Engine Performance problem
1994 Geo Prizm 4 cyl Front Wheel Drive Automatic 118000 miles
I asked a few questions about my car in the past. Thank you for the replies.
My problem is excessive fuel consumption. It is a 1.8L 7A-FE engine, A/T with o/d.
The car had failed emissions tests a few times in the past because of high NOx readings. But the last test it passed.
The Catalytic converter is relatively new, installed by the previous owner a year or two ago.
Spark plugs changed too.
A full tank of gas (13 gallons) lasts only for 200 miles with mostly city driving.
What I suspect is that incorrectly gapped spark plugs were installed by the previous owner.
Even NGK's official website says the spark plug gap for my car is 0.042 inch. Many auto parts stores do the same. Even Haynes manual says the gap should be 0.042. However when I look for a Toyota Corolla with the same 7A-FE engine it says the right spark plug is 0.032 inch. (BKR5EYA). I found out that the factory manual recommends BKR5EYA already gapped at 0.031 (instead of 0.032 of Toyota's) inch.
My question : Is it possible for spark plugs gapped wider than recommended to cause
a/ Emissions test failure based on high NOx readings,
b/ Excessive fuel consumption?
I bought NGK's BKR5EYA spark plug set and I will hopefully be able to install them. Can this correct these problems?
Friday, January 30th, 2009 AT 5:02 PM