Well today I finally got it to start. Primed the engine repeatedly convinced I could hear a woosh/gurgling in the rail. An unhealthy amount of easy start and it spluttered into life. I let it idle, occasional fast idle, for 20 minutes to warm up for coolant flush. During that time it seemed to run perfectly and respond to throttle. Sods law though, immediately after turning it off it wouldnt start again !!! At least I now know its not just a cold starting issue and can rule out a few things.

 

Is the low pressure in tank pump working ok ?
you should see 60>78 psi

 

I cant see a reading for the pump on my scanner, Any idea how to get a value ? Had to take the pipe elbow out today as the scope was useless. Only on rebuilding did I find that the gear linkeage doesnt need removed and the elbow rotated as I had read. Theres a grey outer ring on the end of the pipe that you slide round and the bend pulls straight off. It was all a waste of time tho as the throttle/shudder valve was wide open for starting. Its actually heavily sprung and need the electrics to close it on shut down.
So still no further forward really !

 

I think so, I took a note of all live data with it running so I can compare against a no start on Monday. Its certainly buzzing on ok. Read elsewhere of someone with a similar problem that turned out to be a sticking throttle valve. That might make sense as I believe it closes on shut down so perhaps on cranking again there a problem and with the forced air in still low it wont open properly but does when its running. I'm going to fire a scope down (rather than the hassle of getting the bend off) to see if it opens ok with the ignition switched on. Just so frustrating when such a problem suddenly appears. The oil cooler fix had no electrical/fuel/air side effects other than taking out the alternator and engine earth ( 100% earth cleaned and good) I will win this fight ... eventually.

 

The anti shudder valve snaps shut when you turn the engine off & as you mentioned should open fully to let the air in , it will move when the air flows need altering for the operation of the EGR valve.
Can you not just remove the pipe at the valve end to see what it’s doing ?

 

To remove it involves battery and tray out, ecu moved , expansion bottle and more, plus the bend is a rotate off so gear linkages need taken out too. I think I can get into the air intake pipe below the ecu and feed the scope in. I'll try that first.

 

Maybe you need to recheck over the EGR valve again.
Sure it’s not a crankshaft sensor fault ?

 

What scanner are you using ?

 

Scanner is an Autel 802. As for the crankshaft sensor, at the moment I cant even find it to check it ! Looking at the manual it seems to be located below the starter motor but that area is behind the rear engine mount. The fact its showing rpm at cranking and when I did have it running is steering me away from suspecting a faulty sensor. The way I had it running and hot but it wouldnt immediately restart is really mistifying.

 

It looks as though you may have to upgrade your scanner to get at the info you need,i don't know for sure but it may not be picking up any manufacturer specific codes,and from what you say it's live data capability is limited.
Obviously the best option is something running the Vauxhall gds2 software,but that's not cheap to set up.
If you already have a windows laptop to run the software,the next best and cheaper option is a late version opcom.

 

It does sound as though the crank sensor may be ok,here's what i have on changing one

 

Thanks, that drawing is what I've got tho reading it again I see that the transfer case has to come out, no wonder I couldnt see it. I know I'll probably need to get someone in with more capable diagnostics but I just hate admitting defeat, especially with an issue thats appeared from no where. I can't figure how the egr would effect starting especially as I've tried with it manually set/adjusted but as the high pitch buzzing fromit just doesnt seem right I might replace it as the next try.

 

Not sure if I'm getting anywhere or not but today not even easy start would get her going. I am leaning more towards air in fuel as today the noises from the filter housing were way more obvious when the pump primed. Hard to explain but you know when you can tell the difference in sound between pressurising fuel and fuel air .... more like a skoosh ? The same sound is noticeable at the fuel rail too.I had a close look at all the fuel pipe fittings and the feed from the tank and both at the high pressure pump dont feel particularly tight. Its a plastic connection at the filter and metal at the pump. I've no real experience in these fittings, can they be repaired, bought seperately or only a full pipe ? Hold on, I see plenty plastic ones via ebay.

 

Sorted ... well maybe ! Changed the fuel filters today ( one was well stuck) repeatedly primed the system and convinced myself that the skoosh sound had virtually gone. Tried to start it but of course it wouldn't. Next thing was back seats out to check the pipework at the fuel pump, again seemed fine.
I did some software updates on my scanner last night so had another go at getting some detailed live data, but no joy. Only thing I noticed was that rpm took a few seconds to display. Thinking I might well have to do the crank sensor (transaxle out etc !!) and clutching at straws I wondered if the camshaft sensor had any bearing on that so I disconnected it to see if it changed any data.

WOW I could hardly believe it when it started straight away ! Tried it a few times, connected/disconnected and would start but only disconnected. I switched the sensor back to the original but again would only run disconnected.
Now when I first ordered the camshaft sensor, via a major ebay supplier, despite giving my reg number,the wrong one arrived, wrong shape and too long. I got back onto them with VIN this time and was told they didn't have one listed. Back onto ebay and found a few that looked the part including one from the same seller. How many different camshaft sensors can there be for a particular engine I thought ? One with and without start stop perhaps ? So back on the phone and was told that it might well be right but neither it or any sensor was showing for my VIN. I agreed I'd take it without guarantee.

I am now hoping this was my mistake and that going direct to Vauxhall will see me sorted ,,, if not theres something seriously wierd going on in my ECU, Thanks for previous comments, I'll update when I get a chance to go and get one.

