7 replies to this topic

[radchad]

I have 94 850 turbo wagon and have been getting bad mileage. I replaced the rotor and cap and it seemed to have a good effect for about 10 miles and then went back into the dumpster. I'm not getting any check engine lights. Any thoughts? Could it be an oxygen sensor? I'm baffled since I have no check engine lights coming on.
-Chad

[Mesoam]

There is a multitude of possibilities. The first would be that there is something wrong and your CEL is just burnt out. You should have your dealer or local indy shop check your codes for you. Other possibilities could include throttle body needs cleaning, fuel filter, air filter, plugs, wires, tire pressure. I don't think these minor things would create awful mileage but in conjunction with each other it could have a pretty adverse effect.

[850&S80]

I had the same problem, but the check engine light was on also.

I replaced the Thermostat, which was stuck open causing the engine to run rich. In cold weather the temp wouldn't climb at all.

The front 02 sensor was replaced also. My milage went from 19 combined to 26 combined.

Can't say if it was a combo of both or just the thermostat.

[radchad]

Hi, I have a '94 turbo and I can read all the codes myself and everything is reading fine when I do the diagnostics. Any other help would be greatly appreciated.
-Chad

[Bay13]

If your mileage is down you are burning more fuel, more than likely. Vacuum leaks can cause the fuel trim to adjust with more fuel, check for vacuum leaks. You might check fuel pressure as well, if the regulator isn't working your pressure could be higher than it should be, wasting gas. Bad or slow O2 sensors could also effect the gas mileage. Bosh O2 sensors are at the max a 80K sensor. If you have more than that on your sensors consider replacing them.

[radchad]

Rich, if my O2 sensor(s) were bad wouldn't I be getting an engine code? Also, I replaced the thermostat and it improved but has since gone back to crap. Also, I need to replace the heater core, could that have something to do with it as well?

Thanks
-Chad

[Bay13]

I doubt a seeping heater core would have anything to do with a MPG loss. Stick with the too much fuel theory until you prove it wrong.

[radchad]

OK another problem with my '94 850 turbo wagon. When I drive the power hesitates on and off.... No check engine light either. It is very minor and happens when it is hardly under any boost load. Could a bad pcv hose account for this? I've checked every conceivable hose etc and am baffled. Would a faulty fuel regulator account for the varying power gain and loss or does a bad fuel regulator only account for making the car run rich? Any help would be appreciated. I don't want to add to my mechanics' kid college fund if I don't have to!

Also my purge valve is really ticking super loud. Could that be the source?

Edited by radchad, 07 May 2004 - 08:06 PM.