CIS 1982 930, running rich and loud rear compartment noise

[wcarson]

Hi everyone,

I hoping that someone here can help me solve an issue with my 1982 930. The car is a 3.3L car still running CIS injection. The Fuel distributer, WUR, and AAV were all rebuilt or replaced when I rebuilt the motor 20 years ago and the car has been driven about 5,000 miles since then. I know, not enough. It's been a wonderful car and I try to at least start it and drive it around once a month a bit. Sometimes it sits though for 2-3 months without being started. I know, I know, I need to drive it more.

The fuel pumps run on this car when I turn the ignition to the on position, it's always been that way. Thus when I start the car, I need to quickly turn the motor over so as not to flood it. If it floods, then I simply pull out the fuel relays and burn the extra fuel off before starting the car again. Again, it's always been this way and I'm used to this.

This weekend, when I tried to start the car it was making a very noisy metallic whine sound from the rear motor area. I got under the car and it is definitely not the rear fuel pump. It's definitely not the CD box either. The motor ran, but idled poorly and produced a huge amount of white smoke- it appeared to be running very rich. I pulled the airbox and intercooler off to help determine what is making the noise and I can't quite pin it down. It seems to be coming from the fuel distributor area, but I can't tell for sure. I can't imagine a bad injector making this sound, but that thought crossed my mind.

Here is a youtube link to a video that I took. This is with the ignition ON, fuels pumps running, but the motor NOT turning over or running. As you can see- this is very loud.

https://www.youtube.com/watch?v=v9ubmcjOrTA

Anyone have any ideas???? THANK YOU in advance!!

[DaytonaCoupe66]

Regrets that this won't be much help with your noise, but your fuel pumps should not run with the key on unless the green plug that goes to the fuel pump safety shutoff is unplugged. (I've had two 1982s and both operated this way). It's a green two pronged plug with a wire clip on it that sits behind and slightly to the left of the fuel head. You likely know this, but when the fuel pumps run but the engine is off (as in when you unplug that safety switch), the fuel cycles through the system loop but the injectors should remain closed (until the metering plate on top of the fuel head is depressed). The flow of fluid and pump operation is somewhat noisy, but not as bad as your video.

Sounds like a restriction somewhere. Have you tested your CIS pressures? There is a ton of great guidance on this site for testing fuel pressures.

[Schulisco]

Hi William.

As DaytonaCoupe66 said - the fuel pumps are operated by the air flow sensor plate, when it lifts while cranking the engine, the switch is starting the fuel pumps. It's for security reasons - when a crash occured, and the engine stalls but the fuel is still delivered to the hot engine, this can lead to a heavy fire!

The noise is not normal, it's louder than expected. It sounds to me that either one or more of the injectors is bad and remained fully opened. It floods it's cylinder and this might also be the reason for the white smoke and burning way too much fuel and running too rich.
Pull all the injectors while still connected to the fuel lines and let them spray in clear plastic bottles for a measured time (air flow sensor one time not lifted, one time fully lifted for full throttle simulation) and compare all their fuel deliveries. That also goes with your way too low mileage. Probably they can be cleaned with an ultra sonic bath, but my recommendation - I woould replace them all.
If they spray all equally the same amount of fuel (less than 5% difference) then check the pressures of the whole K-Jetronic (fuel pressure, control pressure low/high temperature). Do not forget the fuel pumps - they can also go bad while sitting. The 930 has two of them, I know that there's one in the front underneath the fuel tank, but the second one is close to the engine...but don't know where exactly. This can also produce noises like this. It might deliver fuel, but sounds awful before it dies.

And: Check the engine oil! Does it smell of fuel? I think so.
I guess there's already a lot of fuel drained into the engine oil reducing it's lubrication capabilities! Do not drive much, best not before solving the probelems. At least after repair change urgently the motor oil!!

All the K-Jetronic cars take amiss while sitting so long. They have to be driven from time to time to drain the old fuel oout of the system. Todays fuels are more aggressive to all components of the fuel injection system than those from 20 years ago. And use a fuel stabilizer in the future when the car is continuing sitting for a longer time between rinding it. It helps preventing such problems/damages and it dramatically reduces the smoke on start after sitting a while! My recommendation is to drive it at least every 2 or 3 months for at least 20mls. The more often, the better.

