Cadillac Owners Forum banner

1 - 10 of 10 Posts

·
Registered
2001 STS
Joined
·
1,575 Posts
Discussion Starter #1 (Edited)
93 SLS with 84000 miles.
Has been going on for a while. :histeric: Averaging 15-16 MPG. Change plugs air filter and oil and filter regularilly. Wires are good as well as a fairly new cap and rotor (Its a high performance cap ?).
I drive through the city to work, but take the highway home so its 50/50 there. I feel I should be getting a bit better mileage
One thing Ive noticed is when I fill up, (always use premium); the amount of fuel I put in is 10-12 gallons more than what it tells me from the information centre, when i check amount of fuel used.
There is also a VERY slight hesitation when pulling from a complete stop. But then grab hard. Not hard enough to cause any clunks but enough to put a passenger back in her seat a bit. Difficult to pull away smooth, but very easy to spin the tires or rocket off the line.
Also once it shifts into 3rd (90% sure its 3rd) the kickdown (forgive me if Ive got the terminoligy wrong) is hesitant. Its as though it comes down in two stages. First stage is fine and seems timed right but then seems to hold for a bit. RPMs arent overly high, but sounds almost as though Im pulling weight or going up hill. Then will kick back down Again, (like I said it seems to have 2 stages. Normal ?) , and RPMs will drop slightly.
Hope Ive explained that right and is understandable. :coffee:

Wether or not these things are related ? Would be cool to get some info on either or. :bouncy:

My daughter is here helping me pick the smilies. Think we got the right ones in the right places.
:worship:
 

·
Registered
Joined
·
4 Posts
I have the same car, same problem. Mine has 160k on it; I've put about 10k on it since the summer. <i>Within the past week</i> the average has gone from 17mpg to 15...and while sitting in traffic the other day the Service Engine light came on. I change oil regularly, fill it with 93, month-old air filter...everything seems pretty gold with the engine though...

I experience the same accelleration/shifting action as murphyg is talking about. I just want to know what could have caused such a huge drop in the avg. mpg in the past few days. Even the instant mpg monitor is showing lower numbers than it ever has before.

The fact that it suddenly turned to below freezing temps here in Massachusetts wouldn't have anything to do with it, would it?

As always thanks for the help guys.
 

·
Registered
2001 STS
Joined
·
1,575 Posts
Discussion Starter #3
At the least its good to know Im not alone on this.
Im in Ontario and the Temperature is constantly going up and down. My mileage has been like this for a while (Hot or cold), and for the life of me I cant figure it out.
Like I said with the shifting. Will try to make it more clear.
It shifts into 3rd, The RPMs start drop as they should, Then it stops and holds for a bit untill it drops again. Its not allways. But it is fairilly consistent. Whether the engine is hot or cold.
Im wondering if maybe Its sucking air somewhere ? But how to find out ?
Had heard about fuel being sucked into a line (Or maybe they said leaking) where it shouldnt, but that site is now gone. They said to check it by dissconecting some vaccum line and holding your finger over it and look for the fuel. Something like that.
Never got around to checking that and like I said that site is gone.
Anyone know what I think Im talkin about on that one ? :confused:
Also have no codes. I check them regularily.
Any help for neverender and I ? Even something in the ballpark would be good. Could at least be somewhere to start. :banghead:
 

·
Registered
94 ETC,97 STS
Joined
·
3,531 Posts
Exhaust Oxygen sensors can have a big effect on gas mileage. The problem here is they are a little expensive to change if you aren't sure they are the problem.
Fuel injectors can get deposits on the tip that give an inefficient spray pattern and hurt mileage. Again, the cost is fairly high if you aren't sure they are the problem.
I don't know of any easy way to check either of them. The injectors can be taken out and flow tested but that's not that easy.
Maybe a bottle of premium injector cleaner would be worth a try.
Even a good additive package in the gas may let deposits build up.

I also know someone who had to change the MAF on his Ford 4.6 and got a big boost in mileage and performance. Apparantly it was bad from new and eventually went out totally. That would be a real long shot though.
 

·
Registered
2001 STS
Joined
·
1,575 Posts
Discussion Starter #5
Thanx for the input zonie.
Didnt even think about injector cleaner. Has been a while since ive used some. Put in a bottle and will wait and see. Does seem to have a bit more power. BTW. what is MAF ?

