Crazy ECU or limp mode?

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Crazy ECU or limp mode?

Postby victor2k » Sun Oct 30, 2016 4:01 pm

Hello,
On a 2001 RAV4/1AZ-FE 4*4 AT I have a strange issue:the engine start ok but the idle is unstable and engine stop.
I checked the relative compression:12,14,14,14 bar .
No fault codes in ECU.I can acces data list only with engine stopped(data list refresh at 700-800 ms).When the engine is started the data list freeze(refresh at 5000!-11000! ms) so no util data can be colected from ECU.
Using the scope I can see a strange "noise " on a cam(or crank) input with engine off but with diag on!
The signals was captured at ECU side(all signals can be readed using back probe pins or clamp(for injectors).
The supply was checked,main relay was replaced,ground checked also.
Any opinion is wellcome.
Now the ECU is on my desk for resoldering...anyone can tell me a trusted source of SPF0001?
Thank you.
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Re: Crazy ECU or limp mode?

Postby STC » Sun Oct 30, 2016 6:31 pm

I checked the relative compression:12,14,14,14 bar


That first cylinder is a good 15% lower than the other 3. Would be good to see those compressions accurate to 2 decimal places.

I have added a RPM channel to the crank trace and could not pick out a misbehaving, weak cylinder although the Idle speed seems a little slow 705 - 725 across that capture. Do you know what it should be ? The other point to note is that it is cutting fuel first but not for reasons associated with RPM, CKP, CMP.

Using the scope I can see a strange "noise " on a cam(or crank) input with engine off but with diag on!


Have you tried a different Diag tool ?

The only thing I can think of that would tie up poor Idle and interference would be a "noisy" throttle body, fuel pump perhaps. Food for thought.

Which other controllers, if any, are giving you communication issues ?
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Re: Crazy ECU or limp mode?

Postby victor2k » Sun Oct 30, 2016 7:17 pm

Hello,
The compression not have any importance in this case...the engine start but ECU controls/corrections give me this issues.
I disconnected VVTi controller,idle regulator,air/fuel sensors(both banks),camshaft sensor but the issue is the same:injectors command missing at some point.
I have some trouble to work with the relative compression in Psi,I need to translate in KPa or Bar so I need to use a round value ...today I asked for this in other post :oops:
And yes,I used also Launch and Bosch instead of Techstream/Mongoose Pro but only the last tool show me the refresh rate...is not a diag tool issue,with all I have a poor connection after the engine start(KTS is very unstable in data readings at start).
Also I disconnected injectors one by one (I suspected a poor connection between ECU and injectors and ECU will protect himself ...no change ).
Many of engine corrections will work after 70*C(advance correction for idle stability), so this is the reason for what I make the capture at 60*C(yesterday I used my scope on warm engine(80-85*c))
Tommorow I will register also the knock sensor instead of camshaft sensor...
Thank you
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Re: Crazy ECU or limp mode?

Postby andrewbishop66 » Mon Oct 31, 2016 12:30 am

Hi all

just my 2p worth from a signal point of view what is causing the spikes in the crank sensor is the coil in the sensor starting to break down causing an inductive spike (back EMF )

They time in perfectly to the crank even where the tooth is missing its unlikely for the noise to be generated by anything but the sensor and it may be normal

Cant do a caparison as my pico is at work but is that normal. the delta difference is 5.7 volts could the ecu read the spike as the tooth signal if thats the case it would put timing out by nearly 2 deg

could by way of as I normally read to much into how clean a signal is

Thanks Andrew
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Re: Crazy ECU or limp mode?

Postby victor2k » Mon Oct 31, 2016 12:00 pm

Hello,
I ordered a new crankshaft sensor.
Today I made some new measurements:the ECU current and the SIL(K-line) voltage.
I think is a strange to see ECU what need 2-3A only with ignition ON(not supply injectors or other sensors/actuators-MAF,injectors,VVT).Only air/fuel sensors preheaters can use this current...
On my recording first freeze SIL communication and then drop the ECU current...if a protection like FC IDLE is ON(fuel cut when idle on and engine speed is higher than a specified value(ex.2400 rpm at cold engine,1800 rpm at hot engine ),fuel cut at low load(above of 2400 rpm),fuel cut at ignition fail(that was the reason why I monitored IGF)) then the communication not drop :roll:
Also I monitored ECU parameters in Data List using Techstream and a second pc :the engine speed is 600-700 rpm(that is readed by ECU) before stall .
Any ideea?
Thank you
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Re: Crazy ECU or limp mode?

