Detailed A/F gauge install?

[Ph0nK]

I figure someone with an EP3 must have installed a A/F gauge successfully, and I'll been able to find is conflicting information.

I've heard you need to hook up the signal wire in the gauge to the black wire in the o2 sensor in the cat. I've also heard that you should tap into the red and yellow wire going into the ecu. Can someone shed some light on where exactly you get the A/F mixture signal from? Has anyone actually successfully installed one?

Thanks

[DynaSpeed]

I just spliced mine to the black wire at the secondary o2 sensor on the cat. Works like a charm.

[CSMsi311]

i thought you were suppose to tap the primary O2 sensor?

other than that i don't know specifically which wire it is

[VIZHUNZ02SI]

its the second second sensor blac wire
but if you ever get a turbo, the a/f gauge is a waiste ur better off getting a egt gauge which is more precise and doesnt have a 5 second delay like the a/f gauges.

[02SilverSiHB]

http://www.ephatch.com/forum/showthread.php?s=&threadid=13527

[JSIR]

I havent hooked one up on this car , but I have a shop manual if you need any wire descriptions.

I read my a/f ratio off my pda unit, the delay isnt anywhere near 5 seconds, I would say maybe 1 second or so. I can read both 02 sensors with my setup which is handy.

[Ph0nK]

Originally posted by 02SilverSiHB
http://www.ephatch.com/forum/showthread.php?s=&threadid=13527

I read this thread too, so I'm wondering which gets the best results: tap into that wire out of the secondary o2 sensor, or find the right wire in the ECU.

I would much rather keep all the wires inside the car and hook directly to the ECU, but I don't have a wiring diagram or the shop manual to find out this info myself. Can anyone find out where the black wire from the secondary o2 sensor hooks up to the ECU, or what wire in the ECU I can get a good A/F signal off from? Someone said pin#6, but I'm not sure where that is :) Any online pictures/scans of our ecu pin out?

[02SilverSiHB]

Originally posted by Ph0nK
I read this thread too, so I'm wondering which gets the best results: tap into that wire out of the secondary o2 sensor, or find the right wire in the ECU.

I would much rather keep all the wires inside the car and hook directly to the ECU, but I don't have a wiring diagram or the shop manual to find out this info myself. Can anyone find out where the black wire from the secondary o2 sensor hooks up to the ECU, or what wire in the ECU I can get a good A/F signal off from? Someone said pin#6, but I'm not sure where that is :) Any online pictures/scans of our ecu pin out?
I'd have to go with the ecu wires being the best signal...that's what I've always been told...maybe the blue connector..usually is..I'll see if I can find out.

[Ph0nK]

Originally posted by 02SilverSiHB

I'd have to go with the ecu wires being the best signal...that's what I've always been told...maybe the blue connector..usually is..I'll see if I can find out.

blue connector? that's a new one. I hope I finally find out :P

[02SilverSiHB]

Originally posted by Ph0nK
blue connector? that's a new one. I hope I finally find out :P
LOL :D just a guess, my ep is in the shop right now so I can't go take a pic for you but this should be easy:

It's connector 31p (or connector A) from the ecu. The red wire which is number 6. The 31p connector should also be labeled A, but in case it is not, you can use these images to help you. It has 30 wires versus the other 31p connector (or connector E).

You should be able to use that one, it is the + a/f signal. The wire 16 (red/yellow) is the - signal. Some autometer gauges can be wired to have both signals to get even more accurate readings.
Hope this helps
http://a2.cpimg.com/image/AA/F4/25585322-dbf5-020000AD-.jpg
http://a5.cpimg.com/image/A3/F4/25585315-28f9-020001D9-.jpg

If you need to see the larger images, go here: http://www.k-series.com/forums/viewtopic.php?t=848

[Ph0nK]

That my friend is exactly what I was looking for. I'll give that a try as soon as it stops raining.

[02SilverSiHB]

Originally posted by Ph0nK
That my friend is exactly what I was looking for. I'll give that a try as soon as it stops raining.
sweet, do you have a autometer gauge?

[karlo_ep3]

Originally posted by VIZHUNZ02SI
its the second second sensor blac wire
but if you ever get a turbo, the a/f gauge is a waiste ur better off getting a egt gauge which is more precise and doesnt have a 5 second delay like the a/f gauges.

5 secs? where did you get that number?

[02SilverSiHB]

Originally posted by karlo_ep3
5 secs? where did you get that number?
not sure about the exact delay, but I believe he is right. I find that a lot of turbo guys, especially rx-7 turbo guys are using egt gauges instead of the a/f gauges.

[karlo_ep3]

Originally posted by 02SilverSiHB
not sure about the exact delay, but I believe he is right. I find that a lot of turbo guys, especially rx-7 turbo guys are using egt gauges instead of the a/f gauges.

Oh I see. This doesnt apply then to our cars. The response time with my autometer UL A/F gauge is good. Infact, it's so good that it keeps on swinging around, but I think that's normal. :D

[02SilverSiHB]

Originally posted by karlo_ep3
Oh I see. This doesnt apply then to our cars. The response time with my autometer UL A/F gauge is good. Infact, it's so good that it keeps on swinging around, but I think that's normal. :D
well maybe not for us if we have minimal natural aspiration mods, but if we have a lot or go forced induction I think the egt gauge would be a good idea.

[Ph0nK]

Originally posted by karlo_ep3
Oh I see. This doesnt apply then to our cars. The response time with my autometer UL A/F gauge is good. Infact, it's so good that it keeps on swinging around, but I think that's normal. :D

How did you install your signal wire? to the o2 sensor or to the ecu?

[karlo_ep3]

Originally posted by Ph0nK
How did you install your signal wire? to the o2 sensor or to the ecu?

I tapped the black wire of the secondary o2 sensor (farthest away from engine). Works like a charm. Pretty accurate and on time.

[karlo_ep3]

Originally posted by 02SilverSiHB
well maybe not for us if we have minimal natural aspiration mods, but if we have a lot or go forced induction I think the egt gauge would be a good idea.

Question: If you use the EGT guage how will this translate to lean/stoich/rich readings with an A/F guage? Will this be like lets say "hotter is leaner"?

[02SilverSiHB]

Originally posted by karlo_ep3
Question: If you use the EGT guage how will this translate to lean/stoich/rich readings with an A/F guage? Will this be like lets say "hotter is leaner"?
I believe so, I remember the guy saying it will show on the gauge what temp it is, so I guess, you'd have to know what temp stock is :o