Northern Auto Tech - ECU and Blue & Me Repairs

Technical Petrol 1.2 starts and idles fine but won't rev up

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Technical Petrol 1.2 starts and idles fine but won't rev up

We'll I've been back to the car. I've put the pedal back on, checked voltage at the connector to the pedal and we have power there. I know the pedal has varying resistance when pushing the pedal so I checked the voltages at the throttle body whilst my partner pressed the accelerator up and down and I have no voltage change. As the pedal shows varying resistance on the pots, I would expect to see at least something but I got nothing. I also checked the ground that the ECU is attached to and it all reads fine.

So I am still inclined to believe it's the ECU, in part because the ECU on this Panda is the same as ones on 1.6 Stilo's amongst others and these have had know issues with throttle body control like no revs. A local auto electrician, who I trust, has also had to deal with throttle issues on other Fiats and it also was the ECU in those cases too.

However......when I rang various ECU testing companies, they all said that they can't test/repair my ECU despite claims that they can do all/any ECU etc. I then looked at replacement units and again, companies listing my ECU part all said they have no stock. So when I called my local Fiat dealer, they quoted £513 for a refurbed unit and £800+ for a new one (can't remember the exact amount as I was falling over at the time)! I can get a used ECU much cheaper but I believe it will need coding somehow to the car.

I've ordered the MultiEcuScan software and associated leads and see if this can help me identify the problem with more accuracy. When I thought an ECU test and repair was circa £150-£200, to me, it was probably worth taking the risk vs recovery costs, diagnostic charges and repair costs......and if it pans out to be the ECU anyway, I reckon I would be looking at total costs north of £750. But now, I need to be sure before I go further.
 
Good decision to go with MES.
btw, which inteface have you bought as almost all ELM based interfaces need a small modification. ?

ref the issue you are having, if the ecu sees an incorrect voltage range on the pedal it will not allow operation (no voltage output to the tb actuator) as it is in an unsafe state. In that case, the ecu would be operating normally.
Anyway, with MES, you will be able to see the throttle travel - and the actual reported diagnostic code description., you will also be able to test the actuator if required.
I am sure you will keep us informed, please do. It will be very interesting to know the final outcome.

When I measure voltage at an ecu or connector - if it needs to be connected - I use an insulation piercing probe (I have a set of four - but one is often enough) - mine are Fluke - but there are various copies .
It basically puts a tiny stainless needle point through the cable insulation into the core in a controlled manner - to allow tests in situ - a useful thing for your tool box if you dont have them.
Here is the type of thing - you might find them useful.
http://www.rapidonline.com/Cables-C...-piercing-test-probes-CATIII-1000V-10A-500240
 
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I went for the full cable set and software from Gendan.....so that's the KKL and ELM cables/interfaces, 4 adapter cables and MultiEcuScan software license so should hopefully cover all/any eventualities??

I guess I'll just have to work out how to use it :/
 
kcdionysus said:
I went for the full cable set and software from Gendan.....so that's the KKL and ELM cables/interfaces, 4 adapter cables and MultiEcuScan software license so should hopefully cover all/any eventualities??

I guess I'll just have to work out how to use it :/
Click to expand...

You wont have any worries with that, Gendon are a bit expensive I must say - but not too bad. You will get support from them as well - as oppposed to ebay - for the cables and adapters.
Excellent, you can DL a copy of MES V19 and use the simulate mode.
 
Cheers. I'll have a play before I go to the car again as I've got a load of stuff to do this weekend so probably won't get back the Panda till next week.
 
captainslarty said:
Actually, I would still presume the fault is the actual pedal assembly - the ecu would be my last suspect, by a long way.
Click to expand...


Thinking back to the diagram showing the pedal as K055, does the diagram show the connecting pins on the ECU?

The diagram at the bottom has numbers underneath each pin on the pedal eg A is 3, C is 40 etc. Are these the PIN numbers at the ECU? If so, are the ECU pins matched for input and output - i.e. Does PIN number 3 have voltage in from the pedal match to pin 3 output voltage to the throttle body or is it not like this?

What I'm trying to ask is, can I back probe the ECU for voltage from the pedal and then back probe the ECU for voltage from the ECU that would go to the throttle body? If so, where can I get a diagram of the relevant pins?

And if I have say varying voltage going in from the potentiometer on the pedal and nothing, or no variance, from the ECU pin coming out, would this identify the ECU as being the problem? If not, how does a garage diagnose a faulty ECU?
 
kcdionysus said:
Thinking back to the diagram showing the pedal as K055, does the diagram show the connecting pins on the ECU?

