Technical ECU and coils

[drdRiz]

Hey everyone.

So to make a very, and I mean very, long story short: I've had lots of problems with my 1.6 Stilo. (ASR, ABS, Car security faults, dipping ref counter, MIL-light etc etc.) I have done quite a lot to come to the conclusion that the problem lies in the ECU.

I've already ordered one from a company that revises them, and makes them plug and play. The one thing that confused me a little is that they advised me to replace the coils along with the ECU.

Now I'd really like to know why they advise this. Do you think that, when a coil is the actual root fault, there's a chance the ECU would get damaged?
To me it's more of a disclaimer than something that has to be done.


I'm getting the coils checked out tomorrow, I'll megger them (don't know if that's an actual English word) to check their resistance and such. As I really don't believe one or more coils are faulty.

Thanks!

 

[yellowstilo]

the old Sagem coils were known to be troublesome - the Champion replacement coils are much better but they certainly don't live forever....
So check their age and when you doubt just replace them together with the spark plugs (NGK 5BKR) - a new ignition kit makes a lot of difference and prevents the ecu to get sparked and die.....

 

[Stilatos]

any way we can check if the coils are at the end of life?

 

[drdRiz]

yellowstilo
I'll check the brand out as well, I believe the Champion ones have the brand on top of them if I'm correct?
By 'ECU getting sparked', you mean a short to ground that gives the ECU a high voltage over it's ground?
Stilatos
There's special equipment to see if a coil still meets it's specifications. You can't really check them without.

I do believe that when a coil is faulty you should be able to notice a pattern. In my case the problem occurs once every 5 weeks or so, but sometimes a couple of times per week. I do not know the exact build up of these coils, but if it's 'just' a coil, you'd expect a regular occurring short, instead of randomly every few weeks. But I could be wrong.


I'd still like to know if I was right in my first comment; whether it's true they advice to get new coils as a 'disclaimer'.

 

[yellowstilo]

I'm not sure about the location of the brand but it should be visible without removing the coils.
The ecu can be damaged by (partial) short circuit in the primary coil (too high current), by wrong spark plugs or too wide air gap or by (partial) short circuit between the secondary and primary coil (high voltage to driver side).

 

[drdRiz]

Thanks.
I assume that would be permanent damage to the ECU, resulting in constant/frequent failure.
I don't think the coils are faulty, and I'm not willing to spend quite some money on replacing them just to make sure the 'new' ECU doesn't get damaged. I still believe the guys that are supplying me the ECU are just stating it as disclaimer.

Meaning, that when the root of the problem lies in a faulty coil, there's a high chance the faulty coil would damage the 'new' ECU right away. Which would result in lots of costumers claiming that they were delivered a faulty ECU.

 

[Stilatos]

so no chance thru the diagnostics thru FES?

 

[drdRiz]

I'm getting really tired of my Stilo, really considering to give up and sell the beast.

'New' ECU installed, everything went great.
Since a month or so my valves are ticking a little after ignition, nothing to worry about but I decided to rev the car a bit after ignition. 'ASR failure' is back accompanied with a stalling car. After a few minutes the car starts perfectly and runs like a dream. ECU fault scan results in 0 faults.

Only thing I've noticed: When I drive for like half an hour and park the car to get something or whatever, the moment I start the car again it drives weird sometimes. When ever I shift or let go of the throttle the car seems to jutter a single time, very noticable, almost as if I'm tapping the brakes for a split second.

I'm guessing there's some sort of ignition problem. There are Champion coils installed. My 'guy' is on a holiday so there isn't much I can do ATM.

Regardless I'm getting a bit tired of replacing parts that aren't inconclusively broken.

 

[richydraper]

when you 'guy' returns from his holiday, get him to read the codes from all the other ECUs. I'd like to know if you have CAN faults in any other parts of the system.

when you say 'new' ECU, was it a reconditioned unit or a brand new unit?

in my experience, with some if not all of the faults you have mentioned it turned out to be the ECU Processor (covered on here a million times). i had numerous, but stored, ABS>Engine and BC>Engine CAN faults. EVENTUALLY, after many months of spurious faults and strange symptoms i got a PCM fault in the Engine ECU.

also check the ecu pins see here

 

[drdRiz]

when you 'guy' returns from his holiday, get him to read the codes from all the other ECUs. I'd like to know if you have CAN faults in any other parts of the system.

when you say 'new' ECU, was it a reconditioned unit or a brand new unit?

in my experience, with some if not all of the faults you have mentioned it turned out to be the ECU Processor (covered on here a million times). i had numerous, but stored, ABS>Engine and BC>Engine CAN faults. EVENTUALLY, after many months of spurious faults and strange symptoms i got a PCM fault in the Engine ECU.

also check the ecu pins see here

I can scan OBDII myself, there aren't faults stored anywhere. In the past I've only had two faults in the instrument cluster, regarding the coolant temp and the rev-meter. It did have Whenever my car tripped out, those gages would drop or rise to their max, for a few seconds. It was a result of a communication error between the ECU and the BCU, at least that's what I think. I haven't had those problems since I've done the this described in this post:

https://www.fiatforum.com/stilo/353024-fiat-stilo-trouble.html

As far as the ECU, it's a completely revised one. Tested in a bench and 12 hours in an actual Stilo. They virginized it afterwards.
Since installing this ECU I've only had the 'ASR-failure' once, when I was revving my car a little right after starting, as my valves are a bit ticking when the engine is cold.

