poor fuel economy running rich

[AdamG]

My camaro is burning about 12 gallons in about 150 miles. which means im getting about 12.5 mpg. My oil is coming out wicked black at 1500 miles but to me doesnt have a gas oder to it but maybe its just me. It smells like its running rich but doesn't have any smoke coming out the pipes.

what should i check?

Im thinking about replacing the o2 sensors as one is a Bosch and one is a a/c delco with 120k on it. Yes i know shame on me for every part of that.

Im going to check the mass airflow seonsor and clean it but is there any way to actually test it?

the coolant sensor is goodish. I have taken 2 different scans the scanner and tunerpro tell me two different things on the o2 sensor they are about 30 degrees apart. im more inclined to believe my hand held scanner

other then that what else should i check.

I can get data logs but i also have a few if you guys want to see them. If you want a specific log or something just let mew know. also let me know how to post them.

[MEAN LT1]

What are your fuel trims lookin like when part throttle. Also, do you have a trouble codes?

[95ImpySS]

Well by your description of the 02's reading 30points off I would say you have a failing o2 or a large exhaust leak up stream. Both will cause a rich condition. You cannot have any exhaust leaks upstream of the O2 sensors. Check to see that your coolant sensor is reading right. Doesn't have extreme or erratic readings. I really cannot comment on how to check the MAF. I hadn't run into a failing one yet :) What are your BLM's?

Try unplugging your 02's and see if the exhaust smells better or you notice a change in fuel economy/power. RockAuto.com has AC Delco o2 sensors for CHEAP $45 IIRC. I highly recommend them as well as changing both upstream O2's if you have no apparent exhaust leaks.

[SeanMac]

I'd probably start with O2's and checking exhaust leaks also, but if you want to check your MAF while you're at it I've got a spreadsheet you can use to check it by. We've started testing this on pretty much any kind of drivability issues at work because its a real quick easy check as long as you have access to a scanner.

Just hook up the scan tool and graph or record RPM and MAF g/s, run the car wide open thru 1st gear and note the highest rpm and highest MAF g/s, come back and check the current weather conditions for your location and plug the info into the spreadsheet and it tells what the actual g/s it should be reading. If your reading is a lot lower than what it says you should have, its likely dirty or faulty (unless there are other issues going on too). But if its off usually a clean and retest will show some improvement. If its still not good enough maybe a new one is needed, if it doesn't make any difference maybe something else going on. There are some more instructions and tips on the sheet.

I had to convert it to the older version of office to attach, so let me know if it doesn't work.

9170

[AdamG]

Sorry i know i said 02 sensors but what i meant to say was that 30 degree difference between the scanner and tuner rt on the coolant temperatures.

BLM jumps all over the place any where between 10-18 the

one scan is very erratic. the right and left BLM is usually between 120-130 spending most of the time at 125. they do go above 130 at times and drop below 120. its very erratic sometimes the left and right are way out of whack but the thing about it is it flip flops between sides.

I just looked at some other data logs and they seem to hover in the 125 range and cell 18 most of the time

I should also add im sure its not an exhaust leak as i was just checking the bolts on it about 2 weeks ago. Ill replace the o2 sensors any one is old they are miss matched so Its probably a good idea.

Is it possible that when i rebuilt the engine some of the oil went out the exhaust and screwed up the o2 sensors.

no running troble codes

[Viper]

Amazon has good prices on sensor parts and is less likely to rip ya off than Ebay. Delphi o2s.

http://www.amazon.com/gp/part-finder/slide-show/1993/Chevrolet/Camaro?ie=UTF8&Model=Camaro%7C432&Make=Chevrolet%7C47&Year=1993%7C1993&partsNode=15730551&carId=001