X trail hard to start when cold. Out of ideas :(

This is the same X trail I posted about a while ago, 2.2 Dci.
A lot of work later (new chains,valves/head work,new turbo) and it now
*runs perfectly* but is difficult to start when cold. Hard to start when cold seems to be a common complaint with these...
Once it has fired up, it behaves impeccably, fast idles as it should whilst warming up and no trace of missing or unevenness.
This car has had a new battery, glow plugs and main ground strap and have also tried the starter motor from a known good vehicle. Injectors have been tested by a diesel specialist for leakage, fuel delivery and response times. Alternator also tests ok. Obviously it has had the fuel filter changed and the pump seems to deliver the required rail pressure. (Target and actual FRP agree in diagnostics graphing)
If you do the usual trick of waiting for the glow light to go out and then repeat and wait 20 secs (by design the plugs are powered for 20 secs after light goes out) it will start after about 4 -5 seconds of cranking. (This engine also lights the glow plugs during cranking, which it is doing.) If you don't do this and try to start it as soon as the light goes out, it will crank for 30 secs or more before starting. Despite the glows lighting during cranking. Sometimes at this point it will throw spurious codes, usually crankshaft sensor - although it still shows the rpm and the waveform is still correct,(measured at ECM terminals using a 'scope) or EGR valve (replaced with known good) and occasionally various moaning about loss of CAN communications to various modules. I'm guessing this is because the ECM is upset about the voltage drooping from extended cranking.
The battery voltage is 12.6, dropping to 11.5 with the glows on and down to 9v when cranking. Now, while this sounds a little low to me, an otherwise identical model exhibits the same behaviour - except that one starts within a second, hot or cold and without needing the 'double glow trick'.
Have tried as many diagnostics comparisons to the other vehicle as I can think of, cranking rpm, fuel rail pressure, target pressure, temp sensors, crank and cam sensors, injector waveforms, air mass readings and there are no obvious differences. For the purposes of clarification the compressions are 320PSi, *but* so is the comparison vehicle...
Out of ideas now :(
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On 04/02/2014 16:30, Lee wrote:

If it hits 9v under load: there is your problem, the battery is poorly.
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On 04/02/2014 16:35, Mrcheerful wrote:

Well it is a generic 'no name' from a certain low cost parts suppliers...
I would have swapped it out already but it isn't my car and the owner isn't convinced. I don't have a spare battery large enough for a proper test so I've left it up to him to decide if he wants to source a decent battery :)
Lee
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wrote:

Ah, a piece of shit, in other words!
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On Tue, 04 Feb 2014 16:30:47 +0000, Lee wrote:
[...]

OEM glow plugs, not pattern?
Chris
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On 04/02/2014 16:59, Chris Whelan wrote:

ADL/Blueprint, sadly the OEM ones have been disposed of.
Lee
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On Tue, 04 Feb 2014 17:32:46 +0000, Lee wrote:

Don't know about the X Trail, but some diesels are really fussy about their glow plugs, and are slow to start when cold without OEM ones.
With everything else that has been done, replacing then with genuine might be the cheapest next step?
Chris
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On 04/02/2014 18:30, Chris Whelan wrote:

The OEM Nissan ones are could hardly be described as cheap, but point taken.
Lee
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"Lee" wrote in message
This is the same X trail I posted about a while ago, 2.2 Dci.
A lot of work later (new chains,valves/head work,new turbo) and it now *runs perfectly* but is difficult to start when cold. Hard to start when cold seems to be a common complaint with these...
Once it has fired up, it behaves impeccably, fast idles as it should whilst warming up and no trace of missing or unevenness.
This car has had a new battery, glow plugs and main ground strap and have also tried the starter motor from a known good vehicle. Injectors have been tested by a diesel specialist for leakage, fuel delivery and response times. Alternator also tests ok. Obviously it has had the fuel filter changed and the pump seems to deliver the required rail pressure. (Target and actual FRP agree in diagnostics graphing)
If you do the usual trick of waiting for the glow light to go out and then repeat and wait 20 secs (by design the plugs are powered for 20 secs after light goes out) it will start after about 4 -5 seconds of cranking. (This engine also lights the glow plugs during cranking, which it is doing.) If you don't do this and try to start it as soon as the light goes out, it will crank for 30 secs or more before starting. Despite the glows lighting during cranking. Sometimes at this point it will throw spurious codes, usually crankshaft sensor - although it still shows the rpm and the waveform is still correct,(measured at ECM terminals using a 'scope) or EGR valve (replaced with known good) and occasionally various moaning about loss of CAN communications to various modules. I'm guessing this is because the ECM is upset about the voltage drooping from extended cranking.
The battery voltage is 12.6, dropping to 11.5 with the glows on and down to 9v when cranking. Now, while this sounds a little low to me, an otherwise identical model exhibits the same behaviour - except that one starts within a second, hot or cold and without needing the 'double glow trick'.
Have tried as many diagnostics comparisons to the other vehicle as I can think of, cranking rpm, fuel rail pressure, target pressure, temp sensors, crank and cam sensors, injector waveforms, air mass readings and there are no obvious differences. For the purposes of clarification the compressions are 320PSi, *but* so is the comparison vehicle...
Out of ideas now :(
What is cold cranking RPM? Needs to be 280rpm at least.
Do you have crank and cam sync within afew crank cycles on your scan tool?
I would like to know what rail pressure target v actual is during cranking...
Glow plugs should be irrelevant til its well below zero.
Tim..
Tim.
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On Fri, 07 Feb 2014 17:06:54 -0000, RHJ Croxton & Son (Farms) Ltd.

