xrmalin

Am I right in thinking it's the brown thermo time switch down the back of the inlet that activates the cold start valve ?

My newest rs turbo is a bitch to start from cold, cranking over for ages then when it does finally start it runs rough for the first few minutes until it's warmed up slightly then it runs perfect, once I've got it warmed up slightly I can switch it off & she'll fire straight up without any issues so I don't think the cold start valve is doing its job.

Cheers Mark.

millybuzzin

If I were you I would disconnect the cold start valve and then try it in the morning mine did this and now it starts first time )

Adder

I think this will confuse the issue but , I have always believed that back in the day dealership used to disconnect the blue cold start valve in to improve starting when the vehicle was hot and not the other other way around. I suppose you've got nothing to lose but I'm shaw some one here will remember.


Adder

rsmog33

Hi. I had exact same issues with my S2. Proper annoying. I replaced all the sensors ( coolant temp , thermo time switch and cold start valve ). Then had the whole fuel system overhauled. New injectors , fuel pump everything. Even took the metering unit off and had it set up on a test rig at KME injection. Nothing worked!!!!!


Then we blocked off the pipe from the metering unit to the oil separator and bang started first time everytime just with the key. Cold start problems can be confused with air leaks in the system. I think mine is on the brake servo. Was an expensive trial and error but at least I renewed a lot of old bits.


However I have stuck with it. Car runs great hot or cold. Quick test is to take the air box off and while someone is cranking the car, push down on the plate and see if she fires up. If so then you have an air leak possibly somewhere. KE jet is so sensitive and a slight air leak will mean not enough vacuum to force the plate down and fuel to the injectors or to the cold start valve if the engine is cold.


Hope this helps

xrmalin

Well I unplugged the cold start valve & it was exactly the same
So I've swapped the two coolant sensors for ones I've got stashed away so I'll try it in the morning & see what it's like if that don't solve it I'll do as you've suggested rsmog & go over the breather system & check all over for air leaks.

Cheers Mark.

Chopshop85

iTrader: (4)

Surely if it's not starting well when cold, that could point to the cold start not working. So I'm not sure what uplugging it would achieve.

Mine used to be a pain on cold mornings. Took the cold start injector out, blocked the hole in the inlet and tried starting the car. The fuel kind of just piddled out at an angle. Got the injector cleaned and its started on the button since.

xrmalin

Well I did think that chopshop but it was suggested so for what it took to unplug it I thought it was worth a try.

I'll have a go at your suggestion too about the cold start valve, did you have yours professionally cleaned ? Or do it yourself ?

Chopshop85

iTrader: (4)

I dropped it off at my tuner as they have a sonic bath then the means to test it.

Chas

The biggest issue with the stock MFI breather setup is that it is very easily affected by vacuum leaks. A crap oil filler cap for example will introduce a leak as will the pipes going hard regarding the breather setup or even the auxilliary air valve pipe. It has been said that even a leaky crank seal can cause the running to go on the piss. Naturally these vacuum leaks will have a knock on effect with the running of the car.

My advice? If the car is relatively stock ensure there are no leaks or iffy hoses, breather filters etc. and only use genuine Ford bits ; I have never known on a pattern oil filler cap to last more than a few months before the rubber starts falling to bits.

I would also check your warm up regulator to ensure it is working as it should. Whacking it in the fridge will soon have you knowing if the disc is OK in addition to whacking 12V on the terminals ; it has a disc inside that upon opening introduces an air leak to aid the running of the car.

rsmog33

Any luck mate with your starting problems??

xrmalin

Well after the sensor swap Saturday morning she fired straight up left the car for the day & went out in my other one, tried again when I got back in the evening straight up again
Did the same thing Sunday too with the same result

Went to go work this morning in it & I was back to the cranking over & over again got in it to come home & she fired straight up again so god knows what's wrong with it lol

rsmog33

MFI is so hit and miss. Nice to keep the originality but so frustrating sometimes. My S2 is running at 220 bhp and sweet but a few months ago I thought whats the point when it wont even start!!!!


When you have the problem of cranking over and over and it eventually fires up, is it lumpy for a while?? Low revs and hunting a bit??

xrmalin

Yeah it does when it does it's turning over without starting malarkey it ticks over at sort of 800rpm ish & is rather lumpy for a minute or so & then it clears & ticks over spot on.

rsmog33

This was my S2 all over


When mine did that it turned out to be the idle control valve was sticking. Pulled it off and gave it a blast with carb cleaner...sorted. It acts as like a secondary throttle on start up.


Worth a look maybe

xrmalin

Do you mean the auxiliary air device thing on the back of the inlet with the black plug ?

rsmog33

That's the one. There is a valve inside that can stick. Especially as most have never been replaced so could be 25 - 30 years old!!! Also check the black pipes going in and out of it as they can get blocked too.


MFI is one big trial and error process but at least every bit you do is illuminating problems.

Chas

I think trial and error is a little unfair for MFI. It is however misunderstood, and it can be tricky to grasp. Some patience in learning about how it works through the various literature online will get you closer to diagnosing it.

As said, the WUR should be checked . Alot of the issues on MFI'd cars (Ford or otherwise) tend to be down to bodgery. I fixed a crap running Volvo 740 GLE due to poor maintenance ; the flap was caked in rubbish and was transformed upon cleaning it (people here simply leave the plate dirty and adjust the mixture :facepalm:. The other issue is spares availability. That may be worth giving a go in yours.

Admittedly when tuned, there are superior avenues out there ; If or when mine goes I'll probably go for an aftermarket setup that can cater for my car (boost control, fans, chargecooler control in addition to possible boost limiting in lower cars will be considerations for me; with it being a ZVH it should in theory be easier to convert with the trigger setup already being present. Touchwood mine is still working OK at 225BHP.

A 924 I saw that had to be the worst K-Jet car I had seen ran badly due to laughable bodgery ; wrong fuel pump fitted with zip ties, cooker gas hose to the metering unit (no, I am not kidding!), wrong and different plugs per cylinder amongst other bodgery ; to think the guy wanted Ł600 for it over a year ago despite getting it for free, yet wanted it fixed on a shoestring.

Chopshop85

iTrader: (4)

The RS Turbo is Bosch KE. IIRC it doesnt have a warm up regulator.

Chas

Gow knows why I called it the WUR later in that post. I meant the auxiliary air valve!

xrmalin

It seems to have solved the issue changing both the coolant sensors but I won't know for sure until we have another really cold morning but I definitely think I'll give the aux air device a blast out with some carb cleaner as it wouldn't hurt just to be sure.

Thanks for the advice so far guys