super low gas milage (10) big noise, black smoke

[pdxroger]

hi, All. got a very serious problem.

my 95 corolla (auto with 1.8L engine) got about 10 miles/ gallon.

started two weeks ago, the car always stalled at idling. and making big noise. I treated the car with sea foam. during treatment, the car gave black smoke instead of white smoke. I can see the black smoke coming from the position above from frond wheel and rear wheel.
After the treatment, the car got little improvement.

I went to autozone and was advised to change the spark plug. After changing all the 4 spark plug, the car seems better, and won;t stall at idling anymore. but the gas mileage is still the same around 10. and still gave the black smoke and make rough idling and big noise. if you standing rear of the car, you can smell some gas like from the smoke.

Getting so depressed bout this. any suggestion?

[mvftw]

Black smoke is tooooo much gas (rich)...I would look into fuel pressure regulator...

[kevmac]

Random guess before reading the op: bad plug wire causing miss or weak spark.

o.k., now for real
What's big noise? Would that be noise from a missing cylinder? Noise from your engine running on no oil?

o.k. get an ohm meter from harbor freight for $5 (or whatever) and check resistance of each wire. One bad reading (very inconsistent with the other three) will give the obvious answer. Better yet, replace the plug wires anyway without checking resistance if you don't know when they were changed last. While your at autozone (or whatever), get a cap and a rotor.
Summery: replace wires, cap and rotor. Check and replace air filter if dirty or unknown.

best parts for this (not at autozone):
ngk plugs,
ngk wires,
denso cap, rotor

If your not already proficient on the above advice as implied by your post, the next step is to test for weak spark.

[pdxroger]

Thanks for reply. After I changed the spark plug, the car won't stall at idling anymore, but I still feel some inconsistency from the engine. I will do what you just suggested to change the spark plug wire. It is very likely. I have saw some video on youtube: they run with one spark plug pulled out. the engine sounds like the same. that's the reason I changed the spark plug firstly. this should fix one of the problem by changing the spark plug and the wire.

there is also another problem. when I treat the car with sea foam. I can see some smoke come from the bottom of the car, the positions (not the actual smoke place, the smoke places are for surely from connections of the emission system) are right at the frond wheel and real wheel (two spots)? Any suggestion or ideas how to fix that or how much it will costs?


also thanks "mvftw". I will buy an used fuel pressure regulator to replace it. this seems easily to explain the super bad gas mileage.

any others suggestion will be seriously considered. thanks a lot. this is an awesome forum. I will stick here.

Originally Posted by kevmac

Random guess before reading the op: bad plug wire causing miss or weak spark.

o.k., now for real
What's big noise? Would that be noise from a missing cylinder? Noise from your engine running on no oil?

o.k. get an ohm meter from harbor freight for $5 (or whatever) and check resistance of each wire. One bad reading (very inconsistent with the other three) will give the obvious answer. Better yet, replace the plug wires anyway without checking resistance if you don't know when they were changed last. While your at autozone (or whatever), get a cap and a rotor.
Summery: replace wires, cap and rotor. Check and replace air filter if dirty or unknown.

best parts for this (not at autozone):
ngk plugs,
ngk wires,
denso cap, rotor

If your not already proficient on the above advice as implied by your post, the next step is to test for weak spark.

[kevmac]

don't dig into the fuel system yet before checking for spark a non firing plug will do all that you mentioned and more, like loss of power and vibrations. You can check for spark one plug wire at a time if you want by grounding the plug on the block and cranking while inspecting the plug for spark.
Or do the easy thing as I mentioned and change wires, cap and rotor. When doing the wires, don't pull them out by the wire or you might stretch them. After changing those, test and report back. The exhaust might have a leak at the manifold. Sounds like you need a major tune up and fluid exchange. Luckly the exhaust is a piece of cake on these cars. Fix the black smoke first though If the problem remains, test for healthy spark next. Then you can check the fuel system.