JB4 vs DP fix debate

[crystaweizen]

i got done bolting on my new catback exhaust yesterday. sounds amazing! next step is down pipes. im debating doing just the DP fix or going JB4. is there a big fuel economy increase with just a DP fix? or will the DP fix and downpipes make me lose mileage? if there is a loss in economy then i probably will just go the JB4 route and get maximum power from the exhaust. but the downside to that is the longevity of my vehicle...

[crystaweizen]

and im asking about the economy because i imagine if you take away resistance from the exhaust and help it breathe better then you would see an increase in mileage. and i know the o2 sensors switching keeps the fuel system at optimum performace/efficiency

[My135]

They are 2 different things. JB4 will increase HP & TQ & suppress error codes but won't help pass emission. You definitely need the DP fix to pass.

[1speedbike]

The above is correct. You have to have the DP fix to pass emissions, but the DP fix isn't necessary for just running the DPs if you can live with an error code. The JB4 will be constantly clearing the codes so there will never be a "ready" signal or whatever that is necessary for the emissions test.

What are you running, otherwise? A JB3? You don't mention if you're just upgrading the exhaust on a stock car or if your car is already tuned. I think the upgrade from JB3 to JB4 is honestly worth it even without the auto-clearing of the codes for the newer features, better smoothness, and improved safety overall.

Without the cats you might get slightly better mileage, but the effect really won't be life-changing or anything like that. There will still be some backpressure on the turbos, even though it will be slightly less, and your fuel pumps are still going to pump more or less the same amount of fuel into the engine. At the power levels you're running your engine at 98% of the time, even the stock exhaust is plenty to handle the escaping gasses and there's really no benefit to upgrading for gas mileage alone. Upgrading the exhaust on a stock car really won't net you much gains. Maybe 20-30 horses to the wheels if you upgrade the entire exhaust with a quality system. Again, I don't know if that's what you're doing since it wasn't clear in the post haha.

[crystaweizen]

Originally Posted by 1speedbike

The above is correct. You have to have the DP fix to pass emissions, but the DP fix isn't necessary for just running the DPs if you can live with an error code. The JB4 will be constantly clearing the codes so there will never be a "ready" signal or whatever that is necessary for the emissions test.

What are you running, otherwise? A JB3? You don't mention if you're just upgrading the exhaust on a stock car or if your car is already tuned. I think the upgrade from JB3 to JB4 is honestly worth it even without the auto-clearing of the codes for the newer features, better smoothness, and improved safety overall.

Without the cats you might get slightly better mileage, but the effect really won't be life-changing or anything like that. There will still be some backpressure on the turbos, even though it will be slightly less, and your fuel pumps are still going to pump more or less the same amount of fuel into the engine. At the power levels you're running your engine at 98% of the time, even the stock exhaust is plenty to handle the escaping gasses and there's really no benefit to upgrading for gas mileage alone. Upgrading the exhaust on a stock car really won't net you much gains. Maybe 20-30 horses to the wheels if you upgrade the entire exhaust with a quality system. Again, I don't know if that's what you're doing since it wasn't clear in the post haha.

my car isnt tuned im doing the bolt ons for now and then when i do the last bolt on which will be the intercooler i will run a tuner. im only worried about losing economy because the DP fix (which is also part of the JB4 tuner) will remove the factory o2 data to the computer and will erase the code. im not sure but i think that the computer would default and make it run rich instead of lean as a self preservation. this is my daily and id love to have the extra power but with out sacrificing the economy. ill do it eventually but if the change in economy is drastic then i will just wait

[crystaweizen]

Originally Posted by My135

They are 2 different things. JB4 will increase HP & TQ & suppress error codes but won't help pass emission. You definitely need the DP fix to pass.

