Technical 1.1 ECO Rev limiter

[John1961]

Yesterday my partner was driving the PANDA 1.1 ECO when she experienced an intermittent Engine warning light.

I have today driven the car and put a diagnostic scanner on the vehicle.

The problem seems to be the rev limiter kicking in at about 3500rpm (No counter so a bit of a guess).
The EWL flashes and there is a sudden deceleration. There are no codes logged in the system.

If you keep to below 3500 in any gear the car drives perfectly.

This has just happened so what has occurred and how can it be corrected?

Thanks for any assistance

 

[koalar]

It's not correct

The rev limit is over 6.5K

The engine light does not come on

Engine light is telling you, you have a problem

There's dozens of reasons for a high rpm misfire

Check there isn't oil on the MAP

Check the plug gap

Connect the scan tool and look at the rpm while driving

Does it drive better if you Unscrew the pre CAT O2 (not easy to do)

What is the inlet manifold pressure at idle and 2000 ish rpm

Are just a few quick checks you can preform before we all start taking wild guess, because that was the cause on our cars

It's a common symptom, it needs sorting ASAP as it can lead to further complications


We need to narrow it down with as much information first

It can get expensive if you just start changing thing and don't hit the correct solution early on

Nobody wants to see you waste money changing say

MAP
Coils
Crank sensor
Plugs

All fairly common

And you still have the same problem

Post a picture of the plugs is always a good start

I take it there's no codes stored

 

[John1961]

It's not correct

The rev limit is over 6.5K

The engine light does not come on

Engine light is telling you, you have a problem

There's dozens of reasons for a high rpm misfire

Check there isn't oil on the MAP

Check the plug gap

Connect the scan tool and look at the rpm while driving

Does it drive better if you Unscrew the pre CAT O2 (not easy to do)

What is the inlet manifold pressure at idle and 2000 ish rpm

Are just a few quick checks you can preform before we all start taking wild guess, because that was the cause on our cars

It's a common symptom, it needs sorting ASAP as it can lead to further complications


We need to narrow it down with as much information first

It can get expensive if you just start changing thing and don't hit the correct solution early on

Nobody wants to see you waste money changing say

MAP
Coils
Crank sensor
Plugs

All fairly common

And you still have the same problem

Post a picture of the plugs is always a good start

I take it there's no codes stored

Plugs fine
MAP OK but cleaned anyway. Removed MAP plug no change to performance.
Disconnected O2 no change to performance
When I had tool rpm went up and down on accelerator depression
As far as I can recall inlet manifold pressure changed with revs.

Not sure I would call it a misfire. It is definitely rpm limit kicking in.

Where now?

 

[koalar]

Does it rev fine stationary in neutral

Plugs okay does not help us much

Colour
Dry or wet
Gap
Are they all the same

It's best to post a picture in the correct order

inlet manifold pressure changed with revs.

Again we need the values at idle and at about 2K

What is the long term fuel trim at idle

 

[John1961]

Does it rev fine stationary in neutral

Plugs okay does not help us much

Colour
Dry or wet
Gap
Are they all the same

It's best to post a picture in the correct order

inlet manifold pressure changed with revs.

Again we need the values at idle and at about 2K

What is the long term fuel trim at idle

It revs up to the point it limits (3500) back off then hunts with the EWL coming on when it limits.
Plugs light brown, dry , ~1mm gap and all identical
I will see if I can get Inlet pressure tomorrow.
what do you mean by long term fuel trim. Is this something on the scanner?
Thanks for your continued help.

 

[John1961]

It revs up to the point it limits (3500) back off then hunts with the EWL coming on when it limits.
Plugs light brown, dry , ~1mm gap and all identical
I will see if I can get Inlet pressure tomorrow.
what do you mean by long term fuel trim. Is this something on the scanner?
Thanks for your continued help.

Is there any other info on the scanner that will help diagnosis. If so I will get it tomorrow.

 

[varesecrazy]

DO CHECK THE CAM TIMING

These motors are not complex

 

[koalar]

It revs up to the point it limits (3500) back off then hunts with the EWL coming on when it limits.

