Unique CIS/ K-jetronic problem, I think...

[SkiVT]

The correct ccp spec is tied to the air temperature (more accurately the temp of the wur) when you took your reading. The graph would say 1.5 bar is within acceptable range if the temp is 12 to 18 celsius so you need to confirm that tenperature. The wur has to fully cool down to get another ccp reading. Looks like your watch has heartbeat but maybe not air temperature!!!!

[AlexJ]

The watch is not mine!

[AlexJ]

Originally Posted by SkiVT

The correct ccp spec is tied to the air temperature (more accurately the temp of the wur) when you took your reading. The graph would say 1.5 bar is within acceptable range if the temp is 12 to 18 celsius so you need to confirm that tenperature. The wur has to fully cool down to get another ccp reading. Looks like your watch has heartbeat but maybe not air temperature!!!!

Taking this chart into consideration...


The temperature at this moment is 17 C.
From the chart, ideal CCP should be between 1.4 bar and 1.6 bar... Am I reading it right?

[SkiVT]

Yes, vacuum assisted as you were doing. My bias is to the lower end of the range for slightly richer AFR at cold start. Also, remember to watch the gauge when you eventually do a cold start of the engine. From prior posts, your TTV should hold off vacuum for 30 seconds or so. At 17C, the cold pressure should be about .6 bar lower than the CCP you set with vacuum, so like .8 to 1.0 bar. This ensures a very rich mixture in the first seconds of "cold running" after the engine first starts.

[AlexJ]

Stuart, I have been also preforming the residual test and after 20 min, pressure was 1.2 bar.
Despite I think value is within specs, before the last chart I have been presenting, I pull two injectors out.
They were both wet. I have cleaned them with paper and after a few seconds, they were leaking again... very little but it shows on the paper.

Important to say that I have been preforming a CCP reading before taking out the injectors. Fuel pump relay was bridged and no movement was applied to the sensor plate.

Could this indicate stuck injectors? My god...this one was the second set I bought...

[Walt Fricke]

Well, that is something. With the engine not running, no fuel should flow from any injector. Old injectors sometimes can start leaking (the cure being new injectors), but with new injectors I'd not suspect that they were bad (though, of course, they could be).

What could cause this? One possibility is that the mixture adjustment screw is screwed too far down, thus allowing a little fuel through - the plunger is a hair open. One procedure to set the mixture after having everything apart is to crack one of the injector lines, and with the fuel pump running, turn the mixture screw clockwise until fuel starts to start coming out of the loosened fitting. Than turn back a bit until it stops (or some fraction of a turn, including having it stop).

In your case, you could just crack a fitting and run the pump and see. If fuel starts coming out, turn the mixture screw counterclockwise until it stops. Keep track of how far you have turned so you could get back if none of this works out. Of course, if it doesn't, maybe there is an issue with the fuel distributor.

[AlexJ]

Originally Posted by Walt Fricke

Well, that is something. With the engine not running, no fuel should flow from any injector. Old injectors sometimes can start leaking (the cure being new injectors), but with new injectors I'd not suspect that they were bad (though, of course, they could be).

What could cause this? One possibility is that the mixture adjustment screw is screwed too far down, thus allowing a little fuel through - the plunger is a hair open. One procedure to set the mixture after having everything apart is to crack one of the injector lines, and with the fuel pump running, turn the mixture screw clockwise until fuel starts to start coming out of the loosened fitting. Than turn back a bit until it stops (or some fraction of a turn, including having it stop).

In your case, you could just crack a fitting and run the pump and see. If fuel starts coming out, turn the mixture screw counterclockwise until it stops. Keep track of how far you have turned so you could get back if none of this works out. Of course, if it doesn't, maybe there is an issue with the fuel distributor.

Thanks Walt! I will try that!
This is really frustrating when you spend a lot of money in new/restored parts and then problems start to arise, from the components you have invested in...

[SkiVT]

It isnt uncommon, after refreshing old parts, vacuum lines, etc to have your mixture off. The mixture may have worked before because it was adjusted with existing air leaks, etc. Assuming the system is now tight, it could be too rich. How things like your wur turned out to not be in spec after paying to be rebuilt is something that would make anyone unhappy. A smile will return to your face when you solve this with your persistence.

