Will Coil Going Bad Cause Miss ?

orph · 08-13-2003, 08:58 AM

Have an '86 911 turbo that has has a bad firing cylinder. Installed new set of plugs, Magnecors, rotor, and distributor cap. Stll have the "miss". Would a slowly dying coil cause one cylinder to misfire ? Any other thoughts what to check next ?

afterburn 549 · 08-13-2003, 02:28 PM

generally when you have a secondary breaking dwn it will be more noticed @ load or higher rpm.
It will not be just one cyl. cause a coil effects them all.
probly a bad wire ,craked cap, bad plug.
chec your fual suply to as they booth can have the same eratic systems

RoninLB · 08-13-2003, 02:47 PM

Does the tack drop?
Is it a consistant miss?

orph · 08-14-2003, 03:05 PM

RoninLB:

Tach does not drop and the miss is constant. From what I've gathered, a bad coil will affect all cylinder firings. Not sure what to check next as plugs, rotor, distributor cap, and plug wires have been replaced and she still misses.

afterburn 549 · 08-14-2003, 03:32 PM

hook a dwell meter to it ,see if its constant. you have to suspect everthing because its the dumb thing that will get ya.
a compression test will verify if its the ign./ fual sys. or not.

Oracle · 08-14-2003, 07:05 PM

Hi.
In my case that was the problem, especially when my foot was off the gas.

I guess it was dying then one day the car stalled...
Next thing my car was getting towed.

So my suggestion is this:
Don't drive it (unless you have AAA) then buy that very expensive ignition coil and keep it handy.

Now with the new coil there are no misses at all...

Seriously get one and you'll save $$ on tow.

Bye
-J

RoninLB · 08-14-2003, 08:27 PM

Quote:

Originally posted by orph
RoninLB:
Tach does not drop and the miss is constant.
From what I've gathered, a bad coil will affect all cylinder firings. Not sure what to check next .

OK.. so a constant miss at idle..
maybe it's not the coil

I would pull each wire one at a time to see if you can isolate a cylinder.. so if you pull #1 and the rpms drop, that's not it.. you'll also have to listen carefully.
and new ignition parts is no garantee.. even new plugs can be bad. in leaded gas days it was easy to see a new bad plug.. maybe a plug will be wet because it's not firing.. and I hate the Beru connectors........Ron

Gunter · Gunter's Garage

When pulling wires off to isolate the missing cylinder, avoid getting zapped. It really packs a punch. Check the connector for the suspected cylinder?

RoninLB · 08-14-2003, 09:13 PM

Quote:

Originally posted by Gunter

. Check the connector for the suspected cylinder?

IMHO, Beru wire connectors suck............Ron

stlrj · 08-15-2003, 07:16 PM

At the risk of sounding stupid, you might double check your firing order.

Cheers,

Joe