Vx out of ideas

[trekking]

Hi brains trust,

Long time lurker here first time poster.
Have a vx 2002 wagon, last 2 year has been an absolute nightmare still haven't found the issue so putting it out there for suggestions.

Idles absolutely fine but as soon as you put light pressure (or slow speeds near roundabouts etc) you can feel a miss. This isn't much of a problem as I just deal with it but when it gets hot it cuts out completely mostly on approach to roundabouts when i lift my foot off the accelerator.

On the freeway or fast roads is fine as you can still see the tacho blipping up and down but it's getting fuel into it so it drives ok. I had 4 mechanic look at it and say they can't see anything.

I'm totally out of ideas.

Changed the
Cam
Crank
Idle
Maf
Sensors

Cleaned plenum , changed fuel pump
Anyone with same problem? Or ideas what it could be?

 

[Ginger Beer]

Fuel filter? Fuel pump going out?

Lose wire or bad connection somewhere?

Start at the battery and finish at the firewall.

Unplug everything and check every wire and connection, clean them if required and spray some dialectic grease on them.

Old cars with hard wiring from engine bay heat and corrosion in connections from water is a thing.

I use dialectic spray whenever I touch wiring connections.

https://www.motortrend.com/how-to/what-is-dielectric-grease/#:~:text=See all 4 photos Since,excess of 500 degrees Fahrenheit.

I also spray silicone spray on everything in the engine bay, hell, I spray silicone spray on every part under the car (no...not the brakes)

Fuel filters are a cheap shotgun approach to fault finding surging issues, when was the last time you changed it?

 

[lout]

sounds like high voltage ignition issue
what codes if any
check/swap with known good dfi module and coils
replace sparkplugs with ngk. genuine from auto parts store, not ebay
was crank sensor genuine

 

[_R_J_K_]

Haven't tried leads yet? That's a pretty basic and easy one for ignition.

Done any tests for vaccum leaks?

 

[trekking]

Changed leads spark plugs all genuine, changed dfi 3 times







Looked for vacuum leaks,







Changed fuel filter 2 times and fuel pump















Would a high voltage ignition cause a car to cut out? If so how check for this,

 

[gtrboyy]

You ever checked fault codes or anyone put a scanner on it?

I'd be looking at all earths & power looking for dirty or loose connections & going over everything...probably something silly that has been overlooked usually something somebody has done to the car caused it.

 

[Pollushon]

As above a scan is the place to start. Some CELs might be a flicker you don't notice

Assuming an Ecotec there are two issues I've had in that category. The alternator high tension lead is a tight squeeze and can rub off the sheathing between the bracket and the manifold so you get little shorts in low rev conditions when the engine rocks. The other is the IAC where the TB port is a bit clogged and the stepper is a bit old so she gets a bit clunky been throttle off/on conditions at low revs

 

[Ginger Beer]

My last intermittent electrical fault turned out to be a lose negative coming off the battery

I also had a new crank sensor faulty out of the box, apparently it was wired backwards

 

[lout]

was crank angle sensor genuine
carefully check wiring between crank sensor and dfi and plug connectors between crank sensor and dfi
what about throttle position switch, has that been checked, may have a dead spot and going into flood clear

 

[trekking]

No codes as no one could read any and the nrma guys wouldn't connect 3 different times.

Would it throw a code even without an engine light?



Everything genuine it really does feel like something a bit loose electrical wise. Is there a link here to check for spark? I've taken the boots off the 3 dfi at the top before and one module wasn't sparking between each other. So I changed it and still same problem.



There was a nic in the wiring where I believe someone cleaned off the gasket for the thermostat housing and slipped cutting into the harness. I taped this up but maybe it's getting some heat sink through this area.

Would it be worth just paying an auto electrician to rewire a new harness in? I

Lout do you have a link for tps I couldn't find to test?