Ok, so over the last few months my 94 volvo 940 non turbo seemed to be getting bad mileage. The last 4 tanks, i tested it and with each tank, i got around 20 mpg. I usually get between 25 and 27 depending on how much city driving I do.

What are some things that could cause bad mileage? I need ideas.

Also, I noticed that my exhaust pipe flange gasket(its a metal gasket between the down pipe and cadillac converter) has a big leak and wen I went to order one, It asked me if I have egr. How would I know? and could this be the cause of my bad mileage?

Some other symptoms that could help. the car of late sometimes will have an issue with random changing or bucking idle speed especially when cold. Once in a while when I first turn it on the car will sound like one cylinder isn't firing. I have changed the injectors, sparks, wires, cap, rotor all within the last 6k miles. is this more probably due to a bad fuel pressure regulator or fuel pump? That was my guess.

 

Would a leak in the exhaust in front of the catalytic converter make a 25% difference in gas mileage?

 

It certainly could if the 02 sensor is in or behind the cat. They need to be at a certain temp to work properly.
Tried pulling codes?

Regards, Andrew.

 

Ya, its in the cat. Good idea, I'll pull some codes.

 

I'm fighting the same battle right now. From what I've read, the EGR is under the intake manifold. For the life of me, I cannot locate mine...it's a '91....pretty sure it should be there?

Anyhoo, In order to service this thing yourself, it's recommended that you remove the plastic intake hose from the throttle body to gain easier access to it. From there, many 'how to's' suggest removing the Throttle Body (TB) for even easier access....and while you're at it, clean up the TB. While you're taking things apart, you may as well clean out the Idle Air Control (IAC) valve too. The IAC might be your answer to the bucking idle? I read that problem is more persistent with a warm car though....such was the case for me.

codes will help you out a lot. O2 sensors, fuel pressure regulators and carb cleaner are relatively cheap.

 

Thanks for the tips on the IAC. Don't the fumes for the EGR come from a pipe that comes from under the exhaust manifold? Could you follow that line until you find it? and I'm pretty sure i read somewhere that some cars don't have it EGR. It might be possible that yours is one of those. I also found some pictures of it on the internet. It looks like a fairly easy to spot part.

 

lol...then I'm going to operate on the assumption that I don't have one! If you happen by any of those pics, send one my way!

I'm heading to the salvage yard here soon...i'll take a look at some of the 240s in there to see what's different.