The JB4 tuning system includes this functionality built in so a DPFIX is not required if you are already running a JB4 Performance Tuner. im not worried about emissions either but im sure eventually my county will require it

[SteveAZ]

Originally Posted by crystaweizen

my car isnt tuned im doing the bolt ons for now and then when i do the last bolt on which will be the intercooler i will run a tuner. im only worried about losing economy because the DP fix (which is also part of the JB4 tuner) will remove the factory o2 data to the computer and will erase the code. im not sure but i think that the computer would default and make it run rich instead of lean as a self preservation. this is my daily and id love to have the extra power but with out sacrificing the economy. ill do it eventually but if the change in economy is drastic then i will just wait

I have done both and I regularily do logs on my car...this definitely was not the case. I believe you're incorrect. There are 2 sets of o2 sensors...one before the cats, and one after. The one before takes your o2 readings and feeds it back to the computer for adjustments...the one after verifies your cats are functioning properly and sends that data to the DME. It is that data that is intercepted by the DP fix or cleared by the JB4.

[crystaweizen]

Originally Posted by SteveAZ

I have done both and I regularily do logs on my car...this definitely was not the case. I believe you're incorrect. There are 2 sets of o2 sensors...one before the cats, and one after. The one before takes your o2 readings and feeds it back to the computer for adjustments...the one after verifies your cats are functioning properly and sends that data to the DME. It is that data that is intercepted by the DP fix or cleared by the JB4.

that was just my guess i still havent had an answer put in stone for me yet. does going catless and doing JB4 or DP fix reduce fuel economy? and if it does then should i just go dp fix and keep it streetable, or should i do the JB4

[TT1351]

The DP fix will not affect economy as it only tricks the ECU into thinking that the o2 sensors are within normal range. The JB4 can affect economy mainly because once installed you can't help but mash the loud pedal. I have catted DP's which still throw a code. The JB4 on autoclear keeps the light off, but as stated in a previous post the ECU will not have enough history to be ready for the emissions test. So you can use the DP fix on its own with non OEM down pipes, or in conjunction with the JB4, with autoclear off, and the DP fix installed and fooling the ECU. In order to get enough history data in the ECU you can't run the autoclear before being tested on an N54 engine. Fran

[SteveAZ]

Personally, my opinion is you're over thinking it. If you're looking for performance, fuel economy can't be a primary concern, it's contradictory in nature. More air flow=more fuel and both equal more power. JB4 will allow you to run economically and give you the best of both worlds by changing maps on the fly. I run both the JB4 and DP fix because in order to pass emissions (OBDII) you've got to have a DP fix, I also don't like running auto code clearing. I was having issues with high trims and running lean (before coding and then flashing) and I can tell you for certain I didn't notice higher fuel consumption than normal after either implementation. Now, that said...normal for me is about 17-18mpg but I'm running e85 and pushing over 400hp to the wheels. Gas mileage obviously isn't my biggest concern but e85 is also $.80 cheaper a gallon.

[JZWBMW]

There other options too, I can turn off the rear 02 sensor faults so you do not get a cel and then you can also have it so it reaches ready status, but does not throw a code or you can just flash back to stock and go to the dealer or whatever you want to do.

I was able to get 416whp on E30 fuel and will soon be attempting to run full on E85 with a better flowing fuel pump.

I was personally able to get slighly better power with the true ecu tune than I was with JB4 set up on my car,

JZW

[My135]

I've both & did not notice any drop in mpg. I did not activate JB4 code suppression feature since I want the ECU to log all error code. The DP fix will send the correct emission signal such that it won't trigger any emission codes

[crystaweizen]

Originally Posted by My135

I've both & did not notice any drop in mpg. I did not activate JB4 code suppression feature since I want the ECU to log all error code. The DP fix will send the correct emission signal such that it won't trigger any emission codes

nice thank you that is what i wanted to know. ive been looking at the BMS downpipes theyre really cheap and have close to if not the same gains as their competitors at double the price. now with the code suppression does it supress all codes? or simply prevent the check engine light? id like to be able to check from time to time to see if anything weird is going on with other systems if they decide to throw an error code

[Elsabor67]

Originally Posted by crystaweizen

nice thank you that is what i wanted to know. ive been looking at the BMS downpipes theyre really cheap and have close to if not the same gains as their competitors at double the price. now with the code suppression does it supress all codes? or simply prevent the check engine light? id like to be able to check from time to time to see if anything weird is going on with other systems if they decide to throw an error code

I have the JB4G5 with the external Dp fix. Before that I had the JB4 with the same DP fix. I kept the autoclear off since I also wanted to know what was wrong with something if it did go wrong.

With the codes, I think it does but am not sure.

