Ive just about done everything to my 2.8 that i can think of to try to get it to have some better gas miliage, Ive calucated that i am getting about 15 mpg, Last thing i can think of is that my Carb is out of tune (if thats the right word) What are the steps to tune this carb, and what tools are needed. Its a Computer controled verson. Thanks for your help.

 

Anybody?

 

I don't know what you already have done but I'll run the list for you and you can check off what you have done.
1. O2 sensor
(edit) 1.5 : Air filter.
2. PCV valve and clean piping back to manifold.
3. PCV filter (if equipped).
4. Spark plugs.
5. Ignition timing set to spec.
6. Fuel injectors or carb kit.
7. CAT converter (check- plugged up?).
8. Tire pressure correct (don't laugh).
9. Thermostat (not closing completely or missing).

And last, but the most common cause:

10. Internal engine wear (perform blow-by test and compression test)

 

Alright, ive done 02 sensor PCV and filter (didnt not clean piping, How would i do that? )

Tire pressure is good,

the CAT is rattleing, how do i check if it is pluged up? by feeling the "force" of the air comming out of the rear end or what?

Thermostat, havent checked yet, will check though

I know the car's OD has not rolled over, and it now has about 78k miles on it, could the wear be so bad on it already? Ive never rebuilt the carb, and i have no clue when it was last rebuilt. Would that be the most probable cause? spark plugs/wires/cap/rotor were replaced last year about this time, tires are also due to be rotated here soon.

Thanks for the help

 

A quick way to check the Cat (not the best) is to remove the O2 sensor and hold thumb over hole (while wearing leather welding gloves) and have another do a 5 sec WOT stall test. This is dangerous if not done correctly. If it is plugged, you will struggle to keep that hole covered.
To clean the pcv tube involves removing the tube, spray can of carb cleaner, and lits of different wires to push thru it. If it's stopped up much, you will have to do likewise with the connection to the motor.
It's possible the engine could have that much wear. 78K miles in 22 years?? How often oil was changed and with which weight oil for the climate, how much % city driving, and # of times overheated, are big factors. Another factor is dirt leaks in the air supply, cracked intake hoses, air cleaner/filter mismatch. The worst engines I've seen had this.
Too easy to do a blow-by test than to wonder.

 

What would be the best way then (short of takeing the cat off the car, if that is the best way short of doing that then ill try that out)? i really dont want to leave anything to chance.

Ill have to buy the related tools for the compresson test and blowby test (minus hand tools)

On the blowby test what exactly would i do? im taking auto shop classes in College, im just not to the Engine class here yet.


Anyways thanks for the help.

 

Check all the other items on the list first (important). Save the compression test for last. The blow-by test is simple: Block all 4 wheels. Engine at operating temp, remove oil filler cap. Have an assistant hold the brakes on full and run the engine to WOT in drive for 10 seconds. Stand beside the car and note how much "smoke" comes out of the oil filler opening. If the rings are fine there there will be nearly none. The worse the rings are, the more you will see. I've seen some that had a plume over a foot tall in the worst cases. Do this test first and most times you won't have to do a compression test. No sense in doing a compression test on a engine with known worn rings.
If the cat is stopped up it will always affect the engine the most when it is making full power. Other way to test the cat is to do a timed WOT acceleration run and note it (from a stop, 15 seconds and note MPH). Back off the nuts that hold the ex pipe to the manifolds to the end of the studs and back the pipes off. Repeat the timed run. Care must be taken that the escaping exhaust doesn't melt anything. Check the two runs and see if there is any significant difference. If there is, then the cat should be replaced. If it passes both these tests then think about a compression test

 

alright thanks, ill do that as soon as i can thanks for all the help

 

do the sparkplug insulators, seem
to have the proper color,
or are they black?, indicating rich

is the distributor 'vacuum advance' working
{only if you have a mechanical dist}

 

ill take a look at the spark plugs today. the wires them selfs are a little dirty but look like they just came out of the box.

 

Check the plugs on the underside of the metering wells for leakage. That will kill mileage.