Technical Low oil pressure alarm - driving me crazy!

[RoyAB]

Hi All

The Qubo continues to be a clown car:

Diesel Multijet 80K on the clock.

History:

Had a loose timing chain, replaced. New oil and filter change.

'Low oil pressure, stop engine' below 10K rpm and, sometimes, slowing for a junction/turning... but also cruising. Blip throttle and clears.


Checked pressure sensor - slight weep at the terminal.

Replaced sensor.

'Low oil pressure, stop engine'

Hmmm...

Looked for leaks, none. Mechanical oil pressure test - fine, good pressure across the rev range. Multiscan connected, idling & cruising says so too.

But, on the outside chance - had checked it when the cover was off to do the chain and the cover was a bit scored but pump turned smoothly/felt OK - that the pump was broke, fitted new timing cover and so with it new oil pump and stop/start valve that come on this model.
New oil and filter change.


'Low oil pressure, stop engine'

Had pro mech re-set the ECU with Snapon kit. No warning ... for a day

'Low oil pressure, stop engine'

Various discussions with local tuning specialist who replaced the injectors (one over-fueling) a month or so before, and industry mate who specialises in rebuilding these motors consensus was, given all that had been done, likely ECU fault.

As no one has ECU testing for this particular vehicle (!), sourced replacement (used) and cloned. 2 days driving all good

Today

'Low oil pressure, stop engine'

:bang::bang:

Help/thoughts gratefully received.

eg.

Anyone know what pin on the ECU the sensor links to - thinking might be a damaged sensor wire?

Do I just drive it until the motor cracks and diagnose that way ?

Is there a way to turn off the alarm?

Thanks All

 

[varesecrazy]

Hi again

Does the light stay off once the pump is spinning?

If the alarm doesnt correlate to the light.. its tricky

If they are in sync. Its probably a fracturing wire..


( it staying off for hours after loom is disturbed is a clue..)

Unplug one end.. and refit

Drive as normal waiting for fault..repeat a few times.. see a pattern emerging

If a fault is deep in the loom.. there are a few other options

 

[portland_bill]

Some thoughts.

1. Get the actual pressure checked, with a gauge. With the engine hot. The replacement pressure switch should remove doubt about the original, but a pressure check will show what it has.

2. If it has a DPF, it can put fuel into the oil, as did the leaking injector, which should evaporate/burn off, but too much will dilute and probably reduce oil pressure. Does it need an oil change? How are the other injectors?

3. Oil pickup pipe and strainer partially blocked, or leaking in air above the oil level. Sump off to check is a chore.

 

[jackwhoo]

Not on a fiat but on a vw-
Stop engine oil pressure warning caused by fractured wire inside insulation near the connector that attaches to pressure switch.

 

[RoyAB]

Thanks Portland_bill

Pressure checked with manual guage many, many times in the saga - fine across all rev range.

New OP sensor

Forgot to mention 1st, but yes, DPF has been stripped & cleaned. 2 fresh oil changes and new filters

EGR also done when I had the exhaust & turbo off. New exhaust at the same time.

Oil pickup and strainer are integral to the timing cover so new with that. Sump off to replace the timing cover (pain in the proverbial! Why oh why Fiat!? ) No leaks from there...

With the exception of the valves, crank and pistons this engine has been pretty much stripped and every sensor replaced to try to sort this...

Conclusion and mech consensus is 'a wire thing'

 

[RoyAB]

Thanks jackwhoo

With everything that's been done that's indeed looking like the general consensus...

Sadly, can find no wiring diagram for this so looks like will have to trace that wire through all the wrapping. Happy days

 

[RoyAB]

Hi varesecrazy

Goes off as soon as the pump is spinning (so, from startup) and doesn't always come on then anyway.

'Sometimes' comes on at cruise, or slowing to a junction/corner. Blip the throttle, goes instantly.

Alarm and light/rubric do come on together tho

Completely irregular.

Had sensor wire off, cleaned contact checked for fit. All good.

As you say, everything is pointing to a 'wire thing' Possibly crimped when taking the loom off to get at the turbo & glow plugs (another masterpiece of Fiat design there!)

