Nanocom Results / Rough Starting

ozzyboydeano said:

maybe worth checking your fuel pressure

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Yes I think I will, I’ve got a fuel pressure test kit but haven’t worked out which of the adapters to cobble together! Although I haven’t checked the fuel pressure it does have a new (cheapo) fuel pump and new (genuine) filter housing. It didn’t make any difference so I assumed fuel pressure wasn’t a factor, maybe it is.

I also wondered if perhaps although there is power to the glow plugs I have only put a multimeter to one, and I also removed one to physically see it glow up, but again only one. If one or more of the connectors is knackered it’s not going to do anything. If I leave the engine idling for 15-30 secs there are no issues at all, and generally it runs very well with no issues.

I’ve done several compression tests varying the order I did the cylinders each time and compression was fine.

IIRC the thread of the FT sensor in the FPR is M14 but if you remove it you'll clearely see which adaptor to use to fit the pressure gauge instead of it

sierrafery said:

IIRC the thread of the FT sensor in the FPR is M14 but if you remove it you'll clearely see which adaptor to use to fit the pressure gauge instead of it

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Cheers. What do you reckon about the GP connectors on the loom, are they a common failure that may cause this?

Not very common though on an old harness they might be well cooked.

sierrafery said:

Not very common though on an old harness they might be well cooked.

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18 years is a long time....

But then would lack of 1 or more glow plugs cause this kind of issue?

It could IMO

Is there any way of turning on the glow plugs for testing? Or should they stay on long enough for me to get a meter reading off each one?

That's simple, remove the glow plug relay and bridge the perpendicular cavities in the socket

Checked the plugs, getting between 10 and 11.5 volts at the connectors (1 and 2 = about 11v, 3 and 4 about 10v) and they stay on for 13 seconds with the ignition - does that sound about normal ?

Was that with the connectors plugged to the glow plugs or unplugged? ... if they were unplugged it's not normal at all cos all the voltages should be the same, if they were plugged then 1 and 2 might not work well, measure the resistance of the glow plugs across terminal and head

Unplugged one at a time starting from No. 4 (leaving them unplugged as I went).

unplug them all and measure the voltage then cos it might have dropped while you measured, also you must get feed there after the engine was started untill the coolant temp gets to 20*C, if the ECT is above 20 then no post heat operation

Thanks I'll do it again with them all unplugged, then start the engine and do it again. Should take a while to get up to temp so should be enough time to quickly check them all

With the engine off and all unplugged each connector read 11.6v (+/- 0.2v)

resistance on each glowplug was 1.3 (multi-meter resistance 0.4, so 0.9 on each glowplug)

With the engine running each connector read 14v+

That side seems OK then, unless there's a voltage drop with plugs connected

sierrafery said:

unless there's a voltage drop with plugs connected

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Difficult to test, but with all the glow plugs unplugged this morning it was no different in terms of starting/rough running,.

What it does is when you start the engine and rev to say 1000rpm, it will run for a second, then the revs will drop and white/grey smoke from the exhaust, then it will pick up and again and repeat this two or three times until it clears..

That's not normal... hook a wire somehow to one connector as to be able to measure voltage with all the plugs connected cos if there's a weak joint somewhere the voltage will drop hard

sierrafery said:

That's not normal... hook a wire somehow to one connector as to be able to measure voltage with all the plugs connected cos if there's a weak joint somewhere the voltage will drop hard

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Any of them ? Could wrap a wire around the glow plug and connect over it then take a reading from the wire.

Yes improvise somehow to measure with all connected cos suspoect is the common feed so if the voltage drops it should drop on all.