Regards, Thomas

[wcarson]

Hi guys,

Thanks so much for the input. I am hoping it's something easy like a stuck injector. I am aware that the fuel pumps are not supposed to run when the ignition is until the engine cranks....this safety circuit has not been functioning since I've owner the car.

I'll need to test all the fuel pressures if the injectors looks good. I've done all the testing years back and will need to review how to do it- I do have a factory service manual that goes through the procedure.

And I will definitely change the oil. I'll also pull the plugs out and crank the motor in to prevent hydrolock in case one or more cylinders is full of fuel.

The noise is definitely not the rear fuel pump. I put my ear right up to it and it's making the appropriate humming/whine sound.

Thank again!

[pkabush]

I’d go around all the components with a stethoscope (a long neck funnel also works)
Check both pumps, accumulator, injectors, etc.

[Schulisco]

Welcome ;-)

I also can heavily recommend to watch the videos of Curt from Klassik Automotive Training School https://www.klassikats.com/ ans its YouTube Channel: https://youtube.com/channel/UCbo48hJkHDikGut5DoL6-sQ

Especially these:
https://youtu.be/slCzVrrST2Q
https://youtu.be/Ii5k773lwKs

Also the YT Channel and Website of Joe Engineer under https://bit.ly/3qfs9p2

And especially these ones:
https://bit.ly/30OnHF4
https://bit.ly/3qcxqh8
https://bit.ly/3FjnqZD
https://jimsbasementworkshop.com/CIS/

They're very informative und great to dive in to the traps and pitfalls of the Bosch CIS.

Good luck!

Regards Thomas

[spuggy]

Hmm. White smoke is steam. You get steam when water condenses into a cold muffler. Oil is grey or blue. Gas is black (or flame-colored, depending on turbine temperature, heh).

The fuel pumps running when the key is on, while not correct for anything past 1976, really shouldn't cause a problem - unless an injector is stuck open, or the AFM plate is misadjusted/stuck too low so that the injectors open. The main reason for it is so you're not trapped in a smoking wreck with a cracked fuel line and the pumps delivering lots of fuel - but the factory didn't interrupt the fuel pump ground with the motor not running on the earlier cars.

My CIS 930 ran the fuel pumps 100% when the key was on for 8 years/40-50,000 miles, and didn't cause any issues whatsoever (my AFM plug was connected, but some mismatch between the 930/911 harnesses).

Most CIS 930's run rich, much of the time. Smell fuel during warmup? Not unusual, because you normally have to get them rich enough hat they don't sputter/cut out when driving around on a cold motor - and then they smell of gas after a cold start... Sometimes they're very sensitive to idle co2 setting when hot as well - mine would actually idle great @ 2.5%, but would lean surge under load with a steady throttle @ 3000 RPM unless idle was set to 3%... They want what they want...

The noise in your video sounds like a unhappy fuel pump to me - they can be very loud. Without an engine blower, there's nothing else in the back that rotates and makes noise, except the big shiny thing.

I could be wrong, but I don't think an injector open/squealing sounds like that. But that's possibly one of the easiest things to check. They shouldn't open at all with the motor not running/air plate on the stop.

With CIS injectors, checking spray pattern and crack pressure is important; pretty easy to make a bench rig to check. These are maintenance items, that you might need to do more frequently if the car is left to sit with ethanol turning to varnish in them. You may also have some success with wiring the pintel open, usiing an utltrasonic cleaner and backflushing with brake cleaner etc. I saved a few like that; RoW 930 injectors were $120 each, last I looked nearly 10 years ago...

A sketchy CIS injector is Not Good on any car, but is especially bad on a turbo.

[wcarson]

Originally Posted by spuggy

The noise in your video sounds like a unhappy fuel pump to me - they can be very loud. Without an engine blower, there's nothing else in the back that rotates and makes noise, except the big shiny thing.

I could be wrong, but I don't think an injector open/squealing sounds like that. But that's possibly one of the easiest things to check. They shouldn't open at all with the motor not running/air plate on the stop.

