will prevent the engine from detonating all day long when you add 89, but the SVX uses a high performance 10:1 compression motor and needs 91 octane at a minimum.

O2 sesnors can be purchased at www.subaruparts.com/. They are quite expensive though and run over $100 each.

-Chike

[ensteele]

Most cars will get worse mileage when using regular gas than with the 91+ gas. There really isn't any savings when you fill up with regular. Most have said that they get much better economy with the 91+ and have never gone back. All of that besides it stating that you are to use the premium gas. These are not cheap cars to maintain. The O2 sensors will help as well. Good luck.

Well, to be honest, I didn't notice any difference between 93 and 89. Wait, I just checked: my dad tld me that he has regularly used 89 in it. I filled it up with 93 and I guess because he filled it with 89 it didn't make a difference. So are there any places cheaper than subaru parts? Where should I look, anything to look for?

[Earthworm]

You may not notice but your car does.

It's been recommended to replace the O2 sensors and use a minimum 91 octane fuel. This should be done before more damage is caused (like damaging the cats).

okay. It's been running on 89 for two years. I have a few questions:

1. If the pump only offers 89 and 93, would filling it half with 89 and half with 93 result in 91?

2. Are there any steps that I need to take to fix the aggregated damage to the engine from 89? Is there any way to clean it out? I'm afraid that since it has used 89 for so long, the sensor won't be able to detect it when I use better fuel grades.

3. What should I look out for in terms of damage to the engine? What steps should be taken to repair?

[Earthworm]

Originally Posted by guynoir

okay. It's been running on 89 for two years. I have a few questions:

1. If the pump only offers 89 and 93, would filling it half with 89 and half with 93 result in 91?

2. Are there any steps that I need to take to fix the aggregated damage to the engine from 89? Is there any way to clean it out? I'm afraid that since it has used 89 for so long, the sensor won't be able to detect it when I use better fuel grades.

3. What should I look out for in terms of damage to the engine? What steps should be taken to repair?

1. yes

2. Try running a bottle of fuel system cleaner in your next tank of gas. After that tank reset the ECU by leaving the battery disconnected overnight.

3. Try a search either here or for "octane". Other than doing #2 and replacing the O2 sensors I wouldn't do anything. Just see how it runs from there.

Does your check engine light come on at all? If so there's a way to check them. Codes & instructions in the SVXipedia on http://svx-iw.com/ (in the codes section)