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Discussion Starter #1
I may be buying an Esprit next year, so I'm in learning mode.

Just out of learning curiosity - Was wondering how does the CIS system on the HCi (and 88s as well, I suppose :D ) handle boost as far as spark and fueling go?

Obviously EFI systems programmatically adjust the parameters as needed under boost; but how does it work on an engine with K-Jet and a mechanical distributor?

Also, what is the part that I'm pointing to with an arrow in this picture?
 

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Mike,
The part you are pointing to is the 'Coolant Temperture Sensor'. This sensor tells the ECU how rich to make the fuel mixture upon start up. All Bosch CIS have these.

For tools to work on these all you really need is the basic hand tools, a good DVOM and CIS fuel pressure tester. I remember years ago NAPA used to sell those fuel pressure testers, they came with the needed adapters and gauge. If I recall they could be purchased for about $100. It's a must have trouble shooting fuel problems on a CIS.

These cars a fairly easy to work on as they do not have electric or second stage injectors. Less computer control over the fuel injection is a good thing. The computer in a CIS Bosch car measures the basic functions and if I recall uses the frequency valve to control fuel flow. The basic fuel flow is controlled by the plunger in the fuel distributor.

Of course there are many electrical circuits that work hand in hand with each other but with the factory service manual and a good DVOM it's nothing that cannot be figured out.

One thing that needs to be taken into consideration... these injectors seldom fail but sometimes they do. They can be cleaned which will save them however I've seen some that cannot be saved although it was very rare.
I have spoken with Bosch techs and these injectors for the 910 motor were designed exclusively for Lotus and this motor. They are no longer available from Bosh and they are not making anymore.

I've had my car 12 years now and wouldn't trade it for anything. I get more looks than my comrades driving 'Skittles' aka Elise.

Oh.... forgot to mention.... REPLACE the tranny circlip and washer before the tranny blows!


Good luck in your search, be prepared to answer many questions by the public and 'gawkers' taking pictures.

Cheers,
Robert
'87 Esprit
 

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Discussion Starter #3
Thanks for the information Robert. I am actually fairly familiar with CIS, as my DeLorean used to have K-Jet until I jettisoned that system in favor of a custom EFI system that I put together.

I actually do still have a CIS fuel pressure gauge sitting around in my garage somewhere. :)

Hopefully I do end up with the car. These and DeLoreans are my dream cars, and to have both in my garage would be just fantastic!
 

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The CIS K-Jetronic can work very well with a turbo as you can see with Deloreans using the Island Twin Turbo system or the BAE single turbo. The system measures total air mass flow so it can accommodate forced aspiration. The choice then becomes, do you have intercoolers and do you "push through" or "pull through" the mixture unit. If you are accustomed to EFI you might want to look at the V-8. It has full EFI management and twin turbos besides the bigger motor. In any case always try to buy the nicest car you can afford, it will always work out to be less expensive in the long run. As mentioned the '88's have a particular weakness with the transmission and if the car has anywhere near 40,000 miles the tranny should be pulled and the fix installed. A LOT cheaper than trying to undo all of the damage caused by failure of the notorious circlip. Before buying a Lotus the very best thing you can do (besides trying to educate yourself) is to have any prospective car looked over by an expert on that model. Each model Lotus has it's quirks and eccentricities. Later models with the Delco ABS has their specific problems for instance. Do not buy a "cheap" Lotus with the idea you can fix it up and still have a bargain. This approach generally fails.
David Teitelbaum
 

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T[snip]As mentioned the '88's have a particular weakness with the transmission and if the car has anywhere near 40,000 miles the tranny should be pulled and the fix installed. [snip]
I have an 88 (Citroen trans) and don't forget the G car Turbo (80-87)also has the same potential Citroen circlip issues.

My car has 58K miles and I'm planning to have the circlip replaced preemptively (along with the clutch, etc) to avoid the potential expense of damaging the crankshaft (see threads on the circlip issue).

Car doesn't display any signs of a bad circlip, but several others have had the issue without warning as well.

If you consider only 89 onward Esprits (Renault trans) , you don't have to worry about this issue.
 

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Discussion Starter #6
But how does K-Jet know to enrich fuel mixture under boost? Or by its very nature does the mass air metering simply cause enough fuel to be injected?

Also, in the Esprit application, how does the ignition system retard the ignition advance under boost?

