280TE not firing all six cylinders and over fueling

[ldd028]

My 280te on a K plate is not firing properly on all 6 cylinders. It is also over fueling badly with fuel coming out of the exhaust.

I've changed plugs, ht leads and coils but it hasn't changed anything.

Could this be an ecu problem? If so how much will it cost to sort out?


Cheers

D

 

[124coupe]

M104 engine with MAF (HFM Bosch system), check these:

Carefully cut into the insulation surround the wiring coming into the coils from the ECU (inside the rubber moulding). If you see crumbling and/or dust where the individual wire insulation should be then you must replace the wiring harness before throwing any more parts at it (£600 plus fitting - DIY with care). Pointless reading codes etc if this is faling as you will get a range of errors, most of them spurious - also, components WILL de damaged.

You replaced coils and leads - did you replace the boots under the coils that connect the coils to the (3) plugs? These fail, causing misfiring (£7 each) - worth changing every couple of years regardless.

Assuming all OK, get access to or make a code reader and read the fault codes.

Details attached.

Codes are:

PIN 8 ECU
1 No fault found
2 Engine Coolant temperature sensor
3 Intake air temperature sensor
4 Hot film mass air flow sensor
5 CTP switch
6 Not used
7 Not used
8 Idle speed control (ISC) system at upper or lower control stop or CC or EA indicates "limp
home" mode.
9 O2S 1 (before TWC) - voltage too high, circuit open or voltage implausible
10 O2S 2 (after TWC)voltage too high, circuit open or voltage implausible
11 O2S 1 heater (before TWC) - Current too high/low or short circuit.
12 O2S 2 heater (after TWC) - Current too high/low or short circuit.
13 O2S (Lambda) control system operating at rich or lean limit
14 Injector, cylinder 1
15 Injector, cylinder 2
16 Injector, cylinder 3
17 Injector, cylinder 4
18 Injector, cylinder 5
19 Injector, cylinder 6
20 Self-adaptation at idle speed or upper/lower partial load at rich or lean limit
21 Ignition output 3 or ignition coil for cylinder 1 and 6
22 Ignition output 1 or ignition coil for cylinder 2 and 5 (Engine 111, cylinder 1 and 4)
23 Ignition output 2 or ignition coil for cylinder 3 and 4 (Engine 111, cylinder 2 and 3)
24 CKP sensor or magnet for position sensor not recognized
25 CMP sensor not recognized or implausible
26 Not used
27 TN-signal (rpm signal ) - open or short to ground
28 VSS - open circuit
29 Not used
30 Fuel pump relay module - open or short circuit
31 Not used
32 Knock sensors 1 and /or 2
33 Maximum retard setting on at least one cylinder has been reached or the ignition angle
deviation between the individual cylinders is greater than 6 degrees crankshaft angle
34 Knock control-output switch in engine control module faulty Momentary fault in
self-adaptation closed throttle speed/partial load
35 Model 124,129 and 140 AIR pump switchover valve and/or electromagnetic AIR pump
clutch. Model 202 AIR pump switchover valve and/or AIR relay module
36 Purge control valve - open/short to ground or B+
37 Upshift delay switchover valve
38 Adjustable camshaft timing solenoid - open/short to ground or B+
39 Exhaust gas recirculation switchover valve - open/short to ground or B+
40 Transmission overload protection switch - open/short to ground or B+ or open or closed or
implausible
41 CAN communication from engine control module faulty
42 CAN communication from ASR, EA/CC/ISC module or diagnostic module (OBD II) faulty
43 Starter signal (circuit 50) not present
44 Not used
45 Fuel safety shut-off of electronic accelerator or cruise control active
46 Resonance intake manifold switchover valve - open/short to ground or B+
48 O2S 2 (after TWC) heating circuit relay module - open/short to ground or B+
49 Voltage supply at engine control module implausible/low volts
50 Engine control module faulty or not coded.45 Fuel safety shut-off of electronic accelerator or cruise control active
46 Resonance intake manifold switchover valve - open/short to ground or B+
48 O2S 2 (after TWC) heating circuit relay module - open/short to ground or B+
49 Voltage supply at engine control module implausible/low volts
50 Engine control module faulty or not coded.

ECU may be at fault, but work this first and then post again with codes.
(or go to the garage, armed with some info!)

 

[kth286]

Idd028

I am puzzled because my similar engine set up, will not allow injectors to pulse fuel into a cylinder if the spark plug is not sparking.

