1997 D21 Ka24 Help!!!

[Dotty620]

Ok so my dad has a 1997 Nissan pickup. Ka24b engine, 5 speed 4x4. 165,000miles. I am chasing a ghost. About 4 years ago dad started complaining about this cutting out and choking problem, especially when going up and down in elevation. Seemingly does it at random. I've been chasing this for years now and it has progressed to all but undrivable. She idles rough, between 2-3000rpms she is just choking on herself, sputtering and struggling to run. She will start to smooth out as the rpms increase from there. She bucks and sputters under load and has no power.

I am a professional mechanic so let's start with what I've done so far. Full tune up, plugs, wires, cap rotor, all new filters. I replaced every vacuum line in the truck, then smoke checked and found no leaks anywhere. New EGR valve installed. New PCV. Fuel pressure is spot on spec, regulated or not with no leaks at the preasure regulator. Replaced regulator. Removed catalyst from exhaust all together to rule that out. Modus gave me codes for absolute manifold preasure. New OEM map and maf sensor installed. Code would not clear, ECM had what looked like a bad prom chip. Replaced with known good part. Throttle body removed and cleaned. Still no change.

Live data stream gives me nothing. Everything I throw at this thing, nothing. I ordered a new distributor out frustration, but I am beginning to think thing damned old truck can't be fixed. New battery and all grounds cleaned and inspected. Cranking compression 165psi. I will send a 6 pack of cold beer to the person who figures this out!

[AZhitman]

Have you tested the swirl valve solenoid and actuator that flips the butterfly valves inside the lower intake manifold?

[Dotty620]

I'll have to look into that one. As far as I can see the intake is a similar looking unit to a carb manifold from the old NAP Z days. It has a throttle body and some other sensors for the injection and emissions, but appears to be a one piece unit.

[AZhitman]

There's an upper and a lower half.

https://repairpal.com/what-else-can-it- ... roblem-605

[whomadewho]

Great thought Azhitman. Might also want to check the fuel line located towards the fuel tank for a cracked or a rusted line Fuel tank maybe rusted out.. I assume you replaced the fuel filter? Check the plug that goes to the distributor for a poor connection or a bad wire. . How much engine vacuum. Check ground wire at the ECU. There is one located next to the ECU and one behind the kick panel (passenger side) Sounds like if you send the beer there will be a few cans missing?

[whomadewho]

Another thought... Check for excessive play in the timing chain.