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  #1  
Old 07-04-2010, 08:47 PM
elemgee elemgee is offline
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Sort of a Rough Idle When Cold (92 SVX)

This is my 3rd SVX and like the previous two, its a wonderful car but..... When i 1st start the car, the idle seems a little bit rough when the car is in park. Seems to get better (but still not perfect) once I put the car in gear. Its not what you'd really call rough, but its not as smooth as the other two that I had. And I dont know if this is related to the slightly rough idle or not, but the gas mileage is not as good as the previous ones. I'm getting around 22mpg with this one - I was getting around 25mpg with the other two (most of my driving is highway). No check engine light lights up, and if I hadn't owned two of these before, I dont know that I'd think the idle is rough.

It only has 38K miles (I'm the 2nd owner and purchased it a few months ago).

Any ideas? Thanks.

Larry
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  #2  
Old 07-04-2010, 11:31 PM
SoCal LS-L's Avatar
SoCal LS-L SoCal LS-L is offline
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Re: Sort of a Rough Idle When Cold (92 SVX)

Start with the basics..... run some good fuel injector cleaner through first. Then if you havent checked the spark plugs, do it. 38K isnt enough to wear them, but they may very well be 19 years old and corroded from moisture. Take it out for a nice long freeway drive, to clear out the combustion chambers and valves too.

If none of those work, then id clean the intake with some spray cleaner, or run Seafoam thru the system as directed on the bottle.

If the issue still remains, then post back and then we can go into it further. You have the downloadable service manual yes?

BTW, nice score!! 38K miles from the original owner is quite a find! How much did you get it for if you dont mind me asking?
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Last edited by SoCal LS-L; 07-05-2010 at 05:22 AM.
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  #3  
Old 07-08-2010, 05:59 PM
elemgee elemgee is offline
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Re: Sort of a Rough Idle When Cold (92 SVX)

Tried the Seafoam treatment and that didnt fix the idle problem. Over the weekend I plan on removing the valve covers to look at the PCV valve.
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Old 07-10-2010, 10:59 PM
sowise sowise is offline
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Re: Sort of a Rough Idle When Cold (92 SVX)

Along with checking/replacing spark plugs, fuel filter and air filter can cause bad or rough idle and usually recommended for the basic tune up. Check your vacuum lines too.
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  #5  
Old 08-27-2010, 02:27 PM
elemgee elemgee is offline
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Re: Sort of a Rough Idle When Cold (92 SVX)

Just to recap, I have a slightly rough idle until the engine completely warms up,and when in drive, the revs will bounce around between around 650 and 750 rpms.

I've since replaced my O2 sensors, knock sensors (I was getting a CEL indicating that the drivers side O2 and knock sensor were bad) and coolant temp sensor (this was the problem per another post by someone with a problem similar to mine), thinking some of that was causing the slightly rough idle when cold. But the problem still persists, so I bit the bullet and took it to a mechanic. His diagnosis was that he smelled engine coolant when opening the hood (I thought it might be due to losing some coolant when replacing the coolant temp sensor). He didnt find anything obviously wrong after hooking the engine up to his diagnostic machine; so he thinks it could be a bad head gasket, valve spring or something along those lines. He wont know for sure until he removes the head, which shows 12 hours of shop time, which I'm assuming is at least $600.

I'm going to take it to a different mechanic for a second opinion but thought I'd ask - would a bad head gasket cause this problem? The idle seems fine once the engine is completely warmed up (after driving for about 20 minutes or so).
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