This may be worth a read as well:

CIS Idle Speed and Mixture Setting Without an Analyzer

[boyt911sc]

Alex,

Let’s start doing the basic tests and report the test results. Test run the FP:

• Pull all the six (6) fuel injectors and place them in individual appropriate container. There should be no sign of fuel delivery at this point.
• Disconnect fuel injectors from the fuel delivery lines and observe for any sign of fuel drips or leak.

A couple of small drips after you start the FP is normal. But no drips after 10 sec. of running the FP. Inspect all six (6) points for any sign of fuel drips while the FP is running (engine off). Share your test results.

Tony

[AlexJ]

Originally Posted by boyt911sc

Alex,

Let’s start doing the basic tests and report the test results. Test run the FP:

• Pull all the six (6) fuel injectors and place them in individual appropriate container. There should be no sign of fuel delivery at this point.
• Disconnect fuel injectors from the fuel delivery lines and observe for any sign of fuel drips or leak.

A couple of small drips after you start the FP is normal. But no drips after 10 sec. of running the FP. Inspect all six (6) points for any sign of fuel drips while the FP is running (engine off). Share your test results.

Tony

Back to this thread...Preformed a smoke vacuum test:
A few leaks were identified:
- between the upper and lower part of the air box
- the axle of butterfly on the throttle body (residual)

Regarding injectors drip:
- injectors are wet all the time. All of them. This is the third set on the car!

Decided to pull out the injection from the car to sort the vacuum leaks.
First thing I found after taking it out:



All six injectors with signs of fuel and all the closed head valves retained a large amount of fuel .

[boyt911sc]

Alex,

Pull out all the fuel injectors and test run the FP. There should be no fuel delivery at this point. Or fuel drips. If they exhibit fuel drips or premature fuel delivery, you got a problem like you are having now.

Adjust your fuel mixture LEANER until you eliminate the fuel drips. You may have adjusted the fuel mixture too RICH to compensate for the vacuum leak. Keep us posted.

Tony

[AlexJ]

Originally Posted by boyt911sc

Alex,

Pull out all the fuel injectors and test run the FP. There should be no fuel delivery at this point. Or fuel drips. If they exhibit fuel drips or premature fuel delivery, you got a problem like you are having now.

Adjust your fuel mixture LEANER until you eliminate the fuel drips. You may have adjusted the fuel mixture too RICH to compensate for the vacuum leak. Keep us posted.

Tony

Tony,
Before I took off the hole injection, I have done that test. With or without fuel pump test running, the injectors were dripping. Obviously less frequently when the fuel pressure was off.

Regarding the fuel mixture screw, I will test it when I assemble the injection back on the engine. But it makes sense... if there is a vacuum leak, AFR has to be compensated.

[SkiVT]

BTW, have you shared a full picture of the car? Always nice to see what’s being brought back to life.

[eastbay]

If you have not seen this, here is the procedure you should be using for the fuel distributor default setting:

[AlexJ]

Originally Posted by SkiVT

BTW, have you shared a full picture of the car? Always nice to see what’s being brought back to life.

Hi,
Car looks like this one. I just have some technical photos to help my work.



.... and this is some work preformed on the car...

[AlexJ]

Originally Posted by eastbay

If you have not seen this, here is the procedure you should be using for the fuel distributor default setting:

Thanks eastbay for your help.
I am planning to put the engine back on car tomorrow and I will use that procedure.
Thanks!

[AlexJ]

Well... back to this never ending story...

- engine out to repair air box, while I was there, new intake boots, new vacuum hoses, etc.
- all fuel lines cleaned, all injectors cleaned through the back flush process

Before I started the car, I blended the fuel lines, and run the fuel pump for a while to check any signs of dripping, assuming the screw was way too far!
No signs of dripping with the fuel pump running (relay jumped).

Started the car, and results of a detailed oriented refresh on a CIS, starting to show up!
The warm up cycle much more evident, very smooth idle... looking good.
When for a ride, reaching the operating temperature and the for 115th time, the 20 minute test.

Remebrering that when I decided to pull out the engine for better check on the air leaks, I found the intakes completely flooded on the cylinders with the valves closed.
Many of you have suggested, logically, that probably the mixture screw was way too far.

At first it looked like that was not the case for the first checking I did before starting the engine.

