karl ruiter

I have also been bringing up a CIS car that had been sitting for a long time, and have also not yet gotten totally satisfactory results, mostly in terms of irregular idle,and poor running when cold. Power is good and BWAA is present and accounted for, and it runs well enough to drive on a daily basis, but not the way it should. I have tinkered a lot and been through every part on the system. I'm going to post the details of what I have done here, not (I hope) as a hyjack, but because I have probably already done the first 4 or 5 things that you may be thinking about doing and am pretty much right where you are.

Here is what I have already done:
1) rebuilt FD. I went totally through it, but the only problem I saw was a blocked inlet screen. I got lucky and the rebuild seemed to work the first time.
2) replaced outside fuel pump with walbro, replaced in tank pump with screen. Fuel delivery is in spec.
3) replaced WUR with ebay unit. Control pressures are close, but not spot on.
4) replaced injectors with new units from Roger.
5) check cold start air valve operation.

Here is where I think I need to be headed next:
1) check carefully for vacume leaks. intake manifold gaskets and hoses are all new, but I am thinking of the seal between the FD and the intake manifold and the seal on the throttle body. Can I spray strating fluid at suspect leak areas an listen for idle speed changes? Should I use carb cleaner instead?
2) adjust idle mixture with an acutal gauge on the exhaust. To date adjustment has been by ear.
3) try to adjust WUR pressures spot on.
4) remove deceleration valve. I kinda suspect it is leaking sometimes. On my last motor it did.
5) what is the deal with the fuel accumulator? I know where it is and roughly what it does, but don't really understand what whould happen if it was bad.

James Bailey

" what is the deal with the fuel accumulator? I know where it is and roughly what it does, but don't really understand what whould happen if it was bad. " It holds system pressure for hot restarts......where with no 9th injector spary to light the fire you may not have enough air flow to move the disc in the intake to cause the fuel dist to inject any fuel...........

jpitman2

IIRC the WUR pressure specs are not that tight, at least a couple of psi wide, so we would need to know what your actual figures are. The WSM shows the specs for each different version (based on last 3 digits of Bosch no- my 83 Euro is 086), so you need to look at those suffix nos. Mine tended to stall a bit when cold, but fixing the AAV fixed that issue, so it may be that simple. I suspect there are some different FD models in use - mine has a multi pin socket on the inner side with a cable connected - was originally disconnected when I got the car, reconnecting fixed a hot start issue for me. A rough idle would indicate something wrong, and an air leak would be high on my list. Replaced my accumulator a few years ago when I worked on the tank/pump/hoses area.
I would spray almost anything lightly flammable over all hoses and joints, pausing between sprays to listen for a change.
hERE IS some Bosch data that may help a little:
928 06.77 - 07.82
[ S1 ] V8 4.5L
Injector Valve 0 437 502 012
Fuel Pump 0 580 254 984 > 6/80
0 580 254 053 7/80 >
Air Flow/Mass Sensor 0 438 120 049 > 7/81
0 438 120 142 8/81 >
Fuel Filter F0179
Thermo-Time Switch 0 280 130 214
Fuel Distributor 0 438 100 027
Cold Start Valve 0 280 170 409
Fuel Accumulator 0 438 170 013 > 3/78
0 438 170 023 4/78-8/78
0 438 170 026 9/78 >
Warm Up Regulator 0 438 140 036 > 6/80
0 438 140 087 7/80 > cont

928 S 09.82 - 07.83 M28.11
[ S1 ] V8 4.7L
K-Jetronic
Injector Valve 0 437 502 012
Fuel Pump 0 580 254 053
Air Flow/Mass Sensor 0 438 120 142
Fuel Filter F0179
Thermo-Time Switch 0 280 130 214
Fuel Distributor 0 438 100 027
Cold Start Valve 0 280 170 409
Fuel Accumulator 0 438 170 026
Warm Up Regulator 0 438 140 086
Auxiliary Air Valve 0 280 140 204
Pressure Damper 0 280 161 007
I did try to line things up, but committing the edit removes extraneous spaces.
The FD and a couple of other things stayed the same, other parts had several updates. I have a pdf called 'efi_vehicleapplications' if anybody wants a copy. Got it off the web several years ago, lists all Bosch injection parts by application. It shows that NOBODY else used the same FD or WUR part nos.
I dont know where my pressure damper is.....
jp 83 Euro S AT 53k

karl ruiter

Just to close the loop on this. Found no air leaks but removing the deceleration valve worked wonders on my idle stabilty and consistency. I used a couple of $0.25 1/2 inch copper pipe end caps from home depot, inserted into the hoses that used to go to the d.v.

