Imperial Home Page -> Repair -> Fuel-> 1981-1983 -> EFI vs Factory Carburetor Retrofits
The following is from an August 2009 email from Craig as part of an Imperial Mailing List discussion on the EFI systems in 1981-83 Imperials:
I am/was a factory GM engineer but also own an 81 Imperial both because I personally like luxury cars and because of the uniqueness of the EFI. When I was looking to buy I would only buy an EFI car. No point in buying a carburetor car as it was no different than common Fifth Avenues that were available aplenty locally. As with any new technology - the learning curve is often high and especially so when it involved electronics.
Unlike today where most things are electronic-based and even new functions can be learnt relatively easily by those that are familiar with modern processes back in the early 80s most veteran dealer techs of course only knew carburetors. Chrysler was forced into engineering for fuel injection because that is where luxury was going. Cadillac introduced a computer-controlled EFI on the Sevilles in 1976 (I owned one of those cars) and while it had its quirks it was generally reliable and well received by the public. Cadillac then introduced a simpler TBI style setup on many models for 1980 and then line-wide in 1981. Lincoln introduced a TBI style setup for their 302 powered cars for 1980. When Chrysler decided to produced an uplevel personal luxury car - first to be just a jazzed up Cordoba or some variant, and then as the comeback Imperial - it was imperative that they were able to keep up with the times. Fuel economy was of great concern as we all know back in the late 70s and early 80s. The domestic makers were having a hard time getting their cars to comply first by reducing the engine size then reducing the vehicles themselves. There is no doubt that the Chrysler EFI system, when fully functional, was impressive both in terms of drivability and economy. Many owners can attest to on-the-road mileage of mid to upper 20s astonishing for a heavy 4,000 lb + car with only a 3 speed transmission. While the 318 with EFI was no slouch it wasn't particularly fast either at least compared to the equivalent Mark VI and Eldorado competitors. Some of this had to due with the fact that Chrysler did not build an OD automatic at the time and coupled with the decision to us a tall gear ratio of 2.20 for economy made the car relatively slow off the line but gave it great cruising capability and great economy on the road. Had Chrysler had a competitive overdrive automatic a more aggressive 2.73 or a 3.23 (I am not that well versed in MOPAR rear ends...) could have been used and the economy would have been achieved with the overdrive. Giving the car a peppier personality but it was what it was then. Economy was the rule of the day and the Imperials was more efficient than the equivalent Lincoln and Cadillac.
The EFI set up at least aside from fuel delivery utilizes inputs and relationships that are common on today's designs. Most early fuel injection systems used a speed-density principle to measure airflow via a MAP or BARO sensor instead of an air meter. Most cars today and many cars from the late 80s on used air meters which give more precise information to the computer - while MAP/BARO sensors only deduce airflow based on vacuum load on an engine. That is why it is imperative on EFI equipped Imperials that the intake system be completely sealed so that the air meter (located in the snorkel) reads only air passing through the snorkel or the air/fuel ratio will be disrupted causing poor performance that often occurs. That was a volatile design because it used the traditional intake setup with an old style air cleaner assembly and lid design that was prone to leaks. Today's cars the air meter is usually mounted to the intake itself which is usually made out of aluminum or hard composite plastic with the air cleaner element BEFORE the meter thus there is no physical tampering of the air stream and thus no disruption of the air flow across the meter even if you remove the air cleaner element. The Chrysler EFI system used sensors and data that is common on today's modern EFI systems like coolant temp, air flow, knock, computer, fuel flow, fuel temperature, fuel pressure, automatic idle control, and throttle position. The major difference between the Chrysler design and most fuel injection systems then and today is that the Chrysler system varied fuel flow based on pressure via the large control pump that sleeps under the air cleaner lid. So in essence the Chrysler system was a constant feed fuel system similar to aviation and many other non automotive applications. When done right can be a very smooth system as attested by many owners. Other fuel injections systems relied on turning the fuel injectors on and off for periods of time depending on need. The more fuel needed the longer the injector stayed "ON" etc. While this type of system can be made to run well and give desirable results it is slightly less efficient (at least on paper) than the constant feed system employed by Chrysler. The upside though to at least the rather crude early TBI systems was that for the most part they were rock solid reliable and remained in production well into the 1990s on many vehicles.
