M35 Misfiring Still

[ddrallystagea]

Hi all

Still got a grumpy stag...

My 2002 M35 VQ25det had a wicked miss in it, replaced the coil packs and it was great for a couple of days, then it came back exactly the same. Replaced the coil packs again and same thing, fine for a couple of days then the miss came back just as bad. New plugs have been put in, and all the piping checked and it looks fine.

When at idle, it hiccups intermittently, and under acceleration feels okay until it comes on boost where it feels like it's running at about 80% power. It's running better than it was before I put the new coil packs in, but still down on power and not happy.

It still sounds like ignition to me. Thoughts? Crappy coil packs? Would the BOV affect it like this? Stuffed turbo?

If anyone has a set of totally stock coil packs that they are willing to part with I'll try that first.

I'm near Parramatta, but am willing to drive to a Stag guy to get this fixed. It's driving me up the wall!

Any help would be greatly appreciated!

Cheers

Andrew

[scotty nm35]

What plugs did you install, and at what gap? I have never had an issue on my stock coils, they are bulletproof. I would say you have a wiring issue or similar.

Go see Craig. Try a new ecu and coil harness perhaps.

I wish I could plug the consult 3 into it for you, it makes for very easy diagnosis for these types of issues as you can switch off each coil individually.

[Jetwreck]

I'm in thornliegh if you want to stop around..........I'll be around most of the day today.

call if needed 0406754304

[de-longhi]

Did anyone manage to get to the bottom of this issue?

Mine is basically doing the same thing, hiccuping at idle and a slight lack of power through ther rev range. Basically have done the same as ddrallystagea, changed coil packs and spark plugs with slight improvement for a day or so but the issue quickly returnes.

Craig, you mentioned a 'sensors on the back of the head.' was that Andrews problem in the end by any chance?

thanks for any input guys

[rosella]

My did the same after the AFM was replaced.

My local mechanic found the o-ring on the fuel pump was leaking and thus the pressure was down particularly when coming on boost.

[scotty nm35]

You have a good mechanic Russel, I would have never thought of looking there without a LOT of head scratching.

Daniel, can you reset the ecu using the manual method? See if it gets better for a short while. If so, you could have a stuffed o2 sensor. Realistically it could be anything though.

[de-longhi]

thanks guys, ill have a look at those couple of things, give the ecu reset a try and yet ya knopw how i go. fuel pump would have been the last palace i would have checked

much appreciated

daniel

[rosella]

@Scott, the mechanic, owner of Steve's Auto Barn does work on el-president Terry's cars. Terry actually recommended him. I'm impressed with his ability. He even rang a friend to ask advice about the M35 when he wasn't sure.

He found the leak when replacing the fuel filter.

[de-longhi]

hey guys

Just thought id give an update on this issue with my car as it is finally sorted… Turns out 2 of the 6 new coil packs I bought (off a US ebay seller) were DOA.

In the end put 2 of the old coils pack in and had to replaced the two corresponding spark plugs but she’s finally running smooth again.

So went from a 1 cylender miss to a 2 cylinder miss and a lot of head scratching due to the fact all coils and spark plugs were changed the first time round. So I guess the moral of the story is don’t buy cheap crap on ebay when its important.

Edited October 14, 2013 by de-longhi

[Daleo]

Great result Daniel; good on you for getting back to the thread for an update.

[scotty nm35]

The old stock coil is most probably fine, I have never had an issue other than dirty boots causing arcing.

Thanks for the update Daniel, I agree, stick to the stock coils.