cavyturbo

Hello, I'm hoping someone can help,


I have a 1990 4x4 cosworth that wont idle after approx. 20 seconds, the most of the sensors around the engine have been changed. I don't know what work has been done to the car before I bought it and not sure what power it is but I have told it is around the 280bhp.


has anyone had a similar problem and fixed it? it has an L8 ecu


is it possible it could be a fuel pressure regulator or ecu related?


any info would be greatly appreciated

cossynut2

Could be map sensor or iscv playing up.

cavyturbo

I have already changed the map sensor. That was the 1st thing I changed as I was sure it would be that. I haven't changed the iscv though

martysmartie

iTrader: (1)

What happens when it 'won't idle' does it slowly just come to a stop, does increasing the revs do anything?

Martin

cavyturbo

Yes it slowly comes to a stop/cuts out

rog

iTrader: (2)

Could be loads of things even a small air leak. You haven't said if the idle raises or drops (or both). You may be lucky and it could be the ISCV, but tbh I'd take the car somewhere to get it checked over properly by a specialist if you can, a decent health check of all the sensors won't do it any harm, but chasing a problem like erratic idle could see you mess around adjusting and swapping things for ages and getting nowhere.

The above might sound a bit over kill for you, but I had a similar issue with my 4x4 for years like this, it was an intermittent fault that was only diagnosed when the correct diagnostic equipment was attached and the TPS was found to be slightly off, plus it had a small air leak in the inlet cover.

rog

iTrader: (2)

Bloody passionford, just seen your reply after I posted!!!

What about when it heats up, is it the same? Disconnect the ISCV and run it like that, if there's no difference then that's likely the problem.

cossynut2

That is exactly what it would do with a faulty map sensor, so eliminate the iscv next as that is the next most likely cause. If its not that then as suggested take it to a Cosworth specialist as it could be lots of things which they will have the expertise to find.

cavyturbo

thanks for your reply. I have given it to a garage that works on them and they think they have it down to the pectal board but they are not 100% sure and they don't have one that they can check it off of. I don't mind buying one if this is the problem but I have all the sensors changed already and the ecu and I don't want be throwing money at it constantly 😭

martysmartie

iTrader: (1)

The fact it stops when ISCV is d/c suggest you should do the basics first, such as setting up the base idle. Changing sensors is never a solution.

Martin

cossie2

if it has lambda sonda than try disconnecting it to see if the lambda is playing up..
if there is no lambda have you tried to play with small screw on ecu but it looks its missing more air through throttle body as suggested before...basic adjustment of idle with iscv disconnected...