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

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

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

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

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.

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

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.

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

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?

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

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

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

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.

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

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

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

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

Have you thought about putting a scanner on it and monitoring some of your sensors such as the MAF, ECT, IAT and fuel trim readings to get an idea of how well the engine is running?

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

You will need a compression gauge. You can get one at any good autoparts store. You will need to remove all sparkplugs.

Do a search on Google for Compression test.

If your Aunt put an engine in your car she can do a compression test.

I also like Toms suggestion of a brake hanging up.

Regards

Dan

when you say crate engine,is this the same engine that was in the car and not altered (racing or larger or high performance)?

when you say crate engine,is this the same engine that was in the car and not altered (racing or larger or high performance)?

No. It was a new in crate and built at a place in town (my aunt was going to rebuild mine, but my uncle was impatient and now he expects me to pay him off for doing it on his own..sigh, luckily we got a decent deal on it). A few things were pulled off of the old engine, like the injectors, and those were new. It's still the same size and type of engine.

No. It was a new in crate and built at a place in town (my aunt was going to rebuild mine, but my uncle was impatient and now he expects me to pay him off for doing it on his own..sigh, luckily we got a decent deal on it). A few things were pulled off of the old engine, like the injectors, and those were new. It's still the same size and type of engine.

Okay....is it new or rebuilt? New = new block, new pistons, get the idea? Rebuilt is....used items checked...reconditioned where needed...ie...cylinders possibly bored out (to clean up taper and out of round), new pistons. Or rebuilt could be just new rings and bearings. Who put the heads on? Where they torqued correctly? (I'm still thinking about poor compression here. Where you able to do a compression test?)

I am really trying to help you out here.

Regards

Dan

Again, it is a brand new, new parts, not remanufactured crate motor. The place that I purchased it from put it together after a down payment. Most parts started at 0 miles (I can't think of anything internal to the engine that wasn't new). Also, I did find out that the previous owner was getting 24mpg just before it broke down.

I haven't had time to do a compression test yet, I should on the weekend.

Again, it is a brand new, new parts, not remanufactured crate motor. The place that I purchased it from put it together after a down payment. Most parts started at 0 miles (I can't think of anything internal to the engine that wasn't new). Also, I did find out that the previous owner was getting 24mpg just before it broke down.

I haven't had time to do a compression test yet, I should on the weekend.

I realized that you had used the word "new", however, the word new can be defined as: new to you, a different motor, our language can be a bit ambiguous. I replaced my tranny in my 97. I got a used one from the bone yard. Is this my "new" tranny?.....


We all now know that you have a brand new motor.

Dan

It's okay, I understand :)

I have also been having a voltage problem - grounds were mentioned when previously brought up on AF and I have checked everything I can, and it all looks clean (removed and reattached many just to be sure). When I accelerate hard enough (usually normal acceleration speed) my voltage drops to ~11.8-12.8v, and sometimes also drops or fluctuates between this and 14.4 when coasting ~40, or >70mph (not on the lower parts of gears) it will be low. Brand new alternator, and battery connections are fine (just checked and reattached minutes ago to be absolutely sure). Don't know how much of a problem this would be on fuel economy, but is something that needs fixed anyway. Any ideas about this?

As I said earlier, I will report on compression sometime this weekend. In a sense I am hoping that is it, because I am getting sick of all these random troubles with this car ;p

Hey, the plug that goes into my alternator was loose. That's been the voltage problem I have had all this time (I swear I checked it before, hmm....). I was trying to fix one of my other little problems and decided to just check that by pushing down - bam, engine decreases RPMs a little and voltage jumps up (have voltmeter near battery).

Anyway, it is running very nice now - engine doesn't rev up as high when accelerating, and it seems like a much smoother ride. I have a feeling that if this didn't completely fix the milage issue, it will at least be a good portion of it. I filled up my tank and will report MPG in a week or so.

Oh, and time for a new battery :/

So what's the update on your car and the poor mpg? It's normal to get lower mpg during the break in period but yours is somewhat low. Is this all city driving?

Did you re-use the old catalytic converter? It might be plugged up with soot from the old engine.

Hey,

Most of it is city driving, from my house to work and back or to the store. Lots of stop and little go. Old owner used it for mail delivery though and it still got ~24mpg doing curbside.

Old cat, probably needs to get replaced anyway. Would it be responsible for that high of a drop though?

Right now, I am at about half a tank (3/4 on my gauge) and it is looking like it hasn't improved much. Will post numbers on my next fill-up, as well as compression test pass/fail if it isn't significantly improved (which it is now looking like it isn't :()