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Discussion Starter #1
90 Turbo R

page B4-1 of TSD 4737 says idle mixture can be achieved by removing the tamper proof plug and rotating the idle mixture screw. Then it does not show me where the tamper proof plug and mixture screw are located. Can anyone tell me where to look, thanks!

I am in the process of replacing all 8 fuel injectors and their rubber sleeves with replacements obtained from Flying Spares. From the perspective of sitting in the car, left hand drive car, the engine bank on the passenger side was fairly straightforward to deal with, removal of the four injectors of that bank was relatively unobstructed. Interestingly, there must have been significant air leaks from the petrified rubber sleeves of the original injectors, they were a very loose fit and the injectors pulled right out. The new rubber sleeves and injectors are a very snug fit, presumably air/vacuum tight.

Getting at the four injectors on the drivers side, especially the two closest to the fire wall, is a more challenging proposition, a lot of stuff in the way. Will tackle those four tomorrow.

Paul LeClair
 

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The idle screw is "plugged" to prevent DIY interaction. The nozzle seals are snug. Use silicon spray to ease them in place.
BTW..The fuel injectors can be purchased alot cheaper from other sources.
 

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Paul, it's not really something that you would want to mess with without a CO analyzer or air fuel ratio meter.
 

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It's here Paul, the tamperproof plug is often missing. Before you adjust it though read through info on the Bosch system as the mixture is adjusted by other components too and they may be at fault. You probably also had air leaks at the injector seals which would throw the mixture off. Adjusting the mixture at this point is the last thing you want to do only after exhausting all other options.
SZ mixture adjustment.JPG
 

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Paul, most wholesalers like www.autohausaz.com , pelican parts etc will sell these fuel injectors as they were commonly used on 80's Mercedes and VW's.

Keep your old ones however as these injectors are basically brass nozzles and can very easily be cleaned at home to function as they did when they were new.

You'll need a 3mm allen to turn the mixture screw. Clockwise for rich and Anti Clockwise for lean. Go in very slight increments, just a couple of degrees will make a big difference with CIS cars.

Best wishes
 

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At another point in time you may want to complete the FI overhaul by removing the fuel dist head and send it out for cleaning, seal, o rings, flow mapping,etc.
It's makes a huge difference when all cylinders get the same amount of juice.
You may be able to find a re-built exchange fuel distributor head
.
 

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Discussion Starter #8
It's here Paul, the tamperproof plug is often missing. Before you adjust it though read through info on the Bosch system as the mixture is adjusted by other components too and they may be at fault. You probably also had air leaks at the injector seals which would throw the mixture off. Adjusting the mixture at this point is the last thing you want to do only after exhausting all other options.
View attachment 28337
thanks, Jim. I have read TSD 4737, section B4, thoroughly several times. I have not had much luck locally for mechanical fuel injection setup, I tried to talk the local highly regarded Porsche specialist into doing a complete fuel injection testing and setup but they say they are too busy with older Porsche's for the next two months. Then I tried to buy the mechanical fuel injector tester/cleaning rig from mercedessource but they won't ship out of the U.S.A during the Covid lockdown, so I bit the bullet and just bought new injectors and sleeves to at least have a known baseline. I was astonished at how shrunken and rock hard the existing injector sleeves were, the injetors were loose in the bores, had to all be leaking air. Even if I had not replaced the injectors with new, replacing just the rubber injector sleevs with new likely would have been a great improvement.

next I am going to figure out how to do the basic electrical tests as outlined in the Fault Diagnosis Chart of TSD 4737, and the basic pressure tests. I have a decent qualtiy multi meter, and am about to figure out what pressure testing rig I need to buy. You are right, mixture adjustment will be last step, however am going to hook up the Innovate LM 2 now that all 8 new injectors and sleeves are installed and get a present baseline air/fuel ratio to see what I am dealing with.

what I am chasing is the car hard starting, then periodically dying at idle when being driven. Very annoying at stop lights. Driving, feels like a cylinder miss from time to time, just guessing. I have already repalced pretty much everythign int eh ignition, now I am lookign at fuel injection. Additionally, and of course only on a closed course test track, the car will not exceed 170 kph flat out, no matter how long the throttle is held flat to the floor, the car should be good for a lot more than that.

anyone with any suggestions as to a source for a decent but not too expensive pressure testing rig for the fuel injection?

Paul LeClair
 

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Paul, I have the factory Bosch fuel injection cleaning tool and I never use it. You can very easily clean the injectors using a fresh can of brake clean and the straw attachment. The boots are made out of rubber and will set up like a rock. The easiest way to remove them is using a sharp blade (wear gloves here).

In my experience, CIS is very vacuum sensitive and it's very hard to get a perfectly smooth idle if you have any vacuum leak.

The Harbor Freight fuel injector kit linked below will have everything you need to pressure test a CIS injection system on the engine including CIS injection test procedures.

 

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Discussion Starter #12
yes, I agree. I am active in the vintage motorcycle community www.laverdaforum.com and it is quite common for many vintage motorcycle "carb" issues to be ignition related....

having replaced the fuel injectors and sleeves now I need to know fuel line pressure and fuel regulator are correct, if so, then turn my attention to all the fiddly electrickery bits and work my way down the fault finding checklist/test specs.

Paul LeClair
 

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the warm up regulator works in conjunction with the ECU in controlling fuel when cold. The fuel delivery goes in/out of it.
All info, fuel press, etc is in the factory workshop manual.
 