Thanks everyone for the continued input. I was hoping someone would listen to this and nail down the issue easily- this is a very metallic whining noise that I initially assumed was the fuel pump. But alas, it is certainly NOT the pump. It very loud and coming from the top part of the motor. I took the drivers side rear wheel off and got down right next to the fuel pump- it sounds totally happy and normal. I really don't know what else mechanically moves or spins or has bearings in the CIS components- none that I know of- and yet this noise is very very metallic and mechanical sounding. It very strange. But I still do think it's possible it's a whine resulting from a stuck injector, or some other highly pressurized CIS component.

WRT the fuel pumps running when the ignition is on but the motor is not turned over yet- Indeed the car has run great for the past 20 years without the "safety" feature of the fuel pumps not operating until the engine turns over. I'm sure the Thermo time switch is not wired properly or the circuit is not complete for some reason. The only reason why I mentioned it to begin with is so people who listened to my Utube video didn't think the noise was my motor running or the starter turning over, etc.

This mysterious loud noise is 100% related to my running issue. It's never made this noise before when running normally, and it's never not run normally ever until now..... and is now making this sound.

My plan is to:
1. Take out all 6 injectors, while still connected to the fuel lines and put them in water bottles. Then I'll turn on the ignition, listen carefully, and also observe the flow.

2. Take out all plugs and crank the motor over to make sure it's not going to hydrolock.

3. When doing #1, also listen carefully to the fuel accumulator, WUR, AAV, etc.

4. Replace the fuel filter.

5. Check operation of the fuel distributor plunger by verifying the sensor plate moves smoothly.

Hopefully I'll be able to see an obvious issue by doing the above. Otherwise it'll be a more in depth approach.

Thank you again everyone for the very helpful input!

[wcarson]

Originally Posted by Schulisco

Hi William.

As DaytonaCoupe66 said - the fuel pumps are operated by the air flow sensor plate, when it lifts while cranking the engine, the switch is starting the fuel pumps. It's for security reasons - when a crash occured, and the engine stalls but the fuel is still delivered to the hot engine, this can lead to a heavy fire!

The noise is not normal, it's louder than expected. It sounds to me that either one or more of the injectors is bad and remained fully opened. It floods it's cylinder and this might also be the reason for the white smoke and burning way too much fuel and running too rich.
Pull all the injectors while still connected to the fuel lines and let them spray in clear plastic bottles for a measured time (air flow sensor one time not lifted, one time fully lifted for full throttle simulation) and compare all their fuel deliveries. That also goes with your way too low mileage. Probably they can be cleaned with an ultra sonic bath, but my recommendation - I woould replace them all.
If they spray all equally the same amount of fuel (less than 5% difference) then check the pressures of the whole K-Jetronic (fuel pressure, control pressure low/high temperature). Do not forget the fuel pumps - they can also go bad while sitting. The 930 has two of them, I know that there's one in the front underneath the fuel tank, but the second one is close to the engine...but don't know where exactly. This can also produce noises like this. It might deliver fuel, but sounds awful before it dies.

And: Check the engine oil! Does it smell of fuel? I think so.
I guess there's already a lot of fuel drained into the engine oil reducing it's lubrication capabilities! Do not drive much, best not before solving the probelems. At least after repair change urgently the motor oil!!

All the K-Jetronic cars take amiss while sitting so long. They have to be driven from time to time to drain the old fuel oout of the system. Todays fuels are more aggressive to all components of the fuel injection system than those from 20 years ago. And use a fuel stabilizer in the future when the car is continuing sitting for a longer time between rinding it. It helps preventing such problems/damages and it dramatically reduces the smoke on start after sitting a while! My recommendation is to drive it at least every 2 or 3 months for at least 20mls. The more often, the better.

Regards, Thomas

Very helpful! Many thanks.

[wcarson]

OK guys, I have some further information. I took the plugs and injectors out and thus was able to run the fuel pumps and manually deflect the air metering plate while watching the fuel lines drip/spray fuel into bottles.

I am still waiting on CIS pressure testing equipment that I ordered- so I have not yet been able to check the pressures.

But here's what I have learned so far:

- With the fuel pumps ON and the air metering plate closed, ie, all the way up and at rest, the fuel line to cylinder 6 drips fuel at a pretty significant rate.

