: Poor gas milage

01-18-07, 05:07 AM
Hello all. I have a '91 Caddy brougham with a 305 and 166,000 on the car. I had a rebuild done about 4500 miles ago. I got really great gas milage when I first bought it about 6 years ago but it has gone down hill slowly since. Right now I am getting like 12.5 to 13.3 mpg and that is highway, city, combined, nursing it or using a heavier foot. It seems to not change much at all. New, the car was rated at 17/25. My best was 23.5 when I first bought it. Does any one have any ideas what can be causing the low ratings? The car runs fine just the mph sucks.

What causes the cruise to loose speed on shight grades? It just can't hold my set speeds and I loos like 10 mph and the recovery is very slow.

I also have had a gremlin in the wiring lately. After getting it back from a routine wheel rotation and brake check (visual) my washer light was on. When I allpied my brakes, the ABS light would come on dimly and the washer light would dim somewhat. Sometimes when I applied the brakes, my chimes would go off for lights or ?'ever. Also, my lights are on Sentinal but now, if I pull on the light switch, the light chimes go off. After getting car back, I did the brake adjustment stops in case I had loose drums or something. That's when I noticed my abs was not stopping with out locking up the wheels. The tire place assured me they did not touch the brakes in any way and I had them re-remove the wheels and tires so I could inspect them myself to satisfy my concerns that a sensor wire was un plugged, pinched or what ever.

I disconnected the washer bottle just because the light was irritating me but now it is plugged back in for freezing weather conditions. All is right for now with the lights.

Looking over some old papers in the car that were stashed in the service book are some reciptes from a dealer from many many years ago showing it was in for electrical problems. But this was like ions ago and all has been fine since then as far as I can tell. Until now.

Oh, and one other thing...my 'service engine soon' light was comming on after the rebuild but it is off all the time now. It seems it is a 'tech1' service call to have the computer read. Unfortunately, it never lit a service soon light when a dealer was open or had time to do it and once the engine was shut off, it quit. Sometimes it would come on quickly and sometimes it would take a while to a long time.

My engine builder tried to retrieve some codes through the climate control but what numbers he came up with appeared to be no help even from HIS contact elsewhere that he called to ask about the codes he did pull up.

I noticed a couple of used Tech1 scaners on e-bay and am wondering if it would be worth my while to buy one and learn how to use it?

One last thing... a couple of years ago, I had a leaky wheel bearing seal and worn bearing on the right rear that was finally repaired. Now i have a nasty sounding whine back in the rear end and was told that because I an the rear low on fluid, there is a coating on the drive and pinion gears that wore off and that is what is causing the (re thought) howling sound. It is most prevelant around 48-54 mph and seems to just be noisiest on load, not coast.

Ah....and.....(sorry lol) my ac has started to blow below the dash on load or acceleration. What could have caused this to start happening?

All suggestions, ideas and input will be greatly appreciated. Thanks...Nick.

01-18-07, 07:10 AM
Wow, your Brougham's got some issues.... I'm no mechanic, by any stretch, but if you posted your questions in the Cadillac technical discussion threads, I'm sure you'd get some good advise/help. Lot's of knowledgeable people on that thread area. Good luck.

I love those early '90's Broughams--got one myself with just over 100,000 miles on it. They are great cars! Take a look. http://www.cadillacforums.com/photopost/showphoto.php/photo/5981/cat/500/ppuser/46623

JRau in central Iowa

01-18-07, 08:20 PM
Thanks for the reply JRau.....Nice ride you have too! Looks like mine. Same colors and everything only you'res is much nicer!!!
I have actually had 3 of these and love them! I started out with a one owner Royal Blue 1990. It was a 350 car. Really nice and I drove it forever then sold to some kid for a grand a couple of years back. It was very high milage but still running strong. I think he was planning on 'pimping it out.'
The one I have now, I actually bought at the same time as my 3rd one which was a 1992 Brougham De'Elagance. It was really sweet with 74,000 miles on it and so clean, I swear you could eat off it! Looked like a show room new car. It had moon roof and pillow top cushioned seats with Cd and security , etc. Now, I paid a premium price for it but it was worth it. Also an Antelope Firemist with tan interior. When I went to see it, I saw the one I still have and decided to look at it as it was priced right and had the 305 which I heard produced near identical performance as the 350 only with much better milage figures. Well, to make a long story short, I just bought them both and made this one my family car, the 1990 turned into my 'fishing car'....LOL! And the '92 was my 'Sunday, going to Church' Car. I don't go to Church, BTW....LOL! But it was so sweet, I kept it in the garage most of the time and even to the point the battery went dead. Finally, I decided not to keep making payments on a car I just didn't drive and sold it to the first guy who called. It turns out, he was going to buy it from the guy I bought it from but I beat him back with the money so he told me he was coming right over once he knew it was the same car. He bought it for his wife and now it DOES go to Church on Sundays....LOL!
Anyway, the '91 that I have got great milage in the beginning and then I saw it had a dirty air filter and thought to myself, "hmmmmm, replace that and I should get the 25mpg advertised!" Funny thing though, I replaced it and a dirty looking PCV filter and that's the beginning of the downfall.
It was a country car and was full of dirt and then I guess it just let loose so to speak. Started smoking while idling and burning oil but not obviously while driving.
I finally blew it up messing around on a hot summer day. Stacked a bearing pretty good...LOL!
So, now I have this brand new custom built engine....(Stock with minor overbore, balanced crank,stouter springs, 3 angle valve job, stainless valvers, etc.) and only getting 12 mpg!!!! This totally sucks!!!! LOL!
Anyway, I'll cc&p my thread and transfer to the other area you suggested. Thanks man! Take care and worship that ride of you'res as it looks super sweet! I always have my eye open for another low milage one. They are just too sweet!!

01-18-07, 09:03 PM
One of these days, I will have the money to totally restore mine and/or buy a
'91 or '92 Brougham D'Elegance in Cotillion White with the white leather interior.

I try very hard not to drive mine in winter weather, and I limit my rainy weather driving as well. Wish I could park it all winter, but can't...

Antelope Firemist was the second most popular color on our Broughams in 1991. Most popular choice was Cotillion White.

Good luck on those repairs.

JRau in central Iowa

01-18-07, 09:30 PM
Replace your differential, that'll help the mileage. More importantly, you don't want it breaking apart, clogging, and killing your tranny and engine in one fowl swoop. While you're at it, pull the driveshaft and relace the U-Joints; there's 2 and it'll run you about $100; $45 for the joints, another $40 for a 6 inch bench vice, a greasegun and 2 sockets to pop the thing out and back in will run you another 20 or so. You may also want to find some adhesive for it as a u-joint can come loose after the first week or so after being replaced if it isn't allowed to rust in.

Check your tranny fluid lately?

If the engine is tripping codes you're going to want to head over to an autozone and have them pull the codes for you. I believe the ECM stores them for you. Once you've pulled em', disconnect the battery for a minute and reconnect it to clear the ECM.

01-21-07, 02:11 PM
Gwokable... I don't see where the rear end comes into play? I have no issues with it. It was serviced a while back as I had a bad bearing but the milage was good with same rear end in the beginning. I believe it's a 308:1.
Tranny fluid is up to level and good. Serviced a while back including torque converter drain also.
The engine codes are a tech 1 service. Auto part stores cannot check it as they are equipped for tech2 level only.
Thanks for you're input. Nick.