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Urgent help needed - misfired, died, wont start

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Last night I was joining a dual carriageway and had to put my foot down in second, I don't usually redline it but on this occasion it just hit redline and immediately lost all turbo power, the dump valve would no longer dump, all I got was wastegate flutter. The boost gauge had a fit and was fluttering so quickly I could barely see the needle (it was only fluttering over a small measurement, probably a 1-2mm's) I managed to cruise about 3 miles to the next exit in 4th gear, as soon as I slowed it started to die and ended up dumped in a parking space.

When I tried to start it, it just about started up with a bit of throttle, it misfired terribly and stalled. Every time after this it got worse until the point it ended up on 1 cylinder before dying and now won't start at all.

There was no CEL, I did an ECU reset via unplugging Battery, I also checked all hoses, pipes and connectors by eye/hand and can't find anything obvious. There was and is no oil or coolant leaks anywhere that I can see. 

I was thinking fuel pump but I can hear it priming when ignition turned on, it just feels like there's no fuel getting to the engine. I also thought could be a bad spark or a coil pack or maybe MAF but would any of these fail so suddenly and cause these symptoms?

Does anyone have any ideas where to start diagnosing this?

I'm supposed to be at work 60 miles away tomorrow and with it being christmas day I cant even use public transport or get a hire car 

Thanks in advance.

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It's a 2000 X reg. It recently had new turbo housing and brackets as it was cracked, and some cracks welded on the downpipe. It was smoke tested and the dump valve was leaking badly so that was replaced also. The guy who did the work is a trusted Subaru specialist and he did say the cam seal has a slight leak, work was planned for new timing kit, water pump etc in January. 

It's apparently been remapped but reads standard boost, although I don't know if the boost gauge reading is correct so it could be boosting more.

It has FMIC and dump valve, Decat, yellow injectors, samco hosing and an aftermarket air filter.

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Also forgot to say it was throwing up MAF and O2 sensor codes for the last month or two. I had the MAF cleaned and it was ok for a while but the codes have come back. It used to run without stalling when MAF was unplugged, if I unplug it now it makes no difference and still won't start.

Could an O2 sensor or MAF cause the car not to start at all?

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If the boost gauge is reading correctly, its probably running the standard map . As I've never seen someone go to the expense of getting a car mapped and not having the boost limit raised?

With those breathing mods and a standard map , the ecu would struggle to compensate the fuelling and timing adjustments needed to reach the o2 sensors targets .

Both that and a unmetered volume of air entering the engine (ie intake/boost leak) can confuse the maf , map and o2 sensor readings and flag a code

Sent from my SM-G930F using Tapatalk

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If you do find a intake / boost leak and have to drive it again , get it ecutek mapped or put it back to standard downpipe and tmic . If the fuelling is lean under boost the engine will eat itself and cost a lot more than a £600 licence and remap

Sent from my SM-G930F using Tapatalk

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I have checked all I can at the moment and nothing obvious. The FMIC pipe popped off once and it had very similar symptoms but it still idled even though it was very rough.

With regards to the boost gauge, I'm not sure how to tell if it's accurate. What makes me think it isn't is that it idles at 30hg or whetever the measurement for vac is, but it was smoke tested and there was no vacuum leaks, from what I've heard/read/know it should idle at 20. Regardless, I agree and and everything you have said sounds like the issues I have been having with the O2 code etc. The code would only come on in 5th going up an incline on the motorway which I think was the sensor being confused by the amount or lack of air vs the amount of load.

I bought the car with the intention of tidying up the bodywork and sorting any engine problems out so if it hasn't been mapped it will be on the list, albeit quite far down as now this problem and the cam seals need doing first. I have the TMIC still so if I sort this I will try get hold of a downpipe and stick it back on until I can get mapped.

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I got it with limited history and no mention of the belt so I would assume it hasn't been done. It's on about 103000 so prime time for a new belt, this plus the cam seal leak is why I had planned new belt, pulleys, water pump etc in new year.

The belt hasn't snapped, I pulled the cover off as far as possible with FMIC pipework still on and the belt's still on and tight (I didn't want to take too much apart as could void my AA cover, I have breakdown repair so they cover £500 of costs)

I changed plugs to PF7RB's and no difference, the old plugs had quite a large gap and plugs 3 & 4 had a little oil on them.

The AA have taken it to the scooby garage now so hopefully get some news after new year, from the tests I've done and my gut, I'm going with jumped teeth.

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  • 1 month later...

So an update in case anyone is interested..

Car sat at the garage for a few weeks, they got it started and did a compression test - cylinder 4 has 0 compression. Timing belts fine, it's suspected to have dropped a valve guide.

Anyone want to buy a Scooby :bangin:

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