# Troubleshoot - Rough Idle



## RawkinRocco (Dec 14, 2012)

Been dealing with this for a while. Car: '81 Rocco with 1.7EN

It runs great, but when it's just a idle it seems to have a hard time remaining at stable RPM with it often dropping from 800 to 200 and then back up. At times it will stall from dropping too low. It's been to the point of me keeping my foot partially on the accelerator pedal to keep it revving.

I've tried looking for vacuum leaks to no avail. I'm sure it'd be running worse if it was a vacuum leak. If it's not a CIS issue, I'll post in the 8v section.

It does this in all weathers, and even after the engine has warmed up.


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## Butcher (Jan 31, 2001)

CIS is a very simple system but most people do not want to put the effort in to make a quality diagnosis. You need to know how the system works. You need to know what the fuel pressures are. You need to know you have no intake leaks [thinking is not enough, you need to know]. 

Ignition timing is simple to do and check. 

Does the car have lambda?


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## RawkinRocco (Dec 14, 2012)

It does have Lamda. 

I've looked through the bookmarks pinned at the top but with half of them gone from geocities being defunct I tried googling around. Not sure if I'll be able to afford a fuel pressure gauge at this time and don't know anyone around me that has one. 

It must be a really small leak somewhere. I'll have to continue looking for it once the degrees are not near 100 during the day.


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## RevolutionMotorsportsCt (Nov 17, 2011)

Check for vac leaks first by the injectors and in the intake sytem, that's the biggest overlooked prob with cis idle issues

Bill


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## RawkinRocco (Dec 14, 2012)

Updates:

After a bit of looking and prodding, it's been deduced to be a faulty frequency valve. I'll have to search for one from a junkyard or used vendor. Hopefully this fixes it.


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