Hugh Jass

P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0304 Cylinder 4 Misfire Detected

Can anyone tell me what could be the cause of this.This has happened twice in my Forester and it only occured when driving quite slowly at around 40-50 mph. My car has a full H&S decat, TD04L turbo, and Andy F Tek 3 remap for about 2 years with no trouble beforehand.

Thanks

Alan

the_msp

What year is the car?

Coil packs?

Hugh Jass

Its a 2002, is there a way to check if they are gone or is it a case of just replace them one by one?

Cheers

Alan

the_msp

What conditions does it misfire under, when your boosting?

There's a way to check them using an ammeter through pin one of the coil and the head of the coil pack, search the gen tech section you should be able to find the subaru manual diagram explaining this (Amp reading should be within a certain range for OK coilpack...)

They generally crack on classics, which is highlighted if you remap and run higher than standard boost

the_msp

Here

https://www.scoobynet.com/drivetrain...coil-test.html

ohms test and ammeter test

Hugh Jass

The two times that it happened , i.e. just before the check engine light came on, I was off boost and doing about 50mph on the motorway. and I had the wife and kid in the car, both times, so I was not driving like a loon.

I have printed out the diagram and will get my mechanic to check them.

Thanks for your help.

Alan

Midlife......

iTrader: (2)

If the 2002 forrester uses any newage turbo components then it might be the neutral position switch...... Faults in this may give spurious misfires

Shaun

KelvSTi

iTrader: (12)

I agree with Shaun, sound like neutral position switch to me.

Kelvin

Hugh Jass

Off I go to do a search for a neutral position switch.

Cheers

Alan

Hugh Jass

Back from my search and having read previous posts it sounds exactly like a neutral position switch problem.

Thanks for the excellent help lads. I will get one fitted in about 2 weeks time when the car is in for service.

Alan

Jolly Green Monster

iTrader: (4)

You don't have to fit a new nps.. I'll PM you though as others seem reluctant (for good reason) to give out the info.

Simon

Midlife......

iTrader: (2)

Hi Simon

Out of interest I just wondered what you meant by saying people are "reluctant" to give out info ?

I'm not that technically minded but do try and help if I can

Shaun

Jolly Green Monster

iTrader: (4)

I make a living from mapping so doesn't effect me.

others make a living from replacing parts, servicing and fixing mechanical problems.. therefore they are reluctant to impact their income by freely releasing the info into the public domain.

I didn't want to annoy anyone but also like to help out where I can..

Simon

Midlife......

iTrader: (2)

Simon

Does this mean there is a "CEL fix" for a dodgy / failed NPS ?

shaun

Jolly Green Monster

iTrader: (4)

no

Midlife......

iTrader: (2)

Simon

Just checking LOL

Sorry to be a pain but looking at your post number 11 it seems you can sort this out without replacing the NPS.. is this the case ?

Shaun

PS I had a few misfire CELS (two cylinders only) which was due to a faulty Lambda sensor diagnosed by a mapping colleage of yours........the NPS might therefore be a red herring