Also...neverender.
I found something that might interest you. While poking around I inadvertently snapped the vacuum line that goes from the EGR valve SENSOR, to the THROTTLE BODY. Thought that I would unplug it for whatever stupid reason and snap !! Turned out to be a good thing though. Got a new line from the dealer, $11.50 Canadian and in stock.
What I found when I went to take the old one off, couldnt quite get my fingers in to grab the end attached to the trottle body. Got a screwdriver and positioned it to pop it off. The instant I touched it (Just lightly touched it), the rubber boot on the end just split. Just by looking at it it looked totally intact. But once it was off I could see that it had been about 75% seperated for a while.
Like I said just by looking at it the rubber boot appeared to be together. Had to have been sucking some air through it. Once I broke it right through could see the difference in where it was just cleanly broken (Like 20%) and where it was on older seperation. The whole boot practicly would crumble in my hand. Very decieving just by a visual inspection.
Next thing is to check the rest of the similiar type of lines. Guess that after 10-11 years those things will get brittle and begin to deteriorate.
Thats one for me. Will keep on pluggin away :yup:
 

·
Registered
1995 SLS 200K miles
Joined
·
372 Posts
Had heard about fuel being sucked into a line (Or maybe they said leaking) where it shouldnt, but that site is now gone. They said to check it by dissconecting some vaccum line and holding your finger over it and look for the fuel. Something like that.
Never got around to checking that and like I said that site is gone.



Pull cover and check Fuel pressure regulator on back cylinder bank side. Pull the Vacuum hose and there should be NO fuell leaking. If you see fuel with engine runnine replace the FP reg...bout 70 bucks at dealer.
 

·
Registered
2001 STS
Joined
·
1,575 Posts
Discussion Starter #7
ljklaiber said:
Pull cover and check Fuel pressure regulator on back cylinder bank side. Pull the Vacuum hose and there should be NO fuell leaking. If you see fuel with engine runnine replace the FP reg...bout 70 bucks at dealer.
Thanx ljklaiber...I believe thats what I was refering to.
Couple more questions if you dont mind ?
1) Pull the vacuum hose while the engine is running ?
2) Do I hold my thumb over the end of the hose ?
3) Am I looking for fuel from the hose or the regulator (Im definately assuming the regulator but just to make sure) ?
 

·
Registered
1995 SLS 200K miles
Joined
·
372 Posts
Murphyg said:
Thanx ljklaiber...I believe thats what I was refering to.
Couple more questions if you dont mind ?
1) Pull the vacuum hose while the engine is running ?
2) Do I hold my thumb over the end of the hose ?
3) Am I looking for fuel from the hose or the regulator (Im definately assuming the regulator but just to make sure) ?


Engine vacuum activates the FP reg. If diaphragm in regulator is bad it leaks fuel. In worst case car will stall in low speed traffic. Suggest an ASE mechanic check it out. won't take long and he can recheck all codes as well. Hope this helps you.
 

·
Registered
Joined
·
1,471 Posts
Here in New Jersey, the oil companies start pumping that oxygenated fuel crap when the fall/winter seasons start. As soon as they do, gas mileage drops and the cars don't seem to run as well as they normally do.
 

·
Registered
2001 STS
Joined
·
1,575 Posts
Discussion Starter #10 (Edited)
The fuel comes from where the fuel comes from. And as far as I know if they start using additives they are bound by law to let the consumer know.
I remember when Petro-Can started adding some kind of cleaner (And still do). Tried it once and have never gone back. Started thinkin bout the price per.....and realized if there is an additive in the fuel Im pumping then Im not only being gouged for fuel but being gouged for something I can Add myself.

If Im paying an X amount of dollars for gas then I want just gas. I will add other shit myself if I want to. We are being ripped at the pumps as it is without being led to believe that this or that added is going to be better. I feel that basicly they are wattering it down some way and decieving the consumer to think that it is good.

I know what your saying El Dobro about the gas compinies but dont believe that it is just seasonal. If you look at the tests and specs done from independent consumer.............they show that there really isnt that much control or consistency in what they put out for us to put in.
Which is very sad seeing as how easily it could be controlled. (But.....and then stock holders, and ..........well too many dollars.........so who cares....)

Dont know if oxenigated counts an as additive. But do know that if it is then they MUST inform us. As to sulpher cont etc... then they can get away with whatever the broad range of (Basikly No Control) government has set.

Was Esso or Shell a bit back that added something to there fuel (And didnt tell) and it started screwing up perticular Chryslers I believe. That messed them over big time.

Either way....this isnt just a sudden seasonal change thing.
Am workin on it and think that might be getting somewhere. Basic and simple (Got to look under or even maybe betwen the lines) maintanence for an older vehicle maybe ?
 
1 - 10 of 10 Posts
Top