Are you sure you have not got the leads to the plugs mixed up and the engine is firing in the wrong order. ??????????? Check again carefully and follow the sequence in Haynes manual.

Regards

 

[124coupe]

Attached is the coil to plug pic (usually also a schematic on the alloy cover). Hard to connect them wrong unless the coil is on the wrong boot because of the lead length.

AFAIK, in these engines misfire detection (and so shutting down up to 2 injectors) is based on the crankshaft sensor output - the failing cylinder doesn't give it a speed-up kick.

Also the ECU can sense open circuit and also the "wrong" current draw from a failed spark in a coil (assuming the ecu-to-coil leads are intact!) and switch it and the fuel to the 2 affected cyls off.

I would still examine the loom as a priority once the misplaced plug leads check is done. The injector control circuits could also be affected.

The rich running will quickly ruin both the o2 sensor and cat so the car shouldn't be driven.

 

[ALAN@ECUCLINIC]

and if the ecu should be at fault.....

 

[dean fitton]

Did you get anywhere with this???

If so can you email me to dean@deanfitton.wanadoo.co.uk

If anyone else has resolved this problem please contact me also...

Thanks Deano

 

[230ceBruno]

Is it idlling smoothly?

 

[kth286]

This post is over a year old and he's not reported back so do not get excited.

Might even be driving a BMW now !!!!!!!!

Deano

Explain what is happening to your car, and provide full details of what car you have.

 

[television]

This post is over a year old and he's not reported back so do not get excited.

Might even be driving a BMW now !!!!!!!!

Deano

Explain what is happening to your car, and provide full details of what car you have.

This car could have been back with a new owner and name also fixed

 

[dean fitton]

have bought new wiring loom and fitted it. Car in now over fueling and not idling properly. (I guess the bad idling is from over fueling??)

The car is a 280te 1993 130k miles

please help.

I eagerly await any helpful reply...

 

[television]

have bought new wiring loom and fitted it. Car in now over fueling and not idling properly. (I guess the bad idling is from over fueling??)

The car is a 280te 1993 130k miles

please help.

I eagerly await any helpful reply...

As above, what was wrong before you did anything, how did the car behave

 

[Stevie A]

Dean, I have read in the past about a faulty fuel distributor causing erratic idle and excessive fuel consumption. Is fuel consumption up? If this part is at fault it would show up in a MB diagnostic test I think.

 

[kth286]

There is no fuel distributor on this car it is all electronic.

Dean

Provided you got the correct loom (and there are several, depending on the options fitted to your car ie. manual or auto, ASR or not, air con or not, etc etc) you must have left a plug off or not connected properly.

Ideally you need the codes read by an independent with the correct code reader as this would quickly identify problem.

 

[kth286]

Dean

How did the parts person determine the correct loom for you ????????? As he would have needed to confirm with you the spec of your car to be sure.

IF you had the incorrect loom the wires to the throttle control would be different again depending on your spec and I feel that it is the throttle control in your case that is giving you the problem.

 

[kth286]

Dean

If you want to give me your VIN and the part number I will check the part number, on Mercs EPC for you.

 

[Stevie A]

David - You learn something new everyday. Cheers.

Please let me know how the fuel gets into the cylinders in this car then? How is the fuel delivery regulated? Is this a more modern system? Is it Bosch?

 

[230ceBruno]

I believe (ibuleve) that there is un metered air getting in the engine somehow.

 

[kth286]

Stevie A

Unlike the electro-mechanical system where there is continual fuel pressure to the MECHANICAL injectors via a distributor as you pointed out, the elctronic system uses electrical injectors which are pulsed by the ECU computer at the appropriate time and for the appropriate duration, depending on demand (eg. accelerator position) and feedback from various electronic sensors.

 

[dean fitton]

I took the part no off the original loom (PS was parts manager at a MB dealer before we were closed).

Also changed air mass sensor.

Car now struggles to start when cold and as you come to stop at a junction it stalls but restarts fine.

It idles fine.

Have looked and check all connections and they are all good.

Any ideas pls.

Exhuast did throw out loads of smoke before the air mass was changed..

Thanks Dean

Ps chassis number begins with wdb1240882f******

 

[television]

I saw something that is new to me the other day, that is the inlet manifold was leaking and caused problems almost the same as yours, though that was a 560