[80Brougham368]

Hello fellow Brougham lovers...well I have been trying to get my 83 Brougham Coupe's running condition to be, well, not so terrible. Have had her a few months; she looks rough, and drives rougher...the plan is to strip the trim, get the body stripped and painted, and install new fillers...this Coupe in my opinion is the ultimate Cadillac (has the finest quarter window and opera light combo ever designed) and is my dream car, but it runs terrible. If I can't get her running right by the end of the summer, I will have no choice but to get rid of her.

Here is the rundown:

-71,000 miles on the original 4100 (has the chrome valve covers). Bought it after it has been "sitting for a while"

-To the mechanic for State inspection. Said probably has bad gas in the tank causing it to die while in the shop. After using ether in the TBI they got it running again.

-Back in my garage. OBD says Code 34 and 52. The 52 is from disconnecting the battery to prevent the parasitic load of the Security dash light from killing it (which I will be pulling out when I get the dash pad off). 34: Map sensor input too high. Diagnosed it with the 83 factory manual. I unplugged the map hose (which has nylon twist ties holding it to the body brace, evincing it had been touched before) from the back of the TBI, no splits or links in the hose and it was fully seated, just some carbon deposits. Under the car I found the air hose had been fully unseated (possibly deliberately) from the Cat pipe, so I rejoined it. Code 34 gone upon new diagnostic, but still idles and runs very rough, so no driveability changes. Air cleaner assembly and filter appears clean. Stovepipe is engaged from the LH exhaust manifold to the snorkel. Also the cruise does not engage, which suggests a vacuum fault. Also a highway test shows a very rich run with a fuel dump condition (16 MPG on the open road, under 9 on surface roads).

-Also when it drives, giving it gas will almost cause a stall out. When it idles, it shakes and feels like it is starving for gas and will die any second (which makes me afraid to drive it anywhere!!!) Here is what I want to do, and I have all the new parts for, but will need time to do it all:

-New fuel pump (need to exhaust the tank and drop it first), and new tank filled with fresh gas so there are no gumouts, sediment or deposits in the system
-New inline fuel filter
-New O2 sensor
-New Plugs, Wires and Distributor cap
-New Alternator
-New TBI injectors and TBI rebuild kit (I should hook a gauge up to test fuel pressure)
-New MAP sensor
-Fully inspect the vacuum hose network at the engine and all peripherals
-New programmer and blower motor (ECC will not blow any air except in Defrost mode)
-If none of the above work, will look into resetting the timing to 10 degrees BTDC, something I've seen in other threads as a possible solution to this driveability issue.

If these repairs don't do the trick, I don't know what will. I have and have had other 4100s before that have not given me any issues, so this is baffling. Any suggestions and input will be greatly appreciated (I know someone replied on one of my replies to another thread and said replace the fuel pump, so that's going in as soon as I get time to drop the tank)...thanks in advance.

(Present):
1985 Eldorado Biarritz 4.1
1980 Fleetwood Brougham Sedan 6.0
1983 Fleetwood Brougham Coupe 4.1

(Past):
1991 Fleetwood FWD Coupe
1993 Coupe de Ville
1990 Fleetwood FWD Sedan
1986 Sedan de Ville

 

[grauhst]

When my car had that fuel dump condition, it was a hole in the map sensor vacuum line. You can take a look at the onboard diagnostic and the value of map sensor. I think it has to be somewhere around 0.30 while running (when I remember correct). If yours is significant higher, there's something with that vacuum hose.
Mine had a hole in it and the value was 0.80 and higher. When the engine is off it should be around 1.0 which is the baro pressure.

 

[85 FLEETWOOD COUPE]

The best upgrade you can do to these cars is the 350 motor swap

 

[GermanBrougham]

Welcome to the club My 4.1 Fleetwood Brougham had exactly the same problems. I recommend you to start with fuel tank cleaning and you can also change the fuel pump and fuel strainer when you are there, they are quite cheap. If your car was sitting for a long time before you got it, it should actually be first on your to do list.

Unfortunately I had more problems with my car (electrical issues, brakes etc) and avoided dropping the tank because it can be really tough job when you work under your car in garage or backyard. Now I finally have some time and I’m going to drop the tank this summer.

 

[80Brougham368]

All, thanks so much for the input. Yes I have a new fuel filter and strainer all ready to go...just need the time to drop the tank. If only Cadillac had kept the 6.0 4BBL in these cars through 1985. I would love to swap the motor to a larger displacement but that would be a very costly job, and then there's the matter of mating up all the DFI electronics and to a crate motor (which is probably incompatible).

 

[80Brougham368]

Thanks GermanBrougham, actually dropping the tank isn't so bad, just a little time consuming, (did it on my Eldorado when the fuel pump died); it's basically the same setup on the C/D/Z platform. Swapping out the old fuel pump with a replacement and purging the tank while the car is at home isn't such a bad idea because those things can go at the worst time and leave you stranded; then once it's in you'll be good to go for years to come. Good luck on your Brougham!!

 

[80Brougham368]

Success today...I went back to basics: 4 things that you need to make an engine run (air, fuel, spark and exhaust); in this case, my lousy driveability was simply the result of robbed airflow. I pulled off the air cleaner assembly to fix the MAP hose (there was a split at the base of the rubber hose where it attaches to the back of the TBI); cut a 1" new piece of hose from the washer bottle feed, reinstalled the hose, code 34 gone. Then I decided to start the car with the air cleaner off, just to see what happens; I got a strong start (several times), a robust idle and when I gassed the accelerator, I actually got a response, no hesitation. So I am tossing my old air filter for a new one, and also cleaning out the inside of the air cleaner housing.
I also unplugged the ISC so I don't get a fast idle or idle surge.
ECM now throws a 15 (coolant sensor circuit) and a 27 (open throttle switch circuit), they are hard and won't go away, flow chart says possibly bad ECM but at least this thing drives decent so for now I'm satisfied.