jbherri2

iTrader: (1)

Hi All,

Not sure if I should be concerned or not. I have a 1985 S, 12a. 78048 miles on it. Original through and through. Recently, I've noticed - especially when sitting at a light, after the engine has warmed up - that my idle will be more of a "whoomp, whoomp, whoomp...." for a few moments, and then it'll settle back to the normal smoooooth idle that I expect. It's not really louder than normal, just more whoompy. At first, I figured the engine/transmission mounts needed to be replaced, so I wasn't really concerned.

This morning, I noticed my oil pressure wasn't as high as it normally is. The needle was sitting just above the second tick mark on the gauge (I forget what that is - I'll have to go out at lunch and check).

So, with the oil pressure appearing lower than normal, I'm no longer thinking the idle is related to the mounts - granted, they should probably be replaced, seeing as they are 31 years old.

jbherri2

iTrader: (1)

Maybe I should work on my description. The sound and idle is - for a few minutes - like a misfire in a traditional piston engine. Any thoughts?

TimWilbers

iTrader: (1)

Try this:
Connect an inductive timing light to the leading coil wire and then the trailing coil wire. It will flash really fast, but that makes it easier to see if your "whoomp" is associated with a miss in the flashes.

Mine does this randomly, and I'm looking into the various components of the ignition.

It may mis-fire at higher rpm's but that is harder to detect than at idle.

Maybe (?)

jbherri2

iTrader: (1)

I notice mine at idle - like at the stop light. And if I tap the throttle very slightly, it'll usually settle out again. But lately, the whoomp seems to last a little longer, and I need to tap the throttle a couple of times for it to settle out.

I'll see if I can borrow a timing light. Thanks for your input.