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Discussion Starter #1
Hi,
can anyone tell me if the valve in the icv should spring back if you move it manually with a screwdriver, the one in my 94 2.0 espace is under no resistance what so ever.
The reason i ask is that i am having the usual fluctuating idle problems, have ordered a new temp sensor and will fit as soon as, but am trying to think on previous cars with a similar setup, that the icv valve would spring back if moved manually, but could be wrong, can someone enlighten me?
 

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Hi,
No , the valve will not spring back if moved. When you turn the ignition on it resets to its home position. Uneven idling can be caused by a vacuum fault / leak. Most likely cause is the thick hose (with a small inside) which goes from the manifold to the top rear of the engine. Very often it falls out. Hope this helps.
 

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Discussion Starter #3
Hi,
Checked all pipes for leaks and replaced the pipe that goes from the icv to the air intake pipe which had a crack, the bad idle only occurs for the first 10 to 15 minutes after start up. The car did suffer with a head gasket failure last year, makes me wonder if it damaged the lambda sensor, getting anti-freeze into the exhaust system. Am i right in thinking the lambda's on the espace have a built in heating element?
could be the lambda is not heating to the right temp, and giving the wrong information to the ecu to adjust the idle correctly. All sounds good but probably all wrong.
 

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Lambda sensor does not have priority when you first start the car as the ecu runs the mixture rich until the car warms up. Having said that , this only lasts for a few minutes , at which point the lamda sensor has priority. The coolant sensor when the engine is cold should be around 3.5 k ohms dropping to below 1k ohms when the engine warms up. Did you check the hose which runs to the map sensor ? any slight hole or split in this is critical. Yes , if its a three wire lambda , then two of the wires are for the heater.(white ones)
 

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Discussion Starter #5
one thing i did notice about the pipe that goes to the map sensor, is that there is no plastic restrictor inserted in the pipe, and i am almost certain there should be.
 

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No thats right - no restrictor - the map sensor needs to know as soon as possible of any changes in the manifold vacuum. A few other thoughts :
An air leak on a manifold seal can cause an unstable idle. (carefully spray carb cleaner in the area with engine running and see if speed changes)
Are the compressions o.k.?
Valve clearances o.k.?
If it only started happening after a head gasket change - is the timing out?
 

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Just had a look at one of my other espaces and it does have a restrictor in the pipe that goes to the map sensor. Its right inside the pipe , so maybe not obvious its in there.
 

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Discussion Starter #8
Checked the pipe and the restrictor is missing, i think the best bet is to replace the pipe and go from there. It seems to hunt worse soon after initial start up then settles down.
 
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