Jump to content
CaddyInfo Cadillac Forum

Missing cylinder

Jan Olsson

Recommended Posts

I had some engine miss for a while now. The no 1 cylinder is weak.

When doing the cylinder balance test no 1 is mostly dead.

I have swapped with another plug, another ignition wire, another coil and another injector but no difference.

I have also cleaned the phenolic spacers, the EGR valve is replaced recently too.

I dont believe its a mechanic problem since it varies, sometimes the is a slight miss when I pull the plug wire, sometimes there is not. That leads me to some kind of electrical problem.

The only things that come in mind now is either the injector harness or the ICM.

Is it possible that a bad connection on the ICM could generate a miss on no 1 cylinder even when swapping between coils?

Link to comment
Share on other sites

Seems like I´ll have to do that.

I still hope it could be something with the electrical system because right after I put it all back together (after the injector swap) I was able to shut all eight cylinders off with the cylinder balance test and they all made about the same difference in feel/ rpm change.

After a couple of miles driving, back to square one again ;)

How common is it to loose compression because of burned valves, leaking headgaskets etc on the Northstar engine at 130000+ miles?

Link to comment
Share on other sites

  • 2 weeks later...

Hello again :)

I did a compression check and it seemed alright.

So it´s just a typical case of those annoying electrical problems that comes with age I guess.

I checked the battery cables and the engine grounds too and the battery has a small leakage at the connections. Only 4 years old that is. I cleaned them and the car did run a lot better. I propably have to replace the battery soon.

I will get an ordinary one with the connections on the top instead, they seem to last about 10 years and don´t get corroded that easy because the use of clamps on the connections.

Checked the spark plug gaps and the connections at the PCM, cleaned all connections at the ICM and for the injector harness. Will try to reroute the ignition wires and see if that makes any change.

Thought of O2 sensors but the values for left and right bank seems close to equal regarding cross counts time, short/long fuel trim etc so they are propably all right.

When I checked the plugs I compared the colours of them and they all seemed fine, including no 1.

I failed to mention that but the miss only occours in cyl. balance test mode . Hard to notice at idle. The only driveability problem is when cruising at just below 50 mph, then I can feel a slight chuggle, that goes away in third gear or when I disengage the converter clutch by touching the brakes.

I would simply just let it be if only I didn´t have noticed the weakness in cylinder balance mode.

The only other thing I notice is when (in neutral) I´m reving the engine it surges and just holds rpm even if I push the accelerator further. This occurs between 1200-2000 rpms.

Link to comment
Share on other sites

You get into the internal diagnosis via the instrument panel cluster.

From there you can disable the injectors one by one to locate an engine miss.

Check this


Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...