The diagram at the bottom has numbers underneath each pin on the pedal eg A is 3, C is 40 etc. Are these the PIN numbers at the ECU? If so, are the ECU pins matched for input and output - i.e. Does PIN number 3 have voltage in from the pedal match to pin 3 output voltage to the throttle body or is it not like this?

What I'm trying to ask is, can I back probe the ECU for voltage from the pedal and then back probe the ECU for voltage from the ECU that would go to the throttle body? If so, where can I get a diagram of the relevant pins?

And if I have say varying voltage going in from the potentiometer on the pedal and nothing, or no variance, from the ECU pin coming out, would this identify the ECU as being the problem? If not, how does a garage diagnose a faulty ECU?
Click to expand...
The connection numbers in reference to the throttle pedal are indeed ecu connections. They do not connect to the throttle body. The throttle body output is from a different section of the ecu. The two parts are completely independent.
Fisrtly you look at the diagnostics to see throttle position and / or error codes. the you do a static test of the actuator.
if the problem appears to lie in the pedal, then it could be wiring or pedal or ecu.
one can use pin probes as I linked to to measure output at pedal, then output at ecu. The diagnosis, if not readily apparant can often be made if there is a difference in V out at the pedal tracks and V in at the ecu - indicative of a wiring fault. If however, there are voltages at the ecu, the thing then is what are the voltages ! ? and are they in relationship to each other !?. if not, the ecu will reject them. (correctly)
If you run an actuator test, then you know the actuator is working, the ecu output stage is working, and the wiring is ok from ecu to actuator.
The ecu 'could' be the problem, but based on the information so far I would doubt it. - but only tests will tell.

edit - ref varying voltage at pedal.
You have to understand that even if you have varying voltage at the pedal, the 2 tracks offer a failsafe design - they both output voltage, but slightly different from each other - but in a constant way. I have seen both a phase lag system and a sine cosine system in the past - I believe this system uses a phase lag system.
If either voltage is not in phase (well ok, in phase lag if you will!) - then the pedal signal is rejected as unsafe. In this context you will see varying voltage, but it is not appropriate,
That is why one would need to graph or test the individual voltages. - varying voltage certainly does not make one believe the unit is functioning correctly.
But, see what the diagnostics say first.
 
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captainslarty said:
The connection numbers in reference to the throttle pedal are indeed ecu connections. They do not connect to the throttle body. The throttle body output is from a different section of the ecu. The two parts are completely independent.
Fisrtly you look at the diagnostics to see throttle position and / or error codes. the you do a static test of the actuator.
if the problem appears to lie in the pedal, then it could be wiring or pedal or ecu.
one can use pin probes as I linked to to measure output at pedal, then output at ecu. The diagnosis, if not readily apparant can often be made if there is a difference in V out at the pedal tracks and V in at the ecu - indicative of a wiring fault. If however, there are voltages at the ecu, the thing then is what are the voltages ! ? and are they in relationship to each other !?. if not, the ecu will reject them. (correctly)
If you run an actuator test, then you know the actuator is working, the ecu output stage is working, and the wiring is ok from ecu to actuator.
The ecu 'could' be the problem, but based on the information so far I would doubt it. - but only tests will tell.

edit - ref varying voltage at pedal.
You have to understand that even if you have varying voltage at the pedal, the 2 tracks offer a failsafe design - they both output voltage, but slightly different from each other - but in a constant way. I have seen both a phase lag system and a sine cosine system in the past - I believe this system uses a phase lag system.
If either voltage is not in phase (well ok, in phase lag if you will!) - then the pedal signal is rejected as unsafe. In this context you will see varying voltage, but it is not appropriate,
That is why one would need to graph or test the individual voltages. - varying voltage certainly does not make one believe the unit is functioning correctly.
But, see what the diagnostics say first.
Click to expand...

It's enough to make you want to don a pair of ruby slippers.

Diagnosing a bowden cable was so much simpler.
 
captainslarty said:
If either voltage is not in phase (well ok, in phase lag if you will!) - then the pedal signal is rejected as unsafe. In this context you will see varying voltage, but it is not appropriate,
That is why one would need to graph or test the individual voltages. - varying voltage certainly does not make one believe the unit is functioning correctly.
But, see what the diagnostics say first.
Click to expand...


OK, that was my misunderstanding. I thought that if there was varying voltage from the pedal potentiometers, the engine (via the ECU) would at least do something..... maybe even if erratically if the voltages aren't as expected by the ECU. But from what you're saying, if the potentiometers aren't operating exactly within expected parameters, the ECU rejects the input and won't work. But I thought the idea behind having 2 potentiometers was that if one isn't working correctly, the other is there. What are the chances of both failing?

