Lack of power especially when cold

[derekpayne]

Had a fault appear the other evening out of the blue.

Started up as normal went to pull away slowly as the road where I park is very uneven, and felt something not right, the engine was popping etc as if it was running too weak, after about 30 seconds the engine warning light came on, and a message came on the dash saying that there was a fault with the ESP circuit. I checked the codes when I got home and I have a recurring one which states that there is a fault with the "secondary air injection system" I have had this intermittent fault for the last 3 years and just clear the fault and carry on until it comes on again. The other fault was something different and I accidently cleared it without making a note of it and although the problem is still there the fault code hasn't appeared since.

I did look at the live data and every so often when I rev the engine it says there is a fault with the o2 sensor, which I think is causing the fault with the secondary air injection system, but could the o2 sensor cause the latest fault?

I have read some other posts about lateral acceleration sensor where is that and what does it do? I am a qualified HGV technician but have been out of it for about 15 years and things seem to be getting more complex than I was used to.

I will post back if and when I get any more codes.

Cheer

Just a small update.

I have been driving the car today and no faults codes have appeared yet, but I can say that it is ok driving with light throttle but as soon as I push the throttle down to accelerate it can act like it is running too weak and hesitate etc, I think the ESP fault was just a coincidence as I was driving over rough terrain at the time when it started running rough.

It almost feels like its got fuel starvation.

Could it be the o2 sensor or the Mass Airflow meter?

 

[derekpayne]

Did a live sensor check with the following results:

Fuel System 1 Status: closed loop, o2 sensor fault (this fluctuates between open loop (driving conditions) and closed loop o2 fault, if I rev the engine to about 3000 rpm and return to idle)

(all the following results are at idle)

Absolute throttle position 3.5%

Calculated load value 24.3%

Intake manifold pressure 41kpa

Airflow rate (MAF sensor) 3.5g/s

Short term fuel trim (bank1) +19.5%

Long term fuel trim (bank1) +13.3%

I am of the opinion that the O2 (Lambda) sensor is the culprit and have ordered one from ebay will post when fitted to see if it cures it.

Any other comments would be greatly appreciated.

Cheers

 

[derekpayne]

I have now fitted a new MAF and O2 sensor, and the problem is still there anyone got any ideas?

Just to add to this, the problem started suddenly one day, I had driven to work, parked for the day and when I started it up and went to pull away I noticed the problem, maybe that will help in the diagnosis?

Cheers

 

[BlackC55]

Where did you get the MAF from?

 

[derekpayne]

A supplier on Ebay called UK Diesel Parts, it is new and the correct one for my model etc.

I am going to do some more inspecting first thing tomorrow (Monday) see if I can find any sticking valves and check the throttle housing, egr valve, etc etc.

 

[BlackC55]

What make was it? How much was it?

 

[derekpayne]

I don't know the make but it was £23.97

 

[E270 Owner]

I don't know the make but it was £23.97

Woops.


Bosch or Pierburg for MB's

 

[derekpayne]

I delved a bit further this morning, tried blanking off various pipes to see if it made any difference, nothing changed, all the vacuum pipes look OK as far as I can see. I can hear some hissing noises from behind the dash panel on occasions, is the heating and ventilation controlled by vacuum? If so it could be a leaking pipe etc causing a vacuum leak. The engine ticks over OK and as I have said before under light throttle it will rev ok but as soon as I floor the pedal it will pop back through the inlet manifold and can in fact stall.

I have fitted the old MAF for now as the new one made no difference, and will wait to see if anyone else suggests anything else to check.

Oh by the way the old MAF is a seimens, the new one is unmarked.

 

[derekpayne]

Just another idea, what is the item in the picture? When the engine is up to running temp I can hear and feel it ticking and there are some pipes runing to it.

https://dl.dropboxusercontent.com/u/93642372/IMG_20150406_094424.jpg

 

[E270 Owner]

Yep forgot Siemens as a manufacturer of MAF's

Sounds like a vacuum leak as most of the vent system uses it to control the flaps etc.

In the pic it looks like a vacuum system switch if those pipes are neoprene.

 

[derekpayne]

Another thing that I havn't checked yet and is rather fundamental is the fuel pump!! Does anyone know what pressure it's supposed to work at, the more I think about the symptoms the more I think it could be at fault.

 

[BlackC55]

Throw away the unbranded MAF. It will not work and cause you no end of issues.

Get a peirburg one from Euro Car Parts.

 

[derekpayne]

Just an update:

I checked the fuel pressure to the injector rail and sometimes when I turn the ignition on it pumps to about 20 psi, sometimes it doesn't pump at all, when I crank the engine it sometimes pumps to about 25 - 30 psi and sometimes to 50 psi, which makes me believe that the fuel pump is failing as from the research I have done it should pump at 55 psi?

So do I buy a new fuel pump or is there something else that is stopping it from getting to the correct pressure, bearing in mind that the fuel filter was changed about 3000 miles ago and everything has been fine up to just last week.

Your help is greatly appreciated.

 

[derekpayne]

I checked my records when the fuel filter was changed and it was September 2013, I didn't realise that it was 18 months ago, how time flies, so I have now changed it again with a new one, but the problem still exists will be fitting a new fuel pump tomorrow evening.

 

[derekpayne]

Major update!!

Replaced the fuel pump tonight with a Bosch one, fault cured, I didn't have a fuel pressure tester to fit this vehicle but I did have a Snap-On oil pressure tester which was capable of measuring upwards of 55psi and managed to adapt it to plug into the hose that feeds the main injector fuel rail, and it was that which indicated to me that because of the huge variations in pressure either the fuel filter or pump was at fault, obviously it was cheaper to change the filter first plus it was due anyway, but it was the pump in the end which was failing!!

My wife is so pleased because I was a bear with a sore head for the last couple of weeks, as I hate it when I can't diagnose something.

Cheers

 

[E270 Owner]

It almost feels like its got fuel starvation.

First feelings are usually the best !!