U-Bend delete, O2 simulator an option?

[JstCloseUrEyes]

Alrighty, I think I am finally going to do a U Bend delete, and, just as luck would have it, I am able to get my friends (one who can weld, and the other with a lift) to help me...

Now, the O2 sensor is the biggest pain, but, would using an O2 Simulator be a reasonable alternative to having a bung welded in, and having the sensor hang sideways?

The part can be seen here:
http://www.pfyc.com/store/merchant.m...ory_Code=GPEXH

So folks, would this work in this application, and still keep the car emissions legal for the time being?

[GTP Dad]

Using an O2 sim is an acceptable option. It will keep the car running correctly without a light but if you have an inspection system that checks the components you will need the actual sensor. A lot of people use the sim and they have no problems with passing emissions but you need to see just how detailed your emissions testing is. If you don't have emissions testing then the sim is just fine.

[BNaylor]

The purpose of the 02 simulator is for off road applications where exhaust mods are causing a DTC to set and turn on the SES light. It is not intended to be a substitute for the rear 02 sensor for the street. The rear 02 sensor is used to fine tune the fuel injection system and determining CAT convertor efficiency so running an 02 simulator may cause a reduction in fuel economy and some emissions readings to be off. You may or may not fail emissions.

It doesn't take much extra work to add the 02 sensor bung to the straight pipe delete. The bung size is 18mm X 1.5mm.

[gprixgtp]

This post had me wondering as well. I plan on the first mod to be the exaust on mine. I am gonna do away with the cat and resonator and the ubend. Am I better off with the O2 sensor or the simulator. I have no emmissions and if need be will keep everything if I ever need it. I am planning the pulley change, computer, rockers, cai. Am I better off using the O2 sim and if so will it be a problem with the OE computer until I do that upgrade. Also what size is the downtube off the engine? Is it already 3" or do I need to increase it as well. I figure I will have 2.5" pipe run. Is it better also to break into the dual pipes closer to the front of the car or keep the pipe run like the OE pipe. And should I run 2.75" pipe to where I split to dual. Oh yeah sorry forgot, it is a 97 GTP.
Thanx as always. John

[jimmyv-21]

i have read on other forums that the o2 sim is really only for drag or offroad and will not give you any performance bonus. you will get lower fuel mileage. if you have a scanning/monitering tool, such as the dhp powertuner, you can moniter your rear and front o2 readings. o2's can be 60% bad before triggering any ses lights. pulling them and cleaning them periodically will keep them working at peak performance. as far as emissions go, you would probably be able to pass fine, but if you dont pass and there is no bung for the o2, you will be in trouble. those who use the sim usually have lots of other mods first.

[graphicassult]

I remember reading the rear o2 sensor has no input into the performance of the cars pcm. The main purpose would be for cat failure detection.

Its also why the o2 sim was created

[BNaylor]

Originally Posted by graphicassult

I remember reading the rear o2 sensor has no input into the performance of the cars pcm. The main purpose would be for cat failure detection.

Its also why the o2 sim was created

I disagree with whatever you read. Under the odb-ii emissions standard in which GM follows the rear 02 sensor serves two purposes. Monitor CAT convertor efficiency and to assist in air/fuel ratio monitoring via the PCM module.

The rear (secondary) oxygen sensor is used for fuel control or to “trim” or correct the output from the front (primary) oxygen sensor. The rear sensor can be used to correct the front sensor for aging, poisoning or deterioration resulting in offset or drift. Some limits are set on the correction by the rear sensor and, when the limits are exceeded, stores a fault code and then illuminates the MIL.

All the 02 simulator does is help overcome this and basically cheats the system.