Chrysler EFI system was plagued by two major problems from the get go:
Due to the extreme measures taken to squeeze maximum fuel economy out of the vehicles the computers were programmed to be overly lean. The cars would 'lean lock' and would require the computer's memory to be reset by disconnecting the battery for a short period of time (or following the arduous recall procedure outlined in the factory service manuals). While a reset wasn't particular difficult it was an unacceptable drivability problem for luxury buyers accustomed to start and go mentality. While we employ various tricks today as owners to get around varying drivability complaints that prove useful - at least during the warranty period it was difficult and illegal in many instances to circumvent emissions controls to improve the situation. Thus the carburetor conversion because a legal and easy (for the customer) out of problems going forward. Since Chrysler decided to extend the warranty on the EFI system for 4 years 50,000 miles most conversions were done at the dealer under warranty at no cost to the owner. Later conversions were done outside of factory parameters at customers cost and usually cut a lot of corners from the factory process and usually due to the lack of parts, desire to properly diagnose and well frankly the fact that a 2bbl 318 V8 setup was as common as day in Mopar circles.
Many of the early electronic components were manufactured poorly. While not necessarily of poor design (aside from Chrysler's decision to put their engine brain boxes in the engine compartment instead of some place else like most), they were manufactured poorly and many parts were bad from the get go. Countless bad parts were replaced until acceptable versions were found and installed. Later versions of the parts from the late 80s on were apparently manufactured much better and the last incarnations of most EFI parts were said to be rock solid. So if you find an intact EFI car with its original 81 style parts and want to continue to drive it - might be a good idea to start accumulating spares of known good replacements just in case. Cars with later support plates, power modules, etc tend to be set for life.
The moral of the story is disconnect the O2 sensor and make sure your car has updated EFI parts and you should then be able to drive and enjoy the car indefinitely. I can already feel the drawn guns aimed at me for saying this but I did say it was the quick and dirty approach. I run my O2 plugged in most of the time although the car is only driven on a limited basis.
The rest of the car's problems/fixed were field engineering updates to fix problems that cropped up after the cars were on the road for some time. Such as the ASDM grounding issues (my car survived without an additional ground wire installed until I bought the car and installed one in 2004), the trunk leak fix, some cars would shut off when the a/c was turned on, radio issues, and various other issues that mainly were subjective complaints by owners. The cars were really well built and based on old platform designs were solid cars. Someone joked to me that the Imperial was a very nicely equipped Volaré coupe that didn't rust. There is truth to that statement but that does disservice to the car IMO.
As for reliability of any 81-83 over the entire production line I would say no in general. By the end of the run of these cars in April 1983 most of the field fixes for small things were put in place at the factory level, however the basic design of the car remained in place. So you could have problems you could not and it was not necessarily a function of when the car was built.
The fact that most Chrysler dealer mechanics were not trained to deal with the Imperial EFI system (since only a handful of dealers were authorized to fix them) service became a problem for many customers. Thus the carburetor conversion was an excuse for dealer personnel as well.
To answer the question if someone were interested in owning one of these cars it really is hard to say for me. As an engineer and a car buff/collector I am in a unique position to get around most/all of the potential problems that could crop up and enjoy the car for what it was intended to be. An original EFI car is not really the car for a novice to own especially if he has no mechanic or close-by collector knowledgeable with the system. If someone were to really like the rest of the car and did not want to deal with EFI find a well kept factory converted carburetor car and you would be set. However a lot of the charm is taken out of the car when you remove the EFI.
It certainly is a labor of love. I also have an 81 Eldorado Biarritz with the quirky V8-6-4 cylinder deactivation system that gave Cadillac as much trouble as EFI gave Chrysler on the Imperial. Fortunately the Eldorado can be easily made able to run as a conventional V8 by simply disconnecting one wire on the transmission if necessary.
Even though many of the problems that the Imperials had tended to occur after production ended the Imperial never really caught on in large numbers as expected. There have been much speculation as to why, the recession, price, Chrysler reputation of impending doom in the early 80s, the rapid shift of Chrysler products as a whole in the early 80s to small FWD. Whatever. The Eldorado sold extremely well in the 1980s until it was downsized in 1986 and the Lincoln Marks reasonably well so there was a market.
I wouldn't say run out and by an EFI car to the average collector but I can think of much more troublesome cars than can get you into trouble much faster and deeper.
Craig M. Séman
Cadillac Craft Center Midland, NC
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