205 Gti6 Exhaust Emissions

[CaptainK 11]

After all the problems I've had with my 205 GTi6 build (not documented on this forum), I finally get it back looking good and running well.

 

But, take it in for its MOT and it fails on a few things, including its emissions:

 

CO2 is around 4.3 (at idle!), lambda is 0.94, and everything else is hugely high as well, except the "O2" readings which are ok. My garage plumbed the values into a Gas Test Analyser bit of software and their computer shrugged its shoulders and said "Dunno".

 

I've replaced the "green" engine temp sensor and that didn't change it. Also checked the plug on it and the wires and they all look solid. Mine is a 1993 205 and the CAT on it is brand new (opted for a sports cat with the GTi6). The garage also don't thing its the CAT as the readings are WAY too high for it to be the CAT. On thursday its booked in for the other failures and at the same time we are going to be trying another Lambda Probe.

 

A few facts:

Its very obviously running rich as it does pop a little when you let off the throttle. The idle runs smoothly around 950rpm. However, its a pain in the backside to start - you have to turn ignition on, let the fuel pump activate and then stop and then start it, otherwise it won't start - keeps turning over and wants to start but "only just" doesn't. It also has issues around 1700rpm to 2300rpm where if you hold a constant throttle it occasionally "stutters" a little - i.e. cruising at 40mph in 5th gear, or 30mph in 4th etc. If you floor it though, engine speed picks up fine and the stutter immediately goes.

 

So I thought I'd ask you fab people for some advice. What else have I missed? Any ideas? Thanks in advance.

 

EDIT: It also has brand new spark plugs.

Edited July 7, 2008 by CaptainK

[Alastairh 47]

I would be tempted to hold out until the new Lamba sensor fitted and see then.

 

I had similar figures with my brothers old 205 S16, when the lamba gave up.

 

Al

[welshpug 1,657]

Try unplugging the Lambda sensor, see if it affects the way it drives at all.

 

Also check the pipe to the Fuel pressure regulator from the manifold.

[smighall 1]

Start by unplugging the lambda. Also make sure the TPS wires aren't broken.

[James_R 3]

As said lambda sensor

 

and if it still fails just say it's from an J plate 405 Mi16, like any garage would tell the difference, then it counts as a pre-CAT engine, and it's not going to fail, then you can get a De-Cat and flog the "sports" cat off

 

Oh and if they say it's blatently a GTi-6 just say it's using a earlier block, since that's where the engine ages really comes from.

[CaptainK 11]

Also check the pipe to the Fuel pressure regulator from the manifold.

Which pipe is this? Is it under the manifold or on the top? Can a fairly incompetent mechanic (i.e. me) get to it with ease?

[CaptainK 11]

and if it still fails just say it's from an J plate 405 Mi16, like any garage would tell the difference, then it counts as a pre-CAT engine, and it's not going to fail, then you can get a De-Cat and flog the "sports" cat off

Oh don't worry, they are quite happy to give me some leeway on the emissions. But at the moment it is just stupid, and to be honest I *want* it to be running correctly.

 

As for the CAT, I opted for that over a decat as I've done the decat thing on my FTO. I'm trying out sports cats now just to see what they are about.

[James_R 3]

Well it's just a CAT media from a bigger car/high output engine on a smaller engine so it's less restrictive and presto it's called a sports cat.

 

Fuel pressure reg pipe is on the top in the middle of the fuel rail, where the fuel pipes connect to the engine, there's a 7mm or so rubber pipe comes off it and drops straight towards the slam panel, that's the vac take off for the FPR.

[Garry 1]

I would say it was the lambda too, the reading of 0.94 is a bit of a sign, it should be 1 if all was well.

Mine is sky high with the emissions too (before SC) changing the CTS helped alot, but as you say, you have tried that.

[CaptainK 11]

Well it's just a CAT media from a bigger car/high output engine on a smaller engine so it's less restrictive and presto it's called a sports cat.

Normal CATs are 400 cells per square inch. Mine is a 200 cell per square inch made from stainless steel so it looks nice and matches the rest of my exhaust. 8) Just trying to do my bit for the environment. My original idea was to do a rolling road comparison between normal CAT, sports CAT and a decat all on the same day. Just out of interest really. But due to technical problems with my 205 I seriously have no money at all. So can't afford to do this. Actually, I can't afford to buy a decat. So it'll stay for now and maybe later I'll go decat.

 

Fuel pressure reg pipe is on the top in the middle of the fuel rail, where the fuel pipes connect to the engine, there's a 7mm or so rubber pipe comes off it and drops straight towards the slam panel, that's the vac take off for the FPR.

Is that the one that joins the manifold at the point above the Peugeot logo here?:

Piccy of my old engine bay before engine was rebuilt

[taylorspug 7]

Yes.

[CaptainK 11]

I would say it was the lambda too, the reading of 0.94 is a bit of a sign, it should be 1 if all was well.

Thats the conclusion that my local garage and I came too as the max tolerance I believe on a lambda probe is +/- 0.02. Mine is at -0.06 so as you say its an indication its not well.

 

Role on tomorrow evening when I get raped by my Peugeot dealership for a new lamdba probe. Funnily, they had 3 lambda probes for my year of 306 engine - and happily the specific probe for the GTi6 engine is actually the cheapest of them all. About half the cost of the other 306 lambda probes. Result !

[CaptainK 11]

Yes.

Thanks, I'll check it later. But I doubt it'll have any problems.

 

On a side note - I'd forgotten how manky it looked before the rebuild.

[maxi 36 1 Cars]

That pic of the bay before the rebuild looks like its been fished out of a river!

 

Usual suspects as have been suggested, although I do have one thought which may have some relevance...... How aggressive are those cams you put in it? These will make a difference with a std ECU to emissions. Also, it will be better once the engine is actually run in. Hope you get to the bottom of the problem.

 

Maxi

[CaptainK 11]

That pic of the bay before the rebuild looks like its been fished out of a river!

I'm not allowed to comment on that.

 

 

Usual suspects as have been suggested, although I do have one thought which may have some relevance...... How aggressive are those cams you put in it? These will make a difference with a std ECU to emissions. Also, it will be better once the engine is actually run in. Hope you get to the bottom of the problem.

Don't know about the Cams. They were sold to me by "Fletch", but we don't know what they are - just a set of Catcams. They're on normal GTi6 timing at the moment. Spoke to my garage about this and they said that the agressive cams wouldn't give such very high emissions that its getting.

 

The engine is now fairly run in - has done just over 1000 miles since rebuild.

[CaptainK 11]

Hurrah! MOT passed. My current lambda was indeed absolutely goosed. When the new lambda went in, the emissions dropped right down.

 

They also found that the rear brakes were binding slightly. Combine that with dodgy lambda engine running and I think I might have found why my 205 GTi6 hasn't been performing as well as I thought it might be.