Rough Running Problems Associated With 1981 - 1983 Imperials


Imperial Home Page -> Repair -> Fuel -> 1981-1983 -> Rough Running

Question from Rolland (1981):

After I start the car in the morning (cold engine) and drive it about two miles it will hesitate for 1 to 4 seconds. At constant throttle it acts just as though someone had turned the ignition off. If I keep my foot on the accelerator it will catch and run fine for a couple of minutes then may do it again. Perhaps a shorter duration the second or third time. If it acts up while idling at a stoplight the engine dies but will always restart. It seems that I must turn the ignition off to get a guick restart.

This problem appears to occur only during the engine warm up period. After it has hesitated 3 or 4 times it will work fine for the rest of the drive. If it stop and restart a few times the problem does not repeat unless the car sets most of the day. Then it will act up once or twice again before it begins to run good.

The behavior may be related to ambient temperature. I cannot be sure of this but it seems that way. On a cool morning it seems to take longer to misbehave (perhaps 3 miles) but on a warm afternoon it will act up much sooner.



From Dick:

Have you checked the ohms reading of the EFI coolant sensor? It is the one screwed into the water passage near the upper hose connection on the manifold, the only such sensor which has two blade terminals arranged in an "L" shape. 

Perhaps it's time to remind folks that I have been repairing some components of the EFI system for IML members free, since late 1996. My only rules are that you pay for any parts I have to buy (usually very cheap) and that you pay the transportation both ways, that you don't expect lightning fast service (I'm old, retired, cranky and slow moving), and that I receive your rebuildable core before I ship you a refurbished unit. I can repair the Power Module, the ASDM, the Control Fuel pump, and usually the fuel flow meter system. I cannot repair the CCC (or the air flow meter if the failure is in the transducer). Fortunately, failures of these components are very rare.

I have a stock of known good replacement parts for each of the items I have been repairing, all of which have been test run on one or the other of my 3 EFI coupes.

I am not going to be doing this much longer, I'd really like a volunteer to take over this function. The requirements are: 1. A pretty complete electronics test bench setup, and the know-how to test analog circuits. 2. A working knowledge of analog and power supply circuit design. 3. A devotion to keeping these cars on the road. 4. About 10 hours per month to devote to the activity. 5. A good running EFI car to test the complete repairs on (I just keep exchanging repaired items on my daily driver, so each one shipped out has a few weeks time on it, usually.)

Since the Power Module has started this discussion, I'd like to say that these are usually quite easy to repair. Unfortunately, they are also very easy to break, the usual cause of a failure is a mistake in troubleshooting which results in a momentary shorting out of the 23 volt power supply. That causes a catastrophic failure which can ripple through the circuit board and make for a real messy job of soaking off the goop to get at the fried components. It isn't glorious, or even challenging, just very time consuming to get the goop off.


From Stuart:

Sounds like it might be the power module--- the electronic control INSIDE the air cleaner. Something is starting to fail. There is no solution. If you happened to come across another power module , it is failing or about to fail. I have five---all no good. I got one to work for a few months, and would then act up after 45 minutes. You can try to make sure it isn't the pickup coils in the distributor. Sometimes they go bad, even in non EFI cars. I have two '81 s. I have persevered for years with the EFI. Even when I did get the cars running right, I still didn't trust them. I am having one car converted to a carburetor now. I have concluded this is the only solution---unless you just want to look at your car and not drive it without anxiety.

From Bob:

I have three suggestions for you to try. First, you should know that a warm EFI idle is a constant rise and fall of the speed as dictated by the Oxygen Sensor to the Fuel Control Pump - this req'd to obtain the optimum emissions control. It is called "Braketing." It is normal, but if your idle speed is not correctly set, stalling might occur.

Secondly - check the Water Temp Sensor resistance 900 or less when cold, 1100 to 1500 when warm - if not there, replace it.

Third, disconnect the lead from the Oxygen Sensor to the CCC and run it like that - it'll should run fine, maybe even better. If this works, reconnect the wires for the sensor then disconnect the battery ground wire - thus dumping the memory. Reconnect and either recalibrate it per the manual or just drive it around. Let us know of your progress.

From Bob:

Sounds like a temp sensor.

This page last updated October 13, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club