'94 940 turbo rough idle, missing, especially when hot

skittlejr · Post by **skittlejr** » 01 Oct 2008, 08:08

Recently overheated about 2 weeks ago due to cracked radiator. Pulled into driveway after overheating, dumped some water in to cool it down, shut it off. Can't remember if problem was happening then. While waiting for new radiator, I removed the turbo and exhaust manifold to replace a leaking manifold gasket. Disconnected 1 plug wire during those repairs. All back together now with new radiator. Most times it starts well when cold then after long highway driving to work or back it idles very when exiting highway. Give it some throttle at a stop and it still runs rough. Accelerate and it goes away. Only code was 1-2-3. I've been reading through a lot of posts and can't seem to find anything that I feel is related to my problem or fix. Thanks for any help.

Post by **vegasjetskier** » 01 Oct 2008, 11:42

If it ever overheats again, don't dump water into it. It can cause a temperature shock which is worse that the original overheat (there are areas of the engine that are very hot and expanded, then the cool water hits them causing the metal to cool and contract quickly, creating stress in the metal), even cracking the block or the head. Just let it cool down by itself, then add coolant.

Have you tried replacing the spark plugs?

skittlejr · Post by **skittlejr** » 01 Oct 2008, 13:02

i didn't fill it with completely with cold water. i put a little in at time to slowly lower the temperature. another way would be to use hot water from the tap which i have done before.

i replaced the plugs a couple of months ago, are you suggesting that i do it again due to the overheat or just as routine maintenance?