cranks but won't start

Just some comments. As I have stated I'm a fuel, compression, spark guy.

Fuel - Do you have fuel pressure, is the pump running? (requires signal form on of the crank sensors to turn pump on. I believe 5-8 bank but not sure.)
Cam sensor.
Are the injectors functioning.
Signals from ECU

Spark - If no spark:
Signal from crank sensors. Check wiring as well as sensors.
Power modules
Coils
Signal from ECU to power modules
ECU
Highly unlikely that any of these would fail on both banks of a 2.7 car at the same time.

Compression: Goes without saying.

It shouldn't be that hard to diagnose this.

Note: A 2.7 car will run on only the 5-8 from my experience.

 

Actually, that wiring diagram doesn't make a lot of sense. I see I crossed some wire (compared with the WSM diagrams), but the WSM diagrams don't make sense either. Both wires going to plug 20018 seem to be joined to earth.

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In the original diagram, it looks like the shield of the cam sensor is attached to earth and the upper pin of 20018 (which is attached to another earth), but pin 3 of the cam sensor is attached to both an earth and pin 8 of the left ECU.

 

Good point, John. There are some minor differences between the left and right banks.. e.g. the tachometer is fed by data from the Left ECU and there is a diode in the Left CEL circuit, but I don't think these would make any difference.

I don't have any diagrams for the 2.7 cars with only one fuel pump (to see how the pump is controlled), but perhaps the pump remaining (the left one), is still only controlled by the Left ECU. This would mean the crank sensor associated with the Left ECU will stop the engine running completely (on cars with only one fuel pump). I would definitely be changing this one first (it's also the one which seems to be not outputting anything).

(EDIT: Fortunately, the left crank sensor is also the easiest one to change (at the bottom of the engine)

 

But that would still leave the mystery of why there is no spark on both banks. Surely at least one bank should have spark?

 

Forgot to mention my comments were for a single fuel pump car.

Yes, no spark on both banks make no sense because you would need failures on both sides. That would seem more likely to be no power to the coils, assuming they both get power from the same lead, or a problem with the ignition switch. Turn on the ignition and check for 12V at the center pin of the coils. Get that out of the way.

 

Now were going down a rabbit hole Both coils are powered directly by the ignition key (no fuses or relays). No power from the key would mean very little would work on the car (no exterior lights, no ignition power going to the alternator, no instruments, no secondary air, no aircon, no fuel cap release.... ).

Power to the left and right coils comes out of different plugs on the relay panel.

 

But it could be a break in a wire or splice. Doesn't hurt to turn on the key. and check for power. A 5 minute check and one less possibility on the list. If there is power to the coils the next thing I would check power to the ECUs. Then the signals from the ECU to the power module. Probably need a scope for that, but if there is power to the coils and the ECU is sending the signals and still no spark, then the power module would be bad. If ECUs have power nut no signal to the power module then check crank sensors. Just saying, start at the source and work forward. Or start from the other end and work backward. It's closed loop. Just pick a point and follow it around.

I just see a lot of jumping around without verifying anything.

 

I found the connectors that interconnect the cam phase signals to each ECU. Continuity is intact. The cam sensor is receiving 12V. I think the next step is to wait for the delivery of the new crank sensors and install them. They are scheduled for delivery later this week. I hope that solves the problem. I won't install the new cam sensor until I have tried the crank sensors.

 

Just as a review: My car has one fuel pump, one cam sensor (situated on the right bank, the crank sensor for the left bank is kaput, there is no spark on either bank, the fuel pump does not start but operates when power is connected to the appropriate terminal of the real (relay P).I wonder if there is some logic in he ECU's that prevents the engine from starting if just one of the crank sensors is faulty. I would seem strange that the logic in the ECUs would allow only one bank to operate without the other. I am going to check tomorrow if there is power going to the power modules and ignition coils. I would be surprised because if a crank sensor was faulty (which it is) there would be no command to initiate a spark.

 

Isn't that basically what SLOW DOWN mode does when one cat gets too hot? It lets you get to the nearest garage.

Excellent. Would you be able to post a photo of it, showing us where it is? I'd also like to see what wire colours are on both sides of the plug.

Anyway, let us know how you go with the new crank sensors. You may be able to get the engine started by replacing only the lower sensor. Having said that, it may be a good time to change both while you're under the car with the panels off.

