Does the Rtek still support Closed Loop while driving? I've seen drops of 1-2 mpg when tuning (richening) at cruise, but I had thought the O2 sensor forces a 1:1 Lambda at cruise, so it shouldn't matter what I tune for?

That seems to be the case on my other NA with an AFC Neo in it, so I wanted to know if that was the case for the Rtek?

 

closed loop works like normal for me. im running really rich in vacuum, and it still finds 14.7 at cruise.

my problem is that it seems to come out of closed loop too early when letting off the throttle. In 4th gear for me, i have to be accelerating slightly to stay in closed loop.. it stays in closed loop all the way up to 0psi (below 3500rpm). If i maintain speed, especially downhill, it goes in open loop. annoys the hell out of me.

I would like to know what are the parameters for closed loop? Does it use the TPS to determine when to come out of it at low throttle inputs?

 

Taking a hint from the FSM, you can go into closed loop even at idle. You pull the TPS plug off, put the shift lever in any fwd gear, and slowly rev above 1500rpm and stabalize it at say 2000rpm. Now look at the Diagnostic page where the narrow band 02 sensor is. The check box next to it will flash on and off, indicating the 02 sensor is working with the ECU and you are in closed loop.

Some time just go for a drive at a steady speed down the hwy, say 65-70 mph. Note the afr is jumping around 14.7. Jumps around a bit on either side. Now pull over to the side of the hwy and pull the plug off the 02 sensor and go back on the hwy at the same speed. On my car the afr will be in the 14.2 or 14.3 give or take with the 02 disconnected and at a steady hwy speed. Actually even in the hood doing 40mph or so will get you in closed loop.

Bottom line........look at the diagnostic page opposite the 02 sensor and the check box there for flashing . IF it is, your in closed loop. IF its a steady x mark, your rich. No x means lean. Or go look at the narrow band output on the ????? regular quad page. It'll flash rapidly around a half volt or so indicating closed loop.

Well, we've beaten that subject to death.

Well, not quite. When in closed loop and now coming to a down grade, the boost sensor drops now to above 15hg or so. Now the afr will fall from the basic 14.7afr to, for me, 12.4 afr, until the down grade turns level and the boost goes to below 15hg or so, then the afr goes back to the basic 14.7afr until you come to a downslope and it happens all over again.

Then there's the deal where you driving along and just barely let off the throttle. The ECU sees this and cuts fuel to the Front rotor. The afr goes to something like the 12.4 afr again. Now why it does not go LEAN instead of rich is beyond me, but it does.

Then again if you let off the pedal ALL the way, now fuel is cut to both rotors and the afr goes to the leanest the wideband will show, like 25 afr. We've all see that. I know this part isn't closed loop, I just threw it in there. Same with the para above.

 

The ECU uses the O2 input as a correction factor in closed loop. In other words, the ECU still injects fuel based on the fuel map and then takes the O2 input and calculates an average correction factor to get the mixture closer to stoich. The richer you tune for cruise, the more the ecu has to correct to obtain stoich. Since it's a calculated average, it takes time for the ecu to adjust. The farther you are from the target AFR, the longer it takes for the ecu to adjust to stoich and consequently you'll run richer longer. The end result is poor(er) gas mileage. Tuning as close to the target AFR while cruising will decrease O2 correction factor resulting in better gas mileage.

 

Is target AFR 14.7:1 (1:1 Lambda)? Where O2 Sensor voltage is 0.5V? How would you tune without a wideband (i.e. using the stock narrowband) and prevent closed loop from kicking in?

 

I'd suggest just reaching down there and pulling the connector off the 02 sensor when your *turning*. If you leave the 02 connected, it's going to be correcting changes your making with the Palm. Sort of fighting yourself. Same applys to using a SAFC and having the 02 connected up.

The again as you know, at WOT the 02 has no effect at all.

 

In closed loop, is the ECU trying to maintain O2 sensor voltage at 0.5V?

but if you pull the connector off the O2 sensor, how would you read AFR's without a wideband?

Is there a way to deactivate and reactive closed loop at low load situations?

Also, am I supposed to be tuning for 0.5V on the narrowband or (14.7:1 AFR)?

 

Oh. I see now. Well you could buy a narrow band 02 gauge and disconnect the 02 wire output to the ECU. You'd run the 02 output just to the narrow band gauge.

