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Discussion Starter #1 (Edited)
After this nerve racking experience that seemed to last forever with my Esprit that was missing, coughing doing all kinds of things a exotic super car shouldn't (holy embarassing it was to drive), I thought I would post some of what I learned about the car and just make a post with a heading and the components involved in case it may help someone else in the future.

Thanks alot to everyone here on the forum for guidance in specific questions about components and location of components as well. And tips on performing certain procedures to solve this problem.

I found that the previous owner of my car had the car's vacuum advance routed in the way the service notes has it arranged, what really solved this problem towards the end of this whole saga was right in front of me the whole time, the vacuum diagram on the trunk lid, it was different than what is in my service notes book, it seems the vacuum port under cylinder four has or gets full vacuum, and the cylinder number three port is limited or "restricted" greatly. That vacuum diagram is really out of sight out of mind on the trunk lid, let me tell ya. I honestly dont know how it ran right for me until lately with it having so much vacuum advance then when it gets so little now the way it should be. It would only act up after driving it for sometime, and that time frame was steadily decreasing with each drive.

I also learned alot about the CIS system, I remember seeing that when I bought this car thinking, "thank god that works right cause I dont know nothing about it, and it looks confusing". Well it seems that now its pretty reliable pending your fuel pump has the correct primary pressure and your warm up regulator works right. Turned out, my warm up regulator's heating element crapped out, I thought this was my whole problem at one point, however upon replacing it and the car still not running properly I was really getting stumped. I bought four different warm up regulators and honestly dont know how they could possibly be different with the exception of the heating elements in them. That porting in the cast top of it really looks identical in all four I have, including the original one that came on the car. And they are really adjustable so if the porting similar and they are adjustable you can just set it to the pressure your car demands. I managed to piece together from all of them two that have the exact same heating elements as the one that came on my car, so now I have a back up. The heaters have a resistance rating right on them. I bought all four of these at a local yard really inexpensively, it took some looking though to find them, they must be a popular replacement, I got one from a Volvo, and three from VWs. I could then get the car running good, but not all the time. Arghh.

I noticed that buzzing sound my car used to make (upon first buying the car I thought this noise was a pulley bearing or something) was no longer there. None of the start components would power up, all that clicking the car used to make is now gone CRAP. I myself troubleshooted it down to it must be the Jetronic ECM is bad as it controls all that stuff. Well I got my trusty service notes out that lead me astray on the vacuum diagram and it helped me find, using the wiring diagram that the RPM relay powers the Jetronic ECM after 4 RPM is sensed off the coil, the service notes now ROCK, cause I had no idea where I was gonna get a ECM, because im sure that is pretty specific to the Lotus, I doubt the VW or Volvo one is the same. Well I disected the RPM relay, and the relay coil on it had every solder connection loose, I resoldered them all and WAH LAH, every problem solved, the frequency valve buzzing is back and car idles and throttles up even and smooth. Both of the warm up regulators I have after testing perform the exact same. Its hard to believe those Bimetals in them make such a quick/drastic change to anything if you have ever seen them, and were like me thinking what could those possibly do, they raise the fuel pressure very quickly and abruptly once they get hot and it changes the idle from slightly unsmooth (cold) to very smooth (warm/hot). Just be sure you adjust your warm up regulator by "knocking the plug" as they call it. Thats a real Mickey Mouse procedure, my neighbor came over when I was doing this and he was looking at me strange when I was pounding the pin in and told him what I was doing. I attempted to make one adjustable by tapping threads in that pin and since I had many warm up regulators now, but I broke my tap so I gave up. Hopefully I wont have to adjust it again now for awhile, because taking the WUR off the car hot is scary, the fuel sprays everywhere and hot car/leaking fuel dont mix. And you have to take it off to pull the pin back out if you dont get the pressure set right the first time. Harbor Freight Tools stores sells a good, well, a okay master fuel injection kit (if you shopped at Harbor Freight you know what I mean, I had to return my first set cause the gauge didnt work) but for $100 I can now trouble shoot every fuel injection system including Bosch CIS that the 88 Esprit has, and this gauge is a must have for this kinda system. Also another procedure I learned here on the forum was adjusting that frequency valve using my dwell meter, just tap the wires going to the frequency valve, if the polarity is wrong you'll get a high reading, switch the leads and you will more than likely get one closer to 50, and around 50 is what you want, mine runs great at I think it was 47. You will know because if you disconnect the engines O2 sensore the idle will not change, if it does you may want to try another number around 50 (my service notes says that).