After the 20 minute test, the problem persists! Rough start for a few seconds (flooded again?) and after that runs normal. Waited another 20 minutes and it was even worse, flooding two spark plugs.

From what I see, I can conclude, injectors are allowing fuel out.
Injectors were new... but after all of this, that does not mean nothing...

Today I decided to try and set up the piston position in the fuel distributor following the procedure suggested by eastbay.

Pulled out all the injectors, fuel pump running, started to turn the mixture screw down (clockwise) until the injectors barely spray. Turned half a turn back.

Started the car and once again it was a perfect cold start. Very smooth.
Drove up to the running temperature and when I stoped, pulled out two of the injectors into small containers to check how much they drip during the 20 minutes after a running temperature stop.

Nothing! 1 or 2 drops in 20 minutes...

How this can be? If I don’t pulll out the injectors, after the 20 minutes the engine will start like it is flooded.... but if I pull out the injectors during the 20 minutes it does not drip any fuel... ????

[AlexJ]

Should I order the third set of injectors?

These were completely clean and doing a good spray after that. I did not check the opening pressure but they were spraying nice when pressure was applied.

is there anything else I can do with them?
Is there a separation between the sealing function of the injector and the spray function? Meaning, It can be spraying well but not sealing the fuel correctly when the engine is off?

[boyt911sc]

Originally Posted by AlexJ

Should I order the third set of injectors?

These were completely clean and doing a good spray after that. I did not check the opening pressure but they were spraying nice when pressure was applied.

is there anything else I can do with them?
Is there a separation between the sealing function of the injector and the spray function? Meaning, It can be spraying well but not sealing the fuel correctly when the engine is off?

Alex,

Were you using brand new or refurbished CIS fuel injectors? You need to know the cracking pressures of the used or refurbished injectors. Even new ones, I test them before installation.

All these CIS tests should have been performed while the motor was out. And I test run the motor before I install the engine in the car. It saves me a lot of time and less aggravation fixing any problem that might prevent the engine from running well.

How long have you been doing the start-up? Either we have communication problem or you are having trouble understanding the suggestions presented to you. As a professional mechanic we have no business telling you how to do your job. The irony is that I have successes helping others but failed miserably with a trained mechanic. I feel frustrated and disappointed at this moment because of my failure to assist you.

Tony

[AlexJ]

Originally Posted by boyt911sc

Alex,

Were you using brand new or refurbished CIS fuel injectors? You need to know the cracking pressures of the used or refurbished injectors. Even new ones, I test them before installation.

All these CIS tests should have been performed while the motor was out. And I test run the motor before I install the engine in the car. It saves me a lot of time and less aggravation fixing any problem that might prevent the engine from running well.

How long have you been doing the start-up? Either we have communication problem or you are having trouble understanding the suggestions presented to you. As a professional mechanic we have no business telling you how to do your job. The irony is that I have successes helping others but failed miserably with a trained mechanic. I feel frustrated and disappointed at this moment because of my failure to assist you.

Tony

Hi Tony,
The injectors were brand new before I started to share this subject here. These were the second set after I assumed (wrongly because I did not test them), pressure was being lost through them. I cannot find here on the Island the proper bench test for CIS injectors. I think I might build one... to test them even when new.

I didn’t do more tests with the engine on the bench because I felt the remaining ones (injectors dripping) could easily be done with the engine on car... specially the mixture screw setup.
And also because all this situation has been creating a big frustration and sometimes I see myself speeding up things, unconsciously...

Regarding the startups, after all the improvements done, they have been reducing significantly. Before, an hot start would take 3+ seconds, now in half time. The actual time would be acceptable if the car would run properly after that... but not. I suspect it does not work properly until the excess of gas is present on the chambers.

Tony, being a mechanic or not, I think if I am here, it is because I recognize my lack of knowledge and was humble enough to search. That is my posture. That is why I have the opportunity to listen to so many experienced guys here and on other platforms - and I am very grateful for that!

I have been searching older posts and I don’t see where I contradict or misleads the tests you and others have suggested.
Maybe I am not able to explain the results or I don’t do it correctly... but I don’t see where... could you please be more specific...?
I really want to share the information clearly so others can help.... but if you could point out where, it would be of a great help.