407 ES9 misfire P0355 P1336 P1341 cylinder 5

[407]

Car started to get a random misfire a few weeks ago but it would go away

I checked all the connectors etc, pulled ECU plugs just in case it was a bad connection (see my old post viewtopic.php?t=68187&start=15)

Now its permanent with Diag reporting Codes P0355 5 ignition coil control, P1336 Unspecified combustion misfiring, P1341 misfiring on cylinder 5

Cylinder 5 is the middle one at the rear of the engine

Pulled the manifold etc off and replaced the coil with a new one, cleaned all spark plugs and swapped them around, checked the coil wiring but no change to the issue

Looking at the standard parameters Me747 ignition screen it seems coil 5 coil charge time of 1.36 milliseconds is 12% faster / shorter ( ??) than the others, which are between 1.54 ms and 1.71 ms

Not sure that a faster / shorter coil charge time would be the issue for coil 5 , unless the shorter time means it does not actually get charged up and so causes the spark plug to misfire ?

Also, looking at the ECU wiring diagram, the wiring codes to coil 5 (1137) are numbered Pin 1 1155 (goes to ECU) Pin 2 1150E (which goes to the Fuse 10 in the PSF1 to 12 volts) so assume the ECU pull Pin 2 down to earth to charge the coil - maybe the pull down transistor is an issue

I'm thinking the ECU has an issue and so may need to swap the immobilizer chip 95320 SOP8 IC (8 pin) into a spare ECU I have.

Any suggestions ?

[407]

I should add that the actuator tests on Diag for both coils and injectors passed / did not report any errors.

I also read that Lexia suggests coil charge times are from 2ms to 4ms and have attached readout that says at idle its approx 2 ms

I've attached the diag printout for the coil times at 1640 rpm in case someone can spot any other issues

Would be interesting to get other 407 ES9 readouts to compare

If so, seems the coil charge time is low on all coils as they are sub 2 ms.

That said, no misfires or errors reported on any other cylinders

[407]

I've started looking at some live data (using Car Scanner, easier to use when driving) and noticed the oxygen sensor readings may also point to an issue.

I understand the 407 ES9 has 4 oxygen / lambda sensors, two in the front bank (B1) and two in the rear bank (B2)

The attached live data readings suggests that O2S1 and O2S2 in Bank 2 are not working, as the voltage stays around 0.015 volts and does not change regardless of rpm, suggesting a lean condition (eg too much oxygen.

The alternative theory is as the misfiring cylinder 5 is in bank 2, the unburnt petrol is flooding the sensor ? However, this would generally means the O2 sensors have a high voltage reading (eg 0.8 volts)

Looks like tool time to pull them and see what's gone wrong but not sure this solves my cylinder 5 misfire issue.

[xantia_v6]

A misfire generally causes the O2 sensor to see too much oxygen and indicate a lean condition.

I would suggest a compression test, and if ok, maybe swap around a couple of injectors.

[407]

Thanks

I checked compression and all 6 cylinders are over 150 and under 160 psi so seem okay

I also pulled all four O2 sensors and checked them

Each O2 sensor has 4 wires, 2 white (heater element) , one black and one grey (assume the actual sensor wiring)

All 4 white wire checks show 10 ohms so heater elements at least seem fine.

I could not check voltages from the sensors (hard to start the car with all plugs out) but did check the plugs from the ECU, and with the ignition on, both female plugs on pin 2 is 2.57 volts and pin 4 is 0.4672 volts on one driver side, and pin 2 is 3.484 volts and pin 4 is 0.462 volts on passenger side.

I was expecting 12 volts on the Pin 2 given these are the heater elements.

Next I guess is to put it all back together and check actual readings when it is running

Any comments suggestions welcome

[407]

Issue solved but can't really say how.

In addition to the prior post, I swapped two injectors around (5 to 4), plugged it all back together and issue gone.

No MIL , no codes (except the P1335 one), no misfire for the last 5 days of daily driving. ps see this Finnish post re possible P1335 fix https://peugeot-foorumi.com/index.php?P ... c=73113.15

Can only assume a connector issue somewhere. I have a few new connector shells coming as some of the injectors and oxygen sensor ones are very brittle so maybe there was a internal short / lack of insulation between the pins.

I've attached the "working" O2 readings in case they help someone - basically they should be bouncing around all over the place, esp if accelerating.

The only one of interest is the low LTFT - B1 (green) compared to the higher LTFT - B2 (yellow), but both seems to be under 10% of 0%, so seem okay according to https://trade.mechanic.com.au/news/unde ... uel-trims1

[levisik]

Hello.
Can I ressurect this topic?

My 407 has some missfire code on 3,4 and 5 cylinder. Swapping coils with working ones does not help.

Someone suggested that this might be related to some transistor of pick up coil in ECU.

Does anyone have any more inforamtion about thise transistors?

Thanks in advance.