Running rich, MOT emissions failure.

[Mord]

So, I just picked up a very cheap Leon 1.8 20v Cupra.

It had a leaking steering rack, so I replaced that no problems.

The problems came when I MOT'd it. The emissions are through the roof.

It drives perfectly, performance is good, fuel consumption is understandably high.

The CO was around 12%, Lambda 0.73 HC around 700-900. EML is on.

The temp gauge seems to work intermittently, if the car idles for a while, it will eventually creep up to 90. CC blows hot, and it warms up quickly, all coolant pipes are hot as normal. When driving normally, the needle stays on 60...

Main issue is that I can't talk to it. I've tried 2 different Snap-on scanners, a generic EOBD reader and my laptop + ELM327. All give no connection errors.

The coolant temp is 90 during normal driving according to the climate control self diagnosis, I don't know how often it updates though.

Whether it makes a difference, the car has no radio fitted, I read somewhere this can cause issues when connecting to VAG cars, can't seem to locate where I saw it though.

Is it possible that these issues are all manifestations of the same fault (ECU?) or do I have several things wrong?

 

[Leon1600s]

Thermostat will be stuck open, common issue. Stuck open = never up to full temp = running rich to compensate. There's loads of info on here about how to replace, it is a bit fiddly but not too bad.

Have a look at the info on the coolant temp sensor on here also. They can be an issue if it's still the original. But from your symptoms, I'd be certain it's the thermostat.

 

[ZRZ]

Thermostat will be stuck open, common issue. Stuck open = never up to full temp = running rich to compensate. There's loads of info on here about how to replace, it is a bit fiddly but not too bad.

Have a look at the info on the coolant temp sensor on here also. They can be an issue if it's still the original. But from your symptoms, I'd be certain it's the thermostat.

Thermostat stuck open also cause the temperature gauge to be unpredictable? I.E Runs to temperature and falls and rises all the time etc.

Probably makes no sense but hard to explain!

 

[ibizacupra]

vcds vag-com required to properly ascertain what codes you have.
anyone in your area have vcds you could use?

 

[Mord]

vcds vag-com required to properly ascertain what codes you have.
anyone in your area have vcds you could use?

I'm in the Sussex coast area, I don't know of anyone personally. Anyone here nearby who would like to earn my eternal gratitude...

I did almost change the 'stat and Coolant temp sensor as they were cheap and fairly quick and easy to change. The 90 degree read from the climate control and the normal behaviour of the rest of the cooling system made me rethink it and seek advice.

Would be so much simpler if the damned thing would talk to me. I did look at the vag.com, looks like an awesome tool, but I don't want to buy one, only to find that it won't talk to it either! I need to get to the bottom of that issue first I think.

 

[Bigjohn84]

I stuck a new down pipe and cat on my car before my mot and mine was through the roof also, guy said since it was new it had to be warmed up first so he revd it like hell then it passed, try changing your oil, also lambda sensors, like bill says tho, get vag plugged into the car and you will find out the problem

 

[747_727]

You can get cheap vag-com leads off Ebay which will read and clear fault codes for very little money.
You could just stick a new stat and sender in anyway if you gauge is messing about. Any fault codes will be stored anyway.

 

[Mord]

You can get cheap vag-com leads off Ebay which will read and clear fault codes for very little money.

Can anyone link me to one that definitely works?

I stuck a new down pipe and cat on my car before my mot and mine was through the roof also, guy said since it was new it had to be warmed up first so he revd it like hell then it passed, try changing your oil, also lambda sensors, like bill says tho, get vag plugged into the car and you will find out the problem

I'm an MOT Tester by trade, this didn't work, the readings never changed, even after 3 minutes at 4500rpm, that will get pretty much anything through. Lambda sensor was my first thought to be honest. I'll throw a CTS and stat in it tomorrow and wait for a vag.com to arrive.

 

[747_727]

As far as I know they all work for reading and clearing fault codes but you can't change settings without the proper lead. There are some Chinese leads that will save settings I know as I have one but its a bit hit and miss getting one that will do everything.

 

[Bigjohn84]

Your an mot tester by trade but you no nothing about vagcom that's abit strange, and yes the emmisons did change I get my mot from the same place all the time, he said since its a new cat on the car and the car wasn't warmed up the temperature then it would fail the emissions,once he revd the car a few times till the cat got hot enough the emmisons were bang on.

Just type VCDS in eBay and there's one for £6, you can only do so much with these and you can't change any setting or anything like that, £400 for the proper software and lead.

 

[Mord]

Your an mot tester by trade but you no nothing about vagcom that's abit strange, and yes the emmisons did change I get my mot from the same place all the time, he said since its a new cat on the car and the car wasn't warmed up the temperature then it would fail the emissions,once he revd the car a few times till the cat got hot enough the emmisons were bang on..

Yeah, it works with most cars, but not mine. I know plenty about VAG-COM, I just don't own one! I have 2 snap-on units, a little eobd code reader and my laptop, none of which will talk to the car! Reluctant to spend out if it won't communicate either, £10 for a cheapo vag-lite compatible lead isn't the issue, it's all the arsing about if it doesn't work, hence asking for feedback about decent ones... I need the damn thing on the road!

 

[Bigjohn84]

Lol that lead should work my mate had the same problem but now he thinks its the ecu. Something is wrong with that

AmD Stage 1 Map, Forge 007 DV, CDA Induction Kit, GT80 Milltek Sports Cat Back, 40mm Springs All Round

 

[DrewCole]

I had similar issues when I bought mine, first things I did was stop and buy a temp sensor and thermostat on the way home and change them along with a coolant flush.

Temp became steady at 90 when driving rather than dropping, quite a common issue on these cars it seems.

I also picked up a OBD2 code reader from eBay which, although isn't VAG-COM did give me enough information to point in the right direction and allows me to turn off any fault lights if they come on from my tinkering!

 

[Mord]

So, an update for anyone with the same issue.

Turns out I did have 2 issue. I replaced the stat and CTS, that fixed the temp gauge, but did absolutely nothing for the emissions.

I found a local garage with VAG-COM, which talked to it first go, the main fault was the Lambda sensor. I replaced this, and with a good hard thrash up the bypass, it sailed through.

Now to sort the annoying low washer bottle warning light...

 

[DrewCole]

So, an update for anyone with the same issue.

Turns out I did have 2 issue. I replaced the stat and CTS, that fixed the temp gauge, but did absolutely nothing for the emissions.

I found a local garage with VAG-COM, which talked to it first go, the main fault was the Lambda sensor. I replaced this, and with a good hard thrash up the bypass, it sailed through.

Now to sort the annoying low washer bottle warning light...

Good work!

Do you mean the coolant header tank or screen wash bottle?

 

[Mord]

Screenwash.

I'll probably just bridge the wires, seems to work by passing a current through the screenwash going by the prongs on the sensor.

Not like its hard to tell you've run out of screenwash, annoying dash light is overkill really...