Rough cold idle - L320 2.7, 2005, 110000miles

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Johny h

Johny h

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Sunderland
Got my car at garage at the moment. It has a very rough cold idle, sounds as though it is missing and vibrating badly until it warms up! Once up to temperature it’s fine and runs fine.

I thought glowplugs. The garage don’t think it is as there is no indication on the diagnostics.

they think it has something to do with dirty fuel/tank, dirty fuel filter or bad injectors.

they have changed fuel filter but problem still persists. They are talking of removing tank and inspecting it and fuel. They will then check injectors.

Now fuel tank securing plate is rusted and if they remove the tank will have to replace and land rover haven’t got any in stock! It all seems to be getting worse by the minute!

Also the while this is all going on they have found that the prop shaft centre bearing is knackered and it needs a new prop shaft as well!

it’s all sounding expensive.

Was wondering if the general opinion was this was the right route to solving the problem? I am sure the garage know what they are doing, but I haven’t got an unlimited budget to ‘rebuild’ the car..
 
The glow plugs can be checked doing a resistance test with a dvm, the glow plug module can fail also.
Is it programmed by any chance?
Injector leak off test would help to eradicate injector faults when cold.
I have a Volvo v50 2.0d that is tuned. It runs a little rough when cold but fine all day after the first ten minutes, more so in winter.
 
Mark Piercy said:
Injector leak off test would help to eradicate injector faults when cold.
Click to expand...

You can't do a leak off test on these injectors, as the leak back line is pressurised to 10 Bar. This injector design uses a high pressure pre-charge system. The injectors won't spray, unless the 10 Bar pre-charge pressure is maintained on the leak back line.
 
Nodge68 said:
You can't do a leak off test on these injectors, as the leak back line is pressurised to 10 Bar. This injector design uses a high pressure pre-charge system. The injectors won't spray, unless the 10 Bar pre-charge pressure is maintained on the leak back line.
Click to expand...
What pump are they using on these?
 
Johny h said:
Yes, 2.7 tdv6
Click to expand...

Oil temperature sensor, passenger side of sump 30 quid, and its old one out and new one in quick oil loss minimal teaspoonful, make sure engine cold air susp at off road height, and you have an axle stand under it, sump guard has to come off for access.

If that dont fix it then you may have an injector issue, have you checked the cylinder balances with a diag tool?
 
lynall said:
Oil temperature sensor, passenger side of sump 30 quid, and its old one out and new one in quick oil loss minimal teaspoonful, make sure engine cold air susp at off road height, and you have an axle stand under it, sump guard has to come off for access.

If that dont fix it then you may have an injector issue, have you checked the cylinder balances with a diag tool?
Click to expand...

Cheers mate. I will pass this onto garage tomorrow. They are suspecting dirty fuel or injectors but I don’t really know what they are going to do next to diagnose - I’ll find out tomorrow hopefully.
 
Apparently oil temp sensor fault does now throw a code (useful!) as it is on the same circuit at the coolant temp sensor, ages since I changed mine.
Have a look on the D3 forum as there are several referencs to it on there.

Just checked on the d3 forum, ask your garage to look at live data, and see what the oil temp is reading, apparently when it defaults it shows minus 20 or 30.
 
Nodge68 said:
You can't do a leak off test on these injectors, as the leak back line is pressurised to 10 Bar. This injector design uses a high pressure pre-charge system. The injectors won't spray, unless the 10 Bar pre-charge pressure is maintained on the leak back line.
Click to expand...
If that's the case why is it a leak back system if it's pre-charge? So it constantly provides 10bar of préssure to return fuel to the tank?
It must be a totally new system then. Wow... You learn every day..
 
Mark Piercy said:
If that's the case why is it a leak back system if it's pre-charge? So it constantly provides 10bar of préssure to return fuel to the tank?
It must be a totally new system then. Wow... You learn every day..
Click to expand...

The injectors are fed with a variable rail pressure of between 25,000 and 180,000 kPa, through the main fuel rail. This is the main injection pressure, and is what sprays out the spray nozzles. The rail pressure depends on many factors, but is all geared to complete atomisation of the fuel, through 7 seriously tiny 143um holes in the injector spray nozzles.

The injectors are actuated using Piezoelectric elements, the lower half of which form an internal piston. However unlike normal common rail injectors, these fast acting injectors don't have a mechanical linkage to the injector needle valve, they use the high pressure, 10 bar fuel from spill line (there is a 10 Bar maintenance valve to keep the pressure correct), to act as a fluid connection between the lift piston on the bottom of the Piezoelectric element, and the needle valve seat. It's literally using this solid column of 10 Bar fuel as a non compressible linkage. This way the injector has no contacting parts to wear, and also automatically compensates for variations in engine temperature, as there's no metal components to expand or contract at various amounts through the engine temperature range.
Each injector is tested when first assembled, and given a parameter code, which needs to be programmed into the ECM, so it knows the timings for correct injector operation.

It's a clever system, but also expensive to fix, as technically the injectors aren't rebuildable when they fail. Actually there are places that do rebuild them, but as to how long they last, is anybodies guess.
 
Last edited:
lynall said:
Oil temperature sensor, passenger side of sump 30 quid, and its old one out and new one in quick oil loss minimal teaspoonful, make sure engine cold air susp at off road height, and you have an axle stand under it, sump guard has to come off for access.
Click to expand...
Good shout.;)
I always forget about that pesky oil sensor, and it's ability to mess up the TDV6 cold running. :confused:
lynall said:
If that dont fix it then you may have an injector issue, have you checked the cylinder balances with a diag tool?
Click to expand...
That's what I'd do next myself. No point in just replacing injectors, unless the injectors are way off in the diag.
Mark Piercy said:
Wow, I never new that.. Being a mechanic and all.. :p
Click to expand...
You'd discover it quickly enough, when you tried measuring the spill volume, and it fills all the vials in a couple of rotations of the engine.;)
 
Johny h said:
Got my car at garage at the moment. It has a very rough cold idle, sounds as though it is missing and vibrating badly until it warms up! Once up to temperature it’s fine and runs fine.

I thought glowplugs. The garage don’t think it is as there is no indication on the diagnostics.

they think it has something to do with dirty fuel/tank, dirty fuel filter or bad injectors.

they have changed fuel filter but problem still persists. They are talking of removing tank and inspecting it and fuel. They will then check injectors.

Now fuel tank securing plate is rusted and if they remove the tank will have to replace and land rover haven’t got any in stock! It all seems to be getting worse by the minute!

Also the while this is all going on they have found that the prop shaft centre bearing is knackered and it needs a new prop shaft as well!

it’s all sounding expensive.

Was wondering if the general opinion was this was the right route to solving the problem? I am sure the garage know what they are doing, but I haven’t got an unlimited budget to ‘rebuild’ the car..
Click to expand...

Sounds like they're guessing. I might be tempted to get a second opinion, preferably from a diesel specialist. Glow plugs only affect starting, not running.

Sensor good call.
 
Grrrrrr said:
Sounds like they're guessing. I might be tempted to get a second opinion, preferably from a diesel specialist. Glow plugs only affect starting, not running.

Sensor good call.
Click to expand...

Times have changed and glowplugs also glow for some time after starting.
The biggest issue with glow plugs on the 2.7 is they snap when being removed, serious amount of effort to get them out if they snap.
 
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