I posted this before but got no response. my idle has a funny intermittent sound. Its kind of like hummmmmmm(normal) bup bup bupp hummmmmm Like i said before it reminds me of the small backfire i hear during downshifts but its consistant. i hear it most under the hood and can feel it in the car when ti happens. Any ideas what it could be?

 

If it misses and the engine is rough, and I mean misses alot, its most likely shitty compression and the intake charge is not firing on that face of the rotor 1/2 the time.

Mine does the same thing, except its much less, more like


hummmmmmm bup hummmmmmmmmmmmmmmm bup hmmmm

It misses like once every 5 seconds or so, so I doubt its compression. Im pretty sure my timing is all fucked up, so after I adjust it and do some other **** on tues, we'll see how well everything runs then.

 

Well this is a fresh rebuild so is this normal? I know low compression is normal for a rebuilt engine till its broken in but never heard about a rough idle.

 

Low compression is normal for a rebuilt engine using used housings.

In reality here im 'hoping' that the small amount of missing in our engines is due to timing, and not actual compression... If its compression, then maybe in my case its carbon buildup, if it aint that well ****....
In your case if it is compression, then yes, you'll have to wait till your engine breaks in before you can expect good compression again.
Hopefully one of the veterans will chime in..

 

Mine does the same thing, fresh rebuild also... mine has compression #'s in high 80's low 90's...

 

Check your timing. My rebuild was missing quite a bit, set the timing from "Way goofy out there" to "dead on" and it improved things a LOT.

Also, you might want to take a brush to your spark plugs. Especially the first few hundred miles, they tend to collect more junk than usual. Get a metal toothbrush type thing and just clean them up - I was able to notice a significant difference after cleaning them up.

-=Russ=-

 

i am unsure about the rebuild thing cause I got brand new housings but i never checked my compression. ill try the spark plug thing. Im gonna wait till thi either goes away or gets fixed before i try to install my MSD 6A. Ill take my first attempt at timing tomorrow. Time to read.....

 

the msd will most likely smooth your idle some... If I were you I would try it..

 

New spark plug wires helps out a lot to.
My FC calmed down a lot after new wires, now it only does it when its really cold.

Gil

 

How many miles on the rebuild? My rebuild did that for almost 1000 miles, then it kinda evened out. Try new plugs too. I went through several sets of plugs on my rebuild.