sam

Hi,

I was wondering if anyone can help me figure something out I have a 88 305 TPI firebird trans am. I am getting 11 MPG in town driving (max 35 mph) and I am not sure if that is normal.....

I know i get more on highway but i dont have the numbers.

I bought the car 6 months ago. it has 140 000 miles on it.

1/ Should i change the O2 sensor? it has one wire attached to it. Can an O2 sensor work halv as well and then fail or do they either work or not?


2/ I guess i need to change the plugs too. It looked pretty tight. any specials tools that i need? I know it was serviced before i bought it but no clue if the plugs were changed.

3/ Same goes for the fuel filter. probably needs changing

4/Does removing the cat converter improve milage and increase MPG?


The c ar does run fine though Better than anything i have driven in the past.

thanks,

Sam

sam

Surely someone can help me out ?

Edmond

11mpg in town is not normal, that is way below what you should be getting.

Yes, change the O2 sensor. It's cheap enough to just change it. I think it should be in the $20-30 range. I have a Bosch sensor in mine, just did it last weekend.

You'll just need a plug socket. The ones on my TPI Vette' were an 18mm size. I used a wrench that had an angled head. Drivers side was done in 15 minutes. Passenger side will take you some time because it's trickier. Be patient, curse a little and you'll get there. I would go with Delco plugs.

Fuel filter is cheap enough to change. I think I have a FRAM in there but I'm going to try Purolator. I think the FRAM cost me $12 or so a couple years ago.

Yes, removing the cat will improve mileage because you'll have less back pressure. Do you still have the stock muffler? You do need some back pressure, though. Some draconian jurisdictions require you to have a cat or risk getting heavily fined. Check your local ordinances if a cat is required.

Tired_Iron

While you are at it I would change plug wires, cap and rotor too if they look old. Even if they look new the still could be junk. Bad wire(s) have plagued more than one of my friends vehicles that ran crummy (poor mileage, rough idle without throwing any codes)

Good luck

Edmond

May as well check the timing too.

sam

I was glad to see all the replies I will begin servicing as soon as I can. I checked the prices for parts and they were not that bad

Edmond, my muffler is pretty much stock. Might have been changed in the past but I doubt it. I dont dare imagin the internal condition hehehe

doc

Do a COMPLETE tune-up, plugs, wires, filters, timing.

If the distributor is the original unit, replace that also.

And buy a new AC Delco O2 sensor, it should be the 1 wire sensor. Do not buy the Bosch sensor.

Do the O2 AC Delco swap first and check out your fuel mileage difference, then do the complete tune-up.

Tired_Iron

Doc:

Why not a Bosch O2 sensor??? I have replaced the AC O2 sensor when it failed with a Bosch and it works fine. Is there a reliability issue with Bosch O2 sensors?

Thanks

doc

Go over to the DIY Prom board. Several guys swear by the AC Delco sensor and have from personal experience have issues with the Bosch O2 sensor. I got my recom from the DIY board. I have not tried the AC Delco sensor myself.

sam

Well,

I checked under the hood and I must say getting the spark plugs out does NOT seem easy. I mean you cant see the sparkplugs that are closest to the firewall.

So if i go ahead and attempt it I dont need to remove anything else inorder to get to the spark plugs? I feel the AC is in the way.....

Do I need a special tool for the o2 sensor? or is there inough space to use a regular tool?

thanks,

Sam

Tired_Iron

Sam:

When I had my stock cast manifolds I used to get those plugs from underneath. Try a plug socket with out a ratchet and then use a box end wrench over the end of the plug socket for tight places. That is now the only way I can get most of my plugs with my headers.

As for the O2, a socket is cheap from most auto parts stores. It's worth the investment. I believe a 7/8" wrench will fit your O2. The socket will save your knuckles since it won't slip off so easy.

Good luck

sam

Tired Iron,

thanks for the tip. I will be doing it over the weekend

Came across a site that mentioned that bad spark plugs can increase cosumption by 2 mpg and that a tired sensor just as much....

Thanks,

Same