VN V6 Stumble / Bogging down

[Saintsinnerx]

Well after a very long hiatus due to some issues with a stolen car..
im now back with another v6 vn converted hilux 4x4..
car has been running and driving, doing it's blowing up gearbox trick..

Anywho, Jump to my currant issue and im chasing an issue

Car idles fine, runs fine until car is under load around the 1800-2500 rpm range.. then it starts to stumble and almost die then it perks right back up super quick and will go for 1-2 sec then stumble again until you let off, if you do not let off and you try to power through the stumble the car will backfire..

Replaced:
Ecu
Injectors
Coils
Fuel filter
Lines
Fuel pump

Car was running perfectly fine last night as did a trip from work > dinner > home so did around 120 ish ks round trip without a fault.

DFI plate or Crank sensor?
or something obvious im missing?
any idea's / input would be greatly appreciated

Engine swap was not done by me but car has been driving fine for around 6 months now ( except for the 3 blown engines / 4 gearboxes, but those can be attributed to Glass house mts and some very angry driving in mud. Pre snorkel )

['quipt4it]

Check the vacuum hose from the Fuel Pressure Regulator to intake manifold. Could also check FPR for proper function.
Also check the vac. hose from intake to MAP sensor.
Do you mean it is running fine otherwise apart from the issue?

[Saintsinnerx]

Check the vacuum hose from the Fuel Pressure Regulator to intake manifold. Could also check FPR for proper function.
Also check the vac. hose from intake to MAP sensor.
Do you mean it is running fine otherwise apart from the issue?

Was just outside tinkering again,
So Vac line to Map is on firm ( cant rule out perhaps pin hole? )
Vac line to FPR is brand new ( i had it pop off once and similar issue but 100% worse )

FPR ( end of fuel rail is 5 weeks old as i had an oring fail behind it so replaced it ( not cheap! )

Just had a friend drop off another DFI plate from a known working car and it's still doing it

so if i have the car in neutral then rev it ( no tacho so just guessing rpm range ) around the 2-2.5k mark it will start to break up and stumble.

If the car is hot, Issue is the same.
If the car is cold, Issue is the same.

When driving the car under load it's between the 1-2 shift around the 2k mark it will bog down and want to die but then perk right back up very quickly then will bog down to an almost die.
When the car is idling it does nothing weird and idles as it should.

car can be driven providing you 1-2-3-4 shift it below the stumble it will get to 60 and drive like it normally should.

Only thing not replaced so far is Plugs / Leads but both were replaced around about 2 months ago roughly with new, just pulled the plugs and they are all the same with the Ground strap nice and white / grey with minimal carbon build up around the plug base / threads. Electrode has no chips / pitting and all ceramic looks to be unbroken..

After today's fuel pump, injectors, lines im at a don't keep throwing money at it hoping to solve it when someone might be smarter then me lol
and yeah the car idles fine, shifts fine, temps are normal no smoke from exhaust, no bubbling in rad etc

['quipt4it]

...After today's fuel pump, injectors, lines im at a don't keep throwing money at it hoping to solve it when someone might be smarter then me lol
and yeah the car idles fine, shifts fine, temps are normal no smoke from exhaust, no bubbling in rad etc...

That's exactly why I didn't suggest replacing anything else, that's quite a bit of chasing.
Do all the basic check-thru's first

[Saintsinnerx]

...After today's fuel pump, injectors, lines im at a don't keep throwing money at it hoping to solve it when someone might be smarter then me lol
and yeah the car idles fine, shifts fine, temps are normal no smoke from exhaust, no bubbling in rad etc...

That's exactly why I didn't suggest replacing anything else, that's quite a bit of chasing.
Do all the basic check-thru's first

Yeah sadly works down my throat so fixing it today is priority as cant afford to have them drop me
But after replacing it all im honestly at a loss as to why it's doing this.. Probably could have bought and swapped in another vn / vp motor for about the same cost now..

[vlad01]

Did you check the ignition leads? They are normally the first thing that goes when you have a stumble/misfire followed by coils.

[vlad01]

Silly question, but assuming you had the DFI main plug off did you tighten the 7mm bolt on it?

I once did that on an engine swap and drove around days before it started kicking and backfiring. I was 70km from home and lucky I stopped near a bus depot as they let me borrow a 7mm socket and ratchet to tighten the bolt I forgot on the plug.

[Saintsinnerx]

Silly question, but assuming you had the DFI main plug off did you tighten the 7mm bolt on it?

I once did that on an engine swap and drove around days before it started kicking and backfiring. I was 70km from home and lucky I stopped near a bus depot as they let me borrow a 7mm socket and ratchet to tighten the bolt I forgot on the plug.

So leads, plugs i haven't done yet but looking like i might as well throw another 120 at it.

Yeah dfi 7mm done up as ive done that before too hahaha
ive also over tightened one before and cracked it slightly not thinking straight

[vlad01]

Just get a mutil-meter and measure the resistance of all the leads, I toss them if they are more than 10k, normally new they are around the 2.5-5 k mark depending on length.

[Saintsinnerx]

Just get a mutil-meter and measure the resistance of all the leads, I toss them if they are more than 10k, normally new they are around the 2.5-5 k mark depending on length.

ill go do that right now actually