Cold start injection problem

[troogly]

It looks like I'm not getting any fuel from the cold start injector on a cold start on my 350i. It looks as if the fuel line to the injector is primed, but that's about it.

I've changed both the cold start injector and the thermotime switch. Any ideas on what could be causing the problem?

Thanks in advance

[paul gotts]

On my flapper 400 the cold start injector was disconnected, and never had any starting probs. Are you getting electrical feed to the injector?

[jmorgan]

Probably no help but my hot wire hase been disconected with no starting problems. Blanking plate over the hole.

[pwd95]

My 350 is having cold start trouble at the moment also. It fires on all cylinders on(I presume) the cold start injector but then missfires very badly for a couple of miles. It's in at the moment having some valves and switches replaced and a general tune-up. I'm having it back today (Friday) so if its better Saturday morning I'll let you know what they did.

[Gerry Attrick]

As with most others, my cold start injector is disconnected. Perhaps the problem is associated with the extra air valve??

[2 sheds]

I can confirm that the cold start injector is better off disconnected as can the heater hoses to the base of the trottle body, these gadgets where intended for Range Rovers used in the Alps.
Tim

[Gerry Attrick]

2 sheds said:

I can confirm that the cold start injector is better off disconnected as can the heater hoses to the base of the trottle body, these gadgets where intended for Range Rovers used in the Alps. Tim

That's interesting. What happens if you leave them connected??

[2 sheds]

Gerry Attrick said:

2 sheds said: I can confirm that the cold start injector is better off disconnected as can the heater hoses to the base of the trottle body, these gadgets where intended for Range Rovers used in the Alps. Tim That's interesting. What happens if you leave them connected??

Basically nothing serious, except increase plenum temp and run more fuel than you need during cold start.

Tim

[rev-erend]

I think someone told me they put in about 2 pints over 2 mins ... loads of unneeded fuel.

I always disconnected mine on my flapper engined wedge !

[dickymint]

Thermotime switch stays open for 12 seconds max (i think).
The 350i has it fitted and works well for cold starting.
The SEAC has it unplugged as it makes no difference if fitted (at cold it runs like a bag of spanners off or on!).

[leorest]

OK, so the general consensus of opinion is that the Cold Start Injector and throttle body heating pipes are unnecessary unless you are dealing with arctic conditions.

Many people have disconnected the CSI, I have not yet but probably will in the future, if I have to fault find in that area.

I am not bothered about the waste of fuel as from what I understand it's only on during cranking and I own a TVR to consume not save

For the sake of interest I was planning on disconnecting the CSI on a frosty morning to see if I can tell the difference (I suspect not!)

The thermotime switch is just a temperature-operated switch so you could link it out and see if it causes the injector to fire when cranking. If it does you could get really flash and run temporary wires to a switch in the cabin! You could even hook up an LED in parallel with the injector to see if it is energised!

Does anyone know what voltage the CSI runs at? Main injectors use 3V, which are dropped by the resistor pack from 12V. I haven't seen a separate power resistor for the CSI so does it run at 12V?

As previously stated these engines seem to start well enough not to need the CSI so it is probably not the problem.

You have probably thought of this but could it be a duff battery or starter causing the poor starting.
Does it turn over quickly? Does jumping it help starting?

If you've paid out for replacement parts which haven't solved the problem then make sure you keep the old parts as they are probably OK and may help you in future fault finding sessions!

PS Has anyone thought of using the CSI for injecting other performance enhancing stuff?
Water injection to reduce pinking and help with today's low octane fuel?
OR… cue maniacal laughter "Nya Ha Ha Ha Harr"… Nitrous Oxide.

Hope this helps. All the best and I hope you get it fixed soon
Leo

[troogly]

Thanks all for such comprehensive replies. Looks like I shouldn't worry about the CSI not functioning. I am having some work done soon on head upgrade etc so that will allow me to have a close look at what's going on.

The car generally starts to fire on the 5th or 6th turn of the key...sometimes a little longer.

It spins around OK so battery and starter look in good shape. Would the Auxiliary Air Valve have any bearing on this (fairly minor, but annoying) problem.

[pwd95]

Got mine back from having a tune up. Still a little rough when cold but clears itself within 1/2 mile. The garage replaced coolant temp sensor, thermotime switch, pressure regulator with overrun valve and adjusted the timing. The extra air valve is the next thing to do, but the car is 80% better.

[Gerry Attrick]

On the topic of the extra air valve, does anyone know how to get this off for cleaning. I thought I might do this over last weekend, but it looks as though there is no easy access or I might need a specially bent and cranked socket on the end of a UJ fitted with a wobble bar

[leorest]

Gerry Attrick said:

On the topic of the extra air valve, does anyone know how to get this off for cleaning. I thought I might do this over last weekend, but it looks as though there is no easy access or I might need a specially bent and cranked socket on the end of a UJ fitted with a wobble bar

I did this a couple of years ago.
I didn't need to buy anything to do the job.
Think all you need is a spanner, Vaseline and a collection of expletives [Vaseline and expletives are optional!]
You'll need to unplug the power connector to get at one of the bolts.
I used carb cleaner but I guess any sort of solvent would work.
Fill it up slosh about and empty out.
Repeat until it comes out clean.
Check operation by looking through it and observing the hole close up as temperature increases.
IIRC used hot water but you could rest it on a metal tray on the stove so long as you're careful not to burn your pinkies!
Leo

[Gerry Attrick]

Thanks for the information. I'll give it a go this weekend.