f22a4 header question.

[deevergote]

The F22A1 manifold is 4-1.
The DC Sports header that we're discussing is 4-2-1, and is not 20 years old.

Get some sleep. You're confuzzling matters.

[Accrdwgnguy]

With that logic, what is keeping the used F22A1 header from a 4th gen prelude from being cracked?

Nothing, really. I have heard of cases of DC Sports headers cracking. I would advise a good looksee of the header before purchasing. Used parts are never a sure thing.

[HelmHoltz]

A guy offered me a set of DC headers with a down pipe for 50. He just said I will have to extend my o2 sensor to make them work. Is this a good deal? Is extending the o2 sensor hard? Thanks. Also, why am I unable to start new threads?

You need Silver solder and nickel wire to do it right, just buy an O2 extension harness off Amazon and do it right.

[Accrdwgnguy]

You need Silver solder and nickel wire to do it right, just buy an O2 extension harness off Amazon and do it right.

Soldering a couple wires isn't that hard....

[Stoner51]

The DC sports header the o2 bung is in the downpipe.
I have an a1 and extended the o2 sensor. My connection is up front as the a1 header has the o2 sensor in the header.
Where is the connection for the a4 o2 sensor located? in the engine bay
I'm a little confused by some of this, but I think everybody is saying it is better to extend the factory harness? and not cut and splice the o2 sensor.

steve

[GhostAccord]

To be honest it might be a cheaper option to have someone drill and weld in an O2 bung before you install it. Vs extending wires or buying an overpriced extension harness.

I know I just welded in a bung on my SS Blox header in about 20 minutes. I also had to change the orientation of the 3" down pipe 20°. That only took me another 20-30 minutes. The header was made for an 00-04 focus, I put it into an 01 tribute.

So for under an hour, $50-$100 you could have a modified header. Even cheaper if you know someone who can weld. I'd do it for a case of beer and an evening in the garage.

[deevergote]

I paid $30 for a new bung to be installed on my oem H22 header.
An added benefit to having a second bung is that it makes using a wideband o2 sensor for tuning much easier. No need to uninstall the old sensor to plug the wideband in temporarily.

And yeah... I wouldn't pay for an extension harness. You can create your own with junkyard bits quite easily.


Cutting and splicing the o2 sensor wires would be a better idea than cutting the stock harness, for sure... but a splice MIGHT alter the resistance significantly enough to prevent the sensor from functioning properly. An extension subharness could as well... but at least that's not irreversible.

[Stoner51]

I paid $30 for a new bung to be installed on my oem H22 header.
An added benefit to having a second bung is that it makes using a wideband o2 sensor for tuning much easier. No need to uninstall the old sensor to plug the wideband in temporarily.

And yeah... I wouldn't pay for an extension harness. You can create your own with junkyard bits quite easily.


Cutting and splicing the o2 sensor wires would be a better idea than cutting the stock harness, for sure... but a splice MIGHT alter the resistance significantly enough to prevent the sensor from functioning properly. An extension subharness could as well... but at least that's not irreversible.

Good point. If I screw it up I can always reverse it.
I looked at my connection and it looks like I can get some length by opening up the loom and routing the o2 sensor up from the back of the engine.

Steve
If I do this I will report back.

[Granite CB7]

The DC sports header the o2 bung is in the downpipe.
I have an a1 and extended the o2 sensor. My connection is up front as the a1 header has the o2 sensor in the header.
Where is the connection for the a4 o2 sensor located? in the engine bay
I'm a little confused by some of this, but I think everybody is saying it is better to extend the factory harness? and not cut and splice the o2 sensor.

steve

Since the F22A4 header is a 4-2-1, the o2 sensor is on the downpipe to read all 4 cylinders when they join into 1 pipe. Since the A1 manifold is a 4-1, the o2 sensor is @ the collector where it joins into 1 pipe, again, so it can read all 4 cylinders. I def. wouldn't add a bung to the DC header (not d/p) just b/c you'd be getting o2 readings from certain cylinders and not all of them.

People are saying do not cut up your engine harness at all, that way it can always be put back to stock. Even w/ some junkyard male and female 4 pin connectors, you could make your own subharness to connect the factory engine harness to the factory o2 sensor.

Sounds like you're on the right track though, esp. w/ seeing if you can get enough wire by delooming.

[GhostAccord]

Since the F22A4 header is a 4-2-1, the o2 sensor is on the downpipe to read all 4 cylinders when they join into 1 pipe. Since the A1 manifold is a 4-1, the o2 sensor is @ the collector where it joins into 1 pipe, again, so it can read all 4 cylinders. I def. wouldn't add a bung to the DC header (not d/p) just b/c you'd be getting o2 readings from certain cylinders and not all of them.

Funny that you mention that, because for some reason all of the OBD2 F22B1,2 and H22A4 primary O2 sensors are located in the #3 cylinder primary header tube......... that is the primary O2 signal sent to the ECU for fueling.

I agree that the collector or single down pipe would be a better place for an O2. However for some reason Honda seemed to think differently on those engines. technically 4 WBO2 sensors, 1 in each primary, would be optimal, but not very cost effective.

[Granite CB7]

Funny that you mention that, because for some reason all of the OBD2 F22B1,2 and H22A4 primary O2 sensors are located in the #3 cylinder primary header tube......... that is the primary O2 signal sent to the ECU for fueling.

I agree that the collector or single down pipe would be a better place for an O2. However for some reason Honda seemed to think differently on those engines. technically 4 WBO2 sensors, 1 in each primary, would be optimal, but not very cost effective.

Good info, I'm so used to OBD1 setups and that was why I mentioned reading all 4 cyls @ the collector! I'll have to pay attention to what Honda did on some of their newer stuff. Do you suppose the OP could cheat and have an o2 bung placed on the header itself to read 2 cyls? I know it's not the best but how bad could it be really?

[reklipz]

I would be hesitant to read only one or two cylinders when the ECU was designed to operate via all four.

I don't think it was ever answered: The F22A4 O2 harness location is in the rear of the engine bay, as the A4 has the O2 in the downpipe. The A6 is the same as the A4, and the F22A1 has it up front, as you mentioned.

Extending the wiring via solder won't appreciably increase resistance at all; here it is at two feet extension:

20 AWG copper hookup wire at 10.15 milliohms per foot
(10.15 milliohms/foot) * (2 feet) * 2 = 40.6 milliohms

The above is for 20 AWG copper, but nickel or silver plated is going to be very similar, maybe dropping the resistance a couple of milliohms overall.

Adding in an extra connector will add more resistance than soldering, and folks are known to have done that with success. I wouldn't worry about it at all.

[deevergote]

Well, the ECU is designed to operate based on the o2 sensor's input. Neither the sensor nor the ECU knows if the readings are from 1 cylinder or 4.

Extending the wire CORRECTLY... proper splice, proper solder joints, proper insulation, correct gauge and material... that would probably be fine. But that's a lot to expect from an amateur. An extension harness can be undone and redone until it's done right, without compromising the integrity of the wiring on the car or the sensor itself.

[reklipz]

My point was that the designers of the ECU knew the effects of the sensor getting all 4 cylinders as opposed to 1, 2, or 3. They designed the system with this knowledge in mind. They even went out if their way to make separate wiring harnesses for the A4 just so thoykd keep the O2 sensor in a location to sense all four cylinders. I'm guessing it should stay that way; I wouldn't gamble it , especially if you have a choice.

[Accrdwgnguy]

You guys are way overthinking this. Reklipz has pointed out that the resistance change would be minimal at most, which is true. I've built 2 engine harnesses for fuel injected Chevy V8's, so I've lengthened and shortened many a wire in the process, just as countless others have done. No negative effects to the engine or ECM have arisen due to wire length.

I also agree an extension harness is a good idea for someone who has not undertaken a wiring project for their car, as it's an easily reversible change.

Best of luck OP.