L - Jetronic Cold start injector not working

[VeeSix]

I got the V6 2.5 litre 12 valve in my 75 project running yesterday and it is running as sweet as you could imagine the beautiful V6s can, i have gone over the entire L - Jetronic system cleaning up all connections and replacing end connections with new but the only thing that will not work is the COLD START INJECTOR and it has stumped me a bit
When the engine is cold it cranks over fine but will not fire up, after 2 to 3 minutes of cranking she fires up slowly then in about 20 seconds starts running excellent and i have no further problems from there on turning off and restarting, it is only when she goes dead cold overnight and i try to start her the next morning it takes about 3 minutes of cranking to get her going
I have swapped over a couple of THERMO TIME SWITCHS from other running engines, no good, i have swapped over a few COLD START INJECTORS, no good, i have left the COLD START INJECTOR off and in a cup and nothing gets sprayed thru when cold cranking, i have also checked the fuel pump and fuel delivery several times and there is no problems there either, for some reason the COLD START INJECTOR is not getting the signal to operate
Any ideas?
Is there anything else that influences the operation of the COLD START INJECTOR?   
 

[Typhoon90]

The CSI on my 90 doesn't work either. I've owned lots of cars with CSI's that don't work, whether they were Bosch L jet or something else. I theorise they gum up because they don';t get used much in the typical Australian conditions.
Try cranking your engine with abotu 1/4 throttle, it commands the injection system to add more fuel through the regular injectors.

Regards, Andrew.

[Jekyll and Hyde]

Try cranking your engine with abotu 1/4 throttle, it commands the injection system to add more fuel through the regular injectors.

NOT a good idea.  The Alfa V6s have a habit of backfiring and blowing the plenum off when you do that...  Can make a nice dent in the bonnet. 

[dehne]

i have the same prob on my 90 but all i did was pull the clip off and i have not had a prob with it since and it still cranks up in 3deg mornings

[VeeSix]

Anyone have any ideas about the reasoning behind mine not working, if the THERMO TIME SWITCH is below 30 deg cel the CSI should fire
As mentioned i have swapped THERMO TIME SWITCHES and COLD START INJECTORS from running vehicles and still no go
Why would the ECU be not sending out a command to the CSI to fire?

[wankski]

now my memory is taxed of the old l-jet system but IIRC there was a manual CSI modification that can be done because of this problem...

or install a megasquirt ECU and eliminate the afm and CSI altogether...

great mod.

[VeeSix]

Hello Paul
The year is 1985 and off memory the ECU number ends in 117
It is a LEADED engine with the electrical two clip connection distributor

Interstingly what is the manual CSI modification?

[Typhoon90]

Try cranking your engine with abotu 1/4 throttle, it commands the injection system to add more fuel through the regular injectors.

NOT a good idea.  The Alfa V6s have a habit of backfiring and blowing the plenum off when you do that...  Can make a nice dent in the bonnet.  

I've owned several L jet vehicles and NEVER had that problem. I've never understood how using the six injectors close to the intake valves is more likely to cause an intake manifold explosion than a single cold start injector hosing the plenum down with fuel, I've also never blown an intake hose off an L jet car either. maybe I'm just lucky?

Regards, Andrew.

[Jekyll and Hyde]

Try cranking your engine with abotu 1/4 throttle, it commands the injection system to add more fuel through the regular injectors.

NOT a good idea.  The Alfa V6s have a habit of backfiring and blowing the plenum off when you do that...  Can make a nice dent in the bonnet.  

I've owned several L jet vehicles and NEVER had that problem. I've never understood how using the six injectors close to the intake valves is more likely to cause an intake manifold explosion than a single cold start injector hosing the plenum down with fuel, I've also never blown an intake hose off an L jet car either. maybe I'm just lucky?

Regards, Andrew.

And how many of those L-Jet vehicles have been Alfa V6s?  My L-jet Range Rover never had that problem either, then again its a COMPLETELY DIFFERENT ENGINE.

Not that the L-jet is even relevant, I have seen the transaxle Alfa V6s backfire and pop the plenum on: L-jet with the CSI working, L-jet without the CSI working, Autronic with no CSI, Gotech, Motec.  It's just one of those things, the design of the Alfa plenum on the V6 seems to encourage a backfire if the throttle is cracked during cranking, and since the plenum is only held on by hose clamps it doesn't take much to blow it off the top of the motor.  Oddly enough, some Alfas will never do it, others are chronically prone to it.

[Typhoon90]

I wonder if it has something to do with valve overlap? Obviously the way the plenum is held oto the runners on the V6 cause it to depart the engine, but why the backfire in the first place? Cold start backfires are usually indicative of burnt valves or valves that aren't closing properly, or ignition timing that's way out.
Perhaps the CSI can be rigged with a switch to temporarily "steal" some of another injectors pulse, so you can flick a switch on the dash for cold start enrichment, when you want it?

Regards, Andrew.

[VeeSix]

Hello Paul, thankyou very much for your reply, i had the brake master cylinder go on me so had to replace that, back to the cold start problem today, when you say pin number 4, are you meaning - looking at the ECU from the side with the code sticker BOSCH xxxxx117 and the top row of connectors starting from the left?

[VeeSix]

Please someone from this forum reach thru and kick me where it hurts! I almost rang you Paul! A couple of days ago when i had a spare afternoon i said to myself today i am going to sort this Cold Start problem once and for all! The main problem was a previous owner had swapped one of the end connection heads that clips on to the thermostat sensors with a different colour newer type of one, why? i do not know, maybe the other head was corroded or similar, anyway i opened up the bonnet of one of my 90s so i could double check wires etc etc it was then i noticed the head connection colourings, i thought to myself you must be kidding, i went back to my current 75 project swapped the connections over 1 to the other, dead cold engine cranked her and she fired straight away!!!!! I have tested her over the last couple of days, no problems always starts first go now cold or hot!
I have severly learnt the time and time again lesson ----> NEVER OVERLOOK THE OBVIOUS!!!!!
But i tell you what i have learnt basically the whole L-Jetronic system thru this process which i guess will let me diagnos quicker in the future!