Cadillac Owners Forum banner

1 - 15 of 15 Posts

·
Registered
1987 BROUGHAM
Joined
·
14 Posts
Discussion Starter #1
Why will car not hold set speed on an incline. Can be going fine on level grade but loses it on hill ( have to use gas pedal)then it will be fine once level roadway is reached. Thanks for any help.
 

·
Registered
84 Coupe w/500
Joined
·
5,671 Posts
I believe cruise is controlled by vacuum, a small vacuum leak may cause this. Either on the cruise diaghram thing or one of the many lines you have on the engine. You might be able to push in the cruise diaghram thing and plug the nipple coming off to see if it loses air.
 

·
Registered
84 Coupe w/500
Joined
·
5,671 Posts
I'm not sure if my theory holds true. If you had a small leak, I would think your cruise control would always be going on and off, on and off. How does the car run otherwise? Any lack of power? Maybe its the 140hp and its just not that strong of a motor. Decent size hills you're talking about?
 

·
Registered
1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
Joined
·
4,256 Posts
Mine would work intermittently. It would never work on hills, and occasionally on flat ground. When I re-did the vacuum lines, and corrected the routing, the cruise control returned to full function.

Here is a vacuum diagram; the green lines are the routing for the cruise control...

 

·
Registered
1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
Joined
·
6,796 Posts
Cruise control slows down on hills with pretty much every car even new ones.
 

·
Registered
1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
Joined
·
4,256 Posts
It depends on the hill... Cruise control is designed for highway travel and the steepest grade in the US interstate system in 8% (I-24). If your using it for non-highway travel, then it is going to bog down.
 

·
Registered
1987 BROUGHAM
Joined
·
14 Posts
Discussion Starter #10
Thanks for all the info. I drive my daughters 2010 cts and my 2001 taurus on cruise control going up hill with no problem, cruise holds perfectly. Hill is "CAJON PASS" IN SO.CA. Just bought this 87 brougham with 51,201 original miles and last registered in 2001, Passed smog check. Been sitting in my daughters neighbors garage all this time and she was not aware the car was even there. Has the locking hub caps with lock tool in glove comp. Dealers tape cassette/gold keys in folder and drivers manuals included and "EVERYTHING WORKS"
 

·
Registered
06 STS-V, 06 DTS Performance - Past 91Broughamd'Elegance,76FWBd'Elegance,98STS,00Eldorado,06STS
Joined
·
778 Posts
this is stright from the owners manual. It sounds like you just need to put your foot on the gas pedal a little bit and this is normal.

 

·
Registered
Joined
·
1,999 Posts
I have this same issue, even after redoing my vacuum system. The car simply slows down about 10 mph on hills and then returns to normal. These cars just don't have the pep of new cars, and hills put them under strain whether it's the cruise or our feet. We just have a tendency to gun it and the cruise does not.
 

·
Registered
95 FWB 81SDV 96 FWB 94 Fleetwood
Joined
·
1,575 Posts
The old Caddys motor just don't have enough power.. It did not have enough power from the day it was made... Just live with it or do something to get a extra 50 or more horsepower.....
 
1 - 15 of 15 Posts
Top