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Airborne9
Trainee


Joined: 30 Jul 2015
Posts: 68



PostPosted: Thu Aug 27, 2015 3:24 pm    Post subject: Reply with quote

alex yates wrote:
So if it is, if I put 95 ron in, it should run fine???? Dont know


no unfortunately not, because it wont detect anything at all, so cant adjust your ignition at idle.

pull them out and inspect, mine was in two pieces.
 
  
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Thu Aug 27, 2015 4:29 pm    Post subject: Reply with quote

Airborne9 wrote:
alex yates wrote:
So if it is, if I put 95 ron in, it should run fine???? Dont know


no unfortunately not, because it wont detect anything at all, so cant adjust your ignition at idle.

pull them out and inspect, mine was in two pieces.


I thought the knock sensor just advanced the timing (or retarded, whichever) when 95 was in. So if it's not working it won't do anything to the timing????? Dont know

It's only an on/off type sensor and doesn't give variable readings, does it not?
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Chris_in_the_UK
Estoril


Joined: 19 Mar 2014
Posts: 3542
Location: Harrogate


PostPosted: Thu Aug 27, 2015 4:53 pm    Post subject: Reply with quote

Faulty knock sensor would show up an error code - if there is no code it's unlikely to be that TBH.
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
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Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Aug 28, 2015 7:56 am    Post subject: Reply with quote

So I went out in it last night for an hour. Car ran like a dream, ticking over fine. Rev it up and engine quickly drops to 1k rpm then slowly down to 700 and locks itself there frustrated frustrated frustrated frustrated

All I've done since it was running poo all day yesterday was wash the car and shove a bottle of redex injection cleaner in.

No doubt it'll be back to running poo again today Confused
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Airborne9
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Joined: 30 Jul 2015
Posts: 68



PostPosted: Fri Aug 28, 2015 8:13 am    Post subject: Reply with quote

Chris_in_the_UK wrote:
Faulty knock sensor would show up an error code - if there is no code it's unlikely to be that TBH.


still worth an inspection in my eyes mate.

Your engine will run rough regardless of what fuel you put in if the knock sensors aren't working.
 
  
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alex yates
Le Mans
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Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Aug 28, 2015 8:37 am    Post subject: Reply with quote

How do you inspect them? They're a Quartz type vibration sensor aren't they?

Genuine question.
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alex yates
Le Mans
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Joined: 06 Mar 2014
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Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Aug 28, 2015 8:41 am    Post subject: Reply with quote

I'll not be checking them before I go on holiday Confused

"The knock sensors (purple arrow) have remained in the same locations. There is one installed on both the left and right side of the engine block. Located under the intake manifold, both of these sensors are relatively difficult to get to (you need to remove the intake tubes to access them)"


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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1204



PostPosted: Fri Aug 28, 2015 12:01 pm    Post subject: Reply with quote

Failing swapping the 02 sensors over and taking readings to rule them out you mentioned cleaning and checking the intake, did that include anything downstream of the throttle body? Did you remove (at any time) the intake tube assemblies or intake manifolds? One of the 6 rubber boots from the plastic intake runners could be leaking air and there's quite a few seals in those joints too.

Since you have strange O2 readings on one bank I doubt AOS is at fault but would also be interesting to pull oil filler cap when the idle is misbehaving and see if the idle speed reacts or not

Good luck
 
  
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Aug 28, 2015 12:29 pm    Post subject: Reply with quote

Stripped top end back to rubber gaitors between plenum and manifolds, everything checked out ok. I am tempted to get a smoke machine pumped through it when I get back off hols if still doing it.
Removing filler cap does alter engine revs and there is vac present, but only low and not to the point that it's hard to get the cap off. I did take the connector off the throttle body yesterday that the pipe locks on to at the top left (breather/vac pipe) and with the engine running there was a light smoky/oily vapour coming from it.
Car had it's oil changed (mobil 1) back in April and since then and a few thousand miles, the level on the dip has dropped about 1mm tops so it's not like it's using oil.

The confusing thing though is the fault is intermittent. I've been to the chippy for lunch today and the cars running great, same last night going to the boozer.

If it's intermittent, wouldn't that rule out: vac leak, AOS, blocked injector, dodgy coil pack/spark plug, sticky tappet, stuck varicam solenoid and any other mechanical issue?????? Dont know Question
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Harv
Suzuka


Joined: 18 Sep 2014
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PostPosted: Fri Aug 28, 2015 12:44 pm    Post subject: Reply with quote

Short runs are fine then? But once you have really warmed the engine upto full temp then problems arise... Perhaps heat soak is playing about with something and expanding it to cause to an air leak.... Question
 
  
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Aug 28, 2015 12:57 pm    Post subject: Reply with quote

I had it fully up to temp with oil pressure just under 1 bar the other day, ragged all over the place, still ran fine. Last night gave it some when fully up to temp and still fine.
You can tell now within a 2 minute drive from cold whether it's right or not just by giving it a rev and watching what happens when it drops.
Good - drops straight down to 1k then slowly down to tickover.
Bad - straight down to about 400rpm, nearly conk out then up to tickover and vary.

frustrated
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Tue Jun 07, 2016 10:16 pm    Post subject: Reply with quote

Surprised I think I've fixed my car Grin

Boogie Boogie Boogie Boogie Boogie


Not saying too much yet until I'm confident the lumpy tickover has been resolved.

