News:

www.W116.org - By the people, for the people!

Main Menu

Cold start valve voltage

Started by revilla, 31 October 2014, 05:21 PM

revilla

Hello everybody,

Does anyone know how many volts should I at CSV connector when crancking the engine at 15 deg C.  I read some where (can't remember where) that it suppose to be 3 V. 

Having cold start issues and I suspect defective thermo/time SW. 

Any help/advice is welcome.

Thanks in advance.

Robert

djenka018

K-Jet CSV has either 12V (battery voltage) or zilch.

It is time controlled valve.
Thermo-time switch will decide how long injector will be running to compensate for condensation on cold manifold walls.

COld start is often affected by vac leaks causing excessively lean mixture.
This can be confirmed by cranking the car with full throttle applied. If it helps, major vac leaks are present
Vitamin C for SL... the SLC

revilla

Thanks dejanka018,

In fact I checked and I have voltage at the CSV connector when I placed the thermo SW in the freezer for a while and crank the engine. However the valve is not spraying fuel even when I bridge the thermo SW connector.  It doesn't look like the CSV can be disassemble for cleaning/maintenance.  What is strange is that when I put 12V directly on the valve it sounds like if the solenoid is moving because it spits out fuel.  Ran out of time today but I need to check deeper into this issue.

Still, advice is welcome.

Thanks again

Robert

daantjie

You can check valve for function, disconnect coil wire and unbolt the valve whilst keeping it connected to fuel feed.
Point valve into container and crank engine. Csv should spray while starter is turning over.
Daniel
1977 450 SEL 6.9 - Astralsilber

revilla

Thanks Daniel.

I did exactly that and nothing comes out it (I thought maybe because temperature was 16 C around here this morning, so thermo SW was open).  So I proceeded to disconnect the plug from the thermo SW and bridge the two terminals G and W (simulating SW closed).  Cranked and still nothing came out of it.  Checked for voltage at  CSV connector while cranking engine and saw 10.xx V.  Re-plugged, cranked and still no sign of fuel came out of it.  Disconnected CSV from fuel line and cranked (lots of fuel came into container from metal pipe).  Reconnected CSV and cranked but nothing.  When I put 12V directly into the 2 terminals of the valve the selenoid moves (makes click noise).

What might be happening?

Help welcome.

Thanks

Robert

daantjie

Might be worthwhile to replace the CSV. Not too pricey, and if it is original to the car, probably good to replace it anyway if you plan on keeping the car for a while.
Daniel
1977 450 SEL 6.9 - Astralsilber

revilla

Thanks Daniel.  You know the part number for the CSV?

thanks


Robert


revilla

I discovered something interesting that could explain the cold start issues.

When I measure voltage in the CSV connector while craking the engine I see no power.  However, if I put the gearbox in R reverse (or anything different than P and N) and turn the ignition I could hear the pump running and I see 12V at the CSV connector.  I think the pump and the CSV are in same circuit (parallel).  So when pump is powered so is the CSV.  My engine runs well after it starts (so the pump is working fine).  What's strange is the CSV receives voltage when pump is ran artificially but it sees no voltage when actually cranking the engine (gearbox in P or N).  This could explain that the CSV doesn't spray when needed (cold start).

Is the situation above normal?  If not, what can be causing this?  Relay?

Your help is appreciated. Thanks.

Robert

daantjie

Part# on my Bosch CSV is 0280170403
Daniel
1977 450 SEL 6.9 - Astralsilber

revilla

Thanks again Daniel.

I tested again the CSV.  She sprays a healthy amount of atomized fuel.  That tells me she in working condition.  But she only sprays when I put the gearbox in R, D, S or L and pass the ignition SW to position 3 (start).  When I do that I hear the pump buzzing. But CSV would not spray (0 volts at connector) when I crank the engine (gearbox in P or N).  Thermo-time SW circuit is closed in all tests done.  Once engine starts (takes a few cranking cycles) all is nice and smooth, so pump is working OK.

Where could the mystery be?  :)

I appreciate any comments.


daantjie

OK here is one more test, not sure of you have tried it:

Remove plug from CSV and bridge contacts with test lamp or voltmeter.  Engine must be cold.
Remove coil wire, and have assistant crank starter for 10 seconds.  Depending on coolant temp, lamp should glow or voltmeter register for a period of 3 - 10 seconds, and then cease to register.  If circuit is not broken after 10 sec, your thermo time switch is buggered and needs to be replaced.
If the light does not come on or no movement on voltmeter at all, double check that you are in fact getting voltage to the switch.

