CIS Troubleshooting for Dummies

[pmax]

Adjustable WUR - WCP and CCP

Building adjustable WUR need starting point


Adjusting WUR using washers

Warmup Regulator Strange Issue Solved

I also found some copper alloy springy door draft stop which was 0.0043" thick, and made a washer out of it to try to get the CP more into range. I didn't want to do the tapping the plug bit, as that seems a bit iffy, and a friend with actual Bosch training said you can only do that a couple of times before the plug gets loose.

WUR servicing links

Warm Up Regulator Dealer

Pop-off Valve aka toilet seat thread

To Pop Off or not to Pop Off?

Smoke machine

CIS advice needed...experts please help

[Charles Freeborn]

Does anyone know the correct impedance readings (cold and hot) for the 0 438 140 008 WUR?
I'm getting a cold reading of 56 ohms.
Thanks.

[timmy2]

Originally Posted by Charles Freeborn

Does anyone know the correct impedance readings (cold and hot) for the 0 438 140 008 WUR?
I'm getting a cold reading of 56 ohms.
Thanks.

PM Tony, boyt911sc, I’ll bet he knows.

[Charles Freeborn]

Originally Posted by timmy2

PM Tony, boyt911sc, I’ll bet he knows.

will do. thanks.

[boyt911sc]

Originally Posted by Charles Freeborn

Does anyone know the correct impedance readings (cold and hot) for the 0 438 140 008 WUR?
I'm getting a cold reading of 56 ohms.
Thanks.

Charles,

I don’t know the electrical impedance of 0-438-140-008, but the electrical resistance is 56 Ohms (+/-)1. The electrical heater in your WUR is good.

Tony

[Charles Freeborn]

Originally Posted by boyt911sc

Charles,

I don’t know the electrical impedance of 0-438-140-008, but the electrical resistance is 56 Ohms (+/-)1. The electrical heater in your WUR is good.

Tony

Excellent. Many thanks.

[Gretz]

Getting prepared to do the pressure test within the next week. Reviewing the directions, it looks like I need to run the fuel pump during the cold and warm pressure tests. Won’t this cause a bunch of fuel to be injected into the cylinders? What’s the best way to clear out that accumulated fuel? Just start it up?

“The next test is the COLD CONTROL PRESSURE test. With the valve on the fuel pressure gauge in the OPEN position (and again with the ignition key in the ON position and the fuel pump running), record the fuel pressure and the ambient temp.”

[Vereeken]

No.
Unless.
a The fuel plunger is stuck in the FD in the upward position
b the air sensor plate sits too high in the throat of the FD
c the co screw is turned so far to the right that it dribbles fuel even when a and b are ok.

Only a can really bring alot of fuel in the chambers in a short time.

You will hear the injectors squeel if a b or c are the case.

Simply stop the FP and correct a b or c before continuing.

[Gretz]

Ah, I get it. I had a fundamental misunderstanding of the fuel system. So the injectors don’t function when the fuel pump is simply ON, the sensor plate has to be lifted as well? That makes total sense and I don’t know why I didn’t realize that sooner. Thanks.

[pmax]

Originally Posted by Gretz

Getting prepared to do the pressure test within the next week. Reviewing the directions, it looks like I need to run the fuel pump during the cold and warm pressure tests. Won’t this cause a bunch of fuel to be injected into the cylinders? What’s the best way to clear out that accumulated fuel? Just start it up?

“The next test is the COLD CONTROL PRESSURE test. With the valve on the fuel pressure gauge in the OPEN position (and again with the ignition key in the ON position and the fuel pump running), record the fuel pressure and the ambient temp.”

Do post the results here when you get to the bottom of your troubleshooting. It will add to the knowledge base of this valuable technical forum.

Links to the relevant threads.

090 WUR resistance measurements WUR wiring connector

Fuel pressure findings CIS Experts Please Help - Fuel Pressure Test Results

[pmax]

Return line checks

Occasional CIS problem

[boyt911sc]

Tim,

Maybe you could request from the moderator/s some help to get access to edit some of your old postings. I have not read this thread for a long time and had a chance to browse it yesterday. Just the first page alone, I found several critical misinformation or misconceptions that you have posted.