 

[drdRiz]

To make the issue a bit more clear:

I'm 5 min home from a test run. I added some cleaner to my petrol thinking it won't harm to clean the injectors and all. After warming up I did a 10 minute drive, getting the car up to about 6000RPM, and holding it there for a while. The car drove like a dream. Everything went great until I decided to head to the highway, as I didn't even make it there.

1. The car seems to hesitate a tiny bit, it's more of a feeling than something very noticeable.
2. The famous 3 beeps followed by 'ASR-failure'.
3. The car 'dies', meaning there's no spark. I just let her roll out to the nearest safe spot.
4. MIL light comes on, but I believe that also happens when you let the car die by faulty clutch use.

I started the car, waited a minute, tried to get home:
5. The engine 'bumps' twice whenever I let go of the throttle, very noticeable. Just like I said earlier when restarting the car 10 min after a decent trip. It's either ignition related or throttle related.

This time I had to pull over 3 times cause of the ASR-failure, never had that before. The ECU didn't record any faults upon reading.

 

[drdRiz]

I hate to reply a lot like this but:

Could it be the crankshaft position sensor?

I've just been reading into problems where the CPS was the problem, and the symptoms seem very similar. I would not know why it would register as ASR-failure but then again, it's a Fiat.

 

[aurick86]

1. How is the battery charging system? Use MES to record a graph right before starting the engine till it warms up. save it .. see if the charging values go outside the normal values (~13.7volts)
2. The only way to see if a crank sensor is faulty is with an oscilloscope. Other that that.. buy one and see.. you could just as easy have a bad wire/connection but will never know it without an oscilloscope to see if the ECU gets the correct signal.
3.Connect MES and check that the brake switch and the clutch switch are working properly .. they can cause ASR related problems.. usually along with ESP.
4. connect MES and select the throttle and acceleration parameters... go to the graph tab press "Start"... wile gently pressing on the accelerator watch for any jittery /uneven movement in the graph...it would indicate a bad/dirty throttle plate potentiometer.

 

[drdRiz]

The throttle doesn't seem to be off, I didn't press the gas pedal very smoothly hence the 'stairs'.

Coil timing is 1550ms for each coil.

The only thing that seemed off was the status of Lambda sensors, but I could be wrong.
Lambda 1 status (Pre-Cat.) - Closed loop.
Lambda 2 status (After-Cat.) - Open loop.
Lambda 2 signal (After-Cat.) - System rich.

Misfires (2), don't know what that parameter holds but it's status was "OK".

The brake-switch was replaced a month or 2 ago, in MES it responded perfectly to pressing and depressing.
Same goes for the gas pedal position.

 

[drdRiz]

This time with RPM

Every now and then the RPM maintain after releasing the gas pedal, don't know if it shows in the graph below but in this trip it happened right before stopping the engine.

 

[drdRiz]

I will try a solder reflow in my oven, with the old ECU.

I'll have my 'garage-guy' work on the car later this week, for a day, if he can't find/fix it, I'll give up and get rid of the car.

 

[drdRiz]

Ok so I went to work, ASR fault once, got to work.

Getting home was a whole different story:

- After 500 meters: High coolant temperature, MIL light, car held in throttle. Didn't have to stop.
- After 2 km: ASR-failure, car died. Pulled over, restarted and continued.
- After 5 km: ASR-failure, car died. Switched ignition while driving and continued.
- Decided to turn on the aircon just to see if it could take the extra draw of power, as I was nearing a traffic light, car held 2000rpm for about 5 seconds, before dropping to normal idle RPM.
- After 5,5km: Car hesitated, MIL light showed up, decided to pull over since it was a really crowded road.

So I parked the car, kept it running. Popped the hood to see if I could tap some random components. Relays, connectors, you name it. Nothing happened. Checked ECU for errors, nothing. Then out of nowhere the car died again, no errors.
Turned on the car and decided to rev a few times, in a short amount of time. I heard a suction noise which later turned out to be normal when reving so fast.

Now here comes the messed up part:
As I revved it some more, like 5 short and small presses on the throttle, I got out to check under the hood. The car continued the revving in the same pattern, ON IT'S OWN. As the RPM dropped lower after each rev, it died after about 6 times.


I was like fck it I'll see if I can get home without getting rear-ended. I cut away the normal ground the ECU (the one that's original and comes from the wiring loom). As I already have placed an additional ground straight to the battery. I drove home like nothing had happened.

 

[aurick86]

So it was a bad ground??
Also check that the ECU has a good ground.
Make sure you don't have some high current circuit right next ( or an the same connector ) to the ECU ground; as that can really screw up the ECU.

Have a look a this video so you can see what a bad ground can cause:

 

[drdRiz]

So it was a bad ground??
Also check that the ECU has a good ground.
Make sure you don't have some high current circuit right next ( or an the same connector ) to the ECU ground; as that can really screw up the ECU.

No it was just a coincidence. The problem of the ASR failure started a few months ago, but just once every now and then. At the moment the car is undrivable, as I get the ASR failure every few 100 meters.

Since the throttle had a life on it's own I suspect a faulty or very dirty crankshaft position sensor.
Metal grain stuck on the sensor, with higher humidity it clogs more, causing the sensor to fail. ECU tries to adjust, can't handle it and shuts down. Maybe even messing with the alternator, causing a voltage drop, which affects the ASR system, hence the fault displayed.

Only thing that messes with this theory is the fact that the ECU doesn't record a single error.

The car will be checked next thursday by two of my professional hero's. If they can't figure it out, I will get rid of the car and cry myself to sleep.

 

[Clivvy]

I hope you find the problem!