 

Now when I first ordered the camshaft sensor, via a major ebay supplier,

Ebay really is not the place to buy components from, especially critical ones. You are so lucky that your car will start without a Cam Sensor. Many wont !!!

Can you imagine the garden path you could have gone along. The mind boggles !!

 

Subject to confirmation this is an A22DM (LNQ) engine there is only one cam sensor listed (96868917) no difference for s/s
looking at the wiring diagram the cam and crank do share a common 5 volt feed from the ecm (5v1)so it may be connected.
On your starting post, which sensor did you change for the pending P0340 code ?

 

It was the camshaft sensor. I've looked back my ebay history. you're right ,,, just realised the first part sent was the crankshaft sensor. That's now a bit worrying that with what appears to indeed be the correct new camshaft sensor it won't start.

 

It is looking as though you've bought a duff sensor,what make was it ?
the OEM is Delphi and i would recommend sticking with either a Delphi or GM boxed replacement

 

The sensor is a Febi, it came from a large motor factors who like many others also sell on ebay and amazon. I live on an island so mail order parts are usually my only option, ebay or eurocarparts. Since they originally sent a crankshaft sensor I now have the dilema of fitting that since as you say the 2 are linked, then if that doesn't fix it,questioning its reliability too,,,, or buying another dealer supplied camshaft sensor.

 

Would that be Guernsey by any chance ? lol
The list price of a genuine cam sensor isn't too bad @ £88.50 + vat
but i'd suggest checking the 5v feeds and earths to the sensors first.
don't know if you already have it but here's the sensor wiring

 

Thanks for that, I was just in the middle of doing an update. With the ignition on if I probe the sensor connector I'm getting 5v at the OG/VT and at the BN/WH. The PK/BK is ok to ground. If I connect a sensor and back pin connect, the OG/VT and ground shows 5v dropping to 0v on metal interference. The BN/WT and ground shows 0v rising to 5v on metal interference. If I understand things correctly the back pinning results are as they should be but the unplugged 5v at the BN/WT isnt right. Although I don't see a common wire colour (as you suggested the cam and crank shared a 5v.) would I be right to suspect that the 5v I suspect to be wrong could be coming from a faulty crank sensor ?
As for location I'm on the Isle of Bute, west coast of Scotland

 

The wiring shows the common feed (5V1) is within the ECM,
supplied from pin 40 for cam and pin 39 for crank,
it also feeds the fuel rail pressure sensor and sensor 1 of the acc pedal

 

Ah right I see now, didn't realise thats what the broken line meant. Any idea how I can be getting 5v to the signal wire ? I've confirmed continuity between the plug and ecu for each wire. Would I be right in thinking that the reason the signal wire doesn't have 5v when the sensor is connected is because until the sensor is triggered there's no ground ?

 

Did you progress this over the weekend ?
The wiring shows it's a pull up design so there should be little or no voltage in the signal wire with the sensor unplugged,
as for where it's picking it up ??? ☕
i think i'd unplug the ecm wiring then check the isolated wire and then the ecm signal pin 59 for voltage,
it's much more common for another duff sensor on the same circuit to drag down the 5v supply,not feed the signal wire.

 

Unplug anything on that circuit and redo the voltage tests with camshaft sensor connected and disconnected.

 

That's a pull down circuit as opposed to pull up, the signal wire is supplied with 5v internally from the ECM through the pull up resistor shown inside the control unit at terminal 59, which then pulls to ground/0v as the sensor operates (depending on the sensor internal circuitry will depend on whether it is grounded with or without metal interference - sounds like from your tests it's grounded without). In other words with the sensor disconnected you'll have 5v on the supply wires and signal wires, so those readings are correct.

Are you seeing any other fault codes that might suggest the 5v rail itself is an issue? Normally if the rail supply is faulty you'll normally see codes for more than one/if not all sensors supplied by it. However, if I'm reading your posts correctly I would not expect to see the OG/VT sensor supply switching at all, this should be a constant 5v supply.?

Failing this you'd want to scope both cam and crank sensor signals at the ECM terminals to get a visual representation of the sensor outputs the control unit is receiving, and also if you can find a reference to check cam/crank correlation (cam timing basically).

 

Thanks for all the suggestions, been away the weekend so no progress yet. Nick ... according to the symbols in my manual and as supplied by Valer too the sensor is a pull up type ? The only fault I've ever had cranking but not starting is a pending P0340 cam sensor.
marks ... I'll look into that , I know the crank sensor is one of them but so far I've resisted the joy of removing the transfer case to get to it.
Valer .. would have thought that if I unplug the ecm then testing the pin would be pointless as the 5v supply is probably in that multi plug too ... but I may be wrong.
My thinking tomorrow is to recheck all the tests I've done to keep my head right. I've tested so many bloody things I'm losing track though I do recall that one test (no idea which wire or sensor) showed full continuity to one ecm terminal but partial to others , that may or may not be relevant. Unfortunately I don't have a scanner that can do the wave signals but if needs be I'll need to pay for that to be done.
Next I plan to cut the signal wire close to the ecm and see ignition on, which side of the cut has 5v. If its the sensor side that would suggest to me a wiring break/cross somewhere though if its 5v on the ecm I'd be fearing an internal and expensive problem.
As I said at the start of this post, I bought the car with a known fault to repair and have been baffled as to how this fault has appeared. I did though do no more than start it for loading/unloading. I guess its always possible that there's always been this fault and perhaps the sensor wasn't fully plugged in which hid it.
I really appreciate all the help ,,, keep with me guys and we will win this one.