Also, another forum members post tipped me off on replacing the capacitors in my modules in the trunk relay box due to the caps just being from the eighties and so old. If they are swollen at all replace them, I did all of mine swollen or not. I already had the iron out to fix that RPM relay anyway. I think this was a great tip as those modules are hard to find and pricey.

This has really been an experience, I could not stop thinking about this problem, I work as a technician (non vehicle but have restored quite a few as my hobby) and absolutley hate when I cant solve a technical problem, it eats away at me and I cant think about anything else clearly until I solve it.

I hope this info helps someone in the future. I left out alot of simple steps, like replacing the spark plugs, plug wires, dist. cap, ignitor, flushing the gas tank, replacing the old battery also to try to solve this problem.
 

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Integrator
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WOW!

Congrats!You just graduated from the CIS University!
Once you comprehend the concept of two pressure circuits and what the Control Pressure does, the rest of it is a walk in the park...
In your research, have you drifted to Turbobricks and Bimmerland?
Hint: boost sensing WUR, perhaps.

PS.
Here is a nice plug for $15
warm up regulator adjustable bolt K jetronic | eBay
 

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Judging by your story and the picture of your warm up regulator party, I'd say you need deserve the label 'Tenacious'! Congrats on the debug and I'm definitely saving your post for my future CIS 'adventures'.
 

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Discussion Starter #4
I did find bimmerland, and another called VWvortex, along with a few others that really helped with the understanding of the CIS system. I did notice that a few cars have a vacuum port on the WUR.

I didnt mention it above, but I also pulled the wastegate apart to check out the diaphragm (which was fine, along with the actuator rod moves really free), however since I did that the car now makes that "sneeze" sound that it didnt before that I have heard mentioned once or twice on Lotus forums.
 

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By the sound of it you are the experts and I need some help please. I have 1988 Esprit MY USA spec but is RHS for Australia. It has the Bosch k-jet tronic fuel injection.

History is a long story.

The car sat for a while and when I ran it at over 3000 RPM one day the car had no power and fuel pump fuse kept blowing. So seemed pretty straight forward fuel pump was cactus.

Replaced it and problem stayed where at 3000 RPM engine stumbles and has no power. Took it to mechanic. He cleaned the fuel system out. Had rust in fuel tank. He put a new single fuel pump on (it has 2 fuel pumps in series), didnt put the accumulator back on. Car would idle OK but wouldnt run over 2000 RPM, so low power you could not drive it.

So took it to another mechanic more experienced with European cars. He put the original parts back in, replaced fuel pumps and pulled the complete fuel system apart. Still car had no power, anything over 3000 RPM and car doesnt stall but stumbles and cannot accelerate. Could not outrun a Vespa.

So started tinkering myself. Pulled the air inlet off to see what the air sensor plate was doing (read this problem can occur if air sensor plate is sticky and not letting enough fuel in). Noticed it bounces when car idles (about 5 times a second I reckon) and when accelerator pressed it goes down like it should but bounces up and down and seems to cut fuel to the engine but then fuel restarts when the air sensor plate bounces. I cleaned all the injectors and seems to be even and consistent. If I hold the sensor plate steady the car seems to run better.

I have checked there are no leaks on the air inlet, can put paper on the air inlet at the sensor plate and it pulls vacuum and stalls car. Warm-up regulator etc seem OK.

I saw a video of another air sensor plate running which was very smooth. So I think that fuel pressure may be bouncing and causing sensor plate (which mechanically controls fuel to the distributor) to bounce.

So can anyone with K-jet system please let me know if they have seen the air sensor plate (located under the air inlet plenum (have to remove air filter etc) and it bounces on their car or if its smooth.

I have not been able to drive car now for over 12mnths.

Thanks

Jason
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Have you explored this?

UnwiredTools, LLC.


I know from "back in the day" of dealing with CIS on the VW Rabbit/Scirocco that the proper fuel pressure gauge test unit was an invaluable tool. The number one culprit of this system was dirt, followed by warm-up regulator and then fuel distributor.

Best,

Jeff
 

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Discussion Starter #8
I second that, I was completely lost on my cars problems until I bit the bullet and bought a fuel pressure gauge for the CIS system, it is an invaluable tool as it will allow you to rule out the fuel system as a possible culprit of your problem. There are a few youtube videos on how to use a CIS gauge on a CIS car, however on the esprit you have to remove a few things like the air filter box to be able to hook the gauge up. You may also want to check the frequency valve and make sure it is setup properly.
 

