2006 Nissan Altima Inline4 | Rough Idling, Stalling and Low Power

What: Rough Idling, Stalling and Low Power happened when my gas tank went quarter and refilled at the Gas station.
Mileage is poor also. It usually runs around 450km per tank, now its around 300km per tank!

History: Got overheated one time when I'm driving back home. So i drove slowly for 2miles then shut-off the car. Waited to cooldown and put some water in the radiator tank then temperature went back to normal. After this, i got my radiator clean because it was blocked and no more overheat from then on.

Here's what I have done with my car so far as part of my DIY.


Replaced my fuel pump and injector, now fuel pressure around 50psi when Idling. Stalling issue solved.

Still rough idling was there and Low Power.
I check and fixed the vacuum leak in my intake manifold. Replaced the hoses and replaced intake manifold gasket. Replaced the cracked exhaust manifold also. Replaced my PCV and its hoses also. Half the engine power is back! Reset the TPS memory and relearn it.

Current: Cylinder 1 and 4 are firing good. 2 and 3 are barely contributing power to the engine.
2 and 3 are barely contributing because every time I disconnect the ignition for 2 or 3, engine vibration changes a little.
I also observed this when I am driving it.

1. Every time I put it on D, RPM will drop and Engine will strongly vibrate at idling. It will also accelerate normally around 2000rpm.
2. When I engage the A/C, it will strongly vibrate and cut my engine by almost 1/3. It will normally accelerate until I do it at 3000rpm.

All injector are firing - Line continuity from connector to PCM pin is full. Constant voltage is present for all line tested with test light. Test injector driver signal with testlight for all cylinder is OK.

All Sparkplug have spark.

To avoid having a bad ignition coil. I tested it with good sparkplug and ignition coil with my buddy car(same model 2006 Alitma) same result. Result is still the same.

Unfortunately I watched this too late from ScannerDanner regarding Misfire. My car cranks long and it sound funny. Not because of weak battery but because of compression.

Now I will do some compression test on Cylinder 2 and 3 for possible leak at the piston ring, valve seal and cylinder gasket. as soon I get the gauge.
Oil is good, no mixture from the coolant.

My question is does having a low compression on 2 adjacent cylinder will make my Car rough Idle like having no spark or fuel at 2 adjacent cylinders?

Thanks in advance for your help guys!

Yes, if the two middle cylinders have low compression, the engine will misfire. This head gasket is from a PT cruiser that had lower compression on 1&2 (and therefore lower contribution)than cylinders 3&4.
The relative compression test on the Verus in the background showed the misfire was the result of lower compression, and a leak down test proved 1&2 were leaking compression between each other via the head gasket. If memory serves the cylinders were: 1)140psi 2)140psi 3) 170psi 4)170psi
(No worries about the duplicate post, happens a lot )

Thank you. Same as what you told me. I did the compression test today after having the tester.

Cylinder 1 and 4 were reading 150psi.
Cylinder 2 and 3 were reading 20-25psi, even after putting oil!

If only I knew it was compression issue earlier, should have not wasted those days going from here and there. xD

Everyone who's worked on engines long enough has been down that path, trust me.
Since you have a known bad at your disposal, try a clear flood crank (accelerator to the floor & crank engine over) and listen very carefully to the sound pattern of the starter moving the engine. Then try it on an engine that doesn't have low compression. Get used to hearing that uneven cranking cadence and you won't end up going down the rabbit hole as often