Postby steevegt » Mon Oct 31, 2016 1:54 pm

Did you properly check all powers and and grounds on that ECU?
Properly for me is with the scope, grounded on the battery terminal, with the engine running, and the symptoms present.
It may be a "lifting" ground that is used by the ECU to ground the K-Line voltage (and injectors also?), causing bad communication with engine running (injectors commanded?)... Just a guess...
It could be a coincidence, but fixing the bad communication cause, you could be fixing the car.
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Re: Crazy ECU or limp mode?

Postby STC » Wed Nov 02, 2016 4:06 pm

I have added a 30hz Lowpass filter to you Green Channel (ECU Current) and added a RPM Math channel to try and paint a clearer picture.
Victor Delete.jpg


It appears that he ECU stops consuming current before the RPM drops ?? Add to that your suspicions that it is not drawing enough current to properly feed its consumers.

I would say you either have a Power or Ground supply issue, faulty relay or an internal fault in the ECU. Maybe time to Volt Drop with a scope and Load Test the power supplies referenced to both battery terminals with it running, add a 21v bulb in parallel for good measure.

As for your K Line issues, could it be that the underpowered ECU is struggling to keep the engine idling, and giving less priority to the diagnostic communications element ?
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Re: Crazy ECU or limp mode?

Postby victor2k » Wed Nov 02, 2016 4:50 pm

STC wrote:I have added a 30hz Lowpass filter to you Green Channel (ECU Current) and added a RPM Math channel to try and paint a clearer picture.
The attachment Victor Delete.jpg is no longer available


It appears that he ECU stops consuming current before the RPM drops ?? Add to that your suspicions that it is not drawing enough current to properly feed its consumers.

I would say you either have a Power or Ground supply issue, faulty relay or an internal fault in the ECU. Maybe time to Volt Drop with a scope and Load Test the power supplies referenced to both battery terminals with it running, add a 21v bulb in parallel for good measure.
I checked for a bad ground/supply/relay so I doubled it/relay was replaced.

As for your K Line issues, could it be that the underpowered ECU is struggling to keep the engine idling, and giving less priority to the diagnostic communications element ?

I can't see a supply drop ,as far as I know in diagnose ECU is slave and diag tool is the master.
Supply voltage descrease only when the speed isn't enough for charging(please look at the attached file).
Regards
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Re: Crazy ECU or limp mode?

Postby STC » Wed Nov 02, 2016 9:25 pm

Hi Victor.
Supply voltage decrease only when the speed isn't enough for charging

Victor 2 Delete.jpg

Supply voltage decrease only when the speed isn't enough for charging

Yes I can see that in the Brown K-Line trace. But look at the Green Trace - Labelled ECU Current. ECU current drops away to nothing before Engine RPM drops.

I'm thinking that is caused by a power supply or ground to the ECU or something in the ECU is going open circuit which is possibly causing your faults. If the ECU is faulty then it could explain your scan tool communication issues, with power dropped out it will not store Fault Codes either.

Would it be possible to see a Crank, Injector, Coil Primary & ECU Current Capture.
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Re: Crazy ECU or limp mode?

Postby victor2k » Thu Nov 03, 2016 7:32 pm

Hello,
Today I made new recordings with some amendments:
-supply from main relay and ground to ECU was doubled
-the voltage was captured at ECU side(using backing pins)
-can't record the ignition primary current(every spark plug coil have his own amplifier)/this is the reason why I record ignition feedback
-the ECU current isn't at the same level as in previous recording because of double supply(only one monitored with clamp) :?
At this point I 'm stucked.No new ideeas,no ECU to replace.
Thank you
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