Car feels totally different though after 1st couple of rides. Will update in the next day or so.
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Ursa911
Imola


Joined: 17 Feb 2016
Posts: 762
Location: Farningham, Kent


PostPosted: Wed Jun 08, 2016 6:09 am    Post subject: Reply with quote

13 months???
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2004 996.2 Manual C4S Cab Arctic Silver - Ursa911
 
  
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NLW73
Barcelona


Joined: 27 May 2014
Posts: 1362
Location: Yateley


PostPosted: Wed Jun 08, 2016 7:06 am    Post subject: Reply with quote

would it not be better to get some rent $$ out and go to a decent garage to get checked over properly in case its doing more damage.

I just could not live with that for 13 months.
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Wed Jun 08, 2016 7:07 am    Post subject: Reply with quote

Yeah!! Although for a long time, the fault was intermittent which made it more difficult to diagnose, but at the same time ruled out (IMHO) most non electronic issues.

Still not 100% convinced I've sorted and also not 100% convinced I know how I sorted it but will probably report back tonight after I've driven it a couple more times. Confused
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alex yates
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 15227
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Wed Jun 08, 2016 7:22 am    Post subject: Reply with quote

NLW73 wrote:
would it not be better to get some rent $$ out and go to a decent garage to get checked over properly in case its doing more damage.
I just could not live with that for 13 months.


Would've been an option if I wasn't currently living below the rent line, although I did take it to a garage within that period (last year) and no codes were showing on the ECU. Read the codes since and nothing showing. If the ECU is controlling the running of the engine within the programmed parameters, then nothing will show, even though this may show slight idle issues. Most members wouldn't even have noticed it, especially if they're the ones who constantly running their HVAC on 'Auto' as it shifts the revs up on tickover (due to running the compressor).
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thebig25
Nürburgring


Joined: 27 Sep 2008
Posts: 459



PostPosted: Wed Jun 08, 2016 9:50 am    Post subject: Reply with quote

My car had some of the symptoms yours had, albeit not the same degree of rev fluctuations, but it had a lumpy idle when warm. Durametric did not highlight any errors, but after checking the car thoroughly my Indy suspected it was lambda related and recommended changing them.

Based on this I changed both lambas as part of my exhaust swap and I'm fairly certain it has resolved the issue as the idle is now stable whatever the operating temperature.
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VinceB
Hockenheim


Joined: 26 Feb 2012
Posts: 632



PostPosted: Wed Jun 08, 2016 12:48 pm    Post subject: Reply with quote

alex yates wrote:
I had it fully up to temp with oil pressure just under 1 bar the other day, ragged all over the place, still ran fine. Last night gave it some when fully up to temp and still fine.
You can tell now within a 2 minute drive from cold whether it's right or not just by giving it a rev and watching what happens when it drops.
Good - drops straight down to 1k then slowly down to tickover.
Bad - straight down to about 400rpm, nearly conk out then up to tickover and vary.

frustrated


Out of interest mate, have you checked what voltage is showing when it runs like crap? I noticed a few weeks back, I had been on a long journey, stuck in traffic a lot and with two phones charging from the car. Battery dropped down to like 13.5 while running and I started getting some idle issues like you describe. Unplugged the two phones draw and it went away?
 
  
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andylang
Spa-Francorchamps


Joined: 30 Oct 2012
Posts: 279
Location: Southampton


PostPosted: Wed Jun 08, 2016 1:27 pm    Post subject: Reply with quote

Been an interesting read spanning you over the course of a year Alex. Do you now have a sweet running car?

Itching to know what the problem was in the end.

I had a similar situation on my race car a few years back, sadly it cant be related as I think that was a vac leak. so a mechanical issue which cant be scanned.

If its still being an issue - has it actually been to an OPC? dig deep I know, but a persistent problem is just a ball ache
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andylang
Spa-Francorchamps


Joined: 30 Oct 2012
Posts: 279
Location: Southampton


PostPosted: Wed Jun 08, 2016 1:30 pm    Post subject: Reply with quote

THAT WAS IT!!!

My post cat lambda sensor was chuffed, it didn't bring a fault up so I replaced it, then still a bit rough so I put a 10mm spacer (from memory) and it completely solved the problem. Or the spacer was for a different issue - either way. rough idle was lambda sensor

Niggling issues are just the worst Sad hope its sorted Judge
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