-When I deflect the metering plate downwards with my hand, I can feel the piston in the FD smoothly working, and I can also feel the rebound is very smooth. All 6 fuel lines seem to be flowing the same amount of fuel relative to one another when the metering plate is moved. So that's good.

-Here's the cause of that high pitched crazy noise- it's the #6 fuel injector flowing a small amount of fuel at rest when the pumps are on! It make a pretty loud scream. I swapped injectors and another injector (in this case from cylinder 4) makes a similar sound when it is screwed onto the fuel line for cylinder 6. That constant small volume flow to cylinder 6 when the metering plate is closed is pressurized enough to spray a small amount of fuel through the injector and it screams!

SO- the cause of the noise and the running rich is clearly the fuel distributor running to cylinder 6 which is filling with fuel whenever the pumps are on. All the other lines to the other cylinders do not spray when the metering plate is all the way up at rest.

So my questions are this:
1. I assume my fuel distributor needs a full rebuild?
2. Is is possible that the flow adjustment screw to cylinder 6 would fix the issue? My FD appears to be a version that has the adjustments screws under allen screw covers near the bases of the of the fuel lines on the FD. Obviously my concern would be that if I messed with it in the car to decrease flow to cylinder 6, I would change the flow across the board to cylinder 6 across the whole throttle range and thus cause it to potentially run lean.
3. Before I go any farther, I still need to check the pressures. It's entirely possible one or both the pumps are not strong anymore or the filter may need to be replaced. Would incorrect system pressure or cold pressure potentially cause a malfunction in the fuel distributor to result in cylinder 6 fuel line running as it is? The best case scenario would be that the filter is partially clogged or one of the pumps is on it's way out and the pressures are low..... that's a lot easier to remedy than a full removal and repair of the FD.

Many thanks for any input from you CIS experts out there!!

Keith

[boyt911sc]

Originally Posted by wcarson

OK guys, I have some further information. I took the plugs and injectors out and thus was able to run the fuel pumps and manually deflect the air metering plate while watching the fuel lines drip/spray fuel into bottles.

I am still waiting on CIS pressure testing equipment that I ordered- so I have not yet been able to check the pressures.

But here's what I have learned so far:

-With the fuel pumps ON and the air metering plate closed, ie, all the way up and at rest, the fuel line to cylinder 6 drips fuel at a pretty significant rate.

.........(edited............


Many thanks for any input from you CIS experts out there!!

Keith

Keith,

I have been following your thread from the very beginning and allowing others to contribute to solve your CIS problem. The culprit is a broken or defective o-ring inside the fuel distributor.

You could run the fuel pump all day long and as long as the plunger is down or at rest, a good fuel distributor will not deliver fuel. There are 2 ways I test a FD for fuel flow:

1. All fuel injectors pulled out and connected to the fuel line.
2. All fuel injectors removed from the fuel lines.

I placed each line with or without fuel injector into a graduated cylinder and run the FP. There should be no fuel delivery when the FD plunger is down or at rest. This is test #1. Any sign of premature delivery at this point the FD FAILED the test. No need to waste time testing the fuel distributor. It needs a rebuild.

If the FD passed test #1, proceed to measure the individual flow rates. Some FD have flow rate adjuster/s and some don’t. The 930 FD’s have the flow adjuster/s and could calibrate each port for uniform flow. If you could not adjust any of the 6 ports to your satisfaction or have so much discrepancy for the control flow rate, then it would need a rebuild too.

The CIS fuel injectors require at least 36 psi. to operate so if you test run the FP with all the fuel injectors removed, fuel line to cylinder #6 will demonstrate dramatically a failed fuel distributor.

SUMARRY:
You have a defective or leaking o-ring inside the fuel distributor and causing premature fuel delivery. You should not run or start the motor with this FD installed. Raw fuel will contaminate your engine oil.

Tony

[wcarson]

Originally Posted by boyt911sc

Keith,

I have been following your thread from the very beginning and allowing others to contribute to solve your CIS problem. The culprit is a broken or defective o-ring inside the fuel distributor.

