Vz sv6 misfire

[Vs statesman2003]

Vz sv6 has mis fire... used to only have misfire undeload eg between 80 and 100kms
Recently replaced plugs and coils and since then it has a rough idle constantly after about 10 seconds of running... any help would be much appreciated
Parts replaced
Throttle body
Plugs
Coils
Fuel pump
Fuel filter
Vacuum lines

 

[ant797]

you could google how to test the injectors on your model car test the tps clean the maf scan for codes 1st if you havnt

 

[Fu Manchu]

With a misfire, there should be a code set. What is the code?

 

[Vs statesman2003]

Tps is saying 14% at idle
And it has no codes which is why im unsure whats doing it... faulty plugs?

 

[ant797]

Tps is saying 14% at idle
And it has no codes which is why im unsure whats doing it... faulty plugs?

I once dropped a plug couldnt figure out why it was running rough turns out i droped it and bent the tab in closing the gap could take them all out check the gaps ...if not clean the maf doesnt always throw a code

 

[Big Red VF-SII Go-kart]

I have experienced this and other similar incidents with the VZ 3.6 Alloytec. And from my experience not a single one of the items you replaced were at fault. That's an expensive throw of money with no proven outcome.

An occluded fuel line or injector(s) can lead to misfires and stuttering from 70km/h-plus, and stalling if the car is travelling uphill.

One solution is to run premium unleaded (98, likely) for 2,000 to 3,000km at speed (not suburban driving). I am not a fan of 91 petrol in engines that can take premium fuel and make better use of it in the correct circumstances (consistently high speed open road driving).

Also immobiliser not fully disengaging and allowing fuel to to the engine, usually generates an Immobiliser Fuel Disable Signal Received error code (1632). This definitely gives rise to misfiring. And this item will most certainly show up on a scanner, though clearing it will not necessarily eliminate it if there is a physical reason for its persistence.

 

[ant797]

Occluded fuel line or injector(s) can lead to misfires and stuttering from 70km/h-plus, and stalling if the car is travelling uphill.
One solution is to run premium unleaded (98, likely) for 2,000 to 3,000km at speed (not suburban driving. Also immobiliser not fully disengaging and allowing fuel to to the engine, usually generates an Immobiliser Fuel Disable Signal Received error code (1632). This will definitely show up on a scanner, but clearing it will not necessarily eliminate it.

i have used nulon injector cleaner and some others they do work only one i had problems with is rissilone

 

[Big Red VF-SII Go-kart]

i have used nulon injector cleaner and some others they do work only one i had problems with is rissilone

Injector cleaners, fuel system cleaners, etcetera also leave their own residual after "clean up", and their efficacy is more of a placebo effect than one of proven improvement in economy or performance. You will also "dull" the engine with these cleaners, a bit like reducing the octane rating of the fuel in use. Commerical fuel injector cleaning usually "scouts" the engine to see if the injectors are at fault and do require a clean. Otherwise, a process of enquiry, test and elimination is followed, with no replacement undertaken unless a specific component is definitely at fault.

 

[ant797]

Injector cleaners, fuel system cleaners, etcetera also leave their own residual after "clean up", and their efficacy is more of a placebo effect than one of proven improvement in economy or performance. You will also "dull" the engine with these cleaners, a bit like reducing the octane rating of the fuel in use. Commerical fuel injector cleaning usually "scouts" the engine to see if the injectors are at fault and do require a clean. Otherwise, a process of enquiry, test and elimination is followed, with no replacement undertaken unless a specific component is definitely at fault.

I have noticed the tank you use the injector cleaner in doesnt last long but its only one tank full of fuel ..if i remember rightly the residue it leaves behind is a lubricant much like the additives they put in premium fuel lubricants and cleaners ..accept this is a drastic clean desighned to work andonly be used in one tank full

 

[Vs statesman2003]

Its already had injector cleaner through it... i havent driven it on the road since i put the new plugs and coils in as it made it worse