Jimboxr4x4

The saga continues! I have taken the 2 bar map sensor off and tested and it responds to vacuum and pressure. It’s reading 2.15 volt at atmospheric pressure and voltage does drop with vacuum and increase with pressure.

The issue is it will idle roughly but it’s over fueling massively so was pinning my hopes on the map sensor being off but seems to be working fine as best I can tell.

list of things changed so far:

Coolant temp sensor
Air intake temp sensor
Phase sensor
Crank position sensor
distributor cap and rotor arm
coil
Motorcraft spark plugs

Plugs soot up within thirty second of idle and black soot out the exhaust.

Going to buy a new ignition amp next but this is getting expensive now!

No error codes showing up at all.

Anything else I could have missed? Thanks.

ray barker

yes m8 the idle control valve i did say before. its got a rubber o ring at the bottom of the chamber that the unit sits in. its like an electrical plunger.it moves a plunger with a an o ring on the bottom up and down. cant think for the fuk of my stupid head what the terminoligy is for it. this controls cold starting fine ecu adjustments when warm and other things. the o ring can become stuck to the side of the chamber it sits in. undo the two screws and pull it out. it will run fine after its warmed if the unit isnt operating properly as long as the o ring isnt jamming it self fully open or shut. you need to phone james at auto dynamix there cossie specialists.he was the workshop manager at motorsport developments in blackpool. no one no anymore than stuart and james. these are sierra cosworth gods.sak auto dynamix if theve got somthing they can sell you to fix the issue. they will talke you right through the car. you will not be able to phone better people i prommise

stevieturbo

The idle valve is only an air bypass, nothing more. It does not "control" anything other than the amount of air it lets past to increase or decrease idle

Seriously, just buy the book I mentioned and it will give you some basic knowledge on how it works, and some test options. Instead of just throwing parts at it which more often than not makes matters worse.

And is it supposed to be a 2 bar map sensor on your setup ? Has it ever been changed ? 2 bar would be totally standard ?

If you think spark, have you actually tested for a decent spark ? Have you verified actual mixtures ? although for cold starts it will of course be rich and if doing this multiple times it can foul plugs.

Or just take it somewhere who can diagnose it properly. Then you can enjoy the car.

Jimboxr4x4

Thanks. If I could drive it I would take it to a tuner but it’s almost like I have to figure this out myself or it’s beaten me! I’ll clean up the ISCV and also swap out the ignition amp. After that I’ve pretty much changed everything!

ray barker

might be worth double checking the timming marks. make sure your on the right lug on the crankshaft pully plenty of people of made the same mistake.if its a tooth out its very noticable

stevieturbo

And as said before, randomly throwing parts at something is almost always the worst option

And it doesn't need a tuner, just a half competent technician/mechanic

Jimboxr4x4

** Update **

Didn’t want to leave this thread unresolved in case some else has same issue.

After changing literally every sensor, dizzy, ignition amp and coil the overfueling was caused by a split diaphragm in the fuel pressure regulator. Even if it’s showing 3.5 bar disconnect the vacuum hose and if there is any petrol in the hose that’s the problem. If petrol is entering the inlet manifold via the vacuum hose that’s petrol rich air being sucked in. Looking back it makes so much sense!

Anyway, hope this helps anyone else with massive overfueling problems as these regulators are old now and it seems it’s a common problem.

Thanks to all for your help and advice over the many months I was tinkering with it!

cossynut2

Glad you finally found the cause of the problem, really helpful for anyone else that has a similar problem. As you said these cars are now over 30 years old and parts do wear out.Some years back I had an electrical problem in my 2wd Saff , tried everything to fix it and in the end it was an intermittent fault somewhere in the original engine bay wiring loom.Changed to a new modern one and it fixed it straight away!!

ray barker

glad you got there in the end thanks for the update. i must start practicing what i preach ive not started mine for a couple of months