GeorgeK

Me, that is.

bear with me:

'89 C4, 160 K miles. Car has developed a rough idle and seems down on power.
Rotors position checked - OK
distributor belt checked - OK
Distributor cap and rotors checked - OK
Ignition cables clean and sound, no arcing - checked by running the engine in the dark.
Spark plugs: new as of last week.

Car stalls when the primary (upper plugs) ignition is disconnected.
Car runs without change when the secondary ignintion is disconnected.

Coil resistance:
upper plugs coil: primary 0.8 Ohms secondary 5.82 K ohms
lower plugs coil: primary 0.7 Ohms secondary 6.02 K Ohms


Doesn't make sense to me. It would seem the coil of the primary set of plugs is bad (N: 0.4 - 0.6 Ohms?)

How can I check the switch units?

I am rather new to that type of work, and want to make sure I am not missing something.

964George

Hi George

If it stalls when the primary coil is disconnected then surely the secondary coil is faulty?
So when the secondary is disconnected car runs as primary is fine...

My tuppence
Cheers

George

HiWind

I'm in the same place ... Thanks for braving the waters ... Want to find out how to 'mist'
And how to check - per lorenfb- if spark is blue and long, not yellow/short
W/o shocking myself!

Vandit

When isolating the coils, you're doing this by disconnecting the ignition module, correct?

Misting the wires is exactly what it sounds like. Get a water spray bottle that shoots a fine mist, turn on the car, turn off all the lights, and mist the engine compartment. Please be very aware of all the rotating parts as you maneuver around the running motor in the darkness.

Indycam

You have two of a bunch of parts ,
switch part A for part B
does the problem follow that part ?

HiWind

George ... Your question makes me look like the dummy! I hope you don't mind me asking my question here as it's on topic ... As you're Swiss I'm going to assume co-operation is inbred

Yes Vandit and thanks .... The car idles with the front one of the two ignition module plugs pulled - ie the one just below the actual coil - but stumbles and stalls if the rearward one is disconnected.
Should I be pulling the actual coil plug wire (beru) off the coil itself instead?

Thanks for the direction on misting - is it just a route to working out if any plug wires are damaged? How close do you need to get re your warning about moving parts - I thought I'd just stand back and spray a fine mist over the left then right engine bay with the bottle just about where the decklid is when closed... But I guess you mean underneath too re the plug wires on the lower valve covers (which I'd forgotten about and they're more likely to have had a knock seeing I don't run the engine tray). But either way, good point ... Don't want my engine fan red for that reason!

Indy ... Teach on! Much appreciated to see you popping up on the update message.

newsboy

I was having electrical problems, my coils tested 0.0 primary, and 5.2 & 5.4 secondary, within limits.
Coils can have internal faults that don't show up in testing. If there old, you might want to change them.

GeorgeK

Update:

further testing showed that removing the connectors from the ignition switches lets the car run on each set of plugs....

So removing the wire from the coil to the upper distributor doesn't let the run car on the lower plugs, but pulling the ign switch to the upper plug coil allows it?

Gets weird.

From this it would seem I have spark on both banks? need to test with a free plug.

boxsey911

Your symptoms are the same as those that mine developed. Plus some stalling. We then found that a hall sensor failure code was logged in the DME. I then unplugged the hall sensor connected and drove the car around. The symptoms were exactly the same with it unplugged. So the distributor was removed and refurbished. It's now running perfectly again and the fault code has not reappeared.

GeorgeK

No fault code on the Bosch hammer.

It starts with either switch unit disconnected, but won't start with the primary distributor to coil wire pulled.
It starts with the secondary distributor to coil wire pulled.

I am stumped, but since it now seems to fire on all plugs, I won't complain. At least while troubleshooting, I cleaned some very dodgy connections and grounds.

HiWind

found this thread worth reading - my problems have tended to be quite simple ones in the past like the door light ground and relay etc... have a read

https://rennlist.com/forums/993-foru...ed-solved.html

and this of Pelican ..
Originally Posted by john walker's workshop
"pull the plug from each ignition module, one at a time, while the engine is running. they're on the left side of the engine compartment. pulling the coil wire can damage the fragile ignition electronics.
if the belt is broken, leave the module for the belt driven distributor unplugged if you have to drive the car before it's fixed. that way there isn't a constant spark to whatever wire the rotor happens to be stopped at. it also won't fight the starter."
distributor-belt-check-done-right.html

HiWind

And another detailed post re leads

https://rennlist.com/forums/10971229-post58.html

GeorgeK

Final (?) update:
After taking all apart, cleaning every connection, I have spark on both upper and lower cylinders. I also found a cracked plug connector that was arcing on the cam cover. Repaired that.

It all works fine now. Questions remain unanswered but since it works, I won't complain:

-Are the resistance values of the coils as written on my first post above within normal range?

-Why does it run on lower bank of plugs when the upper plugs ignition switch is pulled, but *not* when the upper coil cable is pulled?

greg1990964

I had a similar issue that I posted about a lot. I replaced coils 3 times, wires, etc. When I dropped my motor to do a clutch I noticed the positive batt cable from the starter that runs to the frunk was chaffed from rubbing the engine bay at the front of the motor and couldn't see it. I figured driving around on old motor mounts may of caused the insulation to wear off. I believe that was my problem. Just something to think about.
Notice the red wire, that is the batt cable after the black insulation wore off. You can't see it, but there was also exposed wire showing. I wrapped it up with the heat shrinking tube for wires and electrical tape. Problem solved.

greg1990964