[blumango]

Hi,

This is weird. I have been running on an AR catless DP for over 2 months now on my BMW N55 E92 without any check engine light issues for 1 month without a tune or O2 spacer and 1 month with a tuning box without DP fix or O2 sensor....I know DME will retard power if they detect something is not right with the O2 sensor, which usually occurs with catless DPs....in this case, should I still be concerned? Should I still buy the DP fix anyway?

[ksalih]

Originally Posted by blumango

Hi,

This is weird. I have been running on an AR catless DP for over 2 months now on my BMW N55 E92 without any check engine light issues for 1 month without a tune or O2 spacer and 1 month with a tuning box without DP fix or O2 sensor....I know DME will retard power if they detect something is not right with the O2 sensor, which usually occurs with catless DPs....in this case, should I still be concerned? Should I still buy the DP fix anyway?

The DP fix from what I understand just hides the CEL lights.. Maybe somebody can correct me if I'm wrong, but since you aren't getting any...I wouldn't until you do.

[07bmw335iguy]

Is that all dp fix does? I drove my s2000 w/ check engine light on for years. I wanna install my dp's this weekend but havent got my dp fix yet. So if I install my dp's it wont effect anything except the check engine light?

[bootay]

Tune DP Fixes tend to be code clearing only. That means you won't see a CEL, but you also won't get readiness set for states that do inspections from your OBDII port (vs. visual).

For example, JB4/Cobb can clear the codes automatically, but that clears ALL codes and I don't like that as a general practice. So I put in the BMS DP Fix, a small box that handles readiness being set correctly and prevents the DP CEL from occuring (so I don't have to set auto-clear codes).

I believe the Procede has a setting you can play with, tweak a bit, and get something similar done, but honestly don't know much about it.

[07bmw335iguy]

Ok I gotcha, I always thought the tuners manipulated the computer somehow, didnt realize all they did was keep the cel from coming on. Looks like I'm going to go ahead and install my dp's early then

[Gugs]

Originally Posted by 07bmw335iguy

Ok I gotcha, I always thought the tuners manipulated the computer somehow, didnt realize all they did was keep the cel from coming on. Looks like I'm going to go ahead and install my dp's early then

They do. Poster above is incorrect. And as per Terry it's better to Remove the down pipe fix rather than to just leave it in as the Jb4 does a better job. The dpfix is usually just for inspection with jb4 disabled and should be removed after.

[bootay]

Originally Posted by Gugs

They do. Poster above is incorrect. And as per Terry it's better to Remove the down pipe fix rather than to just leave it in as the Jb4 does a better job. The dpfix is usually just for inspection with jb4 disabled and should be removed after.

JB4 simply clears the DP codes.
You can leave the BMS DPFix in place and turn off code autoclearing and drive, plenty of people have the DPFix installed year round. I haven't seen Terry make any statement that you shouldn't have the DPFix in, feel free to link it.

[Gugs]

You can simply email Terry and have him confirm that is better not to leave it in and that the jb4 serves precedence.

[drm916]

Originally Posted by Gugs

You can simply email Terry and have him confirm that is better not to leave it in and that the jb4 serves precedence.

I have never heard that either. What is the harm in leaving it in all year round? Its not exactly just plug in and then unplug. You have to move around some wires and pins.

[bootay]

Originally Posted by drm916

I have never heard that either. What is the harm in leaving it in all year round? Its not exactly just plug in and then unplug. You have to move around some wires and pins.

As much as the DPFix is talked about, and as many times as Terry has responded about it, that recommendation would be loud and clear (in the install docs for it, on the forums, etc.). But there is no such guidance.

[blumango]

Would this scenario be valid:

The catless downpipe flow is much higher, the O2 sensor senses a quick surge, a value much bigger than the ecu's adaptive value thus it pulls back power for a split second and resumes power as it adapts. This causes a slight restard at the beginning of acceleration when pedal is floored suddenly when car is already cruising. I feel the retarding of power, but just not getting any CEL....I'm hoping the DP fix or O2 spacer will stop this split second of retard since the O2 sensor will not sense the sudden surge....

[Gugs]

No. U get lambada error codes.

[TommyLights]

The reason the DP fix shouldnt be left in all year round is that it gives a false fixed A/F ratio that isnt representative of actual running conditions and why would you want that especially if you are running modified? I read this on the BMS website from Ben (theMyst). Good enough for me.

[cn555ic]

I have procede and I have the 02 modifiers on all the time and it doesn't effect performance. I am not sure of the Jb tune though.

[nitehawk]

OP, it depends on your type of driving...do you do alot of stop and go and little highway?
The o2 monitors may not have a chance to complete depending on how you're driving the car. That's the only thing that makes sense.

You can hook up a BT Tool to see if you have codes / monitors pending.

[blumango]

I do about 60Km highway everyday....

[ajm8127]

From what I understand, suppressing the code with the JB4 does just that, suppresses the code. Now the DPFix actually manipulates the signal coming from the sensor before it makes it to the JB4 or the DME.

It is thought that the DME uses the secondary O2 sensors for A/F closed loop control, particularly the long term fuel trims. That is why it is not recommended to keep the DPFix in place all the time.

[blumango]

Now it drives weird especially with increased boost. In auto and sports mode, car drives fine. But if I use manual mode to down shift 2-3 gears from cruising, with my foot depressing the pedal to part throttle (about 50% throttle), the car will rev up to about 3000rpm then chokes for a brief moment, then rev up slowly to 4000rpm then from 4000rpm a sudden burst of power....but if I lift my foot off completely, down shift, then throttle again (like driving a real manual), it works fine....

[Gugs]

You need a downpipe fix or a tune. You cannot run this car with no cats. Once the car tries to become emission ready status cel will pop and call drive like shit until it resets

You people at like we make this shit up. Like we get money for telling u whats actually wrong.

Put a tune on or dpfix and move on with life.

[blumango]

The thing is I have been driving with the AR design catless downpipe for over 3000km with no CEL...car drives great on increased boost in all modes except manual mode...especially manual mode with sports button activated...So I am asking if this symptom is just the norm for shifting manually or it is due to sudden high flow of the catless DP and if the DP fix will resolve this.