zrated57

Lately my car has been getting very pool fuel mileage. I average about 6 to 8 mpg. I don't drive the car hard at all and that's the mileage numbers that my car puts up. What should I do to make the car get better mileage? Could having a bad MAF sensor cause the fuel mileage to be that bad? What other problems could my car have that causes it to be that poor?

The spark plugs and wires are newer and the oxygen sensor is brand new. The computer in it was recently replaced. One strange thing about my set-up is that the car originally had a 5.0L engine in it, but was replaced with a 5.7L engine. However, the computer is still from the 5.0L along with the knock sensor and the fuel injectors. I don't think that would cause the car to get bad fuel mileage, because the injectors are actually smaller than what should be in there. They are 19lb injectors.

Please post if you have any information on this subject.

Thanks in advance!

five7kid

iTrader: (14)

Is the SES light coming on? If so, have you checked for trouble codes?

zrated57

The SES light was on because the EGR was removed, so I removed the bulb some time ago. However, the last time I scanned the computer there were several codes and the cause of the codes was a bad computer, so I replaced it and the codes disappeared, except for the EGR. So I guess the answer you are looking for is that I haven't scanned for any new codes yet, but that will be my next step.

five7kid

iTrader: (14)

Why was the EGR removed? Anything else modified that wasn't mentioned?

The '85 TPI computer wasn't the best of the breed. It should be able to handle the displacement increase, though.

Any other symptoms, other than poor fuel mileage?

zrated57

Gosh, I feel like an idiot for not mentioning what's done to it. Well, it's fairly stock, except for a 6AL box MSD ignition and an ACCEL distributor. I'm not sure why the EGR was removed, but I wasn't too concerned about it because I was going to take the engien out, but plans have changed and now I must stick with this engine now. Of course I want it to get good gas mileage though.

Probably wont matter, but it has K&N Filters as well.

five7kid

iTrader: (14)

Which one?

Garconer

just to start with the obvious, have you checked for gas leaks?

zrated57

Yeah, I checked for fuel leaks and found none.

I'll have to check to see which Accel distributor I'm using.

royslsbry

does the car have a cat on if so id check to see if it is stopped up. Id check the timinig. Also fix the egr.make sure the transmission is shifting in to od and that the tv cable is ajusted properly.check the air filter. and also check to see if any of your brakes are sticking and dragging some.the injectors and computer should be fine. and make sure your plugs are gapped correctly.

89RsPower!

Are there no other symptoms besides poor gas mileage? does it smell like its running rich or anything? Also how did you calculate your fuel mileage?

zrated57

There is no catalytic converter on the car. The timing is set at 10° & the transmission shifts into OD. I know for a fact that the tv cable needs to be adjusted, but I'm not sure of the proper setting. I don't know at what point it should upshift or downshit. It has new plugs and they were gapped to the stock specs. The car does smell like it's running rich. It's very obvious.

Another symptom which may be related to this problem is that it will sometimes... bog down, I would say. Not really a hesitation, but almost bog down under acceleration. I think this may be a problem related to the tv cable not being adjusted correctly, but I'm not sure.

89RsPower!

tv cable adjustment is critical if you plan on your tranny living any amount of time, do a search, its pretty easy to do. Like suggested pull those codes and take it from there.. also have you check fuel pressure at all?

Rayzor32

iTrader: (1)

dude if its runnin rich and gettin shitty gas mileage id say try replacing the O2 sensor, get a delco dont screw with the bosch. I would try and clean the maf sensor too if its dirty. Check and see if its leaking fuel from the injectors, the o-rings can go bad on them, but there would be a obvious gas smell and possible engine fire (personal expierence).

zrated57

When I first started getting terrible mileage I went ahead and replaced the oxygen sensor, so that's new. I am guessing that if there are no codes, then the problem could definitely be in the MAF sensor region. I wish those things were cheap so I could just pop one in and go, but they are expensive indeed. I will check those codes soon. I'll also check to see which Accel dizzy I'm using.
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Oh yeah.... I did get a DELCO o2 sensor ... I don't wanna fudge with that Bosch crap. I'm trying to make my car run better and use less fuel, not more!

Rayzor32

iTrader: (1)

take it out and clean it with some carb cleaner or alcohol or whatever you have and see if that helps. They should be like 10 bucks at the junk yard, it might be hard to find a tpi car though, m&m just got 3 third gens in last weekend but they were all v6s

you said you were gettin hesitation? Does you car have an EGR? Oh and its not missin at all is it?

zrated57

I looked around and most of the MAF's I found were over $100. The car isn't mis-firing, but it doesn't have an EGR either. It does hesitate sometimes.

I'll use some carb cleaner.