vt loses power under acceleration, shudders/struggles to pick up speed...

[CV6Z]

in the last week ive been having some drama's with my car its a VT V6 auto, im not sure whats going on but it seems to struggle under acceleration...very noticeable when going uphill put my foot down to give it some and its as though it has wet spark plugs - shudders as it picks up speed...but when coasting along its fine!!!! its only when you give it some that it shudders...

im thinking it could be the fuel pump playing up? as in not being able to pump enough fuel through when you accelerate up to speed???

though when i was coasting along i put it in neutral and gave it a few revs and it doesnt happen...its only when its in drive. could this be a sign that the gearbox could be the fault?

or should i be replacing spark plugs and leads? coil pack?


im stumped, so any help is heaps appreciated

cheers

[Tree cutter]

Sounds like plug leads to me. Very common problem

[CV6Z]

plug leads hey. will look into getting new leads this week n see if it still has this shudder problem....i hope its only plug leads..

[Finnrizell]

Mate my vt is doin the exact same thing please tell me u figured it out???

[graham7773]

My VT was doing the same thing and I just noticed that this thread is 4 months old. Have you fixed the problem yet?

[Finnrizell]

Grahem mate mine is doin the same thing do u kno tha problem is?I've changed the Fuel filter the plugs leads coil packs and module MAF and it is still shuddering??

[slowandlow]

check the injector o-rings are ok. maybee air is sucking in through the bases.

[Finnrizell]

Tha fuel injectors ay?? Have u fixed it's mate?

[Brett_jjj]

Id say it would be the plugs,leads or if they are ok,one of the 3 ignition coils.These coils can run fine with no misfire or spluttering until they get put under load (going uphill or when accelerating fairly hard) then they can break down and cause the misfiring or spluttering.You can test the 3 coils with a multimeter,but Ive seen them show to be ok,but still cause misfiring. I keep a spare new coil just for testing purposes,just get the good coil,and swap it with the 3 coils ,one at a time, and drive it each time,if the problem goes away,then that coil that was removed is the problem.Its best to replace all 3 coils at the same time.Ive found fitting 3 new coils makes a big difference to the starting ,running ,and fuel economy,even when the coils are not faulty and are just old.They must slowly loose their performance over time until they get to a point where they die and cause mifiring.

[Finnrizell]

I've already swapped the whole coil packs and module wit 1 frm a VS I ave sittin ere it still doin it ay I dnt get it I'm thinkin fuel blockage ay would that course misfiring under pressure like it is ay

[Brett_jjj]

Yeah,if its definitely not the coils at all,then look at the fuel system.Fuel filter,fuel pressure regulator or the fuel pump.Id get the fuel pressure checked,but first thing,replace the fuel filter.Also there might be water in the fuel tank,it can cause crook running etc.You can throw a cup of metho into a quarter of a tank of fuel.The metho wont hurt anything,and it lets the water mix with the fuel so it can be consumed in the combustion process along with the fuel instead of it just sitting there in the tank and stuffing things up.

[Finnrizell]

Yeah tha first thing I did was change tha fuel filter but no luck . Anotha bit of helpful info could be I ran out of fuel bout 2 weeks b4 it started appenin. And would u no wher tha fuel regulator is?wars it look like ?

[Brett_jjj]

Its at the end of the fuel rail at the rear of the engine.Its about an inch or so round in diameter.Also the fuel return line goes from it back to the fuel tank,it has a vacuum line connected to it as well.Also running out of fuel can stuff up these fuel pumps,they use the fuel to keep cool,and they can overheat when run dry.It might be worth looking into if you dont find anything else wrong.

[db_notso]

plug leads hey. will look into getting new leads this week n see if it still has this shudder problem....i hope its only plug leads..

buy a ten dollar multimeter from jaycar
on ohms check lead resistance and you can check your coil packs resistance
if unsure if this shows you which is shagged post readings on here and we'll tell you if ok

also replace your fuel filter can clog up causing this fault

next would be stalling the car in drive foot on brake (stopped car)
if you get a shudder doing this likely to ba misfire
check
plugs
leads
coils

next I WOULD check for codes stored in engine ecu (need scantool drop in to a holden about 45 bucks i think get a copy of what they find and post it on here
they will probably try to sell you a fix for it if so find out what parts it needs and check if you can fit it yourself)
then fuel filter and pump (this requires a fuel pressure test and comparing to specification)

if none of these check if wiggling the wires under the coil packs (has cover and a little bolt throught it) causes it to miss if it ddoes replace dfi module

[tonyrevjet]

Hi,mine is doing the same on LPG or Petrol.Funny it starts cold & runs ok,but once warm starts this problem.Once at speed when I put my foot down again its like the front wheels are about to fall off,its that bad.Have replaced,coils,Leeds,plugs,filters,but no joy.Slight burning smell,but can't find any source.Vacuum hoses are intact.....Help.

[vxcustom]

I'm having the same issue with my vx v6 auto and I've managed to narrow it down to a problem with the rings in number 2 cylinder. Are any of your plugs fouled when you pull out. Do they all look the same or is one completely different?

[3N1GM4]

I changed my plugs n leads last night and also took the coil packs off and durin the process my drunk mate decided to drop a coil pack on concrete aswell as loosing a screw, i tested out the new plugs n leads when done and found that its splutterin when pushed hard so im guessin the coil pack may now be faulty, right? Does someone know a reliable place to get a new set!

[CV6Z]

Well im back everyone, been absent for a year as i sold my VT and bought another car... now ive gotta VX Acclaim =)

I remember posting this thread and from memory im pretty certain it came down to a faulty fuel pump. I replaced the pump and car was in good form again!

The car wouldnt start at times and i had to hit the tank to get the car to start.. bought a new fuel pump, replaced it and the shudder was gone... pretty sure thats what the outcome of my problem was anyway..