BMS JB4 CEL Delete - Please Confirm

[evilb]

Hi All --

I've read some conflicting information on the forums about this, so I wanted to pose this question to everyone and get some real-world feedback.

I've read essentially two competing theories about the BMS JB4 'code delete' feature, in terms of eliminating the CEL when using catless downpipes --


1 - Oxygen sensor codes cannot be selectively cleared, and ALL CEL codes are cleared at a scheduled interval

2 - Only oxygen sensor related codes that would be the result of catless downpipes are automatically cleared


Clearly there is potentially a huge issue if #1 is true: You throw some major codes (not O2 sensor related) that may severely impact engine functionality, and the BMS unit automatically clears them before you have any warning.

Can someone please verify/confirm which is true, and what the risk mitigation methods would be if, in fact, ALL codes are automatically cleared before a dash light is displayed?

Many thanks,
Brad

[Mike@N54Tuning.com]

Real fault codes still throw a light in dash and a limp mode if the DME calls for it. If you are not comfortable with the idea of a tuner deleting codes I'd suggest you not turn on that feature.

Mike

[evilb]

Originally Posted by Mike@N54Tuning.com

Real fault codes still throw a light in dash and a limp mode if the DME calls for it. If you are not comfortable with the idea of a tuner deleting codes I'd suggest you not turn on that feature.

Mike

This is exactly the response I was looking for, Mike. Thanks

[13M5F10]

Originally Posted by evilb

This is exactly the response I was looking for, Mike. Thanks

You are correct with you assumption that it clears all codes at standard intervals. One of the main reasons I went bench flash

[evilb]

Is it also correct to assume that if someone was going to get an emissions test, they could potentially reset to the stock map in the parking lot and clear the error codes prior to them hooking up the diagnostics tool verifying O2 sensor functionality/'readiness'? I realize it would not pass a sniffer test, but at that point should pass an OBD2 diagnostics test, correct?

Thanks
Brad

[13M5F10]

Originally Posted by evilb

Is it also correct to assume that if someone was going to get an emissions test, they could potentially reset to the stock map in the parking lot and clear the error codes prior to them hooking up the diagnostics tool verifying O2 sensor functionality/'readiness'? I realize it would not pass a sniffer test, but at that point should pass an OBD2 diagnostics test, correct?

Thanks
Brad

I don't believe so because when you reset the codes on the DMe will not be in ready state. That's why they recommend you go and drive the 60-100
Miles after a CEL reset. In your case that CeL will return by then and require another reset.

[allmotor_2000]

Originally Posted by 13M5F10

You are correct with you assumption that it clears all codes at standard intervals. One of the main reasons I went bench flash

Let's hope the bench flash isn't randomly turning off CEL triggers

[mike@x-ph.com]

Originally Posted by 13M5F10

You are correct with you assumption that it clears all codes at standard intervals. One of the main reasons I went bench flash

It will still throw a CEL

If you get a CEL, just turn off that feature and read the code

[13M5F10]

Originally Posted by mike@x-ph.com

It will still throw a CEL

If you get a CEL, just turn off that feature and read the code

Are you taking about the flash? Or Jb4

Both paths will still throw a CEL if one is present.

Bench flash disables the loop test on the rear O2s so the CEL will not come on for that. That's what I was saying. Where as Jb4 just clears it but he CeL will still exist.

[A Frankfurt]

Both paths (JB4 and ECU flash) are designed to clear the cat efficiency codes created by the removal of the catalytic convertor.
Your normal function of the "check engine light" will still work normal.
To test it, un-plug a engine sensor and turn the ignition on...a CEL will be stored for that specific sensor.

This feature will keep the Oxygen Sensor and Cat efficiency in a "not ready" state which will not be ready for state emission testing.

A short test drive after installing the factory cats will correct this.
Smog vehicle, and put performance parts back on.

[13M5F10]

Originally Posted by A Frankfurt

Both paths (JB4 and ECU flash) are designed to clear the cat efficiency codes created by the removal of the catalytic convertor.
Your normal function of the "check engine light" will still work normal.
To test it, un-plug a engine sensor and turn the ignition on...a CEL will be stored for that specific sensor.

This feature will keep the Oxygen Sensor and Cat efficiency in a "not ready" state which will not be ready for state emission testing.

A short test drive after installing the factory cats will correct this.
Smog vehicle, and put performance parts back on.

A tuner has the a ability to disable that loop test for the O2 sensor specially. The JB4 simply auto clears the codes continuously.

The difference? The tuner specifically targets and disables the rear O2 loop test therefore all other CeLs will show. You will also be able to pass emissions.

JB4 targets all CELs through the autoclear feature. This is nice if you want to avoid the CeL from illuminating your dash, however, you will not pass emissions as the loop tests are still there and your car will continue to trigger the CEL for it and JB4 just clears it.