Clk200 Komp 2001 won't hold revs at 2500rpm

[rsboy82]

Hi guys hope your all well sorry to drop a tech question on my first post but I need your help,

First off the car has 134k miles on the clock full service history and no warning lights on the dash

Ok so basically I've got 2 probs and I was wondering if they both point to the same thing

Prob No 1:- car went in for Mot last week and failed on emissions grrr I've attached the readings below

Fast idle test
CO =< 0.3%. 0.01%. Pass
HC =< 200ppm. 4ppm. Pass
Lamba 0.97 - 1.03. 1.109. Fail


I've tried cleaning the air filter and took it for a good blast on the way to the mot station for a recheck but it didn't make any difference (wishful thinking)

Ok problem No2

The MOT tester said for some reason the car wouldn't sit at 2500rpm, I tried doing it when I got home and it's true when you get close to 2500rpm the revs keep climbing even if you try and balance the throttle!

Would these problems be connected? The exhaust is blowing slightly but nothing to extreme

I hope you guys can help as I need to get the car MOT'd and sold and I haven't got much money as I'm off backpacking in 4 weeks!

 

[tor_ake]

How is the idle, especially with the AC off? Steady around 750 or higher, fluctuating?

 

[BlackC55]

It needs to plugged into a Star to see what is causing the fault.

Search for "oil in wiring loom"

 

[rsboy82]

Hi Tor the idle is quite smooth if I'm honest buddy slight blip every now and then but overall sits pretty much bang on 750rpm

 

[rsboy82]

Hiya black when you say star do you mean diagnostics? Do you think it would be worth it as I've got no warming lights on,

Cheers guys I really appreciate you both replying

 

[tor_ake]

If the idle is ok, then it isn't an air leak Never heard of the oil in loom sickness until today, but it could very well fit the bill.

 

[rsboy82]

Hiya mate ill look into the oil in the loom,

Any ideas on the emissions?

 

[tor_ake]

theory is: oil runs in the loom, mucks up the o2 sensor - that would cause the emissions fail.

 

[rsboy82]

Hiya mate thanks again, sorry to sound like a a dumb ass but where abouts would I be looking for oil in the loom, I've had a quick search for a how to guide but nothing was found

Also over the weekend I removed both of the lamba sensors and give them a good old clean, while I had the front sensor out I noticed it had a rattle, do you think that could be fooked.

None the less I placed them both back into the exhaust and added some red ex to the fuel,

Today was the last day for a free re-test so I headed back up to the test centre while giving it a good blast on the way! And the results were worse again only on the high idle lamba reading!

I'm in denial to thinking I need a diagnostics as there's no warning lights etc and the car runs pretty smooth so I'm not sure if anything would show up! Is this just me being a fool or do you or anyone else agree?

 

[rsboy82]

Diagnostics done O2 sensor was at fault! New one ordered fingers crossed that will do the job, cheers for the help guys

 

[BlackC55]

Check for oil in the wiring loom plug connector for the sensor. Any oil in there will just cause the sensor to fail again. Also only use genuine sensors. Even the bosch ones seem to be crap too.

Search for oil in wiring loom. Loads of info on here about it.