92 5.7 tbi terrible MPG

[Logant12]

So i got a 92 k1500 with the 350 the engine is all stock with 130k miles it runs good and all that i got true duals no cats with these "coop performance mufflers" and 265/75/16 Kanati Mud hogs my truck has been averaging 7-9mpg i know these engines dont get amazing mpg's but I know many trucks of the same set ups and engines are getting alot better then what i do. I'm pretty certain my alignment is messed up because my tires are wearing really bad on the front tires really unevenly so i am going to get that looked at, but my question is what are some things i can do to get my mpg up i've heard Throttle Body Spacers, Computer Chips,Air intakes? opinions on those? any other options would be helpful.

 

[poncho62]

After getting the alignment looked at, I would look at getting a good tune up...plugs, cap, rotor, wires, air filter etc ......

 

[someotherguy]

"true duals no cats" - do you still have an O2 sensor installed? If no, you need one. If yes, it's probably still the single wire non-heated style that your '92 originally came with, which may not be working very well if at all anymore due to you opening up the exhaust like that. Time to convert to a three wire (heated) O2 like they started using in '94 on light duty automatic-equipped trucks. The extra two wires are just +12V and ground which you need from a "key on" source. The O2 must reach operating temp of about 300F before it begins generating a signal.

Next up, check or replace your coolant temperature sensor (the one right next to the thermostat housing), and be sure the harness grounds attached near it on the thermostat housing and next to it, are in top notch condition.

Be sure the MAP sensor vacuum line is firmly connected at the rear of the TBI unit and that the electrical connector to the sensor is plugged in and undamaged.

Richard

 

[K15 Blazer]

Im only getting 14 mpg ON THE HIGHWAY....

 

[Logant12]

Do o2 sensors make that world of a difference i heard different things bout them

 

[eg30.06]

You need them on you tbi truck. Tell the computer to richen or lean out you air fuel mixture. Do you smell gas out the tailpipe while running the truck ?

 

[Logant12]

yeah i do get that scent often

 

[eg30.06]

yeah i do get that scent often

Then yes I would start with ensuring you have your O2 sensor in place and if so replace it, their just a cheap single wire one.

 

[K15 Blazer]

I also smell gas.... even more so than my carbureted chevelle. But I think thats because we have a huge TBI and my car is a 500 cfm 4barrel.
point is, if the o2 sensor(s) is bad it would trip codes.

how are your sparkplugs colored?

You may just need to blast a can of seafoam through he manifolds and a can through the tank... o2 sensors are expensive

 

[someotherguy]

Size of the TBI doesn't mean anything; it's sized appropriate to the engine. The air/fuel mixture being too rich is why you smell gas in the exhaust. See my previous reply for the usual suspects.

By the way the small block TBI isn't huge. I do believe it's rated at 480 CFM.

Richard