forthehalibut

Hey, all:

I usually just look at all the great info in here, but now I have a certain delimma. My 1984 toyota SR5 pickup--22R with 170k on it--was getting 22 mpg highway last year, and had about 160k miles on it. Then, suddenly it seems, the mileage dropped to between 18 and 19 mpg. I thought it was due to the winter and having to let it sit for a bit and warm up. But come summer, it still got 18-19mpg. In the last month or so, it dropped to about 16 mpg, then went back up to 18. This sucks! There are many V6's and even some V8's with better mileage!

What could be wrong? I replaced all the vacuum hoses, cleaned out the PCV, and cleaned out the carb. I had to replace the AS Reed valve as the old one was shot, but that is only for exhaust to go back into the carb at certain conditions [EPA stuff], and I still left it blocked off for now [it was that way when I bought it last year, too]. I will be cleaning the EGR, as well as the filter that goes to the EGR vacuum control. What else could cause this? It still runs strong, and quiet [now that I replaced the exhaust manifold gasket].

Any help would be greatly appreciated. I am also looking at getting/making a "super-efficient" carb to greatly enhance the mpg's.

fth

SolidDigital

have you replaced the fuel filter lately?

PirateFins

02 sensor???

MTL_4runner

Converter?
Bad plug wire?

Basic tuneup stuff done? ......I would start there first.

Carbs are inherently not "super effiecient" so I am curious what you are doing to get there.

forthehalibut

I changed the fuel filter, just did an oil change [differentials too], and today I changed the spark plugs--from Bosch+4 Platinums back to the NGK's. It doesn't sound like a bad plug wire, either. I just advanced the timing, and will continue until I hear pinging, then back off a hair. Right now my idle [since I advanced the timing] is about 1100, but I will lower that back down once I have the timing set right. I am also thinking of replacing the spark plug and ignition wires, and distributor cap/rotor.

I don't think mine has an O2 sensor. I do not know if the catalytic converter is going bad--how do you tell, and would that cause my 20%+ drop in gas mileage? Getting 16.25 mpg sucks for a 4-banger.

Could the EGR have something to do with it? Mine looks rusted in place, and might be a bear to pull out and clean.

Thanks for the input!!

fth