Failed mot on emmisions again

[recycledjuvenile]

My car is a manual and I'm sure it does rev right up stationary. The vehicle has been off road for about a year with the occasional start, anything else that would give that fault.

Even if it is a manual it would not rev past 4K

 

[brandwooddixon]

Never knew that the manual gearboxes had a no load detection facility.

 

[bouncer]

If the oil has got in the lambda sensor via the wires then this is not good. As said earlier in the thread the lambda sensor samples oxygen in the exhaust gas and compares it a sample of oxygen outside of the exhaust, this is usually done through the wires. So if there is oil getting in then the sensor will be of little use. This is what will be causing the emissions to be out.
It is pointless trying to clean the sensor, under the protective thimble shield there is a porous end made of Zirconium dioxide. This porous end is almost impossible to clean, unless you have ultrasonic cleaning facilities.

sTeVe

 

[david451]

If the oil has got in the lambda sensor via the wires then this is not good. As said earlier in the thread the lambda sensor samples oxygen in the exhaust gas and compares it a sample of oxygen outside of the exhaust, this is usually done through the wires. So if there is oil getting in then the sensor will be of little use. This is what will be causing the emissions to be out.
It is pointless trying to clean the sensor, under the protective thimble shield there is a porous end made of Zirconium dioxide. This porous end is almost impossible to clean, unless you have ultrasonic cleaning facilities.

sTeVe

Run it through the tests today and its giving a fault on the forward stream o2 probe, the same one as last time. Its giving a no voltage toggling to 0.1 or so off and on. The guy thinks it could also be the ecu but there is no oil in there and I would have thought it would have thrown a fault for that. He thinks it possible that the wiring may have an open circuit because of the oil also, but I doubt thats the case, I hope.

Reluctant to cut this probe open at the minute just to satisfy my curiosity that there is oil in it like the last one.

You're right its impossible to clean it, the one I cut open could not be put back together and badly contaminated with oil.

Thinking ahead here but if the ecu is gone, can the tester not pick this up.

 

[bouncer]

I would say the fault is with the sensor. The sensor creates it's own voltage. If it's making no volts to 0.1v I'd change the sensor.

sTeVe

 

[david451]

I would say the fault is with the sensor. The sensor creates it's own voltage. If it's making no volts to 0.1v I'd change the sensor.

sTeVe

Thanks for that, ordered one and should get it on Monday, probably raining by then of course, but I'm going to think carefully over the next few weeks wheither I should hang onto it or move on.

Maybe have a clean sweep and get rid of the wife aswel, heheh.

 

[meanie]

If the oil has got in the lambda sensor via the wires then this is not good. As said earlier in the thread the lambda sensor samples oxygen in the exhaust gas and compares it a sample of oxygen outside of the exhaust, this is usually done through the wires. So if there is oil getting in then the sensor will be of little use. This is what will be causing the emissions to be out.
It is pointless trying to clean the sensor, under the protective thimble shield there is a porous end made of Zirconium dioxide. This porous end is almost impossible to clean, unless you have ultrasonic cleaning facilities.

sTeVe

Pretty poor grammer on my post about cleaning-I should have made it clear to clean the outside of the sensor.I was sceptical about this,until my old Ka failed the emmissions & I cleaned all the oily filth off of it.
In this instance,as the sensor is only producing 0.1v,yet the emmissions are high,it must be a faulty sensor.
We have a local factors who supply NGK lambda probes at sensible money.Found these to be reliable units so far.

 

[david451]

Pretty poor grammer on my post about cleaning-I should have made it clear to clean the outside of the sensor.I was sceptical about this,until my old Ka failed the emmissions & I cleaned all the oily filth off of it.
In this instance,as the sensor is only producing 0.1v,yet the emmissions are high,it must be a faulty sensor.
We have a local factors who supply NGK lambda probes at sensible money.Found these to be reliable units so far.

It was an NGK probe I fitted, 65 quid, mine has the more expensive one, once I get the new one and I'm satisfied its ok I'm gona cut it open and see if there is oil in it. I kind of hope there aint and that it's probably been a bad one, and my oil in wiring issues are resolved. If there is oil then I think I might cut back the wire on the new probe and apply solder in an attempt to stop it travelling up the wire.

Anybody know how oil can travel through wiring without pressure, electron convection or sumut. The landrover td5 has the same issues and unless the manufacturers start fitting proper connectors that prevent this its going to be a real expensive problem.