You could run the fuel pump all day long and as long as the plunger is down or at rest, a good fuel distributor will not deliver fuel. There are 2 ways I test a FD for fuel flow:

1. All fuel injectors pulled out and connected to the fuel line.
2. All fuel injectors removed from the fuel lines.

I placed each line with or without fuel injector into a graduated cylinder and run the FP. There should be no fuel delivery when the FD plunger is down or at rest. This is test #1. Any sign of premature delivery at this point the FD FAILED the test. No need to waste time testing the fuel distributor. It needs a rebuild.

If the FD passed test #1, proceed to measure the individual flow rates. Some FD have flow rate adjuster/s and some don’t. The 930 FD’s have the flow adjuster/s and could calibrate each port for uniform flow. If you could not adjust any of the 6 ports to your satisfaction or have so much discrepancy for the control flow rate, then it would need a rebuild too.

The CIS fuel injectors require at least 36 psi. to operate so if you test run the FP with all the fuel injectors removed, fuel line to cylinder #6 will demonstrate dramatically a failed fuel distributor.

SUMARRY:
You have a defective or leaking o-ring inside the fuel distributor and causing premature fuel delivery. You should not run or start the motor with this FD installed. Raw fuel will contaminate your engine oil.

Tony

Tony-

Many thanks for weighing in-

Sounds like I really don't need to spend much time or effort trying to troubleshoot anything else- the FD definitely needs a rebuild- it failed your test #1.

I will plan to send it out to CIS Flowtech in Alabama. I may send out the WUR to them as well to check it and make sure it's also all up to spec, and also send my Bosch 009 injectors to Witch Hunter in Idaho for "rebuilding"/cleaning and flow testing. Anything else you can think of?

Thank you for sharing your knowledge. I really do appreciate it.

Sincerely,
Keith

PS- I'd love to attend one of your engine rebuild courses. I attended Bruce Anderson's class many years ago before he passed. I'm obviously not too current or proficient with CIS, but I enjoy learning about the cars that I love.

[Schulisco]

Keith,

the older a Bosch CIS fuel distributor gets, the more it rans out of it's specs. Those adjustment screws ontop of some fuel distributors are only for fine tuning while adjusting them in the factory or during overhaul. A defective nozzle/o-ring etc. you cannot "adjusted away" because every screw affects all the other one. This is because we're talking here on liquid pressures: Lowering or increasing the pressure on one output will affect all others! I also tried to balance mine as well in endless tests without success. So the fuel distributor must be overhauled and completely readjusted afterwards by a specialist. Mostly the (stainless steel) diaphragm between the upper and lower half of the case is corroded, dirty (some very fine holes in it, only visible against light) and/or deformed as well...and the o-ring are going bad over time as Tony also wrote.

To send the WUR as well for checkup is always a very good idea and every time recommended while working in that way on the CIS. It also contains rubber seals and a rubber diaphragm which won't last for ever as well...

I recommend to replace all the injectors! Despite 5 of 6 will still work, their spray pattern won't be the same after 20,30 or 40 years: The corrosion through the water from the ethanol and fuel will damage them as well. And what are the costs of the injectors against the costs of a hole in a piston caused by a lean combustion....Especially with the new fuels containg up to 15% of ethanol in the US as I read today ... ethanol and it's attraction to water is THE enemy for the whole CIS system. I already wrote to urgently use a fuel stabilizer...

Despite of checking the pressures I want to advise you to search for air leaks of the whole CIS system. Use a smoke tester as the best tool for that and check all hoses and espacially the air box (for the SCs this is now available again from Porsche, guessing the Turbos as well), like in this video: https://www.youtube.com/watch?v=H_SAcKXJlL0 Despite the water in the fuel the air leaks are the second big enemy against the CIS!

What I e3xperienced as well on mine SC: Check the thermo time switch on the left rear engine case. Those old ones are also mostly defective over the time, Porsche / Bosch release in the meantime a new fully electronic version (with the same oem look as the original one), then you can forget the mechanical wear on this as well. (up to 200bucks...ouch!)
Oh, and also check the temperature sensors as well...putting in the fridge and testing them electrically is the key....mostly they're also damaged after such a long time...

At the end the Turbo will gain it's original power again, less fuel consumption together with a far more better drivability....Good luck!

Thomas

[wcarson]

Thank you all for your expertise and sharing your knowledge. I really appreciate you all- Thank you!!