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Hawkeye PPP misfire when hot (no CEL)
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Old 08 Jul 2015, 08:09 AM   #1 (permalink)
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Hawkeye PPP misfire when hot (no CEL)

Hello all,
I've been a long time Scooby owner 2 Impreza's and a turbo forester, but this is my first real problem where I'm stumped...

My Hawkeye has been misfiring quite badly when hot (I live in France now and imported it a few years back).
On long runs it starts misfiring and gets very lumpy, sounding like it's only firing on 3 at best! As soon as things cool down again the next morning, no trace of the misfire and no CEL codes. I noticed a slight leak from the exhaust between the backbox and the centre pipe, but think this may just have been due to the juddering from the misfire.

It's a 56 (2006 for those of you outside the UK) plate Hawkeye with PPP, walbro fuel pump fitted recently, I just changed the MAF, and new plugs are going in next weekend. I cleaned the K&N air filter after the first misfire incident in case it was over oiled, and am running out of places to look.

Any ideas anyone?
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Old 08 Jul 2015, 11:53 AM   #2 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

was it mapped for the fuel pump
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Old 08 Jul 2015, 12:03 PM   #3 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

No it was already PPP'd when I bought it and the Walbro was fitted about a month back. I still have the original one, so a swap might be in order to see if the pump is at the root of the problem.

Getting it remapped over here would be a nightmare... even trying to find a decent Scooby garage is impossible.

The missfire only seems to happen when it's hot (air temps over here the past few weeks have been up to 35C) and on long runs with traffic jams, i.e. after sitting idling. I'm wondering if the lamda sensor is causing problems, the idle is normal and it starts fine.
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Old 08 Jul 2015, 02:03 PM   #4 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

prob a place to start
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Old 08 Jul 2015, 02:08 PM   #5 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

1st place I tell most people to start with anything temp related is try the CTS, cheap and a common problem.

hth
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Old 08 Jul 2015, 02:14 PM   #6 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

The CTS... ? Sorry, got brain fade this afternoon... Coolant Temp Sensor ?
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Old 08 Jul 2015, 02:30 PM   #7 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

Ok googled it... that looks like fun to replace!
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Old 08 Jul 2015, 02:47 PM   #8 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

Quote:
Originally Posted by Telemarker View Post
Hello all,
My Hawkeye has been misfiring quite badly when hot (I live in France now and imported it a few years back).
On long runs it starts misfiring and gets very lumpy, sounding like it's only firing on 3 at best! As soon as things cool down again the next morning, no trace of the misfire and no CEL codes.
It could also be HT leads and coil pack/s, I had a similar problem with my classic click here >> lumpy when cold, perfect when warm and I had to replace both, do not use cheap HT leads, either use Genuine Subaru or Magnecor, I tried cheap ones from a well known car parts store, when under load the engine completely lost power for about a second. Im using a genuine coil pack with Magnecor HT leads and never had an issues and that was over 2 years ago, probably due to be changed again lol.
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Old 08 Jul 2015, 03:02 PM   #9 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

Thanks guys, I'm going to do the plugs this weekend, so I'll go over the HT leads at the same time to see if nothing is dodgy there.
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Old 15 Aug 2015, 09:32 AM   #10 (permalink)
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Re: Hawkeye PPP misfire when hot (no CEL)

Fixed it with new plugs and coils, after getting the old ones out and seeing that the central electrode was done to almost nothing...
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