car thread - fiesta engine idle problem

[pooley_99]

Yea yea this is a bike forum, but all the ford forums are a bit pants for proper advice and I know there's a couple of decent mechanics knocking around these pages.. so..

Ive changed the head gasket, water pump, timing belt and thermostat on my mrs 2004 fiesta 1.25 The water pump failed and it boiled its cock off so thats why i did the work. It runs up to the correct temp now and cools properly but there is now an idle problem, once the engine is warm and i guess no choke needed, it idles around 500 to 750 up and down and then dies. Ive put new plugs in coil seems ok its defo sparking and ive doubled checked all the wiring and breathers... Running out of ides now
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CBR 900RR Fireblade

[cb1rocket]

run a diagnosis test on it. there on ebay for like 20 quid, got to be a sensor problem, MAF? idle control valve?
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Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852

[pooley_99]

done that, no codes... i'm now thinking its something to do with the evap system because when i unplug the vacuum hose from the evap valve to the inlet manifold it seems to run better
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CBR 900RR Fireblade

[misscrabstick]

Not uncommon, get some carb cleaner and a toothbrush, thoroughly clean the throttle butterfly and the venturi.

Remove the idle valve assy , get it holes upwards fill it with carb cleaner, leave it a bit, drain it and clean inside the best you can.

Shove it back together and see what you got with regards to idle quality, it's also worth checking around the inlet manifold for any air leaks/bad gaskets/pipes off etc, sometimes the idle valve goes tits up, don't automatically expect there to be a trouble code often there isn't.

[misscrabstick]

Unplugging the evap makes an air leak causing a false idle up effect.

[misscrabstick]

OOhh just remembered there was an issue with tin plated and gold plated contacts being mixed on the idle valve plug and the idle valve causing bad contact corrosion, make sure both are clean and bright.

[Triumph1300]

Check the breather hoses under the inlet manifold, we've had a similar problem, the one on the left hand side had split
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BWJ
Back on a BMW R80RT
Punctuation - the difference between knowing your shit, and knowing you're shit

[pooley_99]

ok thanks for all these suggestions. I've now got the valve cover off and checking the valve clearances, I totally should of done this while the cams where out but i didnt.. and.... the gaps seem out! I'm not sure if this is because the engine is still warm. Thinking about it i might of got a couple of the shims mixed up when i had the head and cams off What sort of tolerances do these gaps have?
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CBR 900RR Fireblade

[pooley_99]

finally got round to this, ended up swapping two shimms around that i worked out from the valve clearances that I must have got mixed up the first time.. Cams out shims swapped back and running sweet!
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CBR 900RR Fireblade