Pending Cylinder Misfires

[Ihtisham Rauf]

Hi people,

Got an issue, I had cylinder 4 misfire fault code for a while. I changed the injector and it had sorted the problem - I had no cyl4 misfire fault code for a few days. Today started the car, left it idling for around 2-3 min (it idles nicely at around 250rpm so very low idle), and then checked the fault code reader and I have 'pending cylinder 4 misfire'. When I touched the exhaust headers, cylinder 1-3 were hot, and 4 was cold, indicating that cylinder 4 isnt firing?

Disconnected battery, swapped the coilpacks for cyl1 and 4, thinking that it could be a faulty coilpack. Also unplugged and replugged the injector for cyl4. Restarted car and let it idle for a few min, now all 4 headers are hot. Drove the car for a few min, now I have 2 pending fault codes - cyl3 and cyl4 misfire. Car drove fine though. I have driven on 3 cylinders in the past and I know what that feels like!

Am I right in saying 'pending fault codes' aren't a massive concern as its only happened once and the misfires aren't reoccuring in the engine cycles?
Maybe the excessively low idle causes misfire when the engine starts, but then its fine?
As for the cyl4 header being cold, I am stumped, maybe the injector wasnt plugged in properly...

Any advice is greatly appreciated.

 

[Ihtisham Rauf]

PS - Apologies for the recent bunch of 'i have a problem' posts. All these little issues are coming at once. But all advice is really helpful so thanks to the people who help!

 

[Ihtisham Rauf]

Just did a dry and wet comp test:

DRY RESULTS
138
125
130
135

WET RESULTS
125
135
160
154

So this means a worn piston ring in cyl3 and potentially cyl4? I'm guessing cyl1 was just an anomaly that I got a lower results after adding oil in.

This is what the spark plugs looked like after letting the car warm up to operating temp from cold, at idle.

 

[frank]

those pressures look pretty normal on a 20yr old engine ihtisham, its hard to get oil all over the bore on a wet test
that black #3 looks a bit like oil control ring issues imo, is the piston crown wet ?

 

[Ihtisham Rauf]

those pressures look pretty normal on a 20yr old engine ihtisham, its hard to get oil all over the bore on a wet test
that black #3 looks a bit like oil control ring issues imo, is the piston crown wet ?

Thank you for your reply Frank.
Before doing the wet test, the top of piston 3 looked completely dry. Piston 4 looked slightly on the moist side.

The fact cyl4 header was cold after letting the car idle for around 2 min is worrying, especially considering header 1, 2, and 3 were really hot. When I turned the car on again and let it idle to operating temp, then all 4 headers were (piping) hot. Cyl4 doesn't seem to fire at idle?? This would explain the cyl4 misfire pending fault code I am getting, but don't know why it wouldn't fire. Cyl3 misfire pending fault code could be due to the oil control ring as you say.

 

[Ihtisham Rauf]

I did a wet comp test a few days ago. I haven't driven the car at all since then, its sat at idle revs for a bit yesterday and now again today.
I checked code reader and am getting a pending P0130, this is faulty lambda reading for the 1st lambda sensor.
Is it possible for the oil that I used in the comp test is being burned and so its causing the lambda to alarm out with false readings?

Wondering it this has happened to anyone else in the past?