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Loss of power but no warning lights

10K views 29 replies 7 participants last post by  metalgod23 
#1 ·
Yesterday the car suffered a significant loss of power. Started up cold and immediately when pulling away it just wouldn't pull. Not like limp mode but there was a definite loss of power. It initially sounded like it had dropped a cylinder, quite a gruff noise but that cleared.

Anyway this lasted a few miles and things seem to be getting back to normal but I'm convinced it's still not pulling as strong as before. Never got any lights on the dash.

At the moment the top end feels ok but the low down torque seems to have gone away a little. I checked for charge air leaks and there is nothing and as its pulling ok at the top end this can't be the issue.

My suspicion is that it's related to the turbo.

Any ideas. Filled the car up with Tesco 99 the day before, possibly bad fuel but again it only seems to be low down in the rev range where its suffering.

Only done 3000 miles
 
#4 ·
It might just be poor fuel. So long as there aren't any warnings displayed, I suggest you let the tank go down to 1/4 full and then fill up with fuel from another filling station and hope for the best.

If you know someone with MES (MultiECUScan), it might be worthwhile to see if any DTC errors have been logged.

Andy
 
#5 ·
I've been to Mangoletsi today to get the wheels which should have come with my car fitted, only 3 months late but that's another story.

Anyway I mentioned to them about the loss of power but they couldn't care less. Service guy said if it isn't doing it now and no warning lights then no point investigating.

I'm a maintenance technician and spend most of my time dealing with train drivelines (Cummins and Voith to those interested!) and if a fault isn't present at the time of investigation I can't usually get away with "No point wasting my time on it".

I'll see how it goes and if it keeps happening then I'll take it somewhere other than Mangoletsi.

Does anyone know how the vanes in the turbo are controlled on these engines, I.e electrically actuated or vacuum?
 
#6 ·
...

Does anyone know how the vanes in the turbo are controlled on these engines, I.e electrically actuated or vacuum?
Vacuum, I believe, at least as far as the Quadrifoglio is concerned.

Andy
 
#8 ·
Not likely to be a leak in the vacuum line then. If it was electrically actuated I'd suspect that was playing up.

Also it had the Fuel firmware update yesterday so am I right in thinking they will have flashed the ECU which would have reset the adaptations? Throttle response seems different, needs a heavier foot to get it going.
 
#9 ·
There are many ECUs in the Giulia. My post :

https://www.alfaowner.com/Forum/alf...tesrt-ecu-software-versions.html#post17535479

covers the Quadrifoglio.

My guess is the fuel firmware recall updates either the instrument panel or the BCM or both.

It is possible that while updating those ECUs, they've updated all others at the same time which could mean you experience some change.

By 'adaptations' I guess your meaning things that the car has learnt over time rather than remapping that's been done?

With my Quadrifoglio, few of the settings I'd made were lost, so not all data is overwritten.

Andy
 
#11 ·
Metalgod that's great info cheers.

My suspicion is that the Wastegate is sticking as this would cause the symptoms I'm having. Now that I know its electronically actuated that makes it more likely that this would be the cause or at least that the mechanical portion of the actuator might be sticking. Any electronic issue would likely throw a code.

I should just get it looked at under warranty but being that I'm a tech by trade I can't help myself tinkering.

Cheers
 
#12 ·
It is quite easy to see if the actuating arm linkage from actuator to the mechanical waste gate is moving. With the engine running get someone to switch off the ignition, you should see the arm move the wastegate open. Then get someone to start the engine and observe if the arm moves in the opposite direction. If it remains in one position it is obviously stuck. I like to do some initial diagnosis myself that way the workshop can't bullsh1t you, while you also gain more knowledge about the car in the process.
 
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#13 ·
Sorry I misread your message Metalgod. Actually it's not the Watergate actuator I'm thinking of it's the vane control.

I think at high rpm the actuator is not energised as the turbine is already at optimum speed but at low rpm the vanes geometry is altered to reduce lag.
 
#15 ·
Are you describing Variable Geometry Vane Turbo? The 2.0 is fitted with a twin scroll turbo and the inlet vane geometry is not altered with rpm. On the Giulia, the cylinder exhaust is sent directly to the turbo inlet in what is called 'pressure pulse' design with the direct connect between the cylinders' exhaust and the turbine impeller. There is no traditional exhaust collector manifold as such. I still think you may have a sticky wastegate actuator. Although, if the wastegate was permanently stuck open through it will constantly leak boost and you will feel loss of power further up in the range as well. It is a bit difficult without repeatability.
 

