Mr. C4

Fellows,

I just got a cat by-pass pipe 4 free and will test it tomorrow. Installing the by-pass pipe leaves me with just one silencer since I alrady have the cup pipe fitted.

What I dont know is if my car is fitted with a lambda probe? Anyone? The by-pass pipe came with what looks lika probe of some kind, attached to a cable.

Basically I dont know if non cat cars still had a lambda probe or I will just leave the probe in and cut the wires since it looks as if it will be hell to get the prove undone and plugged.

Any advise appreciated!

Ciao,

Johannes E.

Christer

Johannes

If the bypass came with a lambda probe then just plug it in and go. Do not under any circumstances just cut the wires. If the DME does not get an input from the lambda sensor then the car will be in limp mode. You can get some code plugs for the DME to tell it to disregard the lambda input using a different map, but I would in that case recommend that you install an altitiude sensor so that at least you have that input in case there are any hills where you are (in fact, I am not entirely sure whether you absolutely need the alt sensor or whether it is 'a good thing to have'). The latter IMHO is not a DIY job, but if you have the lambda just plug it in.

Hope that helps.

Jeff Curtis

I'll second that! ...Johannes, does your car have an O2 sensor now??

If it does, follow Christer's advice...or you'll be sorry. <img border="0" title="" alt="[Eek!]" src="eek.gif" />

Bill Gregory

The 964 engine was Porsche's first "world" engine, the same for all markets. It should have an O2 lambda sensor.

Mr. C4

Guys,

Ended up welding the original muffler today instead of fitting the by-pass pipe! The by-pass did not have the brackets welded on that holds the heatshields so I figured it was better to leave it!

Had a good look around said muffler (behind the drivers side rear wheel) and it appears that my car has no cat nor lambda sensor!! I am not surprised since it is middle east spec. and environment issues are not high on the agenda here and has never been.

Bye 4 now,

Johannes E.

Toon

RU allowed to by-pass the cat?

Here in the Netherlands you would fail the APK (MOT equivalent for the Netherlands) and are not allowed to drive.

Or would you install the cat just to pass this MOT and then get the by-pass in agian?

DaveK

In the UK it depends on the age of the car. Cars newer than a certain age must have a cat but I'm not sure what the date is ('92?). Older cars don't need one, even if they had one from new - they just get measured against non-cat values. I removed mine and had no problems.

Dave
90 C4

Andy Roe

Dave,

Even though in the UK it wasn't law that cars needed to have a Cat, 964's were still delivered with them. Even if the Cat has been removed at somepoint, you still need the O2/Lambada Sensor.

Andy

DaveK

True - but you don't necessarily need the O2 sensor. I had mine blanked out and an altitude sensor put in its place. The DME can actually me told there is no O2 sensor fitted (but there's more to that than just not attaching one). Before I had a cat bypass / chip fitted I had some running problems (idle hunting) and the O2 sensor was suspected. My O2 sensor was disconnected and the DME told it didn't have an O2 sensor to see if this improved things - although I was told not to run it like this for long in case the Cat ignited. Not the same as disconnecting it when the DME still thinks it's there obviously.

When I had the car chipped by JZM I was told that the O2 sensor placed restriction on the fuelling so that the cat could not ignite, and greater benefits would be had with the chip if I removed it. It was replaced with an altitude sensor.

Don't know if what I was told was true - and didn't notice a huge difference with the chip anyway.

Dave
90 C4

Christer

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Andy Roe:
<strong>Dave,

Even though in the UK it wasn't law that cars needed to have a Cat, 964's were still delivered with them. Even if the Cat has been removed at somepoint, you still need the O2/Lambada Sensor.

Andy</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Andy pre-93 cars do not need to have a CAT installed regardless of whether one was supplied with the car.

As Dave rightly says, you do not need an O2 lambda sensor if you use the code plugs to tell the DME to use a different fuel map and not to expect an O2 lambda input. The code plugs effectively jumper pins on the DME as I understand it but guess there is more to it than that. You can always speak to JZM for a full explanation.

Andy Roe

I stand corrected!!!

Andy Roe

I stand corrected!!!

Christer

Twice? <img border="0" title="" alt="[Wink]" src="wink.gif" />