What code, is the light on permanent or flashing

Plugs light brown, dry , ~1mm gap and all identical

Light brown is not normal for unleaded petrol?

I will see if I can get Inlet pressure tomorrow.

Cheers

what do you mean by long term fuel trim. Is this something on the scanner?

Yes it the value the injectors timmig is added to or taken away from to insure the O2 readings are correct

Thanks for your continued help.

No problem

 

[John1961]

No codes registered and the EWL is only on seemingly while over the low rev limit
Will get other specific values tomorrow and perhaps get a photo of scanner readings.

 

[koalar]

No codes registered and the EWL is only on seemingly while over the low rev limit
Will get other specific values tomorrow and perhaps get a photo of scanner readings.

What scanner are you using

Any error should be flagged

Sounds like you are only viewing activr

 

[John1961]

I have some data and some photos of data but cannot upload these atm
Idle 740rpm, inlet pressure 338mb, injection time 2696usec
1927rpm, inlet pressure 238mb, injection time 2010usec
3106rpm, inlet pressure 250mb, injection time 2076usecs

at the point of limit i took the following readings
0rpm, inlet pressure 337mb, injection time 2992usec

Does this help in diagnosis?

 

[koalar]

I have some data and some photos of data but cannot upload these atm
Idle 740rpm, inlet pressure 338mb, injection time 2696usec
1927rpm, inlet pressure 238mb, injection time 2010usec
3106rpm, inlet pressure 250mb, injection time 2076usecs

at the point of limit i took the following readings
0rpm, inlet pressure 337mb, injection time 2992usec

Does this help in diagnosis?

Great we are moving forward

33.8Kpa @ 740RPM is correct

We know there isn't an inlet leak

We know to pull that kind of vacuum the timing is correct

0rpm is suspicious

If you can graph the RPM and rev the engine to the error and see if the engine computer is loosing it's signal

 

[John1961]

When the revs hit the limit the rpm signal indicates 0 zero as shown on data

 

[koalar]

That great

It's pointing towards a crankshaft sensor or its wiring

 

[John1961]

Is there anything more we can do now? If not I will go home and get the part ordered.
Should I look for a broken wire or would this be picked up as a fault code. Is it just a failing sensor?
So you think the best bet atm would be to get a new crankshaft sensor.

 

[koalar]

Is there anything more we can do now? If not I will go home and get the part ordered.
Should I look for a broken wire or would this be picked up as a fault code. Is it just a failing sensor?
So you think the best bet atm would be to get a new crankshaft sensor.

A sensor is likely but without an oscilloscope, or another to substitute, it's going to be hard to prove 100%

I am trying to think of a simple test to confirm, with things that you are likely to have at hand

Best I can think of at the moment is to increase the distance between the sensor and the pully a little, something like adding a shim of carboard. If it fails at a lower RPM the sensor would be very likely

 

[John1961]

tried moving the sensor. Does not affect the rpm but if moved too far engine stalls.
Still shall I try a new sensor?

 

[koalar]

Does it fit the symptoms, yes
Does it fit the scan reader showing 0 yes
Can I be 100%, no
Can I think of another easy test, no

They tend to loose some magnetism but unless you know what a good one feels like it would be hard to test

you should Also be getting a P0335 error, this would have confirmed it, unfortunately the error code can not be read


GSF, shop4parts and the like will not sell cheap rubbish. Ebay or amazon would be a lottery in my opinion, Bosch and so on in a discription is no garentee that is what you would receive

 

[John1961]

Thanks for your help. I will get one on order and then add to the post.

 

[koalar]

Here one that would not rev past 2.5K and a new crank sensor fixed it

Plus two cases of cheap sensors online that almost immediately failed

Wont rev past 2.5k. Now won't start. | FIAT Panda (Mk3)

Thanks for the advice everyone. I have had a play this afternoon, and have made some semi progress. This is the state of play atm: - changed fuel pump - changed coil pack (s) - checked and cleaned all the earths - checked fuse box The car will now run at idle fine, however as soon as I try to...

www.fiatforum.com

Fingers crossed