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#16 ·
So this turbo is not Variable geometry then? I'm trying to google the info but can't seem to get any decent info.

Like you said if the Wastegate was sticking then this would probably cause an issue throughout the rev range not just low rpm. I stand to be corrected though as a fully open wastegate might not be optimum for low speed performance.
 
#17 ·
#18 ·
Ok so that's my theory out of the window. So this being a twin scroll design then it could be back to the Wastegate control.

Read that thread on the US site and symptoms sound different to mine as in more severe. However the issues they have had regarding injector weap/leak doesn't sound good!

We get that on the Cummins Diesel engines from time to time and can cause quite a few issues.
 
#19 ·
Ok so, looks like sod's law is at play and I tempted fate by posting about my thoughts on switching my car, how good the 2.0 early engine etc. on other threads!

This morning when I was already pushed for time dropping my son off to school, the engine started very lumpy from cold first thing, very similar symptoms to the OP. Switched off a couple of times and it was still quite lumpy. I had no choice but to carry on with the 1 mile drive and it was stumbling and bucking to the point my son asked me why is it so bumpy? Very much like a cylinder misfiring. It wasn't particularly cold this morning compared to previous days.

So I stopped outside school after drop off and plugged in my BT OBD reader and scanned using Torque Pro app. It confirmed Cylinder 4 misfire. Error code : P0304 - Cylinder 4 misfire detected. No CEL, only Start/Stop unavailable and stayed so. All DNA modes were available throughout. I even tried switching modes to see if the misfire would settle down but it didn't. After driving for a couple of miles and may be with engine coming up a little in temperature it seemed to start running OK. Start/stop unavailable warning remained. Power appeared to be back on all DNA modes. I drove the rest 15miles hard in both N and D partly in manual shift mode to see if that would clear the injectors in case that was an issue. I reached work without further issue. Car restarted fine after stopping.

Code P0304 may mean that one or more of the following has happened:
Faulty spark plug or wire Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer


My symptoms sound exactly like what @Cutterbuck experienced (See Post #14) with the exception that I did NOT get a CEL.
https://www.alfaowner.com/Forum/alfa-giulia/1120322-first-glitch-at-14-000k-miles.html

Some points to note -
1. 3rd service completed recently a week/200 miles ago. New oil and filter. I have asked dealer what oil they used. Car has covered nearly 28k miles.
2. Tank has Shell 95 RON fuel. I tend to alternate between 95 RON and V Power occasionally and predominantly use Shell as it is on the way to work with the odd occasion using Tesco 99RON. The last time I filled Tesco fuel was more than a month ago so I don't think fuel is the problem.

@Twiss002009, I now think the issue could be either a faulty or blocked injector, spark plug (not due to be changed for another year at least) or harness. Cylinder 4 is closer to the cabin - see attached.

I know some early multi air engines on the Giulietta and Mito had the MA unit going faulty or their associated oil filter blocking. I am not sure if the Giulia has a MA unit like those cars and I can't seem to find any info. I do know that the lubrication system also supplies the MultiAir module intake valve actuators with oil it uses to control intake valve opening and also an additional filter screen in the oil supply channel to the cylinder head (seen in picture 2), which ensures that the oil directed to the cylinder head components, in particular the MA module (I am guessing this is the item circled in yellow in Picture 3), is cleaned more thoroughly. The additional MA filter seems to be located by Cylinder 1 assuming I have the orientation correct in my head.

I am hoping @MacGeek can confirm if the MA unit in the Giulia is different and does not suffer the same issues as the early MA units. If it happens again I will get it booked in for investigation. I might try swapping the cylinder connectors to see if the misfire moves to a different cylinder. I think it is likely a plug, injector or harness issue given the engine seems to be running fine after the initial misfire.
 

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#21 ·
.....
I am hoping @MacGeek can confirm if the MA unit in the Giulia is different and does not suffer the same issues as the early MA units. If it happens again I will get it booked in for investigation. I might try swapping the cylinder connectors to see if the misfire moves to a different cylinder. I think it is likely a plug, injector or harness issue given the engine seems to be running fine after the initial misfire.
As I understood, the giulia has the new multiair II unit introduced in 2016, so I would expect the problems to have been solved......
(assuming correct oil is used, and changed frequent enough, which always seems to be a point on the multiair engines)
However, no idea, but I haven't seen any problems mentioned .....
 
