D-Jet Cold Start Problem

[Aussiecsi]

Hi All, my car has recently developed an issue when engine is cold . When it eventually gets going ( after numerous engine stalls , very rough idle etc ) it seems to be fine once it eventually gets to running temperature and fires up straight away on restart . So, this is what has been done so far to try and troubleshoot :-

- There is power to cold start relay /timing delay switch plug .
- The cold start relay has been tested in another d-jet E9 and works fine .
- The cold start valve has been "hot wired" direct to the battery to test if functional... it "fires" .

The upshot is that something seems to be going wrong between the relay and the cold start valve .ie no current is reaching the valve . My gut feel is there is a ground/earth issue but this stuff is not in my skill set. Hope someone can assist . Cheers, Simon

 

[bill]

Is the air-slide working? If it is stuck closed, you will have cold-start problems as you describe. It should be open when cold, closed when hot. Test it in a pot of water.

 

[Aussiecsi]

...it's open Bill ( and closes as it should when hot ). As I suggested , there seems to be some electrical issue between the cold start relay and the cold start valve. Any other thoughts ?

 

[sfdon]

Pin out for ohms connector 1 and 13 at the ecu
And pin 23 and battery ground

 

[Aussiecsi]

Pin out for ohms connector 1 and 13 at the ecu
And pin 23 and battery ground

Sorry Don, not sure what you are actually directing me to do /try

 

[bill]

Not to hijack SFDon....he is saying check the ECU (brain) which has some control over the cold-start valve. In my experience ECUs were never the problem (learned that the hard way with Saabs); wiring, connections, everything else is more likely the problem. Make sure the wiring to the temp sensors, and the sensors, are OK (sensors at the bottom of the airslide mounting bracket.) Good luck....have a beer.

 

[Bwana]

^^^^Yes, agree. The D-Jet brain is just a step above the old Heath Kit stuff so it's incredibly reliable. Although I did replace one that had had a lot of cracked solder joints and it seemed to make a big difference in the overall response.

 

[coupedownunder]

Simon , I have a spare ECU from my e3 wreck, in the unlikely case it is a faulty ECU

 

[Aussiecsi]

Simon , I have a spare ECU from my e3 wreck, in the unlikely case it is a faulty ECU

Thanks for the kind offer Mark but since confirmed it's not the ECU ( substituted a known working one ) . I'm inclined to agree with Bill that it's probably a wiring /connection problem so will plod on ...I also took up his suggestion of having a beer which seemed to help . Cheers, Simon

 

[bill]

Heath Kit.... I still use a pre-amp I built 34 years ago...

 

[Stevehose]

my Heath Kit ignition tuning oscilliscope

 

[mulberryworks]

my Heath Kit ignition tuning oscilliscope

Oh man. Serious Want!

 

[sfdon]

Guys?

Pin out for ohms connector 1 and 13 at the ecu
And pin 23 and battery ground

At the ecu
The connectors

Not the ecu

Looking for shorts and opens.

 

[Aussiecsi]

Well, just over 12 months since the cold start issue started and now another query.....when the key is turned' on" , the cold start valve starts spraying ( before cranking )...therefore , the CSV will continue to spray so long as the key is "on" ; presumably this is not meant to happen ??...I believe it will continues to spray well after the engine fires unless it's disconnected ( which I have now done to prevent possible flooding) . Have tried changing relays and makes no difference . Timing Delay Switch is relatively new too . Thoughts ? Thanks, Simon

 

[sfdon]

https://www.ecstuning.com/b-genuine-bmw-parts/connector/11111250587/

 

[sfdon]

Directly below #6 intake Port.
Check for clogged.

 

[sfdon]

Did you recently change your starter?

Appears pin 86 is staying hot after you quit cranking.

Test for battery + at run at pin 86

Should be hot during crank only.