Quick diagnosis is does it start instantly if you jump start it?
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On 07/02/2014 21:44, Duncan Wood wrote:

or give it a tow start (assuming manual)
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On 07/02/2014 21:45, Mrcheerful wrote:

Tow start is instant, whereas jump start exhibits the same issue. I suspect there is more going on than a simple voltage drop.
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What's the voltage at the starter terminals when cranking?
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On 07/02/2014 23:17, Duncan Wood wrote:

Should have access to a high current clamp sensor for the weekend so I was going to check the starter current and recheck the terminal voltage, but last time I noted it, it was 9v. I also measured 9v at the battery terminals (the battery itself not the clamps, but they were the same anyway), but I didn't measure them simultaneously, which I will do, in case there is an issue with the positive cable. Ground lead has been changed already.
Have already tried another battery and get the same thing, 9v at the battery (both itself and and at the clamps) when cranking - either that's what it should be or both starters are suspect....
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If the starters sticky then two batteries in parallel will often spin it fast enough to start immediatly, & you can bypass the engine earth lead with the jump lead straight to the block.
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On 07/02/2014 17:06, RHJ Croxton & Son (Farms) Ltd. <the.farm. wrote:
<snip> >

That could be a clue as it's about 200rpm

Don't remember seeing that entry on the scan tool, but injector waveform is present within a couple of turns so assuming cam and crank sync is obtained and rail pressure is attained, otherwise it wouldn't drive the injectors?... Admittedly I only checked for the presence of the waveform, I must remember to check the drive amplitude and injector current when I check it next.
Cam and Crank sensors are in sync when checked with a dual channel scope, when cranking and when running. We were *extremely* careful when replacing the chains :)

I'll have to re-check the target pressure when cranking as for some reason I haven't noted that down. 'Actual' I have written down as 25-30MPa
Once it's started, and warmed up, target is 24/26 and actual is 24/26MPa That's actual as reported by the ECM, don't have a suitable gauge and adapter to measure the 'real' pressure.

Allow the manual says otherwise, I tend to agree and think it's a red herring and that something else is going on.

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From what you have said now about cranking voltage dropping to 9v;
a) this is too low- where are you measuring it? At battery or at starter? b) I would be surprised if the ECU is still firing the injectors at 9v.
Test and report back.
Have you missed an earth strap off the engine block?
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On 08/02/2014 19:53, Tim <flexie23 wrote:

Main earth strap has already been changed, it runs from battery to chassis and then onto the engine..
9v at the battery terminals themselves (and the same across the clamps, which are clean and tight) and 8.5v at the ECM main power terminals when cranking, this is with yet another new battery. (ECM voltage is 11.5 when not cranking and 14.4 when the engine is running - measured with a (trusted) DMM at the ECM power relay adjacent to the ECM) Starter has been examined by a local specialist and pronounced fit, not surprised since both starters do exactly the same thing... Engine doesn't feel excessively 'tight' when turning by hand, (feels the same as the other one) and when it cranks it is at a fairly even speed.
It seems completely obvious that it is the starter, but the one which works perfectly on the comparison vehicle still exhibits the same symptoms on this one.
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replying to Lee, Mmeldrum29 wrote: Hi. Did u get to the bottom of this problem. I imagine having exact same symptoms with mine
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On 05/05/2017 01:18, Mmeldrum29 wrote:

Yes, but the actual final cause will certainly not be relevant to your issue. (it was an incorrect part than had been previously fitted)
Obviously you need to have checked all all the usual suspects, ie injectors/temp sensors/maf/ crank and cam sensors etc
Wear in the chain can cause poor cold starting (as I found out)
What I found useful was viewing the timing correlation of the crankshaft and camshaft sensors on a 2 channel oscilloscope. The correlation varied too much between hot and cold and pointed to the (new) chain being badly out of spec.
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