#23 ·
That sounds very very similar to the symptoms I had. I'm just about ready for another tank of fuel so I'm going to put V power in and drive her fairly enthusiastically! See if the good old Italian tune up sorts things out.

I haven't had a repeat of the misfire symptoms but the car definitely isn't quite as responsive as it usually is. I have noticed though that it seems to take a while for the transmission to give me full performance as in speed of shifts. Once temp has come up it's fine but it does seem to take while with the colder weather.

For me now the issue is low down responsiveness. Top end power seems fine.
 
#24 ·
Mine has not misfired except that once from cold start 2 days ago. It has been starting fine and running normally at low and top end. I have not felt any difference to shift speeds when engine is cold or warm. Responsiveness seems normal. I filled up with Shell V Power last night and have been giving it the Italian tune up on and off.

The dealer came back regarding oil and they have used Castrol Magnatec Professional 0w-30 C2 oil which is a trade type oil which does not appear on the consumer website. I know that Castrol do not produce any oils that meet the required Fiat 9.55535 GS1 spec for the 2.0 engine. I have questioned the workshop on this oil and asked for some evidence why they think the oil is OK for the engine. They used to use Selenia but switched to Shell Helix Ultra ECT 0w-30 last year for the second service. Shell meets the Fiat spec. They have now switched to Castrol but the parts department did not seem to grasp the need to check if the oil complies or meets the Fiat Spec which is rather surprising for an authorised dealer. I have made it clear that I need reassurance from AR technical the oil is correct and there will be no long term detriment. If not I shall be asking them to flush out the oil a couple of times and refill with the correct spec oil from Selenia, Shell or Motul.

I'd like to think the misfire just after a week since the oil change was coincidental rather than oil spec related given that it is 0w-30 C2 oil. Surely the right viscosity oil that is new would not cause any blockage in the multiair inline filter. The engine has been running fine since the one short misfire incident. I assume the Fiat 9.55535 GS1 spec relates to additives? Anyone know what the manufacturer specification actually means?
 
#25 ·
I had my first Giulietta MA serviced at the dealer you probably use (Lipscomb?) and they used an incorrect oil at the second service. I called them and Alfa Romeo Customer Services and as a result they sent a driver to collect my car then day from my work in Essex and left me with a loan car so they could correct oil for the MA. The car was swapped back the next day but it’s possible I could have experienced failure of the unit if I hadn’t read the service invoice.
 
#26 ·
they used an incorrect oil at the second service.....

I could have experienced failure of the unit if I hadn�t read the service invoice.
My service was free under the service plan so no invoice by default. I make it a habit to ask for invoice for records which is why I noticed the wrong oil. Their parts department came back saying Castrol said this oil is ok. I however contacted Castrol technical department and I got a prompt email saying they do not have any oil that is GS1 Fiat spec compliant and they should use one that is correct if my engine requires it.

Was your oil correct viscosity but non Fiat compliant or different altogether? Lipscomb have been good so far but it is annoying that I need to hand hold them for something as simple and routine as an oil change! They have offered to have the oil changed to Selenia. I have also asked for them to get AR techical/Teseo to review the oil used a mnd provide reassurance that it would not have been detrimental. Perhaps I will also need to open case with custome care.
 
#27 ·
So I'm about 80 miles into a tank of V power, I ran the tank of tesco down as low as I dared to 25 miles range left. Car is back to her best. Really responsive and the sluggish feeling at low revs totally gone.

I don't know if its coincidence or not. I wouldn't have thought under normal circumstances fuel would make that big of a difference. Maybe I got a bad tank because usually Tesco momentum runs pretty much as good as V power. Only difference I've ever noticed is that on V power its slightly smoother sounding. Whatever the problem was I'm glad it's gone because it really did effect the driveability of the car.
 
#28 ·
That is good news. Sounds like fuel related. I have used Tesco momentum very occasionally and it seemed fine. Currently in V Power and no other rough starts so far.
 
#30 ·
If it happens again, based on further knowledge from other reports, it could be a random/intermittent or one off fault in the Multiair module, specifically the intake valve operating solenoid for Cylinder 4. Just keep an eye on it and if it occurs again you should get it looked at and they will do the usual coil pack swaps, check spark plugs, find no faults and send you on your merry way.
 
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