Question: 1998 Mazda Protégé
Dear Vincent,
I am not sure if you are still answering car questions. But if you do, what do you think about this?
My car is 1998 Mazda Protégé ES, 1.8 liter, 5 speed and 125,000 miles. My car's fuel efficiency declined. Normally, I would get 29.5 to 30.5 miles per gallon. These days it is always below 28 mpg. So, I decided to check the engine. I removed spark plugs and noticed black soot on them, which tells me that too much gas is going into the cylinders.
I started from checking the fuel pressure regulator but it does tested out fine. The second thing I've checked; the Oxygen Sensor. I ran tests on it with a digital multimeter and it is definitely working. It constantly jumps up and down and when I remove the vacuum line from FPR, it jumps up. My "check engine light" is not ON either. Do you think it could be anything else?
Thank you,
Anatoliy
Answer: Over the years, certain adjustments drift out of specification. Not a lot, just a little. What would be a good idea would be to check and adjust all the engine specifications: timing idle speed and idle mixture. These are adjustable to some degree, but you need a scan tool to do it. Best thing to do is have your Mazda Dealer perform the adjustments.
Another thing you can try is to remove the Mass Air Flow (MAF) sensor and clean it out. Get a can of electronic tuner cleaner from Radio Shack and spray the inside of the MAF with it. There is a very thin wire inside it, so you need to be careful. If this wire breaks you will have to replace the MAF. Let it dry out for about 30 minutes or so before re-installing it.
Beyond that, I think a good tune-up will help clear this up for you. A new distributor cap, rotor, ignition wires and spark plugs. I would recommend using NGK BKR5E-11 OR BKR6E-11 SPARK PLUGS. Mazda's don't really like anything else.
Question: 1991 Mercury Cougar
I have a 1991 Mercury Cougar with the electronic dash. Anything related to the gas gauge doesn't work (miles to empty, mpg, fuel remaining). It gives a display of "C5" on the dash where these should be given, any ideas?
Thanks,
Danny
Answer: There was a TSB issued concerning a situation similar to this. I would recommend taking it to your Mercury Dealer and having them look at it. It may be you need a new fuel tank and sending units.
