cossieDavedree

in right thread !!

help needed if possible?

When i was running standard about 5 months ago it'd idle where the revs would go from 900rpm to 1000rpm Then it stopped doing it. Its just returned again.
I took out the icv and cleaned it and its not improved this problem.
It idles up and down from cold and hot,, and theres a very slight jump misfire every now and then below 1000rpm but not in rev range above..
It drives absolutely fine,, boosts fine etc,, but idle is allover the place.
I'VE JUST fitted a msd stage 3 chip its been fine for the week i've fitted it unitl now?

Is it CO2?
Idle base out?
new Idle control valve?
fUEL pRESSURE.

cossieDavedree

When engine hot. And I unplug the icv the engine struggles to idle and dies sometimes

tabetha

You should have checked certain things such as fuel pressure with/without vacuum pipe on(plugged when off)
It should be around 3BAR with the vac on and 3.6/3.7 with the pipe off and plugged.
Your base idle is TOO LOW, and needs setting to 850 rpm or so, with hot engine, no electrical load, by means of the screw with a locknut around it located on the underside of the throttle housing pointing forwards.
The iscv after cleaning will need LUBRICATING, I use a silicone spray and have to do mine around every 3 months.
You should then, as per instructions supplied with the chip set the CO to 2.5/2.7 % CO.
If you have any changes that MSD were not made aware of the chip MAY need reflashing, as any alteration to the airflow charactersitics of the engine can play havoc, but if the usual filter/exhaust etc etc and they were aware of them they woyuld have supplied a suitable chip.
It sounds as though you have got the base idle too low, but also it may well be out idle CO wise so get it checked, the screw although called idle screw, does all off load fuelling and adds to main supply under boost SO IS CRITICAL.
tabetha

cossieDavedree

cheeers tabeth i think i'll get it put on the rollers to check everything is ok.

Daz-rst

could be phase sensor in the distributor or cps sensor or your ignition amplifier.
mine is doing this and im getting a tuner to test it to find the exact fault as i replaced the cps and it still does it.

tabetha

CPS will not cause up down idle.
tabetha

JTECH James

iTrader: (13)

i would start unplugging the iscv, and setting the base idle speed top around 900 rpm, then with the engine hot plug the iscv back in and see if effects the idle speed, it should have no or very little effect ,if it does check the tps settings and voltage adjust if needed

if the ecu sees an incorrect tps signal it can open the iscv

and if you have doubts about any of the base settings ie fuel pressure etc, you NEED to check them! ask stu for the set up spec.

gingeRS

do you set your base idle using a timing light, or the cars rev counter

i set mine using a timing light to 900rpm, and to look at the rev counter it looks more like 600rpm

are cossie rev counters normally innacurate? or is the timing light at fault?

having trouble with an unstable idle on my closed loop stage 3 msd saff

tabetha

Cossie rev counters are not normally too bad, mine is 40/60 rpm out(@900) according to my mates propellor gauge, which is deadly accurate.
tabetha