Hello,

my name is timo and im from thé netherlands. I am new here for some good tips and information.

i have a 86 3 door cosworth that wont idle wel cold.

specs of the car at the moment,

803 green injectors
Stage 2 mountune chip
3 bar map
ngk bkr6eix

problems are that it wont idle cold, when warm no problems besides that it idles high(1100 rpm)

have tryed many things like, water and inlet temp sensors. Spark plugs. Spark plug cabels and distributor. Have fould many plug (champion normal ngk’s and bosch)

has anyone a idea what i could be ?

greetz timo

 

What are mixtures like at idle ? Sounds far too rich.

Have you verified good spark at each cylinder ?

What's the vehicle history ? When did it last run correctly ?

Basic info.

http://www.bigturbo.co.uk/

Or pretty sure this one covers the Marelli system too


And stop throwing random parts at it without doing proper sensible tests and basic setup.

 

Hello,

the story is that my dad drove it last in the 2000 en the i had a sputter under boost. When it was running stage 1 mountune. Then he parkt it and i get it going in 2021. Then got mot but co was hard to get under 4.5%. Then got to stage 2 and co was 1.4% last time i checked. It doesnt smell that bad to.

spark is good but plug getting black from the idle.

bigturbo forum i checked a lot but cant find any thing like what it coule be.

greetz

 

The website has the basic setup and information a half decent technician would need, as will the manual I linked to with a more guided approach.

So you're saying the car has sat and not moved or been used for 20 years ?

So it did not run correctly 20 years ago when it was "stage 1", but now somehow it is "stage 2" ?

Would you not be better to fix the car first, before messing with the ecu ?

If it is idling too high, then the engine is getting too much air. If it is too rich, it is also getting too much fuel.

If it has sat for 20 years, it absolutely will need the tank drained of all fuel, new fuel filled up, new filter etc etc. Injectors may also need tested and either cleaned or replaced as necessary.
Check the fuel pressure regulator is working correctly, and not failed and chucking fuel in via a ruptured diaphragm into the inlet manifold via the reference pipe.

 

Hello,

i am a car mechanic and have a manual.

fuel pressure. Fuel pump, fuel and cleaned everything.
also the throttle body and idle control valve.

my thaught where the stage 1 mountune chip and the yellow injectors.
and so i had the green injectors and stage 2 chip laying arround.

i have checked the basics already.

to much air could be a thing but if its warm it even wont idle below 1000 and sound not right.
also have tryed diffrent fuel pressure’s but no succes!

greetz

 

you have not listened to what I have said.

If it is idling too high, it is getting too much air. That is a simple fact.

And how are you trying to adjust the idle speed if you are saying it will not idle below 1000rpm ?

You say you have checked the basics.....yet also say the Bigturbo website tells you nothing ? This makes no sense. Is the "closed" throttle position where it is supposed to be ? This is an important basic first step.
Is the idle speed control valve working correctly, and is it receiving a signal ?

Are you using the correct map sensor for the chip now fitted ? And is the map sensor reading correctly ? Again, the website gives basic info here to check against.

You said it was hard to get under 4.5% CO......yet you achieved 1.4%

So was it happy at 4.5% ? you said hard to get below this...so how high actually was it ? how are you making changes to this ? Have you verified a good strong spark on all cylinders ?

And why are you trying "different fuel pressures". There will be a fixed pressure it is intended to run. I explained a specific and well known problem with the fuel pressure regulators. Have you checked for that problem ?

 

Hello,

i am sorry.

with the air screw on the under side of the throttle body.
yes the throttle is in the closed position
iscv is working als cleaned the valve and test it with running without the plug on it and the plug it in. Then the idle whil jump up and come down.
yes i’m using the correct map sensor for the chip.
yes it was happy with 4,5% (in the begin it was like 5.2% but then it would fault plugs like no problem) co but then it was running at 1100 rpm.
then for mot i got it to 3.8% with more air and so rising the idle to 1250. (In the netherlands we have to achief less then 4,5% co)
after changing to the stage 2 chip the co got down to 1.4% after settinf the co screw. Also i can get it higher than 1.4% and closer to 0%.
i have turnt it over with the plugs in the cabels an it fired just light blue.
mainly the fuel pressure is on 3.5 bar with vacum of and 3 with it on.
yes i have checked the regulator and doesnt leak true.
also have changed it out for a other good one of a good running car.
I would visit the bigturbo forum again.

greetz

 

If idle is high, it is getting too much air.

Find out why or where.

When it is idling too high, is the ecu trying to reduce the idle ? ie what sort of signal are you getting at the ISCV ? if any ?

Is the throttle blade where it is supposed to be in the "closed" position ? again, check TPS voltage as per specs on the website or a manual.

You do not try and alter fuel mixtures by messing with any screws on the throttle. You need to adjust the mixture screw on the ecu.

Fix idle speed first to a sensible level.

Then adjust mixtures the correct way.

And what sort of ignition timing is it running at idle ?

 

Hello,

found the problem, the little connector on the iscv plug was going up. So no connection there. Fixed that en idles again.

thnx sir

greetz

 

Good job.