Glow Plug Issues - VW engine (Mitsubishi Outlander)

[timg147]

Hi All,

Just wondering if anyone has any pointers. I have a Mitsubishi Outlander that's had a misfire/hesitation issue and the car was almost in a limp home mode but with no engine management light. Have eventually used an OBD scanner and found it was pointing to all four glow plugs being shot, but was initially showing two banks of errors - essentially two entries for each error - cant remember if they were all the same codes though.

I have changed the glow plugs this morning and whilst the engine is better it is still down on power and still misfires a bit. The ODB scanner is still showing codes P0671 to P0674. These codes point to the glow plugs - which are new. When I try to clear the codes and re scan they are still there.

The engine is a VW sourced one - 2.0 DID. The engine code is BSY, but googling it also looks like a BKD engine.

Anyone got any ideas or pointers? I was wondering about the glow plug relay? Anything else?

[Catnip64]

Did you ensure that the replacement glow plugs had the correct voltage rating?

[Decky_Q]

Could the plug for the glow plug rail have come loose or wire pulled/melted/squashed? I'd guess its failing to close the circuit when it tries to use the glow plugs so wiring would be next thing to check.

[timg147]

Just went with the Bosch ones that the GSF car parts said were correct for my vehicle reg.

[tr7v8]

Glowplugs only assist the starting. Once it's running they have no involvement at all. It won't be glowplugs.

[MustangGT]

tr7v8 said:

Glowplugs only assist the starting. Once it's running they have no involvement at all. It won't be glowplugs.

Agreed, more likely to be injectors.

[timg147]

That may be the case. But why is it still showing those error codes after replacing the glowplugs and sending a clear code command?

Any thoughts as to what else it could be?

[timg147]

Hmmmm...injectors, just had a quick look they aren't cheap. Car is 59 plate with 101000 miles.

Don't suppose there is an easy way of checking the injectors.

[stevieturbo]

So did you actually test if the glowplugs were working ?

Would make more sense before changing parts, as it could be their controls, wiring, or the plugs etc.

And glow plugs can be used at various times even when running. Not just for cold start.

eg

https://www.picoauto.com/library/automotive-guided...

https://www.mvwautotechniek.nl/en/gloeistift-gloei...

[timg147]

I have to admit I didn't check the original glow plugs. The car only gets used at the weekend and has been getting harder to start, normally requiring a second attempt to start. That and the car is at over 100k and to my knowledge hasn't had the glow plugs replaced, at least not in the last 50k.
After finding the error codes relating to the glow plugs and reading the symptoms of failing glow plugs I thought I would change them anyway. Probably the wrong way to go about things I know

[TwinKam]

stevieturbo said:

So did you actually test if the glowplugs were working ?

Would make more sense before changing parts, as it could be their controls, wiring, or the plugs etc.

And glow plugs can be used at various times even when running. Not just for cold start.

eg

https://www.picoauto.com/library/automotive-guided...

https://www.mvwautotechniek.nl/en/gloeistift-gloei...

This. Easy to test glowplugs without even removing them, and also to test the supply voltage and duration.

[stevieturbo]

TwinKam said:

This. Easy to test glowplugs without even removing them, and also to test the supply voltage and duration.

current clamp is dead easy to get a reading of each, and all 4 for comparisons against each other.

[Decky_Q]

I'm not guessing here, I'm telling you there is a prob with the supply wiring, either damaged wiring is allowing a short to earth or it's not allowing any power to the plug rail due to a break that's the only 2 scenarios where you will get a fault code. Dont mess about with your injectors ffs.

[timg147]

So a current clamp on the glow plug harness would probably be the best place to start?

[Decky_Q]

Theres usually a metal 'bar' carrying +ve to all the plugs, I'd check along that and see if its touching the grounded engine first, clean any crap off it if there is any, then go back along that wire to find either a break or a squashed/rubbed wire that is grounding. It's a short run of wire so wont be that hard to follow, no need to untape bundled wires they will be fine under the wrap. Connection plugs can be another culprit so undo them and look to see if the pins are corroded as this can cause high current draw too.

By the time you've done these you will have found the problem.

[stevieturbo]

Decky_Q said:

Theres usually a metal 'bar' carrying +ve to all the plugs, I'd check along that and see if its touching the grounded engine first, clean any crap off it if there is any, then go back along that wire to find either a break or a squashed/rubbed wire that is grounding. It's a short run of wire so wont be that hard to follow, no need to untape bundled wires they will be fine under the wrap. Connection plugs can be another culprit so undo them and look to see if the pins are corroded as this can cause high current draw too.

By the time you've done these you will have found the problem.

Most modern stuff will have dedicated lines to each glow plug, or perhaps a pair. This is for fault monitoring etc so it can then report which one is faulty.
Plus likely less current for each MOSFET to handle instead of them trying to run all 4 at once, as they can pull a lot of current.

Ideally scope/clamp, but a regular DC current clamp on each plug, and then you can compare.

[timg147]

The wiring for the glowplugs is from a multi plug. I don't know what else is supplied from this, injectors maybe. I have looked and I can get one of these looms off ebay for around £40.

I'm wondering if I have multiple issues here. As well as the diagnostics pointing to glowplugs, some googling of the hesitation and lack of power could be fuel filter or egr valve. The egr does have some oil around it

[timg147]

OK...so today going up a hill power went down and down until the engine stopped. Eventually wound the engine over on the starter and eventually it started to pick up and got going. 4 miles down the road it did the same
Just waiting for recovery now. But while waiting i did an obd scan and it appears there is still a problem with one glow plug.
However I have noticed that whilst in neutral the engine revs straight round. Try driving it and 2k revs are more the order of the day, perhaps 3k if you are lucky.
I'm a bit lost glow plugs should only really help starting, was thinking fuel filter but surely that would also affect out of gear revs as well
Might change anyway for the sake of £20

[stevieturbo]

as already shown, glow plugs operate at various times. Not just starting.

But it is extremely unlikely one glow plug not working is the actual cause of low power.....however it may push the ecu to being unhappy and deliberately reducing available power, aka a limp mode.

Again, a proper scan tool and revieing data would be useful.