No power + Struggling/Laboring at low RPM

[mulligan-can]

Ok, my VS Ute out of the blue started laboring and jerking at low rpm (below 2.5k) and also lacks power (slow to accelerate even in 2nd with throttle wide open).

The engine seems to run fine when the vehicle is in neutral or park. It also runs fine when cruising at 2.5krpm + with minimal throttle open.

The moment the car comes under load it starts jerking (the engine), sorta like its missing or running really really rough. Like when you've got a manual running too slow for the gear you're in.

I thought it might be the fuel filter but I just changed that and there is no improvement.

A side not however, when I was changing the filter no fuel poured out once I disconnected the filter. I switched the ignition into run and the pump was able to push a fuel out easy enough (didn't seem to be a lot though, the fuel pump on a vl i used to own pumped more out when stuck in a bucket of fuel).

When the fuel filter is removed fuel is supposed to run out right? There is about 2/3 of a full tank there.


Any help would be very much appreciated. In it's present state the vehicle is just not usable and I really really need it back on the road ASAP.

Thanks!

 

[HARVZ-6]

sounds more like a spark issue to me especially since its missing under load,,

if it was lacking fuel pressure it would struggle at higher revs ,also

id be checking plugs and leads mate

 

[mulligan-can]

Hmmm. I discarded spark out of hand as the leads n' plugs were changed at the last service only 5000km ago. And the coil packs less than a year old as well (or so I was told when I purchased the vehicle)

 

[HARVZ-6]

its all worth checking mate

generally when theres a miss underload its due to spark issues

 

[hako]

Fuel should have sprayed out when you changed the filter indicating there is pressure in the line - if it didn't then it could indicate the fuel pressure regulator is stuck open and fuel is being supplied to the fuel rail/injectors at a greatly reduced pressure - maybe this is the cause of your problem. I've found that even after following the instructions to "de-pressurise" the fuel system that residual pressure in the lines will still cause fuel to spray out. Also I've found that fuel will not 'syphon' out with the filter disconnected unless you have a near full tank (sedan).
To check this you could loosen the fuel hose to the filter just after turning off the car - the fuel should start leaking out till the pressure is reduced.
The symptoms of reduced fuel pressure can vary with problems at low or high revs (injectors squirt more at high revs)

 

[mulligan-can]

Fuel should have sprayed out when you changed the filter indicating there is pressure in the line - if it didn't then it could indicate the fuel pressure regulator is stuck open and fuel is being supplied to the fuel rail/injectors at a greatly reduced pressure - maybe this is the cause of your problem. I've found that even after following the instructions to "de-pressurise" the fuel system that residual pressure in the lines will still cause fuel to spray out. Also I've found that fuel will not 'syphon' out with the filter disconnected unless you have a near full tank (sedan).
To check this you could loosen the fuel hose to the filter just after turning off the car - the fuel should start leaking out till the pressure is reduced.

No fuel leaked out till I had the fittings fully disconnected. And then it only just barely dribbled out. That was after just running the car though and I didn't prime it again before taking the fitting off.

I just double checked by priming it and then loosening off the fittings and well, all I can say is thank god for safety glasses.

Ok, so it's not the fueling system. That leaves spark. Cool.

Also, could the transmission be causing this sort of issue?

 

[cxcxcxvcvcvc]

Try this mate,
With the engine off, remove the first 2 leads of the first coil pack and then start the car, a spark should be jumping from metal tip 2 tip on your coils, if the spark jumps anywhere else (like downwards or onto any other part of the coil) then that coil is fualty and needs replacing! Either way mate hope ya get it sorted & best of luck:thumbsup:
Edit: obviously if the first coil pack is fine and works well then turn the engine off, replace the leads and move onto your 2nd then 3rd coils

 

[hako]

No fuel leaked out till I had the fittings fully disconnected. And then it only just barely dribbled out. That was after just running the car though and I didn't prime it again before taking the fitting off.

I just double checked by priming it and then loosening off the fittings and well, all I can say is thank god for safety glasses.

The fuel in that line immediately after turning off should be at about 35 psi - greater than the air pressure in your tyres - it will spray like a pressure pack....dont smoke!!
Good Luck.

 

[mulligan-can]

Try this mate,
With the engine off, remove the first 2 leads of the first coil pack and then start the car, a spark should be jumping from metal tip 2 tip on your coils, if the spark jumps anywhere else (like downwards or onto any other part of the coil) then that coil is fualty and needs replacing! Either way mate hope ya get it sorted & best of luck:thumbsup:
Edit: obviously if the first coil pack is fine and works well then turn the engine off, replace the leads and move onto your 2nd then 3rd coils

Dude you rock. One the coils is rooted. Thanks a lot everyone very very very much appreciated. I'll track one down tomorrow and see if that fixes it!

 

[2khamisj]

Theres a similar trick to the one above to check if one of your leads is rooted, take a spray bottle at night and spray mist around the heads of your leads to see for any spark jumps.