 

[varesecrazy]

Thought so..
As your description hinted that way

Disturb one end.. or the other

See what makes a difference



Years ago I kept getting the 'failed bulb'
Alarm and light

Drivers sidelight.. you would unplug..and plug back in.. good for a day or 2

Did this for a couple of months..
One day popped bonnet.. unplugged

And a short length of cable came with it

It was all green and rotten

Cable issue all the time.. stripped back..blob of solder.. perfect

Yours is probably similar.. a wriggle will find it

Charlie

 

[portland_bill]

Hi varesecrazy

Goes off as soon as the pump is spinning (so, from startup) and doesn't always come on then anyway.

'Sometimes' comes on at cruise, or slowing to a junction/corner. Blip the throttle, goes instantly.

When the engine moves on its mountings, the warning is affected. It's a wire.

As it has a DPF, has the oil degradation index been reset?

 

[RoyAB]

Yup, oil degradation has been reset.

As it's a sunny day, this morning will be spent with the multimeter tracing wires...

Thanks All

 

[RoyAB]

Cheers Charlie

This am, sunshine and multimeter and a-wire-tracing I will go.

Heh ho....

 

[RoyAB]

Hi All

For anyone who's following this saga...

Before wasting my life away with a multimeter, had a long hard think/look.

In the process, I noted that the last oil change I'd used A1/B1 5W 30 not C1/C2 5W 30. Given the viscosities are technically the same, shouldn't make a difference but when logic fails... So, changed the oil. Again.

Even tho it had been in for less than 100Km looked pretty thick. Hmm, wondering if carbon from the EGR/inlet clean hadn't fouled it.

Also, realised, tho I'd reset the ECU after each oil change, I'd not reset it when I replaced the cloned ECU.

Hmmm. Reset.

Now? Holy mother etc, it veeeeerks! No more beeeeep.

Was it the oil, was it the ECU?... no idea, but something in Clown Car was made happy.

Till the next time

 

[varesecrazy]

Progress.. well done

Wasnt it misbehaving on the correct oil previously though..?

Strange the newer oil went so dirty too.

Hope this lasts now..

Do keep this thread updated

Charlie

 

[RoyAB]

Hello folks!

For the die-hard few waiting with bated breath for an update:

Remember the oil change fix a while back?

Well, that lasted all of a week and then back to the beep...

... at this point, wot with COVD 'n all I gave up, shoved it to the back of the shed and used the Land Rover instead which, since I'd built it from scratch, I know every rattle, squeak and leak intimately...and, given this, when it's looking to throw a wobbly.

Still, very fond of the little Fiat so last week I relented and took it to my friendly neighbourhood fixers and asked them to do a pressure test.

Friday's news was 'all good, so 'Monday we're going to see if we can trace an electrical - we have the dias.'

Monday pm 'started it this morning and now no / very oil pressure!and a bit of metal on the sensor'

Aaargfgfhfjl&%!!!

But, continued, 'don't think it's bearings - runs sweet, no knocks or rattles'...

Hmmmm

Anyway, we had a little confab and diagnostic genius (Paul) commented 'the oil looks a little metallic/grey too and seems not to adhere to the surface as oil should. How long has it been in? 'About 50 miles' I replied ... 'but, tell you what, I have the old timing cover that I took off and didn't bother to clean so I can show you the wear on it - maybe that's where the metal came from.. (tho how that would have passed through the filter I can't figure)

So, we had a look at it - 'that looks like little bits of plastic in there' says Paul. 'I think what's happened is when the chain guide failed the plastic sleeve and a bit of the metal guide got ground up and is fouling the oil galleries intermittently at the top of the engine. Let's flush the oil, drop the sump to look for bits and see what happens/we find'

I've been driving a silent car since then.

Moral of the story?

If your timing guide is in any way wearing, you're getting muck through the finely engineered Italian sewing machine that is the Fiat engine - filter or no. So, for happy, beep-free motoring, do a flush for an extra tenner or so!

Forza Fiat!