'87 LeSabre - absolutely horrible milage

[TrueLyFE]

Have an '87 LeSabre Custom that drives pretty well, and received a crate engine not long ago. Have about 1000 miles on it. Big problem - I am only getting about 12-14mpg right now, no matter the driving conditions.

I don't know much about cars, my aunt does the work But it has new plugs, plug wires, O2 sensor, MAF sensor... just wondering what else I can check or any other ideas as to why I could be getting such poor milage.

I will be calling some places around here for ideas, but the more input, the better.

TL

[yogi_123rd]

I'd say you have a gas leak. No CES light I assume.

Inspect the underside fuel lines. They are known for corroding.

[LeSabre97mint]

Originally Posted by yogi_123rd

I'd say you have a gas leak. No CES light I assume.

Inspect the underside fuel lines. They are known for corroding.

If gas was leaking you would smell it. I had the tube inbetween my tank and filter give way. One of the O rings wasn't doing it's job and gas was leaking.

Dan

[TrueLyFE]

I haven't noticed any gas leaks. Checked the fuel filter this weekend, replaced it, and it all seemed fine. No puddles or gas smell in the morning (nor was there any before, mind you).

The fuel lines themselves actually look to be in pretty good condition.

And yes, there is no CES light.

[LeSabre97mint]

Originally Posted by TrueLyFE

I haven't noticed any gas leaks. Checked the fuel filter this weekend, replaced it, and it all seemed fine. No puddles or gas smell in the morning (nor was there any before, mind you).

The fuel lines themselves actually look to be in pretty good condition.

And yes, there is no CES light.

How well does your engine start/run/accelerate? If it's not doing these things very well your fuel injectors may be the problem anything with your fuel injectors? If they are dirty and not spraying a good pattern it will cause cylinders to misfire and require more accerator to get the car going. Search the internet for fuel injectors. There is some good reading out there about this.



Dan

[TrueLyFE]

The car seems to run pretty well. Idles high when cold, normal when warm, accelerates maybe a little slow but not bad (probably normal, I am used to driving a light duty truck, about half the weight of this car - when I floor it, for instance, the car really flies). The fuel injectors are new, too - got them for the previous bad engine and they were moved over to this one when it was built.

Always a possibility though.

[LeSabre97mint]

Originally Posted by TrueLyFE

The car seems to run pretty well. Idles high when cold, normal when warm, accelerates maybe a little slow but not bad (probably normal, I am used to driving a light duty truck, about half the weight of this car - when I floor it, for instance, the car really flies). The fuel injectors are new, too - got them for the previous bad engine and they were moved over to this one when it was built.

Always a possibility though.

I would look into the cold high idle. What are you calling a high idle?

Regards

Dan

[TrueLyFE]

I don't know if it is normal or not, which is why I am here I guess It's just significantly louder when idle than in gear when cold, don't know how to describe it other than exactly that. It idles at higher RPMs cold than warm. I don't have a tach, how would you like me to describe it?

[Loekee75]

Although you don't have a check engine light illuminating after start up, there still could be a trouble code that isnt appearing. some codes don't cause the light to come on. Run a test and see if you get any codes that aren't popping up

[TrueLyFE]

Hmm.. Just got time to check - No codes. Just filled up - 14.5mpg, still low

[LeSabre97mint]

Originally Posted by TrueLyFE

Hmm.. Just got time to check - No codes. Just filled up - 14.5mpg, still low

I know that the engine is relitive new. However, I would run a compression test on each cylinder. Just to check the mechanical condition of the engine. If the compression test pasts, then I would look at the fuel system and ignition system. One of these has a problem.

To answer your question about how fast is too fast on the idle,....that's tough one to answer without hearing the engine myself. I'm not sure how to answer it.

Regards

Dan

[TrueLyFE]

Well, I can charge up my PDA and record it here sometime soon (I did that with a previous problem). Although it is the milage that is the problem, not my probably-is-quite-normal somewhat high idle in park.

And the engine was built just over 1000 miles ago, very new My aunt was saying something about the possibility of the ignition system (fuel system seems to function fine, no leaks, etc), so that is probably where I am at now.

[LeSabre97mint]

Originally Posted by TrueLyFE

Well, I can charge up my PDA and record it here sometime soon (I did that with a previous problem). Although it is the milage that is the problem, not my probably-is-quite-normal somewhat high idle in park.

And the engine was built just over 1000 miles ago, very new My aunt was saying something about the possibility of the ignition system (fuel system seems to function fine, no leaks, etc), so that is probably where I am at now.

The reason why I suggested a compressiong test is the fact that you are convinced that the engine is good. I would hope that it's good. Lets prove that it's good. If you could run the compression test. If all cylinders are withing 10% of each other and being in the 100's then the engine has the compression to compress the fuel/air mixture.

Dan

[TrueLyFE]

What does this involve, where could I get it done / what would I need to do it?

[highlandlake]

Originally Posted by TrueLyFE

I will be calling some places around here for ideas, but the more input, the better.

TL

Might be a longshot - but do you have a brake caliper or wheel cylinder hanging up? Might explain the poor acceleration and lousy mpg. Just a thought. Tom