Citroen c5 2003 Engine trouble

[Kristian27]

Hello! I bought a Citroen C5 I 2003 petrol car a little over a year ago now, it ran fine for a while until i started getting som strange engine problems. it started out with just a little stuttering while driving but would go away when giving it some gas, but over the past couple of months, it's gotten worse, when driving now the engine suddenly starts jerking/losing power to get the engine to run normally I have to almost floor the gas pedal before the engine comes back to life. when idling the engine can run normally for a long time and then suddenly the RPMs start going up and down and it almost sounds like it's missing a cylinder, sometimes it starts running so rough when idling that it stops, but it can also just suddenly start running normally. it's also very random how often this issue occurs, it can happen on every drive for several weeks and then suddenly it can go 1-2 days with almost no issue. also when the engine is running rough in idle and I apply some gas sometimes there is a loud metallic bang coming from the engine.

I have done the following things trying to fix the issue
- battery only one year old
- Replaced Oxygen sensor
- Replaced Fuel pump
- Replaced Ignition Coil
- blocked off EGR valve.
- checked for vacuum leaks.
- checked the air filter.
- tested MAP sensor
- tested intake air temperature sensor.
- listened to fuel injectors
- checked engine ground.
- checked the wiring on plugs going into ECU.
- checked charge voltage around 14V
- Checked air filter
- cleaned throttle body

I hooked the car up to a professional diagnostic tool and read out error code p0603 which has something to do with keepalive memory, but I can't read out this code on an off the shelf diagnostic tool.
also had a code on the oxygen sensor but that is most likely just because it has been running so bad for a long time. also a few days ago the engine suddenly stopped and gave all kinds of error codes, turns out the fuse for "engine management" had blown, don't know if this is relevant.

appreciate any help i can get, starting to get fed upwith this issue now..

[GiveMeABreak]

Hi Kristian

Welcome to the Forum.

Can you please pop up your VIN so we know exactly what engine and ECU you have please.

[Kristian27]

thank you !
sure, the vin nr is : VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Ok, so this is the 1.8 i 16v 117 Manual gearbox 5 with EW7J4 engine and Sagem ECU.

There are very few fault codes with these early petrol engines for the year. From what I can tell P0603 can be an Injection ECU fault, or an internal fault with the EEPROM non-volatile memory.

It could be one of the reasons why the car is behaving like it is if the ECU is playing up. I would have a careful check of all connections to and from the engine ECU and look for signs of broken wires, cracked wiring or wires / pins coming away from connectors for a start.

[ksanturion10]

It seems you've done some work out there, but with no avail.
Don't see what else could be done in your case.

drBR
Martin

[Kristian27]

It seems you've done some work out there, but with no avail.
Don't see what else could be done in your case.

drBR
Martin

yep.. I'm fearing that it has something to do with the ECU

[Kristian27]

Ok, so this is the 1.8 i 16v 117 Manual gearbox 5 with EW7J4 engine and Sagem ECU.

There are very few fault codes with these early petrol engines for the year. From what I can tell P0603 can be an Injection ECU fault, or an internal fault with the EEPROM non-volatile memory.

It could be one of the reasons why the car is behaving like it is if the ECU is playing up. I would have a careful check of all connections to and from the engine ECU and look for signs of broken wires, cracked wiring or wires / pins coming away from connectors for a start.

I have checked that all the wires going into the ECU aren't lose in the connector, but I might have to go through the entire wiring as well.

also today the "engine managment" fuse blew again when trying to get the car up a slippery driveway. the fuse is rated 30Amps

[GiveMeABreak]

Something definitely not right there then. I'm wondering if the engine fuse box is shot.... If the weather is affecting the issues - it may be relevant to the fuse - certainly as you have mentioned replacing the fuses - if there are problems with the internal relays of the fusebox the cold / hot temperature changes could be affecting the connections. Maybe something to consider being that it is electrical and random - but related to temperature.

[Kristian27]

here is a short video showing the engine idling rough, i am slowly applying throttle wich causes it the run even rougher until the gas is almost floored and it jumps back to life
https://imgur.com/a/IVHjz4D

[Kristian27]

Something definitely not right there then. I'm wondering if the engine fuse box is shot....

the left front fender was recently hit by a neighbours car so I am wondering if that might have damaged some wires behind? but it doesn't look like the hit was hard enough to damage the wiring..
also, the engine issues were present before this.
it seems to have gotten worse when it started getting colder

[Kristian27]

So I took out the engine fuse box circuit board but can't find anything that looks unusual except that it's a bit dirty and there is a strange material on some of the components

Measured all relays, coil resistance seems good on all and good connection in NC position
I also measured the resistance on the injectors all 4 are withing 11.2-11.4 ohms so those seem ok

[GiveMeABreak]

It does look like it has been through the wars....

[Kristian27]

It does look like it has been through the wars....

I cleaned it and put it back in, doubt it is the cause of the problems..
one strange thing I noticed, each time the engine starts to run badly the short term fuel trim drops to -25

[xantia_v6]

The short term fuel trim is governed by the readings from the oxygen sensor. What do the readings from the oxygen sensor do at the same time?

[wheeler]

So I took out the engine fuse box circuit board but can't find anything that looks unusual except that it's a bit dirty and there is a strange material on some of the components

If it's the laquer type stuff that looks bubbly in some parts this is completely normal, it appears to be some sort of protection lacquer type stuff to protect the PCB & components.