Ok so my gas milleage is getting worse. I drive about 20 miles mostly on the highway and i cant get much more than 200 miles per tank of gas...

known problems with my car are as follows...

1. Rattleing noise from the cat.

2. Oil leak. "adding 1 qrt every month" I think its leaking from the oil sender unit which was replaced a little over a ywar ago.

3. Very slight trans fluid leak from trans fluid pan. " puddle smaller than a nickel over night.

4. small exhaust leak around the headers.

5. brakes drag in the front. With the car jacked up if I spin the front wheel as hard as i can it turns maybe 1 revolution before coming to a stop. thats the case with both front wheels.

Fixes to help improve gas milleage:

1. Bosch platinum plugs gapped to gm spec" forget what it was" replaced within the last 6 months.

2. new plug wires. "forget the brand" didnt reaplce the coils or packs. "distributer"

3. New o2 sensors left and right.

Tires are kept up to pressure.

Thanks in advance for any advice.

 

So..Are you asking what could be wrong or why your getting such bad milage? You listed all your problems, have you tried looking for more odds and ends? Check your fuel pressure and see if its at a safe psi, get your leaks fixed. I recommend replacing the cat, it can trap the gases caused by the exhaust manifold and ultimately suffocate your engine

 

exhaust leak before the cat can have a fairly large effect on milage. another is it may be that the cat is getting pugged (will cause poor mpg) and is causing a pressure build up which caused the exhaust leak.

 

you pretty much told urself what the problems are. replace your brakes if they are dragging its sticking. clean clean clean.

 

Before I changed my pads and rotors, the original owner let them stick so bad I couldnt turn the wheel on either front tire. Was horrible

 

I found the window sticker in a 94 3.4 junkyard car. The EPA ratings were 19 city and 28 highway. What a joke. Must have been all down hill.

My 94 3.4 auto gets pretty bad mileage around town but much better on the highway. Around 175 miles around town but more like 300 if the tank is mostly highway miles.

Fix the brakes first. Most DIYers (and shops for that matter) do the quickie push the caliper pistons back in, slap in the new pads, and go. Very bad...

First of all, water enters the brake system at a molecular level at the caliper piston boot. The water accumulates in the caliper and that's why you get corrosion there first (and at the wheel cylinder in the back). When you install new pads you do NOT want to push that moisture-laden brake fluid back up the system, you want it OUT of the system. So crack the caliper bleeder screws before retracting the piston and expell the old fluid. Add new fluid to the reservoir when you're done.

Also, it is VERY imnportant that you pull the caliper slider pins out and either remove/clean/install the plastic bushings or install new ones. Clean the slider bore in the caliper very carefully using whatever means necessary. I usually use a very coarse rat tail file.

When you install the bushings and grease them (with special synthetic caliper grease) they must slide very easily on the (non-corroded) pins. If that's not the case the front brakes will drag and it will only get worse with time/use.

On the engine side, the cat rattle is worrisome. The matrix could be partially blocking the cat outlet and that is big trouble. I have seen cars where the dipstick popped out of that tube and the rear main seal blew out of its bore while driving (due to high crankcase pressure).

You need to address the cat rattle. Do you have a scan tool? You really should check the oxygen sensor voltage while driving. It'll tell you if the injection system is delivering the right amount of fuel.

 

u try a new fuel filter and just try dumping in some lucas injector cleaner just see if maybe u got junk in there

 

My 3.4l just got me 37mpg on a 6 hour round trip on the highway with a small amount of city driving mixed in. I usually average around 20-22 in the city depending on traffic and how I feel like driving.