CIS injector test - fuel distributor vibration

[Won]

Car idles really low for about 5 seconds immediately after cold start, pops a few times then it's ok. Figured it's a vacuum leak and realized the fuel injectors can be pulled out with almost no resistance (new o-rings are on the way). Might as well try the spray test, but when the air flow meter arm is pushed up slightly there is a severe vibration on the arm and it won't go up smoothly, unless I push it up nearly halfway. Is this a safety feature for when the engine is not running and fuel pump is pumping, or is this a problem?

[Oracle]

Hi,
The flow meter arm should move perfectly free. There are no safety features that I know. What you describe is like if there is rust or some sort of contamination in the FD.
Probably you'll need to take it off and without opening just soak it in some cleaner and blow air and hopefully that is enough (thats what my mechanic did to clean mine)

Good luck!

[Won]

With the engine running or key not in "on" position there is no resistance to the movement of the arm.

Just went outside and try it again, it sounds more like an electrical buzz and the vibration I feel is from the arm wanting to come down while I'm lifting it. The buzzing stays as long as the arm isn't at the resting point.

[William Miller]

If I'm not mistaken, what you are feeling is actually the pulsations from the fuel injectors. (Fuel pump on right?) The injectors vibrate slightly as the fuel pushes past the valve/tip on the end of them. They require a certain amount of pressure for them to open and start spraying.

My guess is that's what you are feeling along with the resistance of control pressure. The plunger should push back against the air plate with a certain amount of resistance, but should not stick or bind.

At its resting point the distributer stops the flow to the injectors. So no vibration or buzzing. Feel the injector next time when the car is running.
Let me know if this makes sence.

[Scott R]

Sounds like it's working correctly, you appear to have a lean mixture on warmup. I bet if you check your cold control pressure it's out of spec.

[Nitrometano]

spary some carb cleaner under the plate arm to clean that area. Never rise tha plate arm with the fuel pump running and the engine stoped, you will flood the cylinders with gas and can destroy it if you start the engine. Some person in this forum, write a procedure of how to calibrate the mixture into a CIS engine. Only you need a long 3mm allen key and your finger to rise or lower the arm plate with the engine running. Here is:

How to set CO2 Cis System
I dont know who write this, but I take the info from a Pelican's forum.

"I found that every CIS engine has it particular 'happy place' where it likes to run. No two are exactly the same but CO% usually falls between 2-3.5%.

This can be set by ear and is very accurate for best performance. If tuning CIS w/lambda, disconnect the O2 sensor first.

The trick to find your engines happy CO is to get the engine at least running and with the air box cover and filter off, SLIGHTLY lift the air sensor plate via the exposed elbow with a finger, knuckle or whatever. All is needed is very slight pressure to notice any change in RPM. If the engine RPM increases it wants to be richened. This is also true if you were to pull down on the sensor plate. Is RPM's increase, then it wants to be leaned out. Make very small adjustments with the 3mm allen as necessary. The trick is to get the engine at max RPM so when you either push or pull the sensor plate, the RPM's will drom (either being too lean or rich)"

-----------------------------------------------------------------------------------------------

Also I get this from another post writed by Oracle:

"My car had similiar problems some days it was fine others was stuttering like hell...The problem was: -drums here-
The stupid Air Flow sensor boot had the tiniest crack on the neck
http://www.pelicanparts.com/catalog/images/Connect-Images/93011035602-M260.jpg

So that was enough to be erratic and difficult to find.."

[Won]

Bill:

Yeah that makes sense, but the buzzing is so loud I'd expect to hear it even with the engine running, but I can't. I tried to feel the injectors, but I could not distinguish between the vibration of the engine and that of the injectors.

Scott:

It's definitely lean, if I richen it enough to stop the engine from stumbling, then after warm-up the rpm will drop way down and bounce back up. That's running too rich, right? I don't have the CIS pressure tester yet, so we'll see if fixing the leaks would help first.

Nitro:

I know there's a major leak through all the injector sleeves. There could be more (probably), but I need to fix that first before I try the tuning method (Souk wrote it I believe). Last time I tried that, I ended up being way too rich under running conditions.

Thanks everyone.

[Scott R]

Originally posted by i_got_an_SC
Bill:

Yeah that makes sense, but the buzzing is so loud I'd expect to hear it even with the engine running, but I can't. I tried to feel the injectors, but I could not distinguish between the vibration of the engine and that of the injectors.

Scott:

It's definitely lean, if I richen it enough to stop the engine from stumbling, then after warm-up the rpm will drop way down and bounce back up. That's running too rich, right? I don't have the CIS pressure tester yet, so we'll see if fixing the leaks would help first.

Nitro:

I know there's a major leak through all the injector sleeves. There could be more (probably), but I need to fix that first before I try the tuning method (Souk wrote it I believe). Last time I tried that, I ended up being way too rich under running conditions.

Thanks everyone.

You're describing a classic failed WUR issue, no control pressure, correcting the mixture out as it warms up. Hook some gauges up and get a reading.