[crystaweizen]

Originally Posted by Elsabor67

I have the JB4G5 with the external Dp fix. Before that I had the JB4 with the same DP fix. I kept the autoclear off since I also wanted to know what was wrong with something if it did go wrong.

With the codes, I think it does but am not sure.

i can live with the light as long as i know the car is running to its full potential and i will just keep the CT hooked up to read codes every now and then set from have the tuner going

[JZWBMW]

If you have the cel, then you do not know if its for something else too, that would be a problem in my eyes. You can have the cel turned off so you do not get a cel for the rear 02 sensors. That would be a much better option in my opinion.

I just put the catless dp on my own car and I did not want to have any cel's on the car so I went into the file and changed the code so it does not throw the cel and this way I will know if I get a cel, its related to something else.

JZW

[crystaweizen]

Originally Posted by JZWBMW

If you have the cel, then you do not know if its for something else too, that would be a problem in my eyes. You can have the cel turned off so you do not get a cel for the rear 02 sensors. That would be a much better option in my opinion.

I just put the catless dp on my own car and I did not want to have any cel's on the car so I went into the file and changed the code so it does not throw the cel and this way I will know if I get a cel, its related to something else.

JZW

dont quote me but i believe the code suppression is to keep all codes from setting the CEL. im not exactly sure though. but that would be the reason i would keep the can tool hooked up to te DRL so after i push it ard i can read for codes and determine if there are any bad ones

[JZWBMW]

If you were to get my tune, the cel for the 02 sensors would not come in at all, but the rest of the cel codes would continue to work like normal so if you had an additional problem, you would know about it.

I do not like the idea of having any codes and if I do get one, I can read it and find out what it is and then clear it out. I can set the tune up any way you want it and you will be able to swap back and forth between different tunes and back to stock of course and you can read and clear codes at any time.

This way you can run with no cats, Ethanol fuel or whatever you want, different rev limits, speed limit removal and all that good stuff.

JZW

[Mike@N54Tuning.com]

Originally Posted by crystaweizen

i got done bolting on my new catback exhaust yesterday. sounds amazing! next step is down pipes. im debating doing just the DP fix or going JB4. is there a big fuel economy increase with just a DP fix? or will the DP fix and downpipes make me lose mileage? if there is a loss in economy then i probably will just go the JB4 route and get maximum power from the exhaust. but the downside to that is the longevity of my vehicle...

A lot has been covered in the thread already but the JB4 clears the o2 codes by auto clearing them, while the DP fix actually blocks them from occuring. Neither the JB4 or DP fix alter fuel economy, but usually the first tank after installing the JB4 goes faster as you are so excited by the added power that you floor the car more often.

I wouldn't really worry about longevity. The JB tunes have been around for a long time and there are many tuned cars with 100,000 miles on them with no real issues, or atleast no more issues then stock high mileage cars. The N54 engine is pretty rock solid.

Mike

[crystaweizen]

Originally Posted by Mike@N54Tuning.com

A lot has been covered in the thread already but the JB4 clears the o2 codes by auto clearing them, while the DP fix actually blocks them from occuring. Neither the JB4 or DP fix alter fuel economy, but usually the first tank after installing the JB4 goes faster as you are so excited by the added power that you floor the car more often.

I wouldn't really worry about longevity. The JB tunes have been around for a long time and there are many tuned cars with 100,000 miles on them with no real issues, or atleast no more issues then stock high mileage cars. The N54 engine is pretty rock solid.

Mike

nice sounds great. ill be getting a cheap car to daily before i go the tuner route with my car. i know ill get that and the downpipes evntually i just want to play it safe

[crystaweizen]

Originally Posted by Mike@N54Tuning.com

A lot has been covered in the thread already but the JB4 clears the o2 codes by auto clearing them, while the DP fix actually blocks them from occuring. Neither the JB4 or DP fix alter fuel economy, but usually the first tank after installing the JB4 goes faster as you are so excited by the added power that you floor the car more often.

I wouldn't really worry about longevity. The JB tunes have been around for a long time and there are many tuned cars with 100,000 miles on them with no real issues, or atleast no more issues then stock high mileage cars. The N54 engine is pretty rock solid.

Mike

ok cobbv3 or JB4....

[zakyzozo]

Jb4