And I'm just waiting for the MES and leads to turn up.
 
kcdionysus said:
OK, that was my misunderstanding. I thought that if there was varying voltage from the pedal potentiometers, the engine (via the ECU) would at least do something..... maybe even if erratically if the voltages aren't as expected by the ECU. But from what you're saying, if the potentiometers aren't operating exactly within expected parameters, the ECU rejects the input and won't work. But I thought the idea behind having 2 potentiometers was that if one isn't working correctly, the other is there. What are the chances of both failing?

And I'm just waiting for the MES and leads to turn up.
Click to expand...
Hi mate, no, the two pots are there as purely a fail safe and error check. It is such an important thing - it has to be failsafe within reasonable costs. The dual tracking voltage method is a standard way - any differential form the norm and you will get track or position errors (which I believe you have ?), and the car will not allow you to drive it . If you think about it, an incorrect input to the ecu could be fatal to the driver or others. It is one of those items that has to be correct. The ecu will MIL, error code produce and reject in such an important system.
It is also not a case of both failing, one is there to effectively 'prove' the other - the pair make up a valid signal. so, a small fault in a singal track causes a failure.

Bit of a bugger having to wait for mes to arrive ... hopefully it will be here soon.
Cap.
 
kcdionysus said:
But I thought the idea behind having 2 potentiometers was that if one isn't working correctly, the other is there. What are the chances of both failing?
Click to expand...

But if one is working correctly and the other isn't, how is the ECU supposed to know which is the correct one?

The system has to be fail safe by design - an uncommanded throttle input at the wrong time could be dangerous.
 
jrkitching said:
But if one is working correctly and the other isn't, how is the ECU supposed to know which is the correct one?

The system has to be fail safe by design - an uncommanded throttle input at the wrong time could be dangerous.
Click to expand...
Hi Jk, it doesnt need to know which, it only needs valid signals / voltages.
In a standard signal, one pot will cause a voltage lag, for example, lets use 0.5V (just as an example) - so there are two input to the ecu, when 1 is at 1v, the other is 0.5V behind, so is 0.5 in this case, - if pot 1 is 1.35v, pot 2 will be 1.35 - 0.5 (our lag) so = 0.8V ,
if the ecu sees anything else apart from a voltage on one input - you cold call it input 1 or high input, and the voltage on the lag pot is NOT 0.5 behind - it will failsafe.
So, I think you can see that an issue with either pot would cause an error - pot 1 or pot 2 ,
It will also fail if a certain part of the tracking is not correct - for exampe - if it recognised a problem area at 2/3 throttle, it still failsafes totally.
It is one of the few systems where there can be no limp mode.

oops, sorry Jk, I misread your post, I thought you were asking, apologies ..
 
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hmmmm, one thing to note, I am uncertain as to what ecu the model you have uses with the FBW pedal ?
You may have to do a scan with MES to see... it also appears that it may not show individual tracks - it does on the diesel FBW and the 1.4 16V... it does, however, appear to show throttle pedal position independently of throttle position - which is good - there also seems to be a lack of output in the actuator tests for the TB, you can do the idle valve. however, I would expect the issue to be identified rapidly.
That is only on simulate though - you may well find that a selespeed model does show individual tracks (as the other FBW models do)....
Just an observation... I will be extremely interested to know the results of the diags on this one.
 
captainslarty said:
hmmmm, one thing to note, I am uncertain as to what ecu the model you have uses with the FBW pedal ?
You may have to do a scan with MES to see... it also appears that it may not show individual tracks - it does on the diesel FBW and the 1.4 16V... it does, however, appear to show throttle pedal position independently of throttle position - which is good - there also seems to be a lack of output in the actuator tests for the TB, you can do the idle valve. however, I would expect the issue to be identified rapidly.
That is only on simulate though - you may well find that a selespeed model does show individual tracks (as the other FBW models do)....
Just an observation... I will be extremely interested to know the results of the diags on this one.
Click to expand...


Well I'm back at the car with MES and I can't see individual tracks on the pedal - only a percentage of it being pressed.... Which is what shows on MES.

What MES also shows is the Throttle position doesn't move from 91.6 degrees?? But then on another test, it was showing 6537 degrees on the graph. I put the old TB back on and it's still the same, no revs and TB not moving even when the revs increase by 200rpm or so.
 
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unfortunately captainslarty has gone and got himself banned so you're more or less on your own now....
 
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