406oc.co.uk

Posting the issue for the second time since there were no responses...

My 1996 406 D8 has recently developed an issue of engine check light (K light) comes on and off once in a while. It's completely random and you never know when it'll lit up again. The moment it lights up engine RPM drops suddenly to below 1 and sometimes engine stops too. Then it's little hard to start. At times car goes fine and this only happens when the vehicle is moving. I can keep the thing in idle speed for hours without any issue. thought it could be

1. intake air flow sensor
2. intake air temp probe
3. TPS sensor
4. Idle up / stepper motor
5. Vehicle speed sensor
6. Engine Control Unit

Ran the car one sensor unplugged at a time. Today I ran with the Vehicle speed sensor unplugged from the socket as the last ditch and still the K light came, and engine stopped few times. Sometimes the idle is rough. I cleaned the stepper motor and it's working fine and even if the stepper motor is unplugged, the issue is there.

Please fellas, I need a big help in determining where the issue is before replacing the ECU coz ECU's are damn expensive here in Sri Lanka. What is left for me to do is clean and re fix all the wiring contacts in the engine bay and clean the throttle body. When the K light comes no matter at what speed the engine reviving up, the rev meter drops to below 1 as if the correct rev signals are not coming to the rev counter. Could it be the TDC(?) sensor ???

Pick an engine any engine!

I'm guessing it's an HDi, I had a similar problem with my Berlingo years ago, started off stalling at the first set of traffic light I pulled up at.

Local Citroen experts found a duff EGR valve and accelerator potentiometer.

Er,

I'm assuming you've serviced it properly?

Hi there Harshan, sorry you didn't get a response before That does sound like a dirty contact somewhere and I think you're on the right track checking/cleaning all the contacts. Also check engine running relays 'cos I had two go intermittant on a mates Pussat once so I don't trust them anymore.

poddack wrote:I'm guessing it's an HDi

Wrong! It's a '96 1.8 petrol D8.

Thanks Steve and others responded.. yes indeed it's a 1.8 petrol. I'm left out with no option than to guess it could be the TDC sensor which I need to replace with a test one and run for few days which I'm going to do in another hours time. I will check all the relays and contacts other than the sensors. In the mean time keep me posted if any bright idea lights up in your minds.

I doubt very much that the ECU is at fault.

Have you inspected the large ECU multiplug? the pins can be a problem I think.

Hi Welton,

Yup, during the last two weeks I checked them more than three times or so, and cleaned them as well and checked all the pins and they don't have any rust any dirt what so ever which prevents a smooth flow of power. Although I don't have the same confident levels on the wiring harness and the two sets of contact points under the battery cover.

Cheers!
Harshan

Hi All,

I have another update, that is I replaced the TDC sensor, or the flywheel sensor in our local context. However that did not help at all. For me it seems like temporal fuel cut off, checked and cleaned the emergency fuel cut of switch contacts all that. now one more left to do, that is to clean and refix the two sets of wire connectors under the battery. I will do it tonight and update you all. Please post if you have any ideas.... this seems like a sudden fuel cut and ECU light comes up as it struggles to straighten up the engine with the stepper motor/idle up motor

hi all,

i've done the long waited contact clean job in the engine bay. All the contacts sprayed with contact cleaner and cleaned with sand papers.. even the battery terminals and all earthing. Still the problem persists. Another symptom is fans cuts into cool engine for few seconds and goes off. I mean even just after the cold start in the morning, fans engages and runs for few seconds and goes off even without A/C switched on.

Hi All,

First post & desperately hoping someone can help me!!!

Harshans problem is identical to mine. I have problems with the engine lacking power, spluttering and cutting out. The engine warning light comes on fairly regularly. It will run in a 'lumpy' fashion until it seems to finally give up, idle low and then cut out.

So far i have...

-Cleaned then changed idle control valve
-Cleaned Crank Sensor
-Changed coolant temp sensor
-Changed Throttle position sensor
-Changed Spark plugs
-Inspected & cleaned fuel rail, pressure regulator and injectors
-Changed fuel filter
-Removed from tank and inspected fuel pump
-Checked & cleaned earthing strap on engine block

As you can see i have checked quite a lot and am getting very frustrated as it continues to do it!!

Does anyone know of any more sensors so check that may be causing this? I unsure as to whether is the coil pack. Im not sure how to check it?

I have a 1.8 1996 408.

Does anyone have any ideas or problems the same with a solution?

Many Thanks

it's the same model to mine, it could be the ECU it self. However similar symptoms may come due to intermittent failures of fuel pump and ignition coil pack. Can you find a test coil pack and a fuel pump to run and check? I couldn't find. What I did was found an identical model car and interchanged the ECUs ( you have to be careful to see these are coded or not, it wasn't a problem in my case) my car ran fine and similar symptoms were found in the other, so it was obvious that ECU was the culprit. My electrician repaired the ECU but he didn't reveal what exactly he did, may be soldering a loose contact in the ECU but I know it's not that easy. Good luck mate

I will attempt to get another ECU. I did see one at a local breakers recently and didnt pick it up

I will return there tomorrow morning and see if its still about.

In the mean time i shall have to keep an eye out for other 406 1.8 16v owners in Somerset and attempt to 'pull them over' and ask if i can borrow their car!!

As for fuel system, i believe the thing is over fueling if anything. I have better details in another thread.

viewtopic.php?f=1&t=7837

I shall update if any progress is made.

Thanks