 

[brandwooddixon]

Oil travels up the wires by capillary action. This can be in the spaces between wires (if wrapped into a bundle) or even between the core strands within the insulation.

 

[david451]

Oil travels up the wires by capillary action. This can be in the spaces between wires (if wrapped into a bundle) or even between the core strands within the insulation.

With that in mind would I be right in saying therefore that if the source/supply of oil is eliminated, "in my case the sensor mod on the front of the engine" that this capillary action would stop. Oil left in the loom would remain there and not continue to travel.

I know that its good practice to replace the loom, but is there reasons why not replacing it is bad if the oil capillary action has halted.

 

[television]

We have had this up many times and it defy s all known electronics. I have demonstrated this by pouring oil into a working sky box that is 1000 times more sensitive than this car ECU

 

[Number_Cruncher]

If I've understood the thread correctly so far, the problem is that oil is being wicked along the lambda sensor wiring, and is fouling the atmospheric side of the lambda sensor - is that right?

If so, then, the first thing to put right is some measure to stop the oil wicking along the wiring. Where is this oil coming from? Is there a seal or gasket which needs to be repaired?

If the oil is fouling the atmospheric side of the lambda sensor, then, what's being seen is perfectly clear and logical, but, perhaps, throwing sensor after sensor at the problem isn't the best way to effect a cure.

 

[david451]

If I've understood the thread correctly so far, the problem is that oil is being wicked along the lambda sensor wiring, and is fouling the atmospheric side of the lambda sensor - is that right?

If so, then, the first thing to put right is some measure to stop the oil wicking along the wiring. Where is this oil coming from? Is there a seal or gasket which needs to be repaired?

If the oil is fouling the atmospheric side of the lambda sensor, then, what's being seen is perfectly clear and logical, but, perhaps, throwing sensor after sensor at the problem isn't the best way to effect a cure.

Sorted the oil source, the sensor on the front of the engine, modified it with the new style extension plug.

Fitted the new probe today but still wont rev above 4k sitting still and puffing black smoke still.

The ecu looks ok but off the check voltages if I can ref previous quote. Bastid!!!!

 

[bouncer]

co <0.30%vol
6-56%vol

hc <200ppm vol
1261ppm

0.970-0-030
0.827

QUOTE]


Overfueling!!! High HC unburnt fuel.

Lambda 0.827 all fuel and very little oxygen. wont be a misfire causing this overfueling because misfires result in high oxgen.

Would take a look at the EVAP cannister purge system, see if there is any kinks in the return pipes?

sTeVe

 

[turbopete]

i know my car is a diesel, but it will rev right to the limiter in park! regarding the overfuelling here though, short trips could have blcked the breather hoses, im assuming that the obvious air filter has been checked, often the italian tune up can do the trick too!

 

[david451]

Checking the Lambda sensor is reasonably straight forward.
Your car will have either a 3 or 4 wire sensor.2 of these wires will be for the heater element-one should have battery voltage,the other should provide a good earth(use a multimeter with the engine running to check this.Pierce the wires,don't disconnect the plug).When cold the resistance,engine off,plug disconnected,across the heater element should be in the region of 5ohms.
The other one or two wire/s are the sensor circuit-with the engine at full operating temperature,pierce the sensor wire & check the voltage.You should get a fluctuating reading in the range of 0.2 to 0.8 volts.It should be a rhythmic fluctuation (eg;0.3 to 0.6 over a period of about a second).If it's a 4 wire sensor,then the remaining wire is earth,pierce it & check for a good earth with the engine running.If it's a 3 wire sensor,check that the exhuast offers a good earth to the negative post on the battery.

If you get a good result on the above,you can (almost certainly) rule out the sensor.
If you get a low voltage reading on the sensor wire(0.2 volts or less) then the sensor must be faulty,as you have high emmisions-if it's high then get the system read off,as the fault probably lies elsewhere.

Did your test and traced a fault to the 2nd plug from the rear of the fuse box, 6th pin nearest the engine was pushed down a tiny bit and not making connection. Got a spare probe now, but sorted, you guys are brill, thanks a million.

 

[meanie]

Good luck with the retest.

 

[david451]

Good luck with the retest.

It sailed through the mot, and once again thanks a million/trillion times.