Stock O2 sensor ---- for emission
 

long story short

for some reason, the fd here does not want to go Lambda 1.00 (14.7) at both idle (I set it to around 750 rpm), nor high idle (which is around 2200-2500)

I can do it to another fd without much problems.

on pfc the o2 sensor reads 0.1x v , so I replaced it with another used one (new one is on order), this one read slightly better (at least I seen it went up to 0.22v), but still at all time low.

Do u guys think it's a o2 sensor problem ? cuz its kinda weird that it sits at 0.1x most of the time ----- the result is the car is running rich as FUCK = failed emission.

I haven't done any vacuum job to this FD yet but last time I took it apart (just like 3 days ago) the vaccum hose seems to be fine(except it's getting hard, if u know what I mean)

shit, I'm scratching my head here :( :scratch

Airpump delete or no?

air pump is on.

It's not supposed to go Lambda=1 at idle. It's supposed to go leaner than that due to the air pump sending air to the exhaust ports. https://www.rx7club.com/3rd-generati...ntrols-841963/

The engine isn't in o2 sensor feedback closed loop when the air pump is on. You can see that even in the PFC fuel map for the stock Apex'i map. Only when the INJ map is at 1.0 to 1.047 will it engage O2 feedback.

https://www.rx7club.com/attachment.p...1&d=1472997070

Can you confirm the voltage? Low voltage = lean, which is what it should be reading if the port air is running. I have no idea what's going on with that other FD.

Those old o2 sensors are cheap so you might as well replace them. They are unheated sensors with 1 wire.

It's kind of weird that the other FD you are referring to is switching around lambda 1 around idle...

Do you have emissions results?

https://www.rx7club.com/attachments/...onsfailure.jpg

If it's rich, your cat wouldn't be working and your tailpipe CO would be high. CO is directly related to AFR more than HC and NOx are.

The emission tests here(im im hong kong right now) follows the uk standard(mostly)

The requirements are

Idle: 0.5% CO or less

High idle, usually means around 2-2.5k rpm :

0.3% or less CO
Lambda 0.97-1.03
(they supposed to test nox as well, but it looks like no one gives a shit)

I am testing it with pfc and snap on's fga(its old, but its fast and accurate)

Stock ecu runs super rich (around 12.x afr, lambda around 0.8xx) , so i gotta use pfc to lean it out

Even with pfc and stock map, tailpipe is rich at around 0.8xx lambda idle, even when the O2 sensor reads low voltage.

It never went above 0.1x actually, so yes its reading lean, even when the car was warming up, so i.think the o2 sensor might be bad(stuck at lean)

So i disabled o2 feedback, the emission got better, but not good enough

So i start checking broken stuff.

And found that spit air's check valve is broken, same as gasket(someone poke a big ass hole), i replaced both with brand new parts

Jumped back into the car. Lean it out, got it to around 16:1 and my co reads 0.7, anything leaner the engine idles pretty bad.

I got a few more things to try tomorrow to lower the emission, but now im thinking maybe the cat is bad.

I will take a pic of the test tomorrow, im 12-15 hrs ahead of us lol

If the cat and the secondary air injection are working, there is no way you should fail that emission requirement. O2 feedback doesn't do anything at idle, only cruising.

I have been fighting with this 7 for 2 days ...

Yesterday at idle, default PFC map, after a bit of playing around with inj map, i got it down to 0.7 co (which means failed) at idle, forget about fast idle (around 2K rpm), cuz CO got up to 10+ even when lambda was close to 1

Today, I put the stock catback/muffler back on, co went down to around 0.4-0.6 @ idle, fast idle failed but it was around 7-8 co.

sucks.

u mentioned spit air, I was checking the spit air valve and found it was bad (can blow air both ways) so I replaced that (and new gasket too),

I start the engine and I felt air is coming from the spit air pipe, I thought spit air only comes on when I give it part-throttle?(light load) ?

I am going to take this shit apart, replace everything I see, take the ACV out and clean it. hopefully that will fix it ?

btw I ordered a new Magnaflow Direct replacement CAT, a new cat from any company should do better than a used cat that I bought off from here that's like 20 yrs old, I think.

Are you sure your analyzer is calibrated and trustworthy? You said it's old...

Remember, this vehicle easily met such emissions criteria when stock. So the more you can make it behave like stock, the better chance you have of passing. That means:

cat that works
ACV that sends air to the exhaust ports
idle speed correct

What PFC map are you using? What mods are on the engine? It should pass just fine with the default PFC map. That has all the stuff working on it (O2 feedback on etc). Can you just pop a stock ECU in there and see what happens?

Snap on serviced the machine before i got it so yeah its working.

Cat - i really have no idea
Acv - i have to check this one
Idle - i set it to around 730 rpm with stock ecu
O2 sensor - shows 0.1x 0.0x all the time.

Im using the default pfc map

Now im thinking maybe the port air isnt even working ...

Stock ecu its about the same as the default pfc map (emission wise)

maybe, just saying maybe there is a difference between JDM/USDM rx7's emission ?

is JDMs PFC maps same as USDM's PFC I wonder. lemme post it up.

https://cimg8.ibsrv.net/gimg/www.rx7...1f26a1b33b.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...9c905885f5.jpg

basically the US and JDM are the same emissions wise. the US car has an extra port on the ACV so it can have a finer control of the air pump air, but other than that, its the same.

the US car has a precat and EGR too, but these do nothing once the car is warm.

if you're looking at a stock FD, the 02 should be pegged lean until about ~1300rpm at part throttle, where it will go into closed loop and run 14.7, it'll stay there until you hit about 30% throttle OR 3200rpm OR 1psi, where it'll be in open loop again.

if stock ECU and PFC are giving you same emissions result, you've probably got an air pump/ACV problem or a dead cat.

exact same thing, PFC or stock.

I put that 7 on the side for now while waiting for new cat to come, will post results when cat is here.

Ok, no need to put new cat

2 days ago, I took the pain and took every damn thing apart and start cleaning/replacing

took ACV out and Carb clean the shit out of it.

And I replaced all solenoids that controls emission.

pop everything back in (finished everything in 2 hours, remove, clean, replaced)

fired the car up, everything seems fine

took my gas analyser out

Idle @ 700 rpm

CO 0.03

High Idle @ 2200 rpm

CO 0.1
Lambda 1.00-1.03

holy shitz.

took the car to test, it passed with flying colors

Jesus ...

funny thing was it wasn't the first time I remove the ACV, I poke it with my finger everythign seems to be moving well. and I tested all solenoid and every damn of them seems to click (even after I give it heat)

Well maybe it was stuck inside I dunno ?

anyway. the problem has been resolved. thx a bunch for all the ideas :)

Ok, so, it was an ACV problem. Good to know. That's not surprising.

it's kind of weird tho, I checked it with my mityvac before and everything works (at least according to FSM spec)

oh well, whatever. at least it works now :lol: