4-1 headers question

[FearlessNick]

I put 4-1 headers on my 420a and my MPG went down 10 miles. And I felt no power gain or heard no difference.

My friend told me I should of got 4-2-1 headers.

Is this true? What kind of headers to get power? What size? Is he wrong?

 

[erock1399]

yes get 4-2-1 headers r all about air flow so going from 4-1 is not doing u any good. when u get 4-2-1 then the air flow at diff times and give u that lil ex HP we r all looking for. what type of exhaust do u have?

yes get 4-2-1 headers r all about air flow so going from 4-1 is not doing u any good. when u get 4-2-1 then the air flow at diff times and give u that lil ex HP we r all looking for. what type of exhaust do u have?

 

[FearlessNick]

Idk. It's not a brand header. But I do see them all over the place. Their is a picture of them in my gallery.

 

[bryanwheat]

I think that you are expecting too much from adding the header. Realistically i wouldn't expect to notice anything power wise just changing to a header on a 420a.

 

[Shake_Zulla]

^ This, you would notice a lot more if you got rid of your weakest link... the ecu.

 

[Anubis_4_99]

I put 4-1 headers on my 420a and my MPG went down 10 miles. And I felt no power gain or heard no difference.

My friend told me I should of got 4-2-1 headers.

Is this true? What kind of headers to get power? What size? Is he wrong?

Did you happen to unplug the O2 sensor and not plug it back in? I find it hard to believe that a header alone would net a 10MPG loss.

 

[bullettdsm]

This;

I think that you are expecting too much from adding the header. Realistically i wouldn't expect to notice anything power wise just changing to a header on a 420a.

This;

^ This, you would notice a lot more if you got rid of your weakest link... the ecu.

and this;

Did you happen to unplug the O2 sensor and not plug it back in? I find it hard to believe that a header alone would net a 10MPG loss.

Generally speaking the 4-2-1 will give you more midrange and the 4-1 will give you more top end. But, the difference with our cars is negligible. You can notice it, but very little (and you have to have a very sensitive and well calibrated butt dyno )

MB

 

[FearlessNick]

I know not to expect much from a header change. And yes my o2's are plugged in. I have my cat gutted as well but for the back o2 I have a tricker on it.

And I plan on getting the AFX ECU here pretty soon. It's just around 600 bucks for it. And then as well getting some cams for it. As well as most likely getting some new headers.

And I got around 30 MPG in town. And now I get around 20 in town now after I did the 4-1 header.

 

[Fotowntalon]

When you post a new thread, did you notice the topics that show up that are similar and read those? This 4-1 vs 4-2-1 is beating a dead horse. headers also shouldn't effect gas mileage more than 1-2mpg (if that). I'd almost imagine your driving habbits from trying to notice a power difference have effected gas mileage more than anything, either that or around the time of install something else coincidentally went bad? did you notice your CEL blink at all and run the codes? that could give you a big hint into what is causing the horrid mpg.

 

[FearlessNick]

I did this install a while back ago. About 5-6 months. And I went from getting about 320 miles to a tank to 200. Even with the same driving habits.

And with TapaTalk I tried doing a search and I couldn't find anything. So I decided to post something.

And no CEL or it blinking at all. Hooked up my scanner to it and pulled up the data and went on a drive and everything runs fine. O2 sensors are normal and everything to.

Would these be good?
http://m.autopartswarehouse.com/sku/Mitsubishi/Eclipse/Hedman/Headers/1998/RS/4_Cyl_2-dot-0L/H5636080.html?tlc=Engine+%26+Drivetrain

 

[Shake_Zulla]

I did this install a while back ago. About 5-6 months. And I went from getting about 320 miles to a tank to 200. Even with the same driving habits.

And with TapaTalk I tried doing a search and I couldn't find anything. So I decided to post something.

And no CEL or it blinking at all. Hooked up my scanner to it and pulled up the data and went on a drive and everything runs fine. O2 sensors are normal and everything to.

Would these be good?
Hedman 36080 Headers | Auto Parts Warehouse

Headers wouldn't effect your mpg that much. I honestly do not believe that at this point in your build you will be able to tell the difference between a 4-1 and a 4-2-1 (some will disagree ). My guess is there is something else wrong with your car that could be robbing your power. My suggestion is to keep your car under 4000 rpms and record your mpg for a tank so you can loose the "about" portions of your statements. Also try going back to stock and get a acurate mpg calculation. Just trying to save you some money if there is something else wrong you know?

