Technical Limp home mode or something else?

[field500]

Hi

Took the 500 out on Sunday - first drive since timing belt/tensioner/water pump change, other than the drive home from the garage

Drove for about 4 miles and car going really well - got on the motorway and up to speed without issues (70-75 mph)

Then the "Stop Start Disconnect" warning flashed up and the engine management light was on - the car lost power and started popping and banging. Managed to exit the motorway with very little power from the engine. Had to stop for some lights and the car would not pull off - no power what so ever. Popped hazards on and turned engine off, restarted engine and no warning lights and car drove normally back home.

Left it running on the driveway for 15-20 mins without any issues, albeit when blipped the throttle, it would not go over 4000rpm.

Car is 5 years old and only has 9000 odd miles

I assume the stop start warning is a red herring - but clearly the engine management/loss of power is a worry. Initially i was concerned the timing belt was not fitted correctly, but car ran okay once it was restarted - the only other thing i can think of is a TDC or Crankshaft sensor, which may have been removed when the belts/tensioner was fitted? And i wonder if the lack of rpm above 4k is some sort of Limp home mode that reduces power?

Car is booked in for investigation but anyone any other suggestions to the cause

Fingers crossed i can make the 10 miles to the garage !

Thanks

 

[varesecrazy]

A New belt is Fractionally shorter than a belt with wear

The top and bottom timing sensors notice this change.. typical at 60/70 mph


Likely to be an error by the garage..
This SHOULD be remedied by the Engine ECU 'aligning ' these new timing positions.

You may find keeping RPM low wont trigger it.. but it needs sorting

 

[John202020]

Classic symptoms of the timing belt being 1 tooth out?

 

[field500]

Classic symptoms of the timing belt being 1 tooth out?

Hi, I was worried about the belt but the car runs fine now, other than the limit to revs. In the old days when I did my own mtce, I changed the belt on my Uno. And it did not run very well at all. As you said, moving it on a notch on the belt, was fine. Belt, tensioner and water pump were changed by main dealer, so hope they got the tdc lined up! Will see what the diagnostics say when they plug it in

 

[field500]

A New belt is Fractionally shorter than a belt with wear

The top and bottom timing sensors notice this change.. typical at 60/70 mph


Likely to be an error by the garage..
This SHOULD be remedied by the Engine ECU 'aligning ' these new timing positions.

You may find keeping RPM low wont trigger it.. but it needs sorting

Hi, plan to keep the revs as low as possible when I take it to dealer, will see what there diagnostics say.......

 

[John202020]

Popping and banging suggests misfiring again wrong timing did it start once you drove faster? did the mechanic also do the phonic wheel re learn procedure too?

 

[field500]

Hi.
Only got the warning light and then the poor running when I hit 70/75 on the motorway. Main dealer did the work, so hope they know what's what! Been using them for over 20 years and have had no issues with them.
Will keep revs down when I take it back. I assume their diagnostic will show up the error etc. Thanks for the pointer though.

 

[eeeno]

It sounds like a phonic wheel relearn is needed.

 

[field500]

Hi, well, just looked what a phonic wheel relearn is, and sounds like something that can be done quite quickly? I would have hoped the dealer would have done this but they may not have....... Thanks for the pointer though, will mention it

 

[John202020]

Main dealer did the work,

Straight back to them

 

[field500]

Straight back to them

Oh yes, booked in for Monday............. Just hope it does not conk out on the way ! (only 7 miles)

 

[puntodeltathema]

Either phonic wheel or a cam/crank correlation error (timing not set quite right). But either way main dealer should clearly sort without quibble.

They may have set the timing without bothering with the locking tools and it may be it's just now a tiny bit out - enough to throw an intermittent error.

Nick

 

[field500]

Either phonic wheel or a cam/crank correlation error (timing not set quite right). But either way main dealer should clearly sort without quibble.

They may have set the timing without bothering with the locking tools and it may be it's just now a tiny bit out - enough to throw an intermittent error.

Nick

Thanks Nick. Hoping it is a simple tweak required when they get it. Have had timing belts done there on several occasions without any issues. Will update post when I find out what it is.

 

[eeeno]

Or the mechanic didn't bother to align the crankpulley hole correctly with the dimple. Very strange for a Fiat mechanic because he should be the first one to know about these things.

 

[field500]

Or the mechanic didn't bother to align the crankpulley hole correctly with the dimple. Very strange for a Fiat mechanic because he should be the first one to know about these things.

