Hello (my first post) ...

I have a 98 VP, and I removed cats, redid exhaust, added performance muffler, and 3.5x18 resonator tips.

Any advice on defeating the O2 sensor issue -- it runs and sound GREAT, but it is supper rich, and as my mechanic friend says, "she dumps fuel like a boat, but what a sound" ...

 

This may be of interest:
<title>O2 Simulator Mini Cat Cel Fix best oxygen sensor simulator made.

 

Dude, ... Thnx . !


Lance

 

You need to reinstall the cats. They don't effect exhaust or sound but have a big impact on the engine performance. Without them the ECU has no idea what the engine is doing.
Not only are you wasting fuel but quite possibly causing some serious damage with the excess fueling
If you are concerned about performance maybe try Nameless Cat free flow and you get back monitoring. Without the info from the Cats your probably losing horsepower and definitely efficiency.

 

Thnx, ... but I have to ask, as I have several mechanics (certified / good ones) tell me that the issue is the reading of the "downwind" O2 sensors, and a person can use a few different means to change the reading on the downwind, ... either capacitors, or even 'mini-defeaters that actually have a lil chamber w/ a rhodium element to make the change ...?

Thnx Agin,

Lance

 

The way I understand it, those simulators will provide the ECU with a mid range voltage indicating the missing cat is performing efficiently.

But Vern has a point, in that high flow cats will not reduce power noticeably.

 

I don't think I want to participate in this discussion. The law regarding pollution devices mentions disabling, deleting or CAUSING the deletion or disabling of any device................

I don't want some gov't bureaucrat accusing me of some lawlessness because I typed ways to do so. The EPA is a bunch of control freaks that look for excuses to make examples out of minor infractions.

Not saying that they read this forum but................I don't trust gov't.

I think you are talking about your 'off-road' race car anyway, RIGHT?

bob

 

That's what it says in the ad for the device, not for road use. Just because there is no state testing doesn't mean it's okay. A high flow cat is a better choice.

 

I'll start off by saying I don't have much experience with engine tuning. However, in the threads I've read here about engine/performance mods, the o2 sensors are the last line of defense for the ECU. So, if the other sensors are reading improperly, the ECU will run off o2 measurements to prevent the engine from blowing up. Maybe someone who knows better can verify this. I wouldn't want to be sending a simulated signal for something which maintains safe operation...

I hate to be that guy, but sometimes "do it right" is the only answer, as others have mentioned already.

 

Some don't condone it but if you aren't planning on adding cats............you could try distancing your downstream (rearmost) sensors from the exhaust stream via O2 bung spacers (aka spark plug non-foulers, you can buy at almost any auto store). Its a trick thats been used for years when bypassing Cats. Cheap and easy to try.
Are you getting "cat efficiency" codes or does it just stink/smell? Have you (or mechanic) observed your fuel trims? Were you having problems with the Cats prior to mods?

 

You can probably adjust it to run leaner. Fairly easy to be too lean in some situations, without knowing, though.

 

Maybe wrong, but I thought the '98s only had upstream co2 sensors!

If dumping too much fuel into the engine check the ECT sensor.

 

The 98' XJ8 & XJR had downstream 02 sensors as well. The only difference the 98' downstream didn't have was a heater circuit and therefore was a 2 pin connector. The upstream did have a heater circuit.

 

US cars 1996-present require an upstream and downstream O2 sensor for OBDII compliance. It is possible to have your ECU re-programmed to Euro2 spec which would only contain upstream sensors, like andrew is referring to.

 

Okay, couple of things ...

I didn't "choose it" i shouldn't have said "removed them" cause I bought it from a North Carolina Junkyard, with Cats already removed, and when I went to my local SC Junk Yards, they told me don't need them here in SC -- so thanx for the heads up, cause I never even considered legality issues ...

I live in SC - No Emission Testing - So I left cats off / Great sound, but lack of back pressure killed bottom end, until I added Comp Mufflers to increase it.

Thnx for alll the great advice though
Lance

 

Thnx, wasn't my intent to be off-point or illegal ...