 

[FearlessNick]

I shift at about 3000 3500 RPM's all the time. And I reset my trip meter every full tank. And I get 200 to 210 miles to a tank when I got 300 to 320.

And I noticed this change after I changed out the headers. Even before I did my rebuild. Did the rebuild hoping I would get a change in MPG. And nope still the same.

 

[91stocker]

It doesnt matter.

Mitsubishi Eclipse RS - Report - Import Tuner Magazine

 

[Shake_Zulla]

It doesnt matter.

Mitsubishi Eclipse RS - Report - Import Tuner Magazine

I think the OP is wondering more about his MPG or something robbing him of power.

I know not to expect much from a header change. And yes my o2's are plugged in. I have my cat gutted as well but for the back o2 I have a tricker on it.

And I plan on getting the AFX ECU here pretty soon. It's just around 600 bucks for it. And then as well getting some cams for it. As well as most likely getting some new headers.

And I got around 30 MPG in town. And now I get around 20 in town now after I did the 4-1 header.

I did miss this part. Are you sure everything is running right with your tricker? Can you go back to stock cat and see if anything is different? Maybe someone else can back me up because i have never heard of a 4-1 header cutting mpg down by 1/3, hell I even ran one on my first gs.

 

[bullettdsm]

I think the OP is wondering more about his MPG or something robbing him of power.

I did miss this part. Are you sure everything is running right with your tricker? Can you go back to stock cat and see if anything is different? Maybe someone else can back me up because i have never heard of a 4-1 header cutting mpg down by 1/3, hell I even ran one on my first gs.

Nah, rear O2 is simply for checking the cat. Doesn't affect fuel trims or gas mileage.

And OP, it would be highly unusual that the header itself would cause that gas mileage drop. I can't think of any reason whatsoever that putting on a header would do this, So you would need to look at something else (of course changing it back to stock and checking is always a strategy).

As pointed out, the most obvious culprit (provided that your math/statistics are correct and you are actually getting that cut in mileage) would be the O2 sensor. It can do anything from alter fuel trims, to default you into limp mode. These things would affect mileage. Are you sure no wires were broken during the install? Is the connection OK? Did the wires somehow fall down on the header and get melted? Could the tip of the O2 somehow have gotten broken off?

If not the O2, it could be coincidence that it started happening when you did the install. Leaky injectors? Leaking fuel? Try driving around a little with your window down some and see if you smell gas. Check your plugs and see if they are "normal" or running rich. Obviously if they are 'normal" then you have a leak somewhere. See if one plug is much different than the others. That would indicate a possible injector problem.

A little food for thought.

MB

 

[FearlessNick]

Spark plugs look a little on the lean side. All of the wiring is fine as well. Could that front o2 be that bad and throw the mileage off? And I would say its around 10. My math couldn't be off. But I will do it next time I fill up.

 

[Anubis_4_99]

Spark plugs look a little on the lean side. All of the wiring is fine as well. Could that front o2 be that bad and throw the mileage off? And I would say its around 10. My math couldn't be off. But I will do it next time I fill up.

Miles driven divided by gallons put in equals MPG. Pretty easy to find out

I've had bad O2 sensors without throwing a code also.

 

[BoostedPhoenix]

Did this header come from Ebay ? did this header have provisions for the Secondary air injection found on the early models ? Did you make sure that the cap it comes with to block off the unused secondary air injection is tightly sealed and I mean sealed with some kind of sealant not just screwed on tight ?You will notice this provision is located very near the front Oxygen sensor. If this cap is leaking at all it can cause the O2 sensor to read lean thus richening your mixture and dropping prescious MPG.

I have seen the cheap ebay 4 - 1 headers that come with a downpipe, they work to replace a cracked manifold or cheap fix if your flex pipe is broken, but as with most of the cheap parts on ebay you have to do some engineering. Its just a tubular version of the stock manifold and there is not much to gain if its just the same as stock.

 

[FearlessNick]

I don't really care about power. I just want my gas mileage back. And plugs are Brand new. And look to the lean side.

I bought the header from a friend that was going to build a RS. It has no tags on it.

Tricker is fine and everything.

Front o2 looks like its running good.
So does the back.

And yes the cap is sealed off with gasket sealer.

But I'm also thinking of going to 4-2-1. And then probably replace the front o2.

Then get some NGK plugs and wires. Anyone know what plug I should run?