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Discussion Starter #14
I am using TSD 4737 for the fault finding charts and diagnosis of the fuel injection and ignition. Are you referring to some other manual, and if so, what is it and where can I find it? Thanks!

After I replaced everything in the ignition except the coils and ECU, the warm up regulator was the first suspect with the fuel injection and I replaced it with new after cleaning the original did not make a difference. The new warm up regulator did not make any difference either.

Yesterday I went through every hose and every electrical connection, there may have been a few small vacuum leaks, sealed everything up as best I could, cleaned every electrical connection I could get at, car runs much better, still not good enough and still stalls about half the time when stopping for a traffic light. Progress is being made, slowly. Now starting on electrical test procedures of the fuel injection while waiting for fuel injection test rig to arrive.
 

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If you're stalling on stopping ,i don't think it's ignition related. My hunch is vacuum or fuel mixture related.
 

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Attach a volt meter thru the lighter socket and see if voltage drops significantly. There are various books you can purchase for the Bosch system. It was used on MB, Porsche, Ferrari, Delorean at the time.
Solving your issue by replacing parts is what the corner service guy does.
Smart techs diagnose and repair/replace.
 

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Discussion Starter #17
Wraithman, I am a trial lawyer, not a car tech, just a car and motorcycle hobbyist in my spare time. While your point about diagnosis is acknowledged, the only things replaced so far that arguably may not have been necessary are the fuel injectors which might have been able to be cleaned and reconditioned, and the warm up regulator, as I did eventually get the original regulator working after cleaning the crud out of it. The fuel injectors needed to come out anyway, as the rubber sleeves had shrunk and petrified and were clearly leaking air. I have ordered a fuel injection pressure tester kit to test fuel pump and fuel regulator pressures, has not arrived yet. I did try and buy the fuel injector testing and cleaning rig from the fellow at MercedesSource but in response to my online order he responded that he is short staffed and not presently shipping outside of the U.S.A., so I ordered new injectors

Going forward, I am working may way through the fault finding diagnostic charts, and welding an exhaust sensor bung into the exhaust to install a mixture sensor to use with my innovate LM2 to then be able to accurately read and set air/fuel mixture. Clearly a previous owner has removed the tamper proof plug over the mixture adjuster, and from the smell of the exhaust, likely richened it up, possibly to compensate for air leaks around the injectors or elsewhere in the system.

To be really blunt, if I had someone like Jim Walters of Bristol Motors anywhere near me, the car would already have been delivered into his hands for expert diagnosis and repair rather than me trying to reinvent the wheel and trying to become a Bentley/Bosch fuel injection expert. He is about a 13 hour drive from me, and when I get the car running well enough again to make that drive ( and Covid 19 restrictions resolved ) I will give him a call and see what arrangements can be made, as there are a few other issues I would like to have dealt with as well by someone with the knowledge and specials tools and expertise that I simply do not have.

People like me likely would not own some of these special interest cars without the internet resources of forums like this, online availability of tech articles and manuals, and the willingness of various experts to participate with advice through various of these resources. The Rolls Royce/Bentley dealer in my city will not even look at my car as it came from outside North America, so here I am online looking for advice and answers, after thoroughly reading the Technical Service information and manuals and still needing some clarification or advaice from fols with practical experience.
 

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Hi Paul, You arrived at a great forum. There's alot of activity here with Turbo R owners, so reaching for help or advice is available. I passed up a Turbo R last summer that would have been a nice project, but instead added another RR to the garage.
I'm intrigued with your sensor project. It would make a nice subject and keep us informed. I may utilize something like that for a project I have in mind.

PS Jim is a great guy and an asset not only here but the RROC as well. You will be in great hands.
 

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To be fair, if you're doing your own work and have limited access to diagnostic tools, you might have to swap parts in order to diagnose an issue. You will still save money vs spending on expensive diagnostic equipment or paying someone to troubleshoot a problem if the cost of the part is inexpensive. It's a balance.
 

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Hello Paul,

Your first concern is "false air" / vacuum leaks. A vacuum leak post fuel distributor/airflow meter throws off the air-fuel mixture calibration.
Find a workshop with a smoke machine that is willing to work on your car. Stretch a large latex/rubber glove over the airflow meter plate inlet and inject the intake system with smoke.
Repair all vacuum leaks.

Another quick and dirty check is to drive the car with the oxygen sensor disconnected. This puts your car in "open loop."
If your drivability issues lessen, then, you know that your issues are injection-related. connect your Innovate to the disconnected (black wire) oxygen sensor and set to 0.7 Volts. Refer to page B4-47.

Don't waste money on pressure gauges and specialty tools. You will never recoup the expense and 99% of the time your car is in pressure specification.

The injection system on your car is 90% adapted mid 80's Mercedes V-8. Find a Mercedes specialist or search for a Bosch Car Service center in your area.

Porsche specialists don't have the experience needed since they did not use K Motronic / KE Jetronic.

In summary, Tests to perform:

Check for blink coded - Page B4-9. Not codes if any, clear codes, road test, then recheck for codes.

Resolve ALL intake manifold vacuum leaks. A smoke machine is needed.

Fuel pump volume delivery test. This test is overlooked by 90% or workshops and all DIY.

This is performed by disconnecting the return fuel line post fuel distributor at the fuel cooler and measuring fuel pump performance with a 2L capacity graduated cylinder for a specified time.
Intank fuel pre-pump is usually the cause of low volume.

Set AFR with inovate as mentioned above if fuel delivery VOLUME is to specification.




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