Cadillac Owners Forum banner

1 - 3 of 3 Posts

·
Registered
76 Seville W/ EFI
Joined
·
1 Posts
Discussion Starter #1 (Edited)
So, I’m new to the Cadillac forums but, I have spent some time on the VW forums so I figured I’d make a contribution that can maybe help a few 70’s Cadillac owners out there. This is all information pulled from the factory service manual, I’m just sharing my experience.

My Cadillac is an all original 76’ Seville that I had inherited a few years ago. The car was my grandfather’s and had been parked since the early 90’s due to a major drivability issue. I could get the car to run ok at idle but, under any kind if throttle input it would just fall on it’s face and misfire like crazy! Thanks to Coronavirus and some time off work I was able to find and correct this issue.

The issue itself is very basic. On these early EFI cars the ECU is not calibrated to compensate when certain engine conditions are non-existent. In my case it was lack of EGR. When EGR is functioning properly, a certain amount of inert exhaust gas is added to the air/fuel mixture in each cylinder. If there is no EGR operation, the space normally taken up by the exhaust gas is replaced by additional air. Since the ECU has not been calibrated to provide additional fuel, and a lean condition occurs. A quick check for this issue is with the car at idle (assuming the EGR valve operating correctly) manually actuate the EGR diaphragm with an external vacuum source such as a vacuum gun. By doing this the idle should become rough. If the idle does not change, it indicates clogged EGR ports in the intake. As seen bellow.

582734

Don’t mind the vacuum line in the intake. I’m sure I had put it there for a good reason that I can’t remember. Unless you really know what you’re looking for, The clogged EGR ports are almost impossible to see with the throttle body installed. I did the inspection and cleaning with the intake off the car. Before discovering this issue I was planning on swapping in a carb or one of the Holley EFI systems. It’s a big job to remove the intake and I would only do it if you are experienced with working on engines. With that in mind I would still suggest removing it to avoid foreign objects from entering the engine and it allows you clean the intake much more thoroughly.

582735

After a few hours of cleaning it was looking like new. You can really appreciate how badly this engine was clogged. It's no wonder why this thing was barely running. Since the intake was off anyway, I took the time to clean out all the carbon build up and grease that had accumulated over this car’s life.

582736


After all that work the car ran and drove great! Keep in mind when doing this job that the metal gasket for the throttle body is no longer made. Mine was still in good shape so I just cleaned and reused it. I've been driving for the last month with no issues
My Seville still needs lots more work with all the other little issues that it picked up from sitting but I can actually drive the car now!
To my knowledge this should apply to the Eldorado’s and Fleetwood’s that have this early fuel injection system as well.
 

·
Registered
1984 Eldorado Biarritz
Joined
·
1,229 Posts
Nice writeup! Make sure the injector seals are in good shape-they're the reason most of these that end up totaled have all the paint burned off the hood and fenders.
 

·
Registered
70 Deville 78 Seville 92 Deville 03 Deville
Joined
·
778 Posts
I haven't seen that dark blue paint in a while. 76 might have been the last year for it.
 
1 - 3 of 3 Posts
Top