That's what is a bit annoying, if it is related to the belt change, you would hope a FIAT mechanic knows what to do. Of course, it could be unrelated to the belt change, but that would be a suprise. I only have to go 7 miles to dealer, so I assume as the car runs and drives, it is safe to drive there........ If it is some sort of limp mode, the whole idea is to be able to get it to a dealer? Thanks for the pointer though

 

[field500]

Hi
Dealer had the 500 in today for checking - codes showed up on their system - Misfire on Cylinder 1, Cylinder 4, Misfire Random - all showing component or system over temperature. Also Downstream Lambda probe - signal stuck low

They checked the belt/tensioners which had been replaced, all were good. Checked the timing, that was good

Said it was therefore likely to be Plugs/Coil pack or variator

Plugs were good but coil pack was duff - they fitted one they have in workshop and all errors went. Fitted a new coil pack and all seems good !

Drove it to the dealer very cautiously - minimum revs etc, and seemed ok. "Thrashed" it on the way home, and all seems good too - albeit when i mean thrashed, within the speed limit (only 60mph for about a mile) - no motorway yet

One thing did while driving home was dip the clutch and i could rev the engine to the red line. But, this raised another question - when i got home and was stationery on the drive, i could put my foot to floor and only 4k revs - as soon as i drove off and dipped clutch, 5k+ revs. Just wonder if there is a sensor on the ecu that prevents "excessive revs" when car stationery?

Will see how it goes but suspect all is fine now - codes on the diagnostics all cleared etc - bloody sods law it goes after having belt/tensioner and service though.

Thanks

 

[varesecrazy]

Thanks for the update ..

I think the 4k ceiling may be a
'self preservation ' Software setting

 

[field500]

Thanks for the update ..

I think the 4k ceiling may be a
'self preservation ' Software setting

Yes, makes sense - normally you would not sit there in neutral revving the engine that much !

 

[field500]

Hi
Dealer had the 500 in today for checking - codes showed up on their system - Misfire on Cylinder 1, Cylinder 4, Misfire Random - all showing component or system over temperature. Also Downstream Lambda probe - signal stuck low

They checked the belt/tensioners which had been replaced, all were good. Checked the timing, that was good

Said it was therefore likely to be Plugs/Coil pack or variator

Plugs were good but coil pack was duff - they fitted one they have in workshop and all errors went. Fitted a new coil pack and all seems good !

Drove it to the dealer very cautiously - minimum revs etc, and seemed ok. "Thrashed" it on the way home, and all seems good too - albeit when i mean thrashed, within the speed limit (only 60mph for about a mile) - no motorway yet

One thing did while driving home was dip the clutch and i could rev the engine to the red line. But, this raised another question - when i got home and was stationery on the drive, i could put my foot to floor and only 4k revs - as soon as i drove off and dipped clutch, 5k+ revs. Just wonder if there is a sensor on the ecu that prevents "excessive revs" when car stationery?

Will see how it goes but suspect all is fine now - codes on the diagnostics all cleared etc - bloody sods law it goes after having belt/tensioner and service though.

Thanks

Took the 500 out for its first drive since got it back from dealer following Coil replacement (combination of a being a second car and crap weather last few weeks) - car starts and runs fine, got it on a quite A road and up to 80+ without any issue and when it was back down to 60-65, the Stop Start Disconnect warning light came on, engine management light was flashing and started to misfire and lose power.
Managed to pull into a farm shop car park and car was running very rough and misfiring. Turned engine off and back on, and car appears fine - revs and runs as expected without any warning lights
This is what happened originally, which prompted the original post and trip to dealer.

So its booked in again but any suggestions - just wondering why the stop start disconnect warning light comes on and then the engine management light/rough running/misfire ? On this model you can switch stop start off and it stay off - which we do.

Will update you once dealer looked - they checked timing belt/timing last time (it had just been replaced) and the diagnostics pointed them to the coil pack, which they replaced. Clearly not that (or a duff replacement) !

Thanks

 

[eeeno]

Did the problems start right after the timing belt replacement? Then what they should be looking into is the crankshaft pulley alignment. Did they align it with the small dimple so that it goes into the hole in the pulley? If not, it will cause this. Sometimes there is no dimple, it is cracked making it quite difficult to keep the alignment right. Phonic wheel relearn is not going to fix that.

It could be the crankshaft position sensor fault too, but it is not very likely if the problem started right after the belt change. If you had problems with the car even before the belt change, then you should get them have a look at the phonic wheel and its condition and the sensor itself.