K-series failed emissions

[2F45T4U]

My car failed on emissions fast idle test.

speed: 2500-3000RPM
CO: 0.005% = Pass (max 0.300%)
HC: 60ppm (max 200ppm)
Lambda:`1.067 (range 0.970-1.030)


looking back 0ver past MOTs its been sitting at lambda 1 and 1.02 so its been up at its top limit for a while. so its a wee bit lean.

Im thinking the Lamba sensor is sluggish the car runs fine with no misses, exhaust leaks, and the cat was fine when i put it on yesterday.

Anyone had simelar problems or can offer any advice before i stick a new lambda sensor on tomorrow?

Cheers.

[Mikie711]

Sounds like one of two possibilities, either your sensor is on it's way out or you have a leak in the exhaust. It doesn't take much of and air leak to show up as lean but 1.03 is an AFR of 15.1 with a typical 4 wire sensor. What that test shows is your sensor is reading outside its effective range, so would probably change it first assume no leaks like you said.
I've got a couple of narrow band sensors lying around if you want one to try.

[2F45T4U]

ye i thought so. Thanks for the offer but to be honest, with the hassle of dicking about getting the old one off and and putting the ground tray back i think il just stick on a new sensor.

As you say, the range of the test is to ensure the narrowband sensor is working withing its effective range. which mine appears not to be doing. To check this is the case. At between 2500 and 3000 RPM i should be able to measure about 0.2v on my narrowband with a meter. if the closed loop control is operating properly the voltage should swing back and forward as the ECU tries to balance the fueling.



i might shove my Zeitronix wideband and datalogger down the pipe and see what thats saying too.

will have a play tomorrow.
Cheers.

[Rich H]

new generic 4 wire sensors are cheap on e-bay A new lotus/rover one is £££!

[2F45T4U]

ive got the proper one from Aberdeen £56.

no need to test the sensor. this morning when i went to look at it, I pulled heat proof sheath back from the probe and the whole internals of the sensor came out of the threaded part.

fair do's i thought, at least it was deffinately broken. So i proceded to unscrew the remaining threaded part.

"this is tight!" large extension and a tube. "there she goes" turn, turn, turn, turn, turn, turn, swear, cry. The threads sheared and were stuck in the manifold.

got the manifold off now and looking at it theres no threads left at all on the inside. Ive got a tap for lmbda probes so looks like il have to fill it with weld and try and re-tap it.

pics to follow.

[Shug]

TADTS

[s29ttc]

Yeah been there done that with old sensor. I took it into work drilled out the wrecked threads and got a stainless steel sleeve welded in and drilled and taped. Remember the taps quite an unusal one like 10 x 1.5 or something like that! Good luck sorting it, you should mabye have a look about for an old manifold that might be cheaper/less hastle than fixing the one but not sure how much they cost or how hard they are to come by

[2F45T4U]

The female thread is wrecked. http://img72.imageshack.us/img72/1349/p1000720c.jpg

Lotus specialist tool for holding open bonnet "LST-001-BR00M-5H4FT" http://img59.imageshack.us/img59/7452/p1000722e.jpg
Mr die grinder sorted that out thought. MUCH better http://img25.imageshack.us/img25/4944/p1000723n.jpg
http://img191.imageshack.us/img191/9794/p1000725c.jpg
http://img690.imageshack.us/img690/7202/p1000726h.jpg

Std welds are hideous, dangle berries everywhere flow path is sh*t http://img534.imageshack.us/img534/631/p1000717u.jpg

Lambda probe came apart in my hand. looks like its been like that for ages http://img11.imageshack.us/img11/6320/p1000714w.jpg

[ed]

Just had this problem myself.

So changed to an s2 manifold and downpipe so next time I only need to take the manifold!

[2F45T4U]

Yeah been there done that with old sensor. I took it into work drilled out the wrecked threads and got a stainless steel sleeve welded in and drilled and taped. Remember the taps quite an unusal one like 10 x 1.5 or something like that! Good luck sorting it, you should mabye have a look about for an old manifold that might be cheaper/less hastle than fixing the one but not sure how much they cost or how hard they are to come by

ye the thread is M18x1.5 ive had a tap since the last time i built a manifold and saw the prices of the lambda boss's! bought a tap and made a handful of my own on the lathe. After i ran it down, its really not as bad as it looked. I think the Male thread on the sensor is designed (more likley luck) to strip and gaul to save the manifold.

ive cleaned it all up, just away into town to get gaskets and a new probe.

[s29ttc]

Ah found my older post with the worst pictures ever but here you go:

"Well following on from last post my lambda sensor seemed to kick the bucket. The sensor seemed to weld itself to the manifold and by taking it out striped the threads down. Ali kindly supplied a spare manifold lying about which had 2 broken studs and 2 jamed in the downpipe flange. The boss where the sensor was connected had been badly striped with taking out the previous sensor.

In work with lots of WD40 and some bashing and pulling we managed to get two of the studs out from the downpipe flange. The other two wouldnt budge so we drilled and retaped the holes. I have replaced these with stronger studs so hopefully the same problem won't occur.



The boss was very badly damaged so we retaped it first but the sensor seemed a very loose fit due to taking out the other sensor it must have striped a good bit of material. To combat this we drilled out the threads and machined a stainless sleeve which was put it. We then welding this in place and drilled and retaped the boss to the required size leaving a nice clean thread for the new sensor.



We put up both the head face and downpipe flange on the grinder to clean up the faces. Securing the job was quite hard and we only took a couple of thou off as I didnt want to strip too much material. The face doesnt look too good but I am hope the new gasket will seal the edges. I just didnt want to remove too much material from the top.



I got the sensor from eliseparts and hope this one lasts a bit longer than two months. I was just a bit worried of the open wires whether I should use a heat sheilding on them or I would get away with cable tying them away from the manifold to prevent them melting.



Anyways I ordered the gaskets and should hopefully arrive tomorrow and get it swaped over, hopefully the task won't be too hard and the old manifold comes out ok.



I shall keep you updated "

[s29ttc]

Yeah been there done that with old sensor. I took it into work drilled out the wrecked threads and got a stainless steel sleeve welded in and drilled and taped. Remember the taps quite an unusal one like 10 x 1.5 or something like that! Good luck sorting it, you should mabye have a look about for an old manifold that might be cheaper/less hastle than fixing the one but not sure how much they cost or how hard they are to come by

ye the thread is M18x1.5 ive had a tap since the last time i built a manifold and saw the prices of the lambda boss's! bought a tap and made a handful of my own on the lathe. After i ran it down, its really not as bad as it looked. I think the Male thread on the sensor is designed (more likley luck) to strip and gaul to save the manifold.

ive cleaned it all up, just away into town to get gaskets and a new probe.

Ah 18 x 1.5 thats what I did mean! As you see above I didnt have as much luck, I ran the tap down and the sensor was still loose hence the sleeve we made up. Hope you getting it sorted soon!

[2F45T4U]

yep your problem was very simelar to mine. Im getting a Bosch sensor so hope itl last as well.

you really need be carefull with WD40 around a new one, as the silicones in it will kill it instantly. Even a wee bit thats ran down the inside of the runners will poison it.

[s29ttc]

Yeah I would give it a good rub down. I think I power washed it and then rubbed it down with a bit of petrol if my mind serves me correctly.

[2F45T4U]

It all went back together bonny.

re-test tomorrow.