Petrol D22 misfiring?

[Lhaydnc92]

Hey all, im new to this forum and have been having a problem with my 2003 3.3L Petrol D22.

It started happening suddenly a couple days ago, the engine seems to misfire or jerk when under load. Its not at all consistent or in any particular gear or rev range as far as i can tell.
Ive replaced the fuel filter, spark plugs and leads.
I took it in to Auto Masters who scanned it with no results but serviced the injectors and throttle body.
All ive found online so far have been for Diesel engines and the other threads on here dont seem to be too helpfull for my issue.
But any help would be much appreciated as i am out of ideas and would preffer to fix it myself if possible than throw more money away on getting it looked at without the problem being fixed.

Kind regards
Luke

 

[phxeent]

Pretty much all issues relating to your problem are either fuel or electrical. Perhaps an earth continuity test (Multi Meter), some crappy fuel maybe. Also a Sensor, or cat converter. U will find Scan tools are well less than 100% accurate.

 

[Old.Tony]

^ Electrical gremlins could easily be the cause, especially if the problem is intermittent. Consistent (repeatable by following a specific process) problems are easier to diagnose.

Spark plug leads have been replaced, but what about coil connections (coil earth) and distribution?

Under a load, it's quite possibly a fuel issue, I'd first think blocked filter or tank pickup through debris pumped in at a servo, but if you've had a long range tank added or work done under the car, a crushed fuel line may also cause this.

It's also worth looking at things like EGR which could flood the intake manifold under load.

 

[Lhaydnc92]

Just an update..
It only does this when the engine has warmed up after a bit of a drive..

Checked the NPS and EGR today but they are not the problem :-(

Any aditional ideas would be greatly appreciated as this is getting really annoying!
Thanks

 

[Big Mick]

Spark plug lead is earthing out. Maybe a new set! One little crack in the leads will result in a miss fire.

 

[nathand22]

Just an update..
It only does this when the engine has warmed up after a bit of a drive..

Checked the NPS and EGR today but they are not the problem :-(

Any aditional ideas would be greatly appreciated as this is getting really annoying!
Thanks

how did you check the NPS?
the best way is to unplug it and leave it unplugged then go for a drive, if the problems do go then leave it unplugged for good.
there was a few other ways to do so called "tests" but i have heard of that not working in some cases, so again the best way is just unplug it and do away with it

 

[sparra04]

vacium hose leak?
check for perished and cracked lines

 

[Lhaydnc92]

how did you check the NPS?
the best way is to unplug it and leave it unplugged then go for a drive, if the problems do go then leave it unplugged for good.
there was a few other ways to do so called "tests" but i have heard of that not working in some cases, so again the best way is just unplug it and do away with it

That is how i checked it. I read some of the other threads on this forum to find out how to test it.
Was really hoping it would just be the NPS

 

[Black_Outlaw]

I'd say a cracked / corroded lead or wire..

Electronics fail more when they are hot than when they are cold.. Check your earth straps, battery connectors and any earthing points.. undo the earth, clean, re-tighten..