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NeilH

911SC - Cold Start Valve; Company that Cleans or Supplies in Berkshire (UK) Area?

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Hi All
 

New to the forum and in the middle of trying to sort this current issue at present - I will search through for previous related posts;

 

I'm struggling to find a company in Berkshire, Reading area (UK) to initially test and clean Cold Start Valve = Bosch 0 280 170 409.
I can't test in my car as it uses steel rigid fuel line!
 
I've got the valve out on my bench and with a crude test (adapting length of rubber fuel hose, filling with white spirit, connecting and pressurising to only about 20PSI with a plant sprayer!) I get a jet\flame of fuel and not an atomised mist. Not sure if my test is valid though - hence needing someone to initially test it correctly before moving on by testing Control Pressure etc - but testing so far suggests the warm-up regulator isn't the issue.

 
CONCLUSION\REASONING
Car performs and drives beautifully at ALL other times - during warm-up, it fast idles for 2-3mins perfectly and even extreme (for UK) hot starting is all 100%.
 
It is only ever cold cranking that's the issue - no hint of firing until about 7-8 cranks - if left idle more than a day or two.
Lifting the metering\airflow disc for 7seconds instead (light as a feather initially, then immediately pushed back by control pressure the moment the fuel pump fires - so good and strong pump?) it then fires immediately and beautifully!
 
Hence suspecting Cold Start Valve.
 
Thermo time switch all checks 100% as well as wire continuity and 12VDC to thermo switch on cranking.
 
I'm trying to eliminate if the spray pattern is the issue - assume the jet may just hit the back of the air box and sits in a pool rather drawn in to cylinders? 
 
 
Best regards,
Neil    
 

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Harper motors in Maidenhead used to be able to check and clean CIS injectors, worth a call. Alternatively there used to be a Bosch approved garage in Reading just off the ring road near the hexagon that could do it too....

Chris.

 

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JZM have all the kit to do this too.

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Pretty sure that part is common to all early K jet systems.Fitted to 911, 924.Often referred to as "5th injector" some prudent searching usual places, you should be able to source for under £50.I Would be checking AAV first.Then move on to system pressure test.

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Fitted to 928 as well as 2.7 & 3.0 911, Bosch 0280170409

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On 9/28/2019 at 2:08 PM, Chris T said:

Harper motors in Maidenhead used to be able to check and clean CIS injectors, worth a call. Alternatively there used to be a Bosch approved garage in Reading just off the ring road near the hexagon that could do it too....

Chris.

 

Cheers Chris - both nice and close to me. However, neither of them do cleaning or testing anymore :-(

Still looking....

Best regards,

Neil

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I All

 

thanks, I contacted the companies mentioned - not JZM yet though....

None of them seem to do injector cleaning or testing anymore - they all just go for new!

One company I found via google - name escapes me - suggested the cold start injector only comes in on extreme cold and it's more than likely control pressure. Though all the stuff and datasheets I've read suggests the thermo-time-switch supplies an earth to the cold start injector as low as 20Deg Centigrade - it then just waits for 12V from the starter motor under cranking?

Am trying to check control pressure - despite all other driving being 99% ok - it's just firing when cold cranking...

So still on lookout for injector testing or a new\reconditioned one....

Cheers,

Neil     

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It may be worth giving Neil at BS Motorsport a call.

Reasonably local and if he cannot do it himself then I'm sure he would know where to go.

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I gave my cold start injector a permanent earth to cure a similar issue. Means it squirts hot or cold but so far no issue. 

Would eliminate injector from thermotime switch.

chris

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Hi all.

Thanks for advice. Has moved on a bit but in a bizarre way!

- been advised multiple times to put cold valve back and check control and system pressure 

- have done this and get control pressure of 22psi cold and something like 50 hot (about 7 psi higher than datasheet for warm up reg but I'm not worrying about it) and system pressure = 70psi. All fairly good(?)

- however, when bleeding the gauge off I got half a cup full of beer (dark brown and varnish at bottom when it evaporated)- not fuel! Though car fired up straight away from cold and ran beautifully during the test!

- since emptied tank and check tank filter, surge bowl, main filter and system pressure regulator valve and all absolutely spot and clean with all fuel being spotless! All these lead to the same fuel line where the pressure test is done and came out like beer! 

- logic says the test gauge and pipe were initially full of contaminated fuel - but kit was.brand new!

- at a loss as assume fuel towards the warmup regulator flows constantly and something would be have seriously contaminate the flow at a high rate as everything into it appears clean!

I want to try the below - of anyone can advise for or against it?

- connect all back up with new filters and fresh fuel

- disconnect fuel pipe into warm up regulator and place in a huge container. 

- take all 6 continous injector pipes off and cap them.

- ignition on and lift airflow sensor to make sure all runs through clean.

- do the same for each continous injector one at a time.

- if all clean, connect and run it.

 

Any hazards in doing this - all intended so.I don't flood the engine 

 

Thanks

Neil

 

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Hi all

 

Went through all sorts checks and forums - but recently ordered up second hand cold start injector - not happy about the thin stream pattern

Seems to have 95% sorted the issue - just a sticky fast idle issue that's now resulted since and I'm just looking at sorting

 

 

Thanks all

Neil  

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Auxiliary air valve?

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Well done.

On the dark fuel thing. My first set of gauges did exactly the same thing. The fuel drained off was horrid. Maybe it had some oil or something in it to preserve the mech? 

If the fuel runs clear from the injector lines and from the line going into the WUR I’d be inclined to say don’t worry about it.  Are subsequent bleed offs ok? 

Idle speed; is it fast idling or just slow to return to normal? Or sticking about 1200 revs sometimes?  Check the throttle is properly closing all the time; I had it before where one of the throttle return springs had snapped and sometimes it wasn’t snapping shut properly.  Otherwise, aux air valve and check your mixtures is where I’d start. 

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