Anybody out there with experience adjusting CIS?

[scary driving]

Hello everybody:

I rebuilt the CIS distributor on the '80 sc, since it was running some cylinders lean and others rich. I ran the injectors with cleaner, and had 5 flow pretty even, and one about 30% less. We went ahead and ordered 2 new injectors and the new ones flowed 30% more than the old ones. Went ahead and ordered 4 more and got one of the injectors in a yellow box, which hasn't been used by bosch for a while. Decided to flow them all to be sure and behold the result:


These are NEW injectors. I'm wondering if I got a bad batch or if I should ultrasound them, or if they need to be run for a while ... I don't really feel comfortable adjusting these at the distributor, since I have 37ccs on the lowest and 96ccs on the highest.

Hopefully someone can shed some light.

[fanaudical]

Questions: Have you verified that your test rig is not the culprit? If you swap injector positions on the test rig, are the volumes still consistent? What is your test pressure for the injectors?

[scary driving]

The injectors were swapped to isolate the rig as a culprit. It's been ruled out. The injectors ran at 5 bar for 30 seconds.

[scary driving]

Forgot to say, We ran them for over quite a while over several runs. We swapped positions to rule out the rig being the problem. I know the adapters look shady, but they were fabricated that morning for the tests and they pose no problems other than looking like crap.

[Jeff NJ]

Where did you buy them? Do they look new? I cant imagine that kind on inconsistency on legit Bosch injectors. Are they all the same (009, 017, etc)?.

[scary driving]

Got them from our host. All the same part number, but all different lots. Checked on the injectors themselves, the part numbers are the same as on the boxes, but the manufacture dates and lot numbers are all different. The injectors that came with the car were punched in, and the new ones lasered in.

[boyt911sc]

Did you you know that the operating/opening pressure for these CIS injectors is between 36 psi.~52 psi.? I did some testing sometime ago and classified them into different groups:

Group I: 36 psi. ~ 41 psi.
Group II: 42 psi. ~ 47 psi.
Group III: 48 psi.~ 53 psi.

Group IV: 54 psi. and over.........dumpster.

Check the individual opening pressure, spray pattern, and flowate. The flow rate/s adjustment in the fuel distributor is for fine tuning and not recommended to correct or compensate for large amount of fuel flow discrepancies between injectors. Try to use injectors that have closer opening pressures and flow rates values as much as possible.

And as a control, the flow test instrument should be tested and verified with no injector/s installed. Same with the FD on the engine.

Tony

[scary driving]

I thought about just using the old ones and matching one of the new ones to them, but I guess I don't know if what is happening to the new injectors is bound to change, or if this is just what they are going to do forever. I guess I wouldn't like to match them now only to have them go out of spec, so the big rephrased questions are:

1. Are they likely to be stuck from storage and will loosen up to flow more?

2. Is the CIS distributor responsible for flow, since they all pretty much open up between 35 and 39 lbs, and there is not that much difference in the spray pattern (none of them look like taking a leak hungover). I mean, It may very well be that the path of least resistance is just flowing more, and I'm just freaking out over it due to my lack of knowledge on this particular system.

3. Is this just a clear cut case of defective injectors?

[T77911S]

tony,
did you find flow rates different for injectors that had big opening pressure differences?
I would think with big open pressure diff's you would see that more at idle as in a lumpy or perhaps a miss at the idle.


I like that test rig.
I would like to see flow rates at a low pressure compared to rates at hi pressure.

[WERK I]

scary driving, great post.
I thinking of doing the same thing with my 930 CIS injectors. What fuel pressure are you running your test? Is there a safe liquid to run the test with that has the same specific gravity as pump gas?

[dobryan]

Try sending them to WitchHunter?

WitchHunter Performance - Injector Cleaning & Flow Testing Services

[Tippy]

Originally Posted by dobryan

Try sending them to WitchHunter?

WitchHunter Performance - Injector Cleaning & Flow Testing Services

They do electronic injectors. OP is referring to mechanical injectors.

[boyt911sc]

Originally Posted by T77911S

tony,
did you find flow rates different for injectors that had big opening pressure differences?
I would think with big open pressure diff's you would see that more at idle as in a lumpy or perhaps a miss at the idle.


I like that test rig.
I would like to see flow rates at a low pressure compared to rates at hi pressure.

Ty,

I am no expert but just another avid CIS troubleshooter. When I perform a flow test, I make sure that the flow meter (FD or a another rig) delivers uniform volume for all six (6) outlets. This is your basic control. I test flow rates at low, medium, high, and random pressures. The longer the test duration is done, the more consistent are the test results.

Having similar opening pressures does not guarantee similar flow rates. And vise versa. The flow rate characteristics is a more reliable test for CIS injectors done in set of six (6) injectors. I have to look at my logbook for the flow rate test results of different opening pressures and could not remember what I had.

Tony

[T77911S]

i do the same but I cant test opening pressures.
I do a test to see which ones start spraying first and another to check volume at would be idle
just had mine off the 930 testing flow. had to put the engine back in when the BMW sprung a water leak.

[scary driving]

Werk 1, The machine uses a fluid to simulate the characteristics of fuel. I can't recall the name, but whoever has a machine like this, has to use a substitute fluid to run it. It has an ultrasound cleaner and they do run cleaning fluids through the injectors as well. I'm still going over options as to how to properly test the injector flow. I guess I'm going to have to assemble the whole system and flow it that way.

[RarlyL8]

The differences in flow volumes shown in post #1 may be more influenced by the testing method than the variation in injector flow. The best way to test is by using a functioning CIS system, and by first testing that system with no injectors attached. We test for cracking pressure, spray pattern, ml/min flow rate, and residual leaking. I do not waste time with off spec injectors, they hit the trash can. Once it is determined that the injectors are functioning within spec adjustments are made at the fuel distributor to match all 6 injector volumes.

[scary driving]

Awesome! Just what I was hoping to hear. I was going apesh&@t with this since I was afraid I would have returned the injectors only to have the same result with substitutes! I suspected that the fluid was just taking the path of least resistance, hence the variations. I will test the entire system assembled and take it from there.

I apreciate it. I will be testing tuesday or wednesday and will post the results as we're done.

[Charles Freeborn]

Originally Posted by RarlyL8

The differences in flow volumes shown in post #1 may be more influenced by the testing method than the variation in injector flow. The best way to test is by using a functioning CIS system, and by first testing that system with no injectors attached. We test for cracking pressure, spray pattern, ml/min flow rate, and residual leaking. I do not waste time with off spec injectors, they hit the trash can. Once it is determined that the injectors are functioning within spec adjustments are made at the fuel distributor to match all 6 injector volumes.

Yep. This.

You can make 6 separate jars with canning (Ball) jars.

[IMONBOOST]

Agree, what Rarly said, test on CIS system. You could be getting a large pressure drop when the injectors open or who knows what. Your rig is still cool though.

[WERK I]

.....or test one injector at a time instead of 6 at a time. And use the same test fitting for each injector.