Not sure if this will help your case, but might be worth a shot.
Daniel
1977 450 SEL 6.9 - Astralsilber

djenka018

Quote from: revilla on 02 November 2014, 05:54 AM
I discovered something interesting that could explain the cold start issues.

When I measure voltage in the CSV connector while craking the engine I see no power.  However, if I put the gearbox in R reverse (or anything different than P and N) and turn the ignition I could hear the pump running and I see 12V at the CSV connector.  I think the pump and the CSV are in same circuit (parallel).  So when pump is powered so is the CSV.  My engine runs well after it starts (so the pump is working fine).  What's strange is the CSV receives voltage when pump is ran artificially but it sees no voltage when actually cranking the engine (gearbox in P or N).  This could explain that the CSV doesn't spray when needed (cold start).

Is the situation above normal?  If not, what can be causing this?  Relay?

Your help is appreciated. Thanks.

Robert

It appears like normal except...
if you try to crank whilst starter is disabled (like your test in D or R), you are energising the thermo-time switch and once it times-out... no more

as far as what I remember, at 15*C it runs only for a few seconds and after that it need a bit of time before it will work again. This is to prevent flooding that could happen if CSV was running at every unsuccessful engine crank.

Thermo time switch is powered when engine is running/cranking but no power will be fed to CSV after it times-out

Have you tried the full throttle whilst starting the engine?
Vitamin C for SL... the SLC

revilla

Hello dejanka018,

Thanks for your reply.

I have tested the circuit of the TT SW and it's working fine.  I placed it in -5C and the circuit closes (as expected).  At about 15C the circuits opens as per spec.  Because I tested the CSV when ambient temp was around 16C, and in order to remove the TT SW out of the equation (as it tested fine) I placed a jumper in the plug of the TT SW.  That artificially simulates cold temp, closes the circuit and provides voltage to the CSV even at 16C.  I did that only temporarily in order to test the CSV. 

It turned out that the CSV is spraying fuel just fine into a container when ignition SW is turned to start (pos 3) and gearbox lever placed in R, D, L or S (12V observed at CSV connector).   Clearly the engine is not cranking because the gearbox isnt on P or N position, but I can hear the pump buzzing as long as the ignition is kept turned into pos 3.  Strangely, when gearbox is placed back to P or N, the engine now cranks (as expected) but the CSV sees no voltage thus it doesn't spray.  That tells me the CSV is doing what it suppose (opening and spraying fuel when 12V are present in its connector).

The wiring must have been fiddled with in the past.  Question is what wires and where to start looking for root causes.

Suggestions?

Thanks forum.

Robert

djenka018

#13
I think you may have TTSW cyclic function mess with your test.

1. TTSW will provide power to CSV as per temperature/time table
2. TTSW is energised ONLY whilst the key is in "Start" position (cranking phase)
3. #2 means that after you stop cranking, CSV stops immediately, irrespective of coolant temperature.
4. After TTSW did its time cycle, it takes long time before it will do another.

With some electrical knowledge, looking at the diagramme makes things easier to comprehend

As per your test,it seems to me that there is nothing wrong with the wiring of TTSW/CSV but you get confused because TTSW will time-out and it will not work again unless there was a long pause between the cranks.

Put the TTSW in a bucket of ice and water, gear shifter in R, D, S or L and turn and hold the key in "Start" position.
CSV wires should have power for 30-45 seconds. Run the test again and it should either not provide power to CSV or it should be noticeably shorter.
This concludes TTSW functionality.
Vitamin C for SL... the SLC

revilla

Hello dejanka018,

Test done.  I completed 20 cycles of the following:

- Lever in R, start pos 3, 12V observed at CSV connector, pump buzzing, CSV sprays fuel into container
- Lever in P, start pos 3, engine cranks, 0V observed at CSV connector, CSV doesn't spray fuel into container
- Lever in D, start pos 3, 12V observed at CSV connector, pump buzzing, CSV sprays fuel into container
- Lever in N, start pos 3, engine cranks, 0V observed at CSV connector, CSV doesn't spray fuel into container   

These 20 cycles were completed in a period of 2 minutes.  CSV always sprayed in R and D and never in P and N.

Any idea why CSV sees 12V only while in R or D and not while in P or N?   It should also see 12V while in P or N therefore spraying fuel to aid cold start.

Thanks again.  Advice is appreciated. :)

Robert