[Quiet Lunatic]

The first thing I installed was the Magnaflow cat-back and the mileage increase was quite impressive. Now I'm noticing that with the headers on my mileage has gone back down. Have any of you guys experienced a decrease in mileage after the headers were put on? Also, is anyone having a hard time keeping the bolts tight that holds the y-pipe to the header? I've had to tighten mine 3 times so far and they weren't just a little loose, they were a lot loose. My suggestion is, if you haven't checked them since the installation then do so soon. I'm either going to double nut the bolts or find some sort of locking nut because I'm sick of tightening them all of the time.

 

[AirJunky]

I haven't done headers on the Nitro, but I do recall my Chevelle headers rattling the nuts loose at the collectors. I just used lock washers & was fine.

 

[Ed B]

The first thing I installed was the Magnaflow cat-back and the mileage increase was quite impressive. Now I'm noticing that with the headers on my mileage has gone back down. Have any of you guys experienced a decrease in mileage after the headers were put on? Also, is anyone having a hard time keeping the bolts tight that holds the y-pipe to the header? I've had to tighten mine 3 times so far and they weren't just a little loose, they were a lot loose. My suggestion is, if you haven't checked them since the installation then do so soon. I'm either going to double nut the bolts or find some sort of locking nut because I'm sick of tightening them all of the time.

Past experience with headers and a little knowledge of new vehicles tells me you may have reduced the temp of your nitro. Most new vehicles have so many sensors which all connect to the on board computer, which reacts to these changes, mixtures, oxy, co2, heat, etc. I would suggest you speak to a good auto tech and I beleive all he will tell you to increase the operating temp of your nitro to reflect the cooling of the motor by adding headers. If you have an 165 thermostat you most likely need to go to a 180 -185. Headers do decrease the operating temp of the motor, so to get back the GPM which you lost, talk to the tech and buy the thermostat and things will be right where you want it. This is what I needed to do on another mopar product. Good luck with the headers I beleive the fix is an easy one.

 

[NitroTech]

I didn't think you had changed out your thermostat. I'm surprised the headers are coming loose at the flange to the y-pipe. Headers are known for loosening at the cylinders heads.

This is a long shot concerning your fuel mileage, but, if the exhaust is pulling in extra air (oxygen) at the flange to the y-pipe because its not sealing properly, the upstream O2 sensor would be seeing the extra oxygen and your fuel trim could be skewed from this. This may be a cause for your drop in fuel mileage.

 

[Pshrynk]

Past experience with headers and a little knowledge of new vehicles tells me you may have reduced the temp of your nitro. Most new vehicles have so many sensors which all connect to the on board computer, which reacts to these changes, mixtures, oxy, co2, heat, etc. I would suggest you speak to a good auto tech and I beleive all he will tell you to increase the operating temp of your nitro to reflect the cooling of the motor by adding headers. If you have an 165 thermostat you most likely need to go to a 180 -185. Headers do decrease the operating temp of the motor, so to get back the GPM which you lost, talk to the tech and buy the thermostat and things will be right where you want it. This is what I needed to do on another mopar product. Good luck with the headers I beleive the fix is an easy one.

Good thought, but mine seems to run at the same temp as before??

I have the exact same set-up, magnaflow catback and JBA headers and my mileage has increased by about 1-2 city and 2-3 highway.

 

[Quiet Lunatic]

I didn't think you had changed out your thermostat. I'm surprised the headers are coming loose at the flange to the y-pipe. Headers are known for loosening at the cylinders heads.

This is a long shot concerning your fuel mileage, but, if the exhaust is pulling in extra air (oxygen) at the flange to the y-pipe because its not sealing properly, the upstream O2 sensor would be seeing the extra oxygen and your fuel trim could be skewed from this. This may be a cause for your drop in fuel mileage.

I haven't changed the thermostat, wasn't even a thought. I was thinking the very same thing about additional air being pulled in at the flange. One way or another I'm going to get those nuts to stay tight. I'd love to know why it appears that I'm the only one having problems keeping the y-pipe tight. I check the headers periodically to make sure they are staying tight and so far they haven't loosened up at all. I went on a short drive yesterday, roughly 240 miles round-trip, all highway miles with the cruise set between 70-75 with nothing in it but my wife and I and I've confirmed that I have lost about 2-3 mpg. The mileage increase that I started getting after I installed the Magnaflow is now gone.

 

[Pshrynk]

Have you taken into account environmental conditions when you checked your mileage numbers? Headwinds, tailwinds, crosswinds, ambient temperatures?

 

[Quiet Lunatic]

Yes, all of that was taken into account. The vehicle definitely lost mpg! Where it is most noticeable is city driving. It went from about 18 to 15.6 mpg.

 

[drjram02]

those darn jba's

i could not agree more bh4l.my milelage definately went down.in addition to that sometimes when i accelerate she acts real slugish for a moment or two. i don't really notice an improvement in overall power either,thaough my main concern was getting the mpg. i'm really bumed. i would have to say i would not recomend these headers to anyone else. maybe the k&n intake will make a diff.:shakehead:

 

[Pshrynk]

^^^^

Something is definitely wrong. Mine increased power and mileage.

Did you reset the ECU by disconnecting the battery??

Is the O2 sensor or it's wiring damaged or is it leaking?

Headers leaking maybe?

 

[Quiet Lunatic]

^^^^

Something is definitely wrong. Mine increased power and mileage.

Did you reset the ECU by disconnecting the battery??

Is the O2 sensor or it's wiring damaged or is it leaking?

Headers leaking maybe?

The battery was disconnected the whole time I was installing the headers and I periodically check them and they are staying tight. Oh well, doesn't matter now anyway because I'm trading it in. I can't taket the sluggish performance anymore not to mention the terrible shifting that I've described in a previous thread. At this point, the only thing I like about the vehicle is the looks and I can't keep a vehicle just for it's looks. Needless to say, the headers and Magnaflow will be coming off and the factory stuff put back on. Luckily I saved the factory exhaust.

 

[Pshrynk]

^^^ Bummer man.

That header and exhaust should take you to that 225hp and 250ft/lbs of torque range. Mine actually hops along pretty good now.

Maybe take it too an independent shop to get a scan done to see if there is a faulty sensor somewhere or something first -- before you throw the baby out with the bathwater?!?!?

 

[Quiet Lunatic]

I've pretty much made my mind up. As soon as I get the deal I am looking for it's history.

 

[Pshrynk]

Aren't ya gonna take that big depreciation hit though???

 

[Quiet Lunatic]

Probably, but time will tell.