The current owner purchased this car 2 months ago with already existing “unsolvable” problems. So, unfortunately (or luckily) we don’t know anything about the author of this “exclusive” solution.
Patient: E90 325Xi; N53B30 U0.
One of the complaints: the engine performs bad – it has a reduced power, high fuel consumption. Also, the starting of the engine takes a long time.
When connecting INPA, I concluded, that in addition to usual error messages also the error message 2A94 is recorded:
the error message regarding the signal of the crankshaft. Status of the error message: active. When the error message is deleted, next start of the engine is as if normal (it starts quickly), but after some seconds it shuts down and the error message is recorded again. Next try of the start again was with a long turning of the starter – the engine started to work, ignoring the crankshaft sensor (instead, it used camshaft sensors).
Of course, this is a complete emergency mode – it’s intended just to reach the service station. EML symbol in the KOMBI: active. Obviously – there are problems with a sensor because of the contacts of the plug a plug itself was in perfect order.
The sensor was replaced – but the problem didn’t disappear…
A defect of the tooth ring? Hidden wireset defect?
It’s clear that we need the oscilloscope.
When connecting the oscilloscope to X60005, Pin 29, the following picture appears:
In the image: around 7 seconds, 4 seconds of successful engine performance – in the center of the screen. As you see, this signal of 4 seconds was received, after then – it (the signal) suddenly disappeared.
Let’s check the signal more closely. As you see, the DTC moment of the 1-st cylinder is correctly visible:
Also, the teeth of the tooth ring are identified correctly:
And the fulfillment of the signal: correct
Obviously, the signal of the crankshaft sensor is disconnected by some external system.
Do you see this suspicious piece of the duct tape? It looks that the cause of the problem hides here!
When opening the duct tape, we see the following picture – the signal of the crankshaft is distrupted!
And here also the culprit – the standard-size relay.
Obviously, this is an anti-theft system! The author of this “creation” is not quite educated. He was not aware, that since M52 (since BMW started to use VANOS), the BMW engines are able to work, using only camshaft sensors. Even more – he even hasn’t tried to test, if his invention works. Or deliberately returned the unprotected car to the customer.
In addition, to manage the sensor signal, not the appropriate signal relay is used, but the relay, intended for high current aplications, is installed. If the non-signal relay is used in such aplications, usually the troubles start – the signal appears and disappears chaotically. The cause – the current of the signal is very low (too low for the relay of the exact type). The choice of an appropriate relay is a critical requirement!
How does the engine with such defect (the signal of the crankshaft disappears) works?
- DME disconnects VANOS;
- the responsiveness to the accelerator pedal is significantly slower;
- the power of the engine – limited (to preserve the CO catalytic converters);
- DME doesn’t create any adaptations – even fuel trim offset and multiple LTFT are 0;
- DME doesn’t create the tests of the injectors on the go, don’t uses Stratified charge.
When reading the diagnostics data: ../F5/F6: LTFT is 0.00; ../F5/Shift+F6/F2: all learnbits are not coloured; ../F5/Shift+F6/F3; 4.+ lines are 0.00; ..F5/Shift+F6/F5: all data are 0.00.
Let’s return to the “solution” once again. I have principal objections for such execution. For a moment, let’s assume, that such solution blocks the engine. Would it be hard for the thief to find this “creation”? No. It would take some 10 seconds to open the DME compartment (the cover of the box is locked with several clips), see the huge relay next to the DME unit. If he would open several windings of the duct tape, he would detect that the DME wire is disconnected. Even if the thief is not well educated regarding electrical connections, he would require a minute or two to restore the connection.
Thanks to such “methods of protection”, interesting internet memes appear:
“if they decide to steal the current car, they will steal it”;
“my friend’s car was stolen, although it had an anti-theft system”;
“don’t spend money on the immobilizer, they will steal the car with imo also”, etc.
And supplementing the topic regarding blocking of crankshaft and camshaft signals. For N43/N53 series engines blocking of all (3 pcs) sensors cannot be used. If the starter will turn the engine with blocked sensors (for example, the user has forgotten to enter the secret code), the error messages regarding oil supply and HPFP system pressure sensor, air mass meter and other pressure sensors will be recorded. The engine will continue to run in complete emergency mode. Even starting a new driving session, these error messages will leave profound consequences in the performance of the engine. DME of these engines can be blocked only via CAN data bus!
And finally – pay attention to this bundle of wires.
Also, these wires have been disrupted, then connected back. These are the DME power supply wires. Obviously, the “specialist” haven’t heard anything regarding the necessity of communication between DME and CAS units. Obviously, he was thinking, that it’s enough to simply stop the electricity supply to DME – and it’s done.
And now – how does it look the bundle of wires, restored by a true specialist (this time without an irony):
For the repair, the wires of corresponding colors and cross-sectional area were used, and also special sealing connections were used.
Sentence of this entry – don’t install cheap security systems! They will cause only troubles! Don’t use the services of “cheap” specialists!
After receiving the car back from the installation of the security system, certainly make sure, if it’s possible to start the car without entering the special code (or with a taken-out battery of the immobilizer chip, if such one is installed). Test, if the horn works after installation of the security system. Make sure, if the alarm goes out when opening the engine hood and the luggage compartment. It is very important because the horn is located in the motor hood, but the car’s battery – in the luggage compartment.