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The RPM relay is a major source of problems on Deloreans too. There is a vender who developed a solid-state version to replace it. Generally resoldering all of the connections will get you going but if the pump is drawing too much current it will take out the relay again. Know how to jump it to bypass it and/or keep a spare in the car. A pressure gauge is nice but not really required for much of the service. About the only reason I use it now is to check the warm-up regulator, aka control pressure regulator. The injectors are prone to plugging up and getting a bad pattern or leaking. They usually can be cleaned in an injector tester/cleaner. The biggest problem is as the K-Jet system ages it develops vacuum leaks because of the rubber hoses, seals, and "O" rings. Easy to find and fix with a smoke machine. The other BIG problem with K-Jet is that it does not store well, especially with today's fuels. The plunger can get stuck, the injectors get a bad pattern, the fuel pump and pick-up system gets plugged up. Regular use will prevent that but a "sleeping" car (stored for more than a couple of years) needs a lot of work to get running right again. It is a mechanical fuel injection system! Most mechanics in the US do not know anything about mechanical fuel injection and would mess it up. It is good you can do it yourself now.
David Teitelbaum
 

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Hi Guys
Pulled the RPM sensor apart, all looks good. When I pull the coil to close the contact can hear the buzzing sound in the frequency valve. I have short movie showing my air sensor plate if anyone wants to see as cant help think this is telling a story. When car is running the coil is powered and contact closed. My mechanic told me that the primary pressure he set at 4.3bar but bosch says it should be closer to 5.5bar. I dont have a gauge to tell but I have removed and increased the spacers behind the sping in the distributor and did not change anything. That I could tell. My accumular has a small leak, is it possible it is giving bouncing pressures ?. Jason
 

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A bad accumulator is going to make it difficult to restart hot. If your pressures were really that low the injectors would not open. Raising the pressure will affect the A/F mixture and would make the motor run richer. It should be where the spec calls for it to be for everything to work properly.
David Teitelbaum
 

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ISTR that the Lotus CIS uses a relatively high fuel pressure, about 6.5 BAR or 90 PSI.
 

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Discussion Starter #14
I dont know if any of this helps you but when I repaired my CIS system, it was because I had no idea what my cars problem was. I literally messed up everything from the ignition to the fuel injection (including the WUR, and this is where the fuel press. gauge is vital to have) and had to take the time to study and learn it all to make the car work properly again.

But I cleaned my injectors by clamping a rubber hose to the inlet side, then filling the hose with carb cleaner, then sticking my air compressor on the other end of the hose, hence forcing the carb cleaner thru the injector, and you could definitley notice a spray pattern difference til I was done.

Also, for a while, my car was running on no computer for the fuel injection. (It was actually driveable and ran sorta well, but something wasnt right) And if I remember correctly that RPM relay that was mentioned senses a certain RPM that switches power on to the FI computer to sense with the O2 sensor, you will know if this is happening because that frequency valve will be buzzing, if its not there is a problem. My problem was the RPM relay had broken solder connections at the relay on it, one wire that was broken on this module is like a piece of hair going to the coil on the actual relay portion of it. I managed to solder this tiny wire back together and it still works since then, however I have a replacement, I just didnt install it yet. Those relays in the trunk the larger ones are more what I would call a module, as its a board with a relay on it, and they are not interchangeable.

This type of system can be nerve racking to repair, its not difficult, its just the way certain things are layed out in the car and way you have to get to them is overwhelming at times. I dont think anyone with an Esprit relies on it for their only mode of transportation, so what I did is I would take a step back or a day or so off from it and watch CIS videos on youtube, study the sometimes hard to understand "service notes" book I have and just stay away from the car for a few days and just not touch anything on it til I learned more. Because like I said above, I messed everything up and had to start from scratch to get it right again.

But if you know your fuel accumulator is bad due to leakage or something, replace it and start with things you know are bad.

I found alot of old deteriorated wires inside the looms around the intake manifold as well upon doing this work to my car, I fixed them all, as you never know where your problem may lie. It was usually within 6" of a connector to a sensor or something, these cars have HOT engine bays due to the turbo, and it crisps that wire insulation over time, good thing to check out if you cant pinpoint a problem.

