sir nose

iTrader: (3)

what can i do to bring down the idle speed and c.o % on my 1990 saph cossie 4x4.

its idling at 1200 rpm
idle co% is 7.5
co% drops to 0.5 at fast idle.
hydrocarbons 10.00

i have access to a gas analyser as im an mot tester,i tried adjusting the mixture screw and the co% came down a little bit to about 6.5 and the hc's to about 400.

any help greatly appreciated.

RS SHAUN

iTrader: (24)

maybe an air leak on your inlet side mate!

tabetha

Firstly unless it's very new put in a new coolant temp sensor(ecu one), then adjust, disconnect the iscv and check what the base setting is on the air bypass on the throttle housing underside, pointing forward is the adjuster screw for air bypass.
tabetha
ps welcome to PF.

sir nose

iTrader: (3)

cheers fella's,ill get a temp sender tomorrow.whereabouts is the temp sender located?

if i had an air leak,would i be able to tell via the boost gauge?

how can i test the iscv?,if i disconnect the electrical multi-plug when engine is idling, nothing happens.

whats the procedure for adjusting the air bypass valve?

cheers

tabetha

The ecu coolant temp sensor is located at the rear nearside of the head under the inlet manifold, a bit of s shit to get to, done by feel rather than sight, think it's a 19mm deep socket to do the job, with a short extension.
Boost gauge not any help with small leaks, just spray easy start, if it gets sucked in revs climb, if it doesn't it still cleans your engine bits nicely!!
If the revs are raised above normal hot idle temp when it is cold then the iscv is working, but give it a good clean with carb cleaner anyway, I test mine by whacking a 12v fed through them, one way round it will work if it doesn't work with wires either way round on both pins it's goosed, when unplugged when hot it should speed up momentarily when plugged back in.
The procedure for setting the base idle is get up to temp, leave all lecky turned off, apart from engine running of course, and using the screw on the underside of the throttle housing adjust this screw until it is about 900-950 rpm, leave all the pipes etc on whilst adjusting, it's a bit cramped but not too bad, reconnect iscv.
tabetha

sir nose

iTrader: (3)

ive tried adjusting the base idle to the point that there was a gap between the screw and throttle linkage,made no difference.screwed the adjuster back so its just touching the linkage.

whats the deal with the air bypass?i saw the fat screw on the underside of the throttle body when i had the throttle body off but i didnt try adjusting it.

sir nose

iTrader: (3)

ive just noticed the lambda sensor is dis-connected,my guess is its a later turbo and the senser isnt required.am i right?

martysmartie

iTrader: (1)

Sounds like the turbo fitted has not got the hole for it. Most 4x4s had lamba it's the 2WD models that diden't.

Martin

sir nose

iTrader: (3)

its got a lambda sensor fitted but the electrical multi-plug has been dis-connected from the wiring harness.

martysmartie

iTrader: (1)

Oh that seems strange, have you tried reconnecting it? Is your engine YBG (Green cam cover)

Martin

sir nose

iTrader: (3)

ive not tried reconnecting as im not 100% sure where in plugs into.i guess it had a green r/c but is red now.

i thought being a 1990 vehicle it would not have lambda sensors,i cant think of another type of car that old with a lambda sensor.

martysmartie

iTrader: (1)

That may well be correct, hence me asking the early 4x4s such as yours had YBJ engines with red cam covers although this was 1989 cars only (Although it's possible yours was manufactured in 1989 and registered in 1990) these engines have many RS500 revisions and did not run closed loop. All the later 4x4s had lamda sensors along with 3 cats.

Martin

jht

Connect lambda, it should connect only one way. If that does not help, search for air leaks to intake: small tubes from intake to map sensor, check dump valve, amal valve tubes, check connection to boost gauge if you have one. search for loose fittings, cracks, etc. It needs only a small leak to screw your emissions.

sir nose

iTrader: (3)

connecting the lambda makes no difference,new boost gauge fitted,new coolant temp sensor fitted,ignition timing ok,must have an air leak,ill check again.

jht

detecting an intake leask is easy with boost gauge: my car has a vacuum of 0,8 bar on idle with all electircs shut, lights, heater fan, etc. On overrun vacuum should be close to 0,9 bar, both values being negative. finding a leak is one bitch of a job, succes follows triple checking everything. I re-clamped all connections of my small air tubes that were connected to dump, amal, intake ,map, boost gauge... pay extra attention to boost gauge connection, it is not original, so propably a diy job... also, old gloe on tubes may have worn out so clamp those connections!! sorry for poor language, i am not a brit

sir nose

iTrader: (3)

i found a leak today on the inlet,fixed that and the idle has dropped but the c.o% is still high,ive changed the ect sensor,changed the air filter,checked the timing,set the tps,the c.o% adjustment screw does'nt make much difference.

is it worth checking the phase sensor gap?

what would be a reasonable idle c.o % level for a cossie running light blues?

james

jht

check the dump/by-pass valve. if yöu have the original bosch plastic item you might want to change it anyway, it is crap. co level depends on many things, mine is 0,4% with warm cat. like i said, the vacuum mentioned on previous post should make the co right, if your engine is ok otherwise

sir nose

iTrader: (3)

its a forge dump valve and the diaphragm is good.

how can i check the amal valve?it has 3 pipe in/out lets but only 2 pipes fitted one from the turbo inlet housing the other to the actuator,is that correct?

mine is a non cat model and the manufactureres spec co% is 1.00-2.00 i think,i would of thought it will be higher than manufacturers spec with a tuned engine,correct

martysmartie

iTrader: (1)

Theres 3 plastic connectors marked C,W,A (Compressor, Wategate and Atmosphere) Originally A would have had a pipe connected back to the airbox, many now don't as have aftermarket air filters so it just vents to atmosphere so thats fine.

When you buy a chip, that chip has it's own CO and fuel pressure parameters, you need to know the spec of the chip for the car then contact the manufacturer for these.

Martin

sir nose

iTrader: (3)

cheers martin.ill contact pj motorsport when its all back together.