Cadillac Owners Forum banner

1 - 15 of 15 Posts

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #1
i have a 81 sedan deville i have been driving. it has a v8 6.0 8-6-4 motor... only problem wrong was the fuel gauge not working. replaced the sending unit and now im getting all kinds of problems. it started to stall out on me so i figured it was the catalytic converter. cut it off and it ran fine. started stalling again. replaced throttle position solenoid, air temp sensor and coolant temp sensor. ran fine for a day and the next day acted up again. the engine code reads 30 , which is idle speed control circuit. anyone know how to fix that? i changed the fuel filter also. it has an exhaust leak on the driver side manifold that i havent got around to fix yet... can that be the reason for it stalling? any comments or suggestions are greatly appreciated. i just want my car to run good again. thank you
 

·
Registered
95 FWB 81SDV 96 FWB 94 Fleetwood
Joined
·
1,476 Posts
It sounds to me like you have a problem with your idle speed motor. Your idle speed motor bolts to the trrottlebody with 3 nuts.. It has a plunger that is pushed in when the throttle is closed..It has one plug with 3 or 4 wires... I might have one if you can't find one
 

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #4
thats the part i actually replaced... they called it the idle speed solenoid

It sounds to me like you have a problem with your idle speed motor. Your idle speed motor bolts to the trrottlebody with 3 nuts.. It has a plunger that is pushed in when the throttle is closed..It has one plug with 3 or 4 wires... I might have one if you can't find one
----------

i read on another post that the 30 code could be tripped because of the exhaust leak and o2 sensor... could this be true??
 

·
Registered
1981Cadillac Fleetwood Brougham D'Elegance Coupe m
Joined
·
392 Posts
Oxy sensor would not trip Code 30... with the 368 engine a faulty EGR valve would cause constant stalling and is an easy and inexpensive fix. When you speak of the Oxy sensor it wouldn't be a bad idea to change it anyway. The replacement interval was rated at every 30,000 miles. If after the EGR and the problem persists the I would move on to distributor components like the ignition module or the pickup coil, making sure that the pole piece and the magnet are still in good condition when you are in there and have it all apart. ISC would not cause this problem either nor would the TPS sensor. If the TPS sensor is not set properly you will get poor performance and gas mileage. Not that they are great at mileage anyway.Exhaust leaks at the manifolds would not cause it to stall. If however you have some vacuum leaks that would be a culprit to check out. Go over all the Vac lines and connections and replace hoses as necessary. Good luck with the old beast.

----------

Just to go back and address the code 30 you have. It is definately the ISC but not related to stalling. The ISC is a real bear to solve. The trouble tree is long and extensive, so if you want to get to the bottom of that one I could send you the Code 30 Trouble Tree. Even with a new solenoid the problem could persist as the speed sensor circuit could be the culprit. I have been working on this one myself for quite some time and still don't have it solved. I have eliminated the ECM, and the Solenoid motor , but it could be speed sensor circuit or idle switch, wiring shorted somewhere??????????????
 

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #6
The idle speed control motor was defective I think... had warranty and just replaced it. It is running better. I'm getting code 18 now which is open crank signal circuit. Distributor?
 

·
Registered
1981Cadillac Fleetwood Brougham D'Elegance Coupe m
Joined
·
392 Posts
Are you clearing the codes each time you replace a part?? The Code 18 will be short to ground in circuit #6 between fuse and ECM connector, bad crank fuse, open wire to ignition switch.
 

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #9
Took it to a shop to get a diagnostic check... they said its in the wiring but gonna charge another 300 to pinpoint exactly where. I know its in the wireing. Should I check all wires goin to and from ecm first?
 

·
Registered
84 Coupe w/500
Joined
·
5,665 Posts
Unless you are familiar with a DVOM and can read a wiring diagram from a service manual, the only thing you will be able to do is physically look for damages which they probably did already. I will say problems with the engine harness are new to me.
 

·
Registered
1981Cadillac Fleetwood Brougham D'Elegance Coupe m
Joined
·
392 Posts
Are you using the special silicone grease between the module and the base of distributor?? You could also try taking off the three attaching screws that hold the magnetic shield to check and see if the pole piece and magnet are in good condition. Sometimes the pole piece will break. Also see if the pickup coil under there looks ok.

----------

As a side note make sure non of the insulation on the wiring is cracked or loose from the heat. Wires could be shorting out to base of distributor.
 

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #14
Yea I use the grease....checking all the wiring now and pickup coil is still good. Bout to fire it back up.. wish Me luck
 

·
Registered
81 sedan deville
Joined
·
15 Posts
Discussion Starter #15
So I been working wit this car for a month now.... I think the only sensor I haven't changed is the tps sensor. When it warms up it drives perfect. But takes a while. When I start it in the morning it is real rough and dies constantly untill it's warm I'm guessing. Could the tps cause that?
 
1 - 15 of 15 Posts
Top