I was just thinking of this past battle with my Lotus today, as I own a C3500HD bucket truck for my business, and yesterday it broke down on me, I had it towed home, turns out the ignition module in the distributor was bad. I was thinking how long that problem would have taken me to diagnose in the Esprit, compared to the 1 1/2 hr it took me on my chevy. Just because of the layout of things, and the wealth of knowledge available on the internet about testing individual ignition components for a Chevy. Where as with the Esprit, especially a CIS Esprit, there is not nearly as much.
 

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I don't think anyone with an Esprit relies on it for their only mode of transportation,

heeHee,

Eddie: (SleekGT) are you listening? -eek-



Oh, unless your Alternate Mode of Transportation is a flatbed truck? rotfl




Seriously, I own a complete set of spare relays for my K-Jet CIS Esprit. I bought 'em from a guy who converted his '86 to the later GM MPFI.

So now, instead of agonizing over "what could it be"? I can just pop in a relay (or TPS, for example). Murphy's Law being what it is ("If you have the spare part, the originbal will never fail") my car has been very reliable FI-wise. (Hopefully it's year-long layover for a tranny rebuild and engine re-seal will not affect the record...) :panic:
 

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From amanda11270
>I don't think anyone with an Esprit relies on it for their only mode of transportation,

From Atwell:

heeHee,

Eddie: (SleekGT) are you listening? -eek-
[snip]

Seriously, I own a complete set of spare relays for my K-Jet CIS Esprit. I bought 'em from a guy who converted his '86 to the later GM MPFI.

So now, instead of agonizing over "what could it be"? I can just pop in a relay (or TPS, for example). Murphy's Law being what it is ("If you have the spare part, the originbal will never fail") my car has been very reliable FI-wise. (Hopefully it's year-long layover for a tranny rebuild and engine re-seal will not affect the record...) :panic:
Saw this way late :crazyeyes

My 88 Esprit is a DAILY DRIVER (7 days/week) averaging about 1000 miles/month since Oct 2011. Now, as amanda11270 says "..with an Esprit as their only mode of transport.." - he is correct.

I daily DRIVE the Esprit, but at home there are 3 other fully functional cars - if the Esprit goes down (which it has not since Oct 2011), I can pick from the 91 or 06 Mustang GTs or the 07 Ford Focus. Both Mustangs have been rotting in the garage for over a year with minimum driving to keep them alive.

But better for the Mustangs to rot in the garage than the Esprit, yes? :coolnana:

I also got a full set of relays for my 88 Esprit - same exact reason as Atwell's - in it for the long haul.

The Esprit out grocery shopping:



Anytime, anywhere, anything. rotfl
 

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Discussion Starter #18
A while back when I was still working the bugs out of my 88 I never would of thought I would have the confidence in it that I now do. Since I came full circle in my understanding of the fuel injection system, im real confident in it. I too take my Esprit shopping, but seldom if I have to let it sit alone for very long. This time of year I only drive it though if there is no snow or the roads are wet with snow residue and it will get very dirty. Where I live there are not many exotic cars, or if there are I dont see them, about once every two months you might see a Ferrari, once a year a Lamborghini, the occassional Exige or Elise, I did see one other Esprit on the street too in the two years I owned mine (there is however a broken down one nearby thats been at the same garage sitting outside for like 5 years). I kinda like owning and driving mine because almost no one knows much about it. My sons friends say it looks like a Delorean, but I dont thinks so.

I was selling my Esprit, and still may someday, but I kinda gained interest in it again recently, well I never really lost interest in it, I just got more interested in something else for a while.
 

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Something to note on the air sensor plate, is you want minimum friction on its pivot points. Back probably 20 years ago, I was tuning a early 928 with bosch cis, and I pulled the plenum with the air sensor plate, took it apart on the coffee table, and cleaned the heck out of the pivot shaft - bearing ball, lubed with a light coat of mobil 1 synthetic grease. I could then move the plenum around, and the air plate would stay fairly constent in position. How much it would move while moving the plenum around indicated how much friction was left in the pivots.

Installed it all back, grabbed an allen wrench to tune the mixture using the allen wrench to adust the air/fuel ratio of the air plate, adjusted a little both ways until I found the sweet spot where the car ran best.

Never ever had another problem with the cis, or how the car ran. Any friction from old grease or dirt or whatever on the pivot points makes the air plate stick, respond too slow, and cause your a/f ratio to be wrong.

Brian
 
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