You are doing a great job updating the thread. I know you are a voracious reader and search a lot in the Internet. But you can not just use data or information you found in the Internet without further verification. People reading your posts will have a tendency to use and believe it is a fact. We all make mistakes and I commit a lot too.

When you mentioned this idea “CIS for dummies” to me many years ago, I was all in favor of it and even today. If you are not allowed to edit the old posts, maybe you should make an updated version with the “correct or edited” version. Just my two-cents.

Tony

[Larmo63]

I recently acquired a '78 SC with CIS and after reading this thread, my head is spinning. I wish someone would post simple pictures of each component. Maybe I should buy a book, but I don't know where to start. I know Weber carbs and low pressure systems. My car runs super good, but I pray it never breaks or starts running poorly. What is a "FD?"

I couldn't tell you the different between a WUR and/or an AAR if you gave me a billion dollars cash.

(I was encouraged to ask the dumb questions.)

Are you guys all automotive engineers with degrees from MIT?

[boyt911sc]

Lawrence,

These are the most common acronyms you will encounter in the CIS discussions in this forum. I copied these acronyms from an old post and pasted here for your perusal. Get some reference book or manual about the K-Jetronic (CIS). There is booklet I highly recommend issued by Bosch (Technical Instruction) and printed by Bentley.

This is the ISBN: 0-8376-0468-0.

Some CIS acronyms:

AAR (auxiliary air valve)
AAV (auxiliary air valve)
AFS (air flow sensor/switch)
CSV (cold start valve)
DV (deceleration valve)
FD (fuel distributor)
FP (fuel pump)
FV (frequency valve)
CCP (cold control pressure)
RP (residual pressure)
SP (system pressure)
TTS thermotime switch)
TV (thermovalve)
WCP (warm control pressure)
WUR (warm up regulator).
Etc.

Tony

[Rawknees'Turbo]

Originally Posted by Larmo63

I recently acquired a '78 SC with CIS and after reading this thread, my head is spinning. I wish someone would post simple pictures of each component. Maybe I should buy a book, but I don't know where to start. I know Weber carbs and low pressure systems. My car runs super good, but I pray it never breaks or starts running poorly. What is a "FD?"

I couldn't tell you the different between a WUR and/or an AAR if you gave me a billion dollars cash.

(I was encouraged to ask the dumb questions.)

Are you guys all automotive engineers with degrees from MIT?

This old school CIS/K-Jet training video, along with Tony's acronym list above, will go a long way toward helping you understand this dinosaur-tech injection system.

[Larmo63]

Thank you, I'll buy the book and keep the prayers up for good measure.

[Spokes7]

I followed the CIS test and ended up with following results: interpretation?

Test @6.5C

1982 SC ROW

WUR 32ohms

System Pressure 4.5 bar

Cold Control Pressure 1 bar (note while fuel pump running it was 0, after I turned off the fuel pump I recorded 1 bar which held for 10 seconds or so)

Warm Control Pressure 2.3 bar after 5 minutes

Residual Pressure Test: pressure just fell away after 30 seconds to 0

Thoughts?

[SkiVT]

I would start a new troubleshooting thread and not bury your data in this thread.

[boyt911sc]

Originally Posted by Spokes7

I followed the CIS test and ended up with following results: interpretation?

Test @6.5C

1982 SC ROW

WUR 32ohms

System Pressure 4.5 bar

Cold Control Pressure 1 bar (note while fuel pump running it was 0, after I turned off the fuel pump I recorded 1 bar which held for 10 seconds or so)

Warm Control Pressure 2.3 bar after 5 minutes

Residual Pressure Test: pressure just fell away after 30 seconds to 0

Thoughts?

Spokes7,

As suggested earlier, it would be better to start a different thread than have it here. Anyway, you need to fix your residual fuel pressure first. There are several culprits which I will tell you later. And your WUR is out of spec.

Re-post this to the Technical Forum for more and better responses.

Tony

[mike sampsel]

The Bentley book "Bosch Fuel Injection & Engine Management" (page 17 or chapter 6) says to disconnect electrical connections for the Control Pressure Regulator CPR (AKA the WUR) and the Auxiliary-Air device. I assume the air device is the AAR. I find no referral to disconnect the electric connection to the AAR in this fine thread.

Is the Disconnect of the AAR wires needed to run fuel pressure tests?