 

Since you have one fuel pump, it is probably activated by the ECU based on the signal from one crank sensor only and it could the one that is bad. In this case (pump not running), starting on one bank is impossible as there is only one pump for both. As to the ignition, it is quite possible that the ECU will not activate the ignition if the pump is not running as there is "no point". However, there is still a possibility of a failed cam sensor as well. You can try swapping the crank sensors left-right or just wait for the new ones.

 

There is a plug each side behind the rear shock absorber.
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Thanks!

Now I'm really confused ... The diagam shows a single 2-pin plug. The car has two plugs and your photo shows a 3 pin plug with 3 wires becoming 2.

green to empty slot
black to black
brown to white(?)

On the left hand side of the car, does the 3 wire side of the connector go to the Left Hand ECU?

I assume the green wire is connected to the conductor shield.

 

Yes, each connector goes to the respective ECU. I noticed that the diagram shoes two conductors and the plugs have three. Do you think the third conductor is there to indicate from one ECU to the other that there is a problem on the respective bank of cylinders?

 

?????????? My car is like the diagram below.

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That’s the test buttons on US cars, John. We’re talking about the cam sensor wiring.

Since there is one cam sensor and two ECUs, the cam sensor needs two outputs or one output and pigtails/splices in the wiring.

Cam sensors appear to need 3 wires (minimum) and indeed photos of Ferrari cam sensors have 3 pins:

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Power
Signal out
Earth?

The wiring diagrams show a fourth wire which seems to be a shield, but this doesn't seem to be on the real car (although I don't know if there is one on the female connector of that blue plug).

Since the Right ECU is providing power to the cam sensor, I would have guessed the Left Bank only needed two wires (plus an optional shield if required), but the wiring diagrams only show 2 wires and one of those is a shield. The other wire seems to be connected to the earth wire on the cam sensor (which doesn't make sense at all).

Trevor says there are two disconnects. I don't see the point of having two. Also, there are 3 wires on the plug on the left hand side of the car (which disagrees with the original diagrams also).

 

I'm guessing the car is set up like this (see second image):

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Only wiring checks on the real car would prove this

 

Yes. Unless I'm mistaken the pictures posted in #87 are the diagnostic test button connections. I was responding to your post #88 where you seemed confused by them.

Also, the cam sensor needs 4 wire, ground, signal, power, shield. But the left ECU only needs to be connected to signal and probably a shield for noise. Not sure how it is wired. Might be signal and ground, but that could cause a ground loop.

 

That would make more sense, although the colours seem quite different from the schematics.

Trevor, are you sure you checked the right wires?

Is this assuming the Left ECU circuit has a chassis earth?

 

No doubt about it. They are the diagnostic button connectors.

Yes. And obviously, it does.

 

Not sure if I'm confusing myself with this but my understanding is you only need 1 cam phase sensor as this only tells the ecu where No 1 is in regards to rotation location. There is only 1 No 1 cyl. This sensor does this so the crank angle sensors tell each other cyl injector when to fire fuel along with spark. If the cam phase sensor isn't working or either of the crank sensors then the engine will not spark or have an injector pulse as it needs reference from all all 3. In regards to sequential injection anyway.

 

On dual ECU setups with independent injection and spark spark control, how will the left bank know where cylinder #1 is?

 

I believe that's why it has 2 crank reference sensors. The trigger wheel has generally 2 teeth missing to create a rising or a falling signal. There has to be some inter connection between the two sensors and ecu input in regards to the phase sensor. I cant see how it would or could work mate

 

Yes, the signal from the Cam Sensor is connected to pins 8 of both ECU-s to provide the cam position. The left and right ECU-s then interpret this signal "in their own ways", i.e. in combination with their respective Crank Sensors. The +12v and the Ground wires are for the sensor to operate and they are not needed to come to the sensor from both sides, only from one (RH). If you look at the 348 diagram, the connections are much clearer.

The 355 diagram appears to have some errors. The shield should not be shown as connected to the Cam Sensor connector as there is no such connection (the connector is plastic). The shield probably ends inside the cable near the connector. As it is not necessary to connect the shield to the ground at both ends, it is probably grounded somewhere on the way to the ECU or inside the large ECU connector. As to the connector 20018, it should certainly carry the signal to the LH ECU pin 8 and I am not clear about the other wire, could be ground or shield. If shield, it, again, should not be shown as connected to the Cam Sensor connector but ending just before it.

 

Miro I don't want to hijack this to another subject. Would it be ok if I sent you a PM in regards to the heater valve blend motor (355)
Regards Paul