P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

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stappin
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P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by stappin »

Hi

I have a Citroen C2 VTS 55 plate that I run as an Autocross car. It’s using standard loom ecu and sensors. Only engine mod is 4:1 manifold.

Starts fine, but if I drive the engine hard (with esp on or off) it drops to 3 cylinders and throws a P1336 crank position sensor fault with engine mgmt light on. If I flick the ignition off and on it runs on 4 cylinders again.

I’ve changed for new coil pack, all plugs, crank sensor, bypassed the fuel pump relay and cleared faults but happens again when driven hard. Flick ignition off and back on runs fine..

Ideas welcomed!
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by xantia_v6 »

P1336 is a fault code that has different meanings depending on which engine and which make of engine management system. If you are not sure what you have, it would be a good idea to post your VIN for someone to check, it may save some wasted effort.
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by stappin »

VF7**************[VIN obfuscated, can be read by forum staff]
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by stappin »

I think it has a Bosch system based on the Eurocarparts parts offerings off my Reg. i posted my vin above for confirmation.

Does anyone know if ALL sensors throw a code? For instance if the Knock sensor throws a wobbly does it generate a separate code on the C2?

Seems quite difficult to find information on how the ECU determines how to display a certain code.
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by Hell Razor5543 »

I would not trust Euro Car Parts any further than I could throw them. ECP have an alternative name here; Euro Crap Parts (and they deserve it).
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by xantia_v6 »

I don't know much about that engine (so can't give any specific advice), but I am thinking that there is possibly a partially broken wire or corroded connector that is throwing a fault when the car is driven hard.
Does the fault report from the ECU give the RPM where the fault was detected? Is there a pattern?
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by stappin »

So did my Vin confirm it’s a bosch ignition system?
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by GiveMeABreak »

You do have a Bosch injection system (engine TU5JP4S). There are several TSBs for the fault you describe.

One of these is to do with engine pollution due to poor fuel quality. I don't have the other one unfortuantely.
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by stappin »

So would the second exhaust sensor beyond the catalyst set this off as a byproduct of its measurement of “rich” exhaust gases?
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by ozvtr »

The VTS runs the Bosch ME7.4.5 engine ECU on the TU5JP4(s) engine, as pointed out by GMAB. The standard 1.6 (TU5JP4) runs the BOSCH ME7.4.4 ECU.
stappin wrote: 12 May 2021, 13:55 So would the second exhaust sensor beyond the catalyst set this off as a byproduct of its measurement of “rich” exhaust gases?

No, I don't think so. The P1336 fault appears to be in relation to the crank angle sensor. HOWEVER without putting a LEXIA on it it's very difficult to determine what Citroen define the P1336 fault as.

The post cat O2 sensor will only throw up an "aging catalyst" error if the O2 sensor voltage output is not steady around 0.5 Volt. Yes, If the air/fuel mixture gets too rich it could throw an "aging catalyst" error but you will also get other errors from the pre cat O2 sensor and the catalytic converter will glow red hot!!

The only thing you haven't tried are the fuel injectors.

A dysfunctional fuel injector will turn up as a "indeterminate misfire" error in LEXIA. But I cant tell you what the error code is.

If your code reader can monitor the fuel trims, you might see whether it's an injector. If you are loosing an injector, the trims should go up by about 25% (when the injector fails).
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by ozvtr »

stappin wrote: 12 May 2021, 06:35 I think it has a Bosch system based on the Eurocarparts parts offerings off my Reg. i posted my vin above for confirmation.

Does anyone know if ALL sensors throw a code? For instance if the Knock sensor throws a wobbly does it generate a separate code on the C2?

Seems quite difficult to find information on how the ECU determines how to display a certain code.
Basically there are sensors and actuators on the engine to allow the engine ecu to control the engine or tell the ECU whats going on.
Actuators, on an engine are typically a coil of wire. An example is a fuel injector, a purge valve or an electric motor. The engine ECU can tell if it is faulty by testing if its a short circuit or an open circuit.
Sensors typically produce a voltage. That voltage is NEVER 0 Volts OR full voltage (say, 5V or 12V). If the sensor outputs 0 Volts or full volts then the engine ECU deems that sensor faulty. Some sensors are compared to other sensors to see if something is wrong. However there may be sensors that the engine ECU can not determine if the sensor is faulty and it will take the output of that faulty sensor as gospel. For example, a Mass Airflow sensor with dirt on it. It will report the wrong values because the element is insulated by the dirt from the air flow. However there is technically nothing wrong with it and no reason for the engine ECU to report an error.
If all the sensors are functional and the engine throws up a fault, then the problem will be mechanical. HOWEVER that may be a mechanical problem with a sensor or actuator as well as a mechanical problem with the engine (like a vacuum leak).
For example a blocked fuel injector. The Engine ECU will determine that the injector is OK because it's not open circuit and it's not short circuit! BUT the crank angle sensor will tell the engine ECU that some thing is wrong by reporting that when a cylinder was supposed to speed up after firing...it didn't!! So the engine ECU reports to you "misfire on cylinder X". All that means is that cylinder X did not produce a power stroke at the moment that the engine ECU expected it to. You have to use all the clues the engine ECU is programmed to tell you! Some times that involves what the engine ECU didn't tell you. For example, in this case, the engine ECU didn't report a problem with the coil pack...so it's not that!
Sorry, but the engine ECU speaks it's own language and you need to be more of an interpreter than a mechanic.
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Re: P1336 CPS fault drops to 3 cylinders, turn off and on fine!?

Post by xantia_v6 »

It may be worth considering that the error gets thrown due to a lack of fuel flow (causing misfire) when the engine is worked hard. This could be due to a blocked fuel filter (if there is one), a weak fuel pump, or a blocked strainer in the fuel tank.
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