Renault misfire diagnosis

nmacc

Hi folks,

Ran into a problem with our 2004 Renault Grand Scenic 1.6 with 95,000km on the clock. It started to misfire yesterday on cylinder 3. I put in a shiny new pencil coil this morning, but to no avail. I ran the codes and got the following:

P0300 Random/multiple cylinder misfire
P0303 Cylinder 3 misfire
P0313 Misfire with low fuel
P0203 Injector circuit malfunction – cylinder 3
P0010 Camshaft A position actuator A control circuit open

LTF -17.2%
STF -100%

O2 Sensor 1 0.515V
O2 Sensor 2 0.445V

The O2 sensor voltages are not reliable as it had stalled out just before I read the values.

I'm open to suggestions on this, but it's clearly not burning all the fuel, presumably on cylinder 3. I'm not sure if the 0203 & 0010 are real, or just artefacts of the poor running. I'm guess a failed LT circuit, or the new coil is a dud, or perhaps the injector is sticking open.

As a first step I'm going to check the coils by clamping them in the vise, putting in a plug and triggering them, but the book says the primaries are paired in series. I'm guessing that the primaries are wired in series, two at a time and fed with 12V, but can anyone tell me the polarity of the connectors?

Alas, Haynes is useless on this subject.

Thanks in advance

w211

Injector does not work (properly) and it mess with everything else. At least this is the most common problem on that list.
O2 sensors does not act properly because 1 cylinder does not work.

Wow, short term fuel-trim -100% it is completely out of strategy.

Check the cylinder 3 injector connector and wires. Good tool to check the wiring harness are oscilloscope. Compare the waveform by other cylinders and you get the quick and easy result about the wiring harness. If the wiring harness are good, it means the fuel injector inside are toast. If yo do not have a oscilloscope and like to do extra wrenching, just swap the injectors. Only remember to order the new injector seals too, 2004 and 95k are enough to replace these seals. Entire set may cost only some euros.

If you have a trouble with coil pack, just swap cylinder 3 to other easy accessible cylinder one. Only remember to swap the spark plugs too, then you are 100% sure no variables left.

Waterson

did you check the spark plug on cylinder 3?

nmacc

Thanks folks, this is helpful

Yes Waterson, the plugs are clean and I swapped cylinders 2 & 3 just to check.

That's very detailed W211, I do have a scope and I will try that. In the meantime I have belled out the wiring of the coils and it is attached for anyone else that might need it.




I had planned to test the coils, but given the extremely low primary resistance and their small size, I'm going to look at the waveform on the primaries before I do anything with them. It's not like the old days when you could clip a battery onto an oil-filled coil!

Not much I can do in this weather however, as my scope would not thank me for working in the rain.

richardsheil

nmacc wrote: »

Thanks folks, this is helpful

Yes Waterson, the plugs are clean and I swapped cylinders 2 & 3 just to check.

That's very detailed W211, I do have a scope and I will try that. In the meantime I have belled out the wiring of the coils and it is attached for anyone else that might need it.




I had planned to test the coils, but given the extremely low primary resistance and their small size, I'm going to look at the waveform on the primaries before I do anything with them. It's not like the old days when you could clip a battery onto an oil-filled coil!

Not much I can do in this weather however, as my scope would not thank me for working in the rain.

Surely go after injectors add that is the error?

nmacc

richardsheil wrote: »

Surely go after injectors add that is the error?

I have an injector error, but I also have a misfire error and it's a lot easier to check the coils than the injectors. On this car the inlet manifold has to be dismantled and a ;lot of kit removed to get at the fuel rail and then all 4 have to be removed with the rail. Lots of single-use seals required, not just for the injectors, but for the manifold as well. A real PITA

nmacc

An update for anyone who happens across this thread.

