whorider

Just got my wideband in my S5 NA streetport today. Idling it is in the mid 21's too 22's. Cruising freeway speeds light throttle 15's. Heavy load (hill) 12's to 13's. Why would it be so lean at idle? I haven't gone over 4K rpms yet as it is a fresh rebuild (550 miles).

HAILERS

If the ACV and airpump are still on the engine, then that would account for LEAN at idle. Air is injected to the EXHAUST PORTS, which are before the 02 sensor.

Air is NOT injected at other times. Well not 100% true, but not injected to the exhaust ports 99% of the time when not at idle. Ah, maybe 90% not.

Try this at idle and hot engine. Pull the BLUE plug off the Relief solenoid. NOW the afr should go to the high 12 low 13's. Takes but a moment to prove this. Do it NOW and write back.

Roen

iTrader: (2)

Can you lean out your idle further via tuning with the ACV/Air Pump disconnected?

whorider

I did it now. Went from 22.4 to 16.6-17. Still seems lean. I guess this explains why my fresh engine doesn't have trouble with flooding. I'm pretty sure there are no vacuum leaks.

HAILERS

He really does not have to disconnect the airpump or ACV. IF he removes the blue plug from the Relief solenoid, then the poppet will close on the passage to the exhaust ports, meaning no airpump air will go to the exhaust ports now. Then when he gets the afr where he wants it on the idle, he can reconnect the blue electrical plug. Afr will go lean again, but he'll KNOW that the mixture is NOT really that lean. The real mixture is what he saw with the blue plug off the relief solenoid.

whorider

Not sure what you mean. I have never messed with ACV/air pump. All emissions equipment is intact. Water temp stays pretty constant at 190f (aux. gauge below t-stat in pump housing)or middle of the road(stock gauge).

HAILERS

That's UNUSUALLY lean. Most cars (RX) don't like mixtures over 13.5afr at idle. That's just MY opinion and there certainly are other opinions out there. I can't account for the unusually high numbers. But you did see how the air to the exhasut ports effects the reading at idle and how removal of the blue plug makes a difference.

In this case you might do what was suggested in the post above. Remove the airpumps belt tomorrow and see how the reading reads with the engine hot and at idle. Let us know if the number changes from the 16 you just saw today.

whorider

So tune idle with relief solenoid unplugged. How bad is 17:1 at idle. I have to smog by the end of Jan.

whorider

I'll try it tomorrow. Thanks a bunch hailers.

HAILERS

Here's something that might very well work and is easier. The ACV is fed vacuum by two vacuum hose just directly above the ACV. Remove both hose and plug both HOSE. Use maybe a couple of 10mm bolts or such. Then look at the AFR again. I bet it fell down to the 13's afr when you do this. When through, reattach both hose again.

I made a slight mis-statement in a earlier post. Pulling the Blue plug makes the relief diaphram open and lets the air go overboard to the silencer in the right fender. ALSO removing the vacuuum from the Switching solenoid will make the poppet cover up the passage to the exhaust ports. THAT should now for sure keep air from the exhaust ports and the AFR should drop more.

The internal diagram of the ACV is in the Fuel section of the FSM and you can figure out how it works.

Turbo ACV a bit different.

whorider

10-4.

HAILERS

Another hint about the steady speed afr's. Let it be known that if the narrow band is connected to the ECU, it will try to keep the afr at 14.7afr. It does a VERY good job doing this. IF you remove the plug from the 02 sensor, you will see a different afr at steady speed than you have been seeing. 10/4 the 10/4

But as you know, over 3500 rpms and or when at WOT at any rpm, the 02 is not in closed loop anymore and is not a factor.

initial D is REAL!

+What gauge do you have? My aem only goes as low as 10:1- and as high as 16:1 i think. I have to double check. My streetport idles at 12.5ish :1. A friend helped me set mine up

arghx

iTrader: (3)

The innovate LC-1 can read between 7.2:1 and 24:1 I believe. It is what I use in my T2 currently. I used to have the AEM unit but I had build quality issues with it, it's not as accurate (does not have calibration feature), and its 0-5v output is notoriously crappy.

The AEM UEGO is basically a solid and inexpensive gauge for a car that doesn't need serious tuning with extreme precision, or for a car with an AEM EMS. Just don't try to call their tech support/warranty line because their reps are ******** and won't fix it when you send it back to them. Ask me how I know.

Roen

iTrader: (2)

Is there a point for leaning out the cruise if the O2 sensor goes into closed loop???

whorider

It wouldn't seem like it.

Hailers. I will try both with the O2 disconnected with the airpump disconnected and both at the same time. Thanks.

dguy

iTrader: (8)

do you have the sensor installed in a downpipe bung or with their tailpipe adapter?

HAILERS

If in closed loop, the ECU is going to do its best to hold 14.7.

Say you REAL afr is 13.5 afr at a steady 3000rpm. The ECU will pull that up to 14.7 if the 02 sensor is connected up.

Say your REAL afr is 15.0 afr at a steady 3000 rpm. The ECU will richen things up so the afr is 14.7afr.

