BH5 Legacy cold idle problem

[rob.121]

Hi all, i have a 99 BH5 legacy with the non turbo ej20 engine. car runs perfectly fine but won't idle while cold, holds idle once warmed up.

drives fine while cold but no idle, just dies as soon as your off the gas.

Any idea as to what could be causing this? Just started doing this all of a sudden.

any advice appreciated

cheers

[Rosssub]

Welcome. Could be a vacuum leak somewhere, a sticky idle air control valve or a faulty coolant temp sensor.

Make sure there aren't any perished, split or loose vacuum hoses. Then remove the idle control valve on the throttle body and give it a good clean out with carby cleaner.

IACV is bottom left in this pic:

[rob.121]

cool,thanks for the tips. Does the idle control valve come straight off once the two screws are removed?

[Percy]

 rob.121 said:

cool,thanks for the tips. Does the idle control valve come straight off once the two screws are removed?

Yep, dont loose the Oring, its just sitting around the IACV.

Also be careful with it, it is easily damaged.

[rob.121]

I removed the Idle control valve, was filthy with carbon. cleaned it down and sprayed into the valve to try flush it out abit. Hasn't seemed to have made a difference. Its 50-50 wether it idles fine or dies but always drives perfectly fine. Where is the best place to buy a new Idle control valve?

Cheers!

[Rosssub]

Is it ever hard to start when it's warmed up? Could test the coolant temp sensor out first. Assuming it's the same sensor as the turbo model it should be giving 0.6V when the engines warmed up. Could also try a cold start with the coolant temp sensor unplugged to see if anything changes. The CEL will come on with the sensor unplugged, but it will go out once plugged back in.

Resistance through the sensor should be something like this:

20degC 2-3 KOhms

80degC 350-400 Ohms

90degC 200-300 Ohms

Voltage should be something like this:

A new genuine ICV isn't cheap, this is USD:

https://partsouq.com/en/search/search?q=22650AA192

[rob.121]

ouch, thats expensive in nzd. i might see if parts master can do a aftermarket sensor tomorrow. I think it could well be the ICV due to the amount of carbon on it when removed. its cleaned up now but the damage is probably already done internally. Its never hard to start hot or cold, but i could try unplugging the coolant sensor to see what effect it has on the idle. I dont have a multimeter or the electrical know how to accurately test the sensor unfortunately. but thanks for the tips! much better than paying somebody $80/hr to scratch there head and change the air filter.