Mark in Japan

This is a sensational thread, gents!

Is there a simple English walk through of each of the components of the CIS, where they are, and what they do, anywhere?

EG

FD - (Fuel Distributor)

WUR - ('Warm Up Regulator")

You probably have them all there in the part nos list

Cheers!

MIJ

Mark in Japan

Is "Control Pressure Regulator" = "Warm Up Regulator (WUR)" ??

karl ruiter

Yes, the WUR regulates the control pressure.

Simple walk through:
The pump by the tank makes high pressure fuel, then it goes through the filter and accumulator to remove the crud and whatever it is the accumulator does. Then the fuel goes to the Fuel Distributor where it is regulated down the the system pressure. Also, a little bit of fuel goes through a tiny hole and out to the WUR. The WUR regulates that little bit of fuel to make the control pressure which varies based on temperature and vacume. The fuel coming out the other side of the WUR goes back to the tank.

Air comes in the air filter and past the control flap, pushing the control flap open. The control flap is connected to the plunger in the fuel distributor and as it moves it exposes more or less of these slits that allow fuel to go out to the injectors. The control pressure is the spring that pushes on the other side of the control plunger. So when the control pressure is high it takes more force (moving air) to push the control flap (and thus the plunger) a certain amount. The fuel going through the slits is at system pressure, but the fuel pressing at the top of the plunger is at control pressure.

Lots can go wrong, but as Jim has said, control pressure is key. There are three restrictive elements that go into regulating the system pressure down to control pressure:
1) There is a small (0.020?) hole is the steel gasket in the middle of the fuel dist that the fuel must go through.
2) There is an inlet screen at the entry to the WUR
3) There is a diaphragm in the WUR.
The fuel goes through this in order and then back to the tank. Control pressure is tee'd off between 1 and 2. #2 plays a huge role in setting the cold control presssure. #3 kicks in when the car is warm, raising the control pressure which leans out the mixture.

Tampa 928s

Has anyone opened the Distruibter to check and or clean the meating hole with good results? How about the screens/ rubber diaphram on the Wur can they be purchased as a seperate part?

80 Euro: will be checking the pressure again after a few more miles: The car runs realy good but not 100% so before I start repacing parts my paln of attack is this:

I have put about 50-miles on the car with Sea-Foam in it after replacing the Check-valve and accumulator; the car sat for 10-Years.

When cold it starts right up but has to wait about 30-seconds due to when giving it gas it stumbles. It runs very well but notice a little skip at idle but not real pronounced. All the Electrical is replaced.

Some times when hot it will start then stall then takes 15-Seconds of cranking. Before I added the cleaner number 2-Plug was black, I am assuming the injector maybe leaking causing some of these issues. I checked the Fuel pressure and it is holding at hot but remains in the 70’s all the time.
(blockage or diaphram)

So I have a couple of questions:

Should I put 200 or so miles on it stop and go to heat soak it and see what happens?

Pull the injectors and have some one clean them?

Replace the Wur, or just the screen or flapper?

Replace any other Filter/Screens on the system?
"If avaliable"

Any feed back would be helpful.



Thanks

karl ruiter

I took my F.D. all apart and cleaned it all out. There is a procedure on here somewhere for doing this and I followed it closely. I found nothing wrong with mine, other than there is a secret screen in the inlet fitting which was clogged. If you were thinking of rebuilding your FD I would suggest just checking the secret screen and perhaps removing the FD and checking out the motion of the control plunger. The plunger can removed and cleaned without disassembling the FD. It can come out the bottom. Spraying some carb cleaner on it an making sure it moves freely is not a big task and not a bad idea. Lots of times folks have trouble with the FDs after opening them up, so it is a last resort kind of deal.
No internal parts for either the FD or the WUR can be purchased as far as I know, although most of the O rings are standard sizes that can be purcahsed at a hardware store. The diaphragm in the WUR is stainless, not rubber and it can be taken apart and cleaned, and with some trial and error you can modify how hard it kicks in. I don't think anyone sells the screen in the WUR, although this kind of material is available (e.g. mcmaster.com) and I think it would be pretty easy to devise a replacement if you had a bunch of time to fiddle with it.
I think you can have the injectors cleaned, but Roger offers MB replacement units that work great for such a great price that it made sense to me just to go new.
My suggestion (for Tampa) would be put in some fuel system cleaner and run 2 to 5 tanks fulls through the car before you do much of anything. Next, check your control pressures and do nothing else until you have them in spec.

Tampa 928s

I am with you Karl, after 10-Years of sitting and observing it getting better and better a drive and wait appoach maybe the best course of action.