Finally got around to dismantling the inlet manifold and associated sensors and hardware to get at the fuel rail. Disconnecting the flexi pipe to the rail released very little petrol, supporting the theory of a leaking injector. I was fortunate enough to be given a couple of injectors for the same model, but I was unsure how it would work out, as I had no easy way of testing them, apart from reassembling enough of the kit to turn over the engine with the rail off the manifold.

I decided not to try that and simply popped a spare injector into cylinder 3 and reassembled. To my surprise it effected an instant cure. The car is now running smoothly and the figures are looking a lot better.

It's now showing STF at +5.5% and LTF at -7.8, but I'm expecting that to improve over time.

Still showing some DTCs however. It seems there is a suffix to the code to supply more detail; for example, P0203-41 is Cylinder 3 injector issue - general checksum failure.

Does anyone know if this is a characteristic of OBDII DTCs in general, or Renault specifically?

On the subject of the checksum, I understand that during manufacture the flow rate of an injector is checked and the injector is marked to reflect this. When the vehicle is built this information is coded into the ECU so that it can compensate for the differences between injectors.

Obviously when an injector is changed this data should be updated andcI don't have the means to do that, but I'm curious about the checksum error.

Each injector has just two connections, which I am presuming are power and ground/signal, but how does the ECU know that the injector has changed?
Is there data encoded on the power cable?

Answers on a postcard please...

rex-x

What are you scanning it with? Renault specific codes are DFXXXX instead of PXXXX so it sounds like you just have a generic OBD reader thats not capable of getting the more specific Renault data which would likely reveal more about your problem

nmacc

rex-x wrote: »

What are you scanning it with? Renault specific codes are DFXXXX instead of PXXXX so it sounds like you just have a generic OBD reader thats not capable of getting the more specific Renault data which would likely reveal more about your problem

I couldn't justify (or afford) a reader that cost more than the car, so I'm using a Klavkarr OBD Facile, which at least has the advantage (?) of being French.

I daresay that the Renault DX code will correspond to the P0203-41; all I need now is a cross-reference!

I'm reluctant to call it a problem at this point, I suspect that it will run indefinitely like this. I'm showing a number of codes, but none of them are sufficient to bring on the Check Engine light. There will be a mis-match between cylinders, but so far it's running better than it ever has.

rex-x

nmacc wrote: »

I couldn't justify (or afford) a reader that cost more than the car, so I'm using a Klavkarr OBD Facile, which at least has the advantage (?) of being French.

I daresay that the Renault DX code will correspond to the P0203-41; all I need now is a cross-reference!

I'm reluctant to call it a problem at this point, I suspect that it will run indefinitely like this. I'm showing a number of codes, but none of them are sufficient to bring on the Check Engine light. There will be a mis-match between cylinders, but so far it's running better than it ever has.

OEM codes such as the DFXXXX Renault codes don't correspond to P codes in as much as they are independent of each other. You may have no P codes but 10 DF codes in the ecu. What you might find is you have 3 or 4 more DF codes that will reveal the real reason for the P0203.

But given the age and value of the car, if it's running fine then drive away id say. Renault petrol injectors are not coded to the car and their values are not programmed to the ecu (just how much that injector flows as a model) so you haven't issues there. Different horsepower models will all have different injectors however which may cause a problem.

w211

When you removed the pressure hose and almost no fuel leaks out, it does not mean automatically the leaky injector. It can leak back to the tank. This is simple manometer test. Install the manometer before the fuel rail and block the access to the fuel rail. Long term and short term fuel trim are ok if it is under 10%

EDIT: If your car have a fuel return line (not 100% sure) then check the solenoid leak too.

PukkaStukka

On Renaults, No1 cylinder is at the gearbox end, not the crank pulley end

rex-x

PukkaStukka wrote: »

On Renaults, No1 cylinder is at the gearbox end, not the crank pulley end

Only on some models and engines, they like messing with people ....

PukkaStukka

That engine, no 1 is flywheel end. Guess how I figured it out

Also, some EOBD codes can be misreported. You need to Renault specific scantool to get the manufacturer specific ones you don't get with a generic EOBD scanner.