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maccers
Member Since: 08 Dec 2012
Location: SE Kent
Posts: 276
  
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| V8 occasionally struggles to start |
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Had a couple of instances of a bit of a weird start up experience.
Sometimes it seems to struggle to start, fires on a couple of cylinders for a couple of seconds then it's up and away. Weird thing is that when it's doing it, if I stop turning the key, the starter motor just keeps turning the engine over anyway til it fires  Never seems to happen when hot or stone cold, only if it's been left for maybe an hour. I'd have tried to get a video but it only happens every 50 starts maybe.
Got some fault codes read and quite surprised at how many there are! Including: PO301/302/303/304/305/307/300. Plus PO171 (Bank 1 too lean) PO174 (bank 2 too lean) and PO175 (Bank 2 too rich). Surprised as it runs and drives so well! Would any of the more informed V8 users be thinking along the lines of the previous owners LPG use coming back to haunt the engine?
Other thing is my idle is around 550-600rpm, does this seem about right with other V8 owners? Seems a bit low to me, and rocks the whole car when cold but much smoother when warm.
Cheers 
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 5th Apr 2016 4:58 pm |
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ST53VEN
Member Since: 18 Dec 2012
Location: Aberdeenshire
Posts: 260
  
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Has it been run on lpg before?
Idle seems low to me. Mine in quiet as a mouse at idle and it definitely doesn't rock the car. Pretty sure idle is around 900 rpm but can't be sure off the top of my head.
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| 6th Apr 2016 2:51 pm |
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TheOneAndOnlyNikolaus
Member Since: 13 Jul 2008
Location: Vienna
Posts: 140
 
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Starting the engine is automated so you turn the key and the engine continues the start process until successful even if you return to the normal position (similar to the behavior of a start button). You can stop by turning the key back to lock position.
On idling: The engine should start and run smooth. When really cold (winter night in the Alps) the RPM might be higher for a few seconds and lower by itself to normal level after about 30 seconds.
The V8 engine is normally bullet proof (except on LPG) but every cylinder has its own coil directly on top of the spark plug. The coils have been a known problem on other versions of the engine (i.e. early Jaguar S-Type V8)
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| 6th Apr 2016 4:48 pm |
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maccers
Member Since: 08 Dec 2012
Location: SE Kent
Posts: 276
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Learn something new every day, thanks!
On cold start it does idle at about 1100 for a minute then drops down to the 5-600 mark. Will look into coil packs, gets expensive when possibly looking at 8 of them!
Relatively new to this AJV8, is there any kind of idle control valve or similar? Or is it a mix of parameters that the ECU uses to control it?
Yup been on LPG before, not a fan of the stuff but knew what I might have been letting myself in for. [/quote]
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| 6th Apr 2016 7:44 pm |
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HappyEater
Member Since: 25 Jun 2014
Location: Ontario
Posts: 23
  
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I'm no expert but it has to be worth cleaning the Throttle Body and MAF?
Its so easy to do. I spent a few $ getting actual Throttle Body and MAF cleaner - with the throttle body it was so bad on the back of the Butterfly Valve that I had to carefully use wire wool and cleaner!
I was worried that the MAF would be delicate so just used the cleaner as per instructions.
Ours had a rough Idle and that has seemed to cure the Problem - it never showed up any codes though.
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| 7th Apr 2016 4:02 pm |
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brisbrain
Member Since: 14 Aug 2013
Location: Brisbane
Posts: 11
 
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Just wondering if you resolved the issue.
I occasionally experience the same issue.
Thinking it could be the fuel pressure regulator dropping pressure off over night Sucks they put it in the tank.
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| 17th Apr 2016 1:49 am |
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maccers
Member Since: 08 Dec 2012
Location: SE Kent
Posts: 276
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Whoops, sorry missed the latest replies!
I cleaned the throttle body, pretty mucky and it did improve slightly. I haven't touched the MAF yet, though thinking about it the power feed in seems a little notchy (not in a torque converter shuddery way), and flies off when it hits 3000rpm, just big sluggish below, so certainly worth a look, thanks.
Brisbrain, I was thinking of some sort of leak back too, as experienced it on a TD5, but it only happens after an hour of being left, overnight it usually starts on the dot in the morning!
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| 17th Apr 2016 11:45 am |
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Bungle
Member Since: 07 Apr 2015
Location: Wanborough
Posts: 256
 
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I get this when I have started from cold, briefly shuffled on the drive and stopped again. The next restart will be as you describe (struggling to start). Basically if starting from cold you need to run it for at least 5 minutes then restarting is not a problem.
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| 18th Apr 2016 11:03 am |
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Discoveringcomfort
Member Since: 16 Sep 2015
Location: Berkshire
Posts: 637
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One thing I found is that applying any throttle during starting the engine would not start, leave your foot off the peddle and it starts fine. I put this down to the start program in the ECU?
I also notice that the first inch of foot travel is very sluggish, you can blip the throttle with no reaction from the engine!
My engine ticks over at 600 ish and does rock the car but tick over is very stable and does not hunt. Series 1 V8
Series 2 Hibrid V8
Discovery 3 HSE V8
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| 18th Apr 2016 9:52 pm |
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