1991 festiva gl recent tuneup

[ut76vol]

I have search the threads first but have not seen anything quite like my problem I have now.

A couple of months ago my 91 was getting around 40-42 MPG around town. The car has about 190,000 miles on it . I have had it about the last 50,000 or so. I decided to give it a tune-up since I had not done it since I had it. A reliable shop did change the timing belt about 160,000 for me since I did not know much about it. Anyway I changed the fuel filter, ( very dirty), put new NGK ? plugs in, new pcv valve and used Lucas fuel cleaner in the tank. Drove it a couple to tanks of gas and it did not run as good as before and got about 34MPG. I had previously purchased new plug wires, distributor cover,cap and button. I changed the wires and again drove it for a couple of tanks of gas and got about 32MPG. Went on and changed the distributor cap,cover and button. Also ordered the same spark plugs from ford that was in it in the past and original equipment. Set gap per my manual and changed the NGK plugs out and off I went again. I am not so proud to say that now I can get about 28MPG. Still does not run as well as before the first tuneup.

Any thoughts from those with vast more experience is appreciated!!

:cry_smile::cry_smile:

[TominMO]

Has the catalytic converter ever been changed? Apparent good running with lower gas mileage is a common symptom of a clogged converter. The mileage and power gradually decrease so that you don't notice it.

[ut76vol]

Not to my knowledge. I did have a new muffler installed at a muffler shop a few months prior to my tuneup. He did not mention any thing about the coverter at all but he did tell me that he would install a new resonator later if I wanted him to. He said it was fine as is but would make a little noise. It does but no problem for me. I am not even sure what the resonator does unless it is a noise reducer.

[TominMO]

Not to my knowledge. I did have a new muffler installed at a muffler shop a few months prior to my tuneup. He did not mention any thing about the coverter at all but he did tell me that he would install a new resonator later if I wanted him to. He said it was fine as is but would make a little noise. It does but no problem for me. I am not even sure what the resonator does unless it is a noise reducer.

The resonator is just a noise reducer. As for the cat, some people have been known to drill a hole thru the center of the cat in areas that didnt have emissions inspection.

[ut76vol]

thanks for the cat update. i do not have to deal with those issues. if that could be be problem i may do it if something else does not come up.

Thanks

[FestYboy]

make sure your o2 sensor is swinging (use a cheap gauge or a reliable DVOM). if your o2 is bad, the car will run rich and cut your milage. also, if your intake manifold engine temp sensor is bad, the car will run rich. if either of these are true, the elevated fuel mixture can cause premature cat failure which can cause lower MPGs and lack of power. if this continues, the cat can melt and clog to the point of causing the car to stall while trying to accelerate.

[FestYboy]

to put it shortly, a factory manual would be a very good investment for you. i can walk you through each test but it'll take some time.

[ut76vol]

thank you i have a manual.

[FestYboy]

a factory manual? if so, it'll walk you through what i mentioned above.

[ut76vol]

yes it is a online manual 1991 ford festiva manual. If this is going to be as time consuming as it appears for you, I will try on my own by the manual.
Thanks for your time!!

[WmWatt]

The ignition on the Festiva can be sensitive. If you have a vacuum guage it will show if the engine is missing by a rapidly changing vacuum. I usually wipe the ignition wires clean. I can't think of anything you did which would normally lead to a reduction in fuel efficiency. Maybe you picked up some dirt or moisture. Try wiping everything down with a clean rag. Spraying with WD-40 will remove moisture. I also crimp the clips on the ends of the iginition wires for good contact. Did you use the dielectric paste on the boots and cap that should have come with the new wires? Also cleaning the connections on the coil might help.

[ut76vol]

Thank you for your response. There was no paste in the box with the new wires. When you say wiping everything down, are you saying connections, rotor, cap, etc? Also I made sure all the connectors were good and tight on the rotor and the plugs in last few days. Do not know what should be sprayed with WD-40 to remove the moisture. I guess i can purchase a vacuum guage to check the engine . Any particular type of whatever would be reliable. Should I get some of the paste and use it on the boots etc?
This whole thing has been so unique to me and I am one who usually can fix minor problems on my vehicles.
thanks again!!!!

[trimless]

Did you check the gap on the new spark plugs?

[ut76vol]

regaped them all according to festiva service manual specs.

[nitrofarm]

In your original post you mentioned the fuel filter was dirty.... How do you know? Was there a lot of restriction when you blow through it? A dirty filter can cause poor performance & fuel mileage. Does your engine seem very low on power? Just a thought.