E430 failed emissions x3

[nadeem]

Hi,

I recently purchased an E430 1998 covered 209k miles with sight missfire / hesitation during idle speed of 650rpm, no problem when engine revved above 1500rpm.

Took my car to my local garage for mot and it's failing on emissions. During the tests i was running on Shell's Vpower unleaded with cata-clean.

First attempt;

Failed only on lambda figs as follows; min 0.97 max 1.030 actual 1.031

I used carsoft diagnostics and ME recorded the left o2 sensor as lazy, ok borrowed a new sensor from my cousine replaced fault cleared and so far no errors.

Second attempt;

Failed on lambda again actual 1.034 (strange) all sensors working. Garage recommended changing the spark plugs, air filter and the lambda again.

At this stage i borrowed my friends star system which confirmed no missfires or faults hmm okay, but he did notice the car temp @ 104oc during idle speed (cluster gauge reads 85oc temp sensor issue??

Third attempt;

Note at this stage i've replaced the plugs, filter and another o2 sensor.

Failed on CO2 max 200 actual 390 & lambda actual 1.041, what the.. i don't understand what's going on???

I've had my dad check for air/oil leaks could the increased temp have an affect on emissions?

Much Appreciated...

Nas.

 

[lynall]

Have you checked the plug leads?, check with them removed from coil, the ohms reading is on the tin cap bit of the lead.

Mine had 3 that were out of range much smoother idle with all new ones fitted.

Have you watched the lambda sensor readouts when engine idling to make sure there is a difference between front and rear sensors to confirm cats are working, as below pics
02s11 bank 1 sensor 1, o2s12 bank sensor 2 etc etc

Also with the star you should be able to see what the maf is doing, ie it could be feeding duff info to the ecu hence to much fuel

Is your new car black with wing vents?



Lynall

 

[bouncer]

AIR LEAK. . . . . hi lambda reading is air leak.
Check gaskets seals and fexi pipes.

Lambda reading is not the condition of the sensor but a ratio (lambda) of oxgen in the exhaust gas. Perfect conbustion is Lambda 1.000



sTeve

 

[lynall]

Steve so it could be an air leak after the cats?



Lynall

 

[nadeem]

Guys thanks for the input, we've checked with star no problems detected only my DCM's lol and the parktronic system faulty. No air leaks at all from the engine and surroundings, the front top part of the engine is making a rattling noise. My dad's friend ex MB tech said he'll need to look into the engine to determine the fault. Therefore i do not have the dosh to fork out on labour changes and any parts ...

It'll be cheaper for me to break this car for parts.

Oh well it was fun driving the V8 back to my E320 V6 :-(.

Cheers,

 

[Ian B Walker]

What about the engine temp sensor. On some models they also effect the injection. I had this on a E220 and changed the temp sensor. Re test and passed.

 

[bouncer]

Steve so it could be an air leak after the cats?



Lynall

Quite possible Its a tailpipe lambda reading so any holes leaks in the system can draw in air and add to the exhaust gasses

High lambda reading at tailpipe = Air leak

sTeVe

 

[nadeem]

We've decided to repair the car,

Firstly the overheating was due to the viscous fan failure. We'll check the exhaust system for any leaks and all the major pipe works.

 

[lynall]

Mine also reqd a new fan hub, check the small exhaust flexi sections under the floor below the front seat as my drivers side has rubbed a couple of times.



Lynall

 

[nadeem]

Update

We've checked the entire car and no air or exhaust leaks, Viscous fan working well and engine temp stable at 87oc.

Live data on the ME conrol unit;

Cold start idle speed;

Lambda right 1%
Lambda left 22%

High Idle speed;

Lambda right -3%
Lambda left 12%

If we reseat MAF sensor lambda left comes down to 5%, Another thing we have noticed with the MAF sensor disconnected engine shake stops and no hesitation. Reconnecting MAF engine begins to shake engine.

We borrowed an identical MAF from a friend still same

I've attached the live data readings including the injection timings as the left seems half a second higher.

so what do you think?

 

[nadeem]

Hi,

My MOT is round the corner and need help with the engine shaking, with MAF connected the engine shakes and runs rough at idle. If I disconnect the MAF no shakes and runs smooth, plugged a new genuine part still shakes. Is the engine temp sensor built into the MAF or separate sensor. There are no air or vacuum leaks so with maf why the shakes?

Cheers...

 

[Ian B Walker]

It may be an idea to do a compression test or a leakdown test on the affected side. It could be that you have a sticking valve or pitted valve seats that is letting fuel into the exhaust system. Or even a dribbling injector. Its just a thought and I am probably way off the mark.

 

[nadeem]

A friend did a compression test via Star, results were 250-251rpm in all cylinders. Not sure if that's the proper test but suppose it gives an idea of the engine?

 

[bouncer]

A good read.

http://www.petercoopercarrepairs.co.uk/new_page_3.htm

Note:- " If the fault is a high lambda reading, with a high O2 reading but with normal CO and HC readings, the most common cause is post combustion air leaks. A small exhaust system air leak will leak air into the exhaust before any blows can be detected. Only a small volume of clean air introduced into the exhaust will cause a car to fail the MOT test. "


sTeVe