REAL meaning the afr with the 02 disconnected therefore not influencing the ECU.

And I've assumed *whorider* has the acv and airpump on the car because he has to pass emissions at sometime and he has a catalytic converter. That's one reason I did not recommend removing the airpumps belt, but capping the two vacuum lines to the ACV. IF done that way, the two lines can be reattached in a few moments. It has the same effect as removing the airpumps belt i.e. no air going to the exhaust ports which are prior to the 02 sensor.

He would not want to run without the airpump/acv for extended periods of time in order to save the catalytic converter $$$$$$$$$

whorider

Hailers. I was unsure what vac lines to pull from the ACV. The fsm doesn't go into much detail about it (that I could find). I removed the airpump hose to the acv just for a minute or so (aware of catalytic converter damage). Only went to 17ish. My O2 sensor has no effect on AFR. I have had some trouble with intermittent hunting a couple hundred rpm's. It seems to have got more consistent. So I'm suspecting a vac. leak. Tried to locate with propane, what a waste of time. Tried to locate with brake clean possible located a suspect area. Nothing conclusive. I'm going to drop by a buddies shop and see if I can bum some smoke of his smoke machine.
On a side note: I got rpms in the 750 range to check timing. When I jump the intail test connector it seems as though nothing changes.

HAILERS

Well, I have a series four,and that's why we may not be communicating about the vacuum hoses. On a series four, NOT on the ACV itself, but just above the ACV, there are two vacuum hose right next to each other. Those were the two I was referring to. I guess I need to find a picture of a series five ACV and work from there.

Actually the initial set coupler does close to zip for timing. I never jumper it when timing, ever. Only jump it when setting a idle, and then rarely. I usually just pull the bac's elect plug when setting idle.

No car I ever owned could idle at 16-17 afr. What more can I say. Anyway, pulling the hose off the acv obviously should have removed any effect the airpump had on the AFR at idle.

EDIT: I probably shouldn't, but I'm starting to wonder about the wideband. The 15's while cruising seem a tash high, sorta like the idle afr. When cruising, the relief solenoid is wide open allowing the airpump air to dump out to the silencer in the right fender and the Switching solenoid is energized which means no vacuum going to the switching diaphram in the ACV which in turn blocks the path of airpump air to the exhaust ports.

Bottom line: at cruise, especially if cruising for 120 seconds or more, results in no air going anywhere but the right fender (from the airpump).

HAILERS

I looked at page FI-43 of the online FSM for non turbo series five, and just above where the ACV mounts, there are two vacuum lines on two metal nipples. Those are the ones.

If the engine is fully warmed up, both HOSE will have vacuum on them. IF the blue plug to the Relief solenoid is pulled off, vacuum should be removed from ONE of those two lines. That would prove those are the two lines from the Switching and Relief solenoids. SO. Plugging both of those HOSE would make the ACV dump ALL the airpump air overboard and none to the exhaust ports in any way.

I wonder if there's some sort of *calibration* for that wideband?

What I'm saying, is when I have a airpump/acv working on either of my cars, I can just pull that blue plug off the relief solenoid, and the afr will go from the 16afr range to the real deal 13.0afr that I have at idle. It's a little different on the Turbo cars. On that one I just pull the vacuum line from the Switching solenoid to the acv and that does the job. Drops from the 16's to the 13.0-13.4 range. It's the same thing as pulling the belt off the airpump. Figures read no different.

I might be a little rash suggesting the wideband as a suspect. Don't pay a lot of attention to that remark. It's just I have a hard time thinking a RX will idle even halfway decent with a 16afr.

whorider

I checked intake with smoke. Found a leak under the intermediate manifold. I guess I know what I will be doing tomorrow (if it doesn't rain). I too have been suspecting the wideband O2. It is a new innovate LC-1. I tried recalibrating it today. Thanks for the help, I will update when I fix vacuum leak under manifold.

arghx

iTrader: (3)

do a FULL recalibration of your LC-1. Wait at least 10 hours after you have driven the car, or remove the O2 completely from the bung. Disconnect the sensor and turn the ignition on (engine off) for about ten seconds, then turn it off. Follow the instructions for the heater and free air calibration.

HAILERS

Always good to fix a vacuum leak. I'm not real sure that will fix the 16/1 reading at idle though.

I sort of wish you had a seperate way of seeing when the ECU goes into closed loop while at a steady road speed. If you saw that and at the same time looked at the wideband and saw 15afr, then you'd know the wideband was off.




Don't get me wrong, fix the vacuum leak for sure. Then look again.

EDITED FROM THE ORIGINAL POST. Wrote too much *stuff*.

whorider

So I finally got the S5 back together after a couple of weeks. I had no extra time for quite a while. So I found the leak under the manifold to be injector grommets. Replaced those and the air bleed o-rings. Put it all together, now its idling (800 rpm) at 14.6-15. Much better. I did notice that if I open the throttle to anywhere between 1500-2000 rpms it hunts and the AFR goes to around 21. It doesn't hunt 100% of the time. Cruising at that rpm the AFR is 14-15.
One more thing the AFR goes to 22.4 on deceleration. Is that normal?