: 1981 Fleetwood Brougham



RJD81
01-07-10, 04:26 PM
I recently acquired a 1981 Fleetwood Brougham 4 door with the 8-6-4 engine. The car is in great shape and only has 45,000 original. It sat in a garage for two years. It had a complete tune up, replaced the fuel lines pump and sending unit, and the water pump. The car runs great and starts right up even in single digit weather. The 8-6-4 even works, pretty smoothly too. The only issue I cannot figure out is a problem with the idle. When you start the car cold, it runs great for about five minutes. After five minutes the check engine light begins to flicker, and the idle will go up and down. The idle lowers almost to the point of stalling, then the car idles itself back up. This will continue for about five minutes, then the idle smooths right out, the check engine light stops flickering, and the car runs smooth. I changed the MAT sensor because when I did the self diagnostic for the check engine light that was the only code that was displayed. Now with the sensor changed the car still does the same thing, but is not showing any codes. The check engine light never stayed on, it always flickered when the car felt like it was going to stall. Any advice?

carnut
01-07-10, 06:27 PM
This engine has a throttle control motor mounted on the driver side of the throttle body. Called an ISC ( idle speed control) That should extend out upon cold start and slowly retract and lower the idle as the engine warms. Sounds like its doing that but once warm its not able to control the idle. I would verify that its adjusted by the book. Best thing to buy for this car is the factory service manual. Most mechanics werent born yet when this car was a few years old. The 81 8,6 4 was a one year engine management system, so most people have very little or no mechanical history with this engine.

drmenard
01-07-10, 06:52 PM
I think you could have a bad switch in your idle speed motor... when your foot is off the gas, the throttle body arm hits the ISM plunger and the plunger goes in and out to control idle... when it is at idle, foot off the gas, the plunger has a switch that tells the computer that your foot is off the gas...Now if that switch does not work right you will get this problem..
The idle speed motor is real eazy to change, 3 nuts and a plug... can be changed in a few min...I might have a good one if you want to try it ... I'll go look....

Bro-Ham
01-07-10, 09:44 PM
I had a 1981 Fleetwood Brougham Coupe V8-6-4; the best $500 car I ever owned! Seriously, it was a gem! The V8-6-4 was a challenge. My advice is to call around to the local Cadillac dealerships and see if you can find a veteran mechanic who was wrenching when the cars were new and hook up with the dude and bribe him to diagnose your car. Here in the FL city I live in there are a couple of guys like this who know the V8-6-4 and also diesels and it is a blessing when owning an older Cad with all the exotic technology. :) I miss my '81 for the smooth fuel injected big Cadillac engine although the V8-6-4 was a nightmare. If I could get a smooth running '81 I'd do another one in a minute though! :)

carnut
01-07-10, 11:04 PM
The idle motor adjustment is to raise the idle away from this switch then depress the shaft with your thumb till it fully retracts. Takes a few seconds with contant pressure for it to ratchet in, then quickly remove the wiring connector on the motor. the car should be idling very low. With it still running make sure theres at least a .060 thou gap between this shaft and the throttle lever. Shut the car off and reattach the wiring plug. Restart the car and rev it up. As you rev it up, you should see this idle motor shaft extend. If it doesnt, THEN it needs replaced.

carnut
01-07-10, 11:59 PM
A surging idle warm could be other things as well, A misadjusted TPS switch, Timing incorrect. To name 2 . We used to cut the Orange? wire at the driver side of the trans by the shifter arm that controlled the 4,6,8 switching and wired in a toggle switch so 99% of the time it stayed in 8 cyl mode. Once on the freeway at a steady speed, flip the toggle switch and it would switch to 4 cyl mode. Great engine all cast iron except for the plastic valve covers.

jayoldschool
01-08-10, 02:36 PM
We used to cut the Orange? wire at the driver side of the trans by the shifter arm that controlled the 4,6,8 switching and wired in a toggle switch so 99% of the time it stayed in 8 cyl mode.

Yes, it is the orange wire.

RJD81
01-22-10, 09:09 PM
The ISC adjustment worked. The car idles smoother than my 2007 Lincoln. Thanks for the help. I did have to replace the vacuum pump, the brake pedal was getting hard to push. Everything is working pretty good (even the built in CB)...for now anyway.

RJD81
01-31-10, 09:50 AM
Everything was great until yesterday. 5 below yesterday morning, the car started like a champ. I have been using as my daily driver to make sure all of the bugs are worked out. The car was running great. I was on the highway doing about 65 and the check engine light came on. The car didn't feel like it was running much different. When I was on the gas the light would flicker and go out. When I let off the gas or am at a complete stop the light is on steady. The code is 44 O2 sesor lean. Where should I start? The car seems to hesitiate a little now but not much. Could it be as simple as replacing an 02 sensor?

I~LUV~Caddys8792
01-31-10, 10:14 AM
I had a 1981 Fleetwood Brougham Coupe V8-6-4; the best $500 car I ever owned! Seriously, it was a gem!

That car was $500? Damn.

csbuckn
01-31-10, 11:02 AM
I have been lucky with that code because its been the sensor each time, mainly after heavy rain or a big puddle. But as long as your sure theres nothing causing your fuel to starve, maybe do a fuel filter and the sensor.

carnut
01-31-10, 02:32 PM
A lean OXY sensor code can be set be low fuel pressure, more so at higher speeds, So yes, replace the fuel filter first, then check fuel pressure. After all, the fuel pump is almost 30 years old!!

RJD81
02-11-10, 04:18 PM
The sensor was replaced, and the car is running great. Actually, better than ever. Thanks for everyones advice. Now my next question, the original window sticker on the car lists illuminated entry as one of the cars options. According to the manual when I press either the passenger side door or drivers door handle, and the door is locked the interior ligts should illuminate as well as the ring around the lock keyholes. The light does come on around the passenger side lock, but not the drivers. Also, the interior lights do not come on until the door is actually opened. Any advice?

csbuckn
02-11-10, 06:20 PM
My friends inside lights only came on when he open the door also, the ring around the keyhole is aluminated by a light tube connected to the light on the inside of the door.

carnut
02-11-10, 06:22 PM
Should be a new thread. Make sure the white lens ring around the lock is clean 1st. The light comes from a fibre optic cable from the door arm rest courtesy light bulb. Pull off the lens and lift out the plastic reflector, you should see a fibre optic line attached to it that plugs into the door lock cylinder inside the door. The entry feature could be many things because of the cars age. 1st thing to check is that the switch on the door handle is connected with a wire. That requires door panel to be removed. If you are capable of doing your own work, buy a factory manual.

cadillacEddie
05-08-10, 12:44 PM
hello cadillac friends,Im trying to get a 1981 Deville coupe 4 6 8 running again I found it sitting in a field,the old farmer said it ran when they put it back there and that it has been there for about 4 0r 5 years and that he thought he started it last about 2 years ago anyway I found that the positive cable had been cut so I replaced that,also the starter was bad so I replaced it and the oil was good,water coolant good,put a new battery in and turned the key and I have dash lights but,it was like the crank was so tight that the starter was having a hard time with turning it over,not sure if I got a complete cycle of all the pistons broke loose,after sitting so long is it that the oil has completly drained to the pan and it is locked up and just needs to be turned fully and how can I turn the crank manually,because there's no nut that I can tell where the crank pully is unless its behind that. Can anyone Help me out? thanks

Angry Matt
05-08-10, 05:12 PM
how can I turn the crank manually,because there's no nut that I can tell where the crank pully is unless its behind that?

The crank pulley should be directly below the water pump/fan.

carnut
05-08-10, 11:48 PM
Remove all spark plugs. Get an oil can with a pump nozzle and spray ATF auto trans fluid in all plug holes and THEN crank the engine. Crank about 10 to 15 seconds, then wait a minute then crank again. Then reinstall NEW spark plugs. Turn the key from off to run NOT START! 2 times to fill the fuel lines with fuel, then crank it to start it. Once running let it get to temperature and drain oil, relace oil filter add new oil and drain the coolant and then replace it along with a new radiator cap. DO NOT FLUSH either the engine or the radiator. The pressure of the flush machine can burst seams and circulate oil crud through the engine. I would use oil designated for a diesel because it has some cam shaft antiwear additives most other oils dont. ROTELLA is a good type 15/40 weight.

melan
05-09-10, 09:50 PM
I think you could have a bad switch in your idle speed motor... when your foot is off the gas, the throttle body arm hits the ISM plunger and the plunger goes in and out to control idle... when it is at idle, foot off the gas, the plunger has a switch that tells the computer that your foot is off the gas...Now if that switch does not work right you will get this problem..
The idle speed motor is real eazy to change, 3 nuts and a plug... can be changed in a few min...I might have a good one if you want to try it ... I'll go look....

Since this is an old thread, I hope this isn't hijacking. I'm having idle problems and would very much like to have a known good ism, if this offer is still available.
My first replacement was dead on installation and the second doesn't seem to work properly. Thanks.

carnut
05-09-10, 10:45 PM
This idle motor needs to be adjusted first, THEN if still acting up, be replaced. With the throttle raised off the switch, car running, press firmly on the shaft of the idle motor till it fully retracts, then let the throttle arm rest on the retracted switch. Verify .060 thous clearance between it and the throttle arm. Now shut car off. Count to 30, have a beer and restart it. By the way, have the climate system off prior to adjustment. Even a new switch out of the box needs to be verified for proper clearance.

melan
05-10-10, 10:38 AM
Thanks for the advice. I've had the ISM adjusted by no fewer than three mechanics, one of whom used to keep these engines running for a limo company. Now I'm trying to sort it out myself, so will try your method.

Thanks again.

carnut
05-10-10, 05:23 PM
Make sure once the ISC shaft is fully retracted, that you disconnect the wiring harness to it. Failure to do this will short out the ISC driver within the ECM. Once adjusted, shut car off reconnect the harness. then restart.