Thanks for the input, Dave. I am specifically looking at an HCi model Esprits; that's the exact model I've wanted since I was a child growing up around Lotus cars.
 

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Discussion Starter #7
And let me tell you guys about the issues the Renault gear box in my DMC has had sometime..... Woof!
 

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Wingless Wonder
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But how does K-Jet know to enrich fuel mixture under boost? Or by its very nature does the mass air metering simply cause enough fuel to be injected?

Also, in the Esprit application, how does the ignition system retard the ignition advance under boost?

I am specifically looking at an HCi model Esprits; that's the exact model I've wanted since I was a child growing up around Lotus cars.

The mechanical K-jet system in the Lotus is made to run a bit rich over 30% throttle.The Lambda (O2) system (at low engine speeds) make the engine pass emissions.

The Lotus-specific "tune" includes specially calibrated warm up regulator, higher fuel pressure (hence more fuel delivery) and the 'specially flowed injectors.

There is no electric Mass Air Sensor as in more modern systems. Just the metering plate that you love to access, under the air filter housing. :)


The ignition only uses mechanical advance. The dizzy diaphragm is only used to adjust timing during cold operation.

++++++++++

A local club member is selling a nice '86 HCI. It's due for a C service based on time, but is otherwise in good shape, with many years of service records. PM me if you have an interest in looking at it, it's in NJ.
 

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I have done quite a bit to my 88 CIS, but coming from only owning EFI and carbed cars ever, the CIS was a real learning experience for me, I think it took me a year of messing with the car to get it set right, some of the issues I even caused by not understanding it before working on it or replacing this and that. It was however never completely undriveable during the whole learning process. The Citroen gearbox, clutch and circlip issue was another journey I also went on as well, I rebuilt it in about two months over a winter mostly waiting for parts to be machined or shipped. Something that would be almost impossible to know for sure is if the car you were buying has had the roller spigot bearing replaced with a beefier ball bearing, that would be a deal breaker in choosing between two different Esprits 88 and older for me with what I know now. The 89 and up cars don't have the circlip/bearing issue. It is cool to say the car has inboard disc brakes though, I never saw a car that had them before owning this one, I tell people that and they are like "it has what?"
I also fell in love with the shape of these cars when I younger. I did not care what model 4cyl turbo, intercooler, or V8 as long as it had the Stephens body (88 and on) I wanted it. There was not a big selection of Esprits around to go and see in my area (within 200 miles) I still after owning the car for 3 yrs find myself just staring at it, its a timeless design that used to make me drool whenever I saw one in a movie. To have one and make it mine is a great feeling, but it also taught me that since owning it that it IS just a car and it is not as out of reach or "I'd give my left arm for one" as it once was as im older now. But almost everytime I drive it somewhere I can see someone who'd probably give their left arm for one.
I feel now that I know a lot more about this car though, its real reliable, and I would drive it anywhere.
This forum is great place for Q/A on the car also.

If you need a fuel pressure gauge for working on the CIS system, Harbor Freight tools sells a master fuel pressure set for $99, the gauge in the set is a piece of garbage, but all the adaptors it comes with are priceless, and they are brass which is impossible almost to make bad or cheap. I replaced the gauge with a nice liquid filled one from my local parts store and now have used this set on numerous makes of vehicles incuding my Lotus with great success!
 

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Since you seem to have your heart set on a particular model take your time and search for the best one you can afford. Try not to limit your search geographically since they are not common. Even if you have to have one shipped for California or Florida. Having a service history on an exotic like a Lotus is VERY important. The better it has been taken care of the better it will be to you. A "C" service is a big deal with Lotus and can be expensive. It needs to be done on a time and mileage schedule and if it is not up to date you will be doing it. Turbos also wear. If you find one over 50,000 miles and it has never been done you can expect to do that too, especially if maintenance was neglected in the past. Tires have to be changed after 7 years, battery after 5. The car should come with all of it's "bits" including keys, spare tire, jack, tool kit, owner's manual, wind deflector and both roofs and a bag. To do any serious work on the car you will need a set of manuals and a Tech 1 with the appropriate cartridges. All of the warning lights should come on during start-up and then go out. Before buying the car, during the inspection, a Tech 1 should be hooked up to see if there are any codes.
David Teitelbaum
 
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