Or disconnect the 02 output wire from the ECU and tie it to a digital meter to read dcvolts on the meter.

Or there's another thing we know, I think. The ECU won't go into closed loop in neutral. So you could fix it so the ECU sees the transmission in neutral all the time. I'd have to look at the manual to see how that works. Probably puts a gnd on the ECU pin when in neutral and revoves the gnd when out of neutral.

I say the part about neutral because in the FSM when they test the colsed loop mode, the tps plug has to be off and the transmission in any gear i.e. not neutral. I think this applys to normal driving also. I might check this out if it interests me later.

If that would actually work, faking neutral, then you could look at the RTEK 02 output and not buy anything else.

I might be missing a easier way. Anybody that knows another way, have at it.

 

Doesn't the 2.0 allow you to log 0-5v on the ATM sensor input? Seems like another possibility.

 

I just went out and put a permanent gnd on the Neutral switchs input to the ECU. Sure enough, the ECU won't go into closed loop if you gnd that wire. Pin 1G on a series four. I drove for about ten miles and guarantee no closed loop seen.

You could backprobe the 1G with a wire going to a switch so you can put things back to normal with a flip of a switch. I notice on a *wish list* thread where a way around closed loop was mentioned and turbo2 took notice.

It took all of about ten minutes to install a gnd on 1G. Big deal. Its' called a piece of single strand 18-20 gauge wire with a alligator clip on one end and the other end bared and shoved in the back of 1G.

 

nice, thanks for the work, HAILERS....

which section of the FSM did you look at? Was it Fuel and Emissions? I ask just because I have an S5 and I need to find the corresponding ECU pin.

Can you confirm that my target voltage to tune for at cruise is 0.5V? Does 0.5V on the 0-1V Narrowband correspond to 14.7:1 gasoline AFR or 1:1 Lambda?

 

That would be pin 1R for a series five ECU. If you look in the Fuel and Emission section there should be a couple of pages listing the pins on the ECU and what they should read at idle or with the key to just ON.

Also I looked first at the series five wiring diagrams I downloaded a couple yrs ago. Shows it to be a green/black wire. Looks to be on the bottom row of the far right connector. Third wire from the left on that bottom row. So if you look and you don't have a green/black wire on the bottom row, third from the left, don't do anything until we figure out what the deal is.

I'm going to pass on any tuning remarks and let someone else step in. But when your WOT you do NOT want a afr of 14.7 or 0.5. You want something like 13.5 on your non turbo at WOT and only have 14.7 or 0.5 when at steady cruising speeds. 02 disconnected or the neutral wire at the ECU grounded when doing so.

Don't try adjusting fuel with the 02 connected at steady speeds. The closed loop at steady speeds will befuddle you. But you know that.

By the way, if you have a working ACV and airpump, you want to work aroud those if setting afr at idle. The air mixing with the exhaust ports air will fool the 02 sensor into showing mixtures leaner than they really are.

 

nono, I meant tuning at cruise......in reference to the previous post stating that the ECU in closed loop tries to fix the mixture at 14.7:1 AFR, which by my guess is 0.5V.

My questions are just pertaining to tuning under cruise.

My objective is to tune open loop AFR's to the AFR that the ECU tries to fix in closed loop. I'm asking, is the ECU trying to fix the AFR at 14.7 or 0.5V?

For the idle AFR, since the engine is under zero load at idle, my plan is just to lean out the fuel to right before the engine starts to stumble, and then richen it up a tad. Would that not be more fuel efficient than setting it at 14.7:1? I'll pull the belt off the airpump before tuning idle.

 

The narrow band O2 sensors are very non-linear so the ECU doesn't adjust injection to achieve a fixed voltage reading. Instead it constantly cycles between rich and lean during cruise (a few times a second). If you have a narrow band AFR meter (autometer or the like) you can tell when the ECU goes closed loop by the AFR starting to cycle up/down. http://www.aa1car.com/library/o2sensor.htm has a reasonable description and some pics.

Other than correcting for different injector sizes, all Rteks don't interfere with closed loop operation. Any fuel corrections you make apply only to open loop operation. The ECU is open loop at idle (under 1000rpm), mid to high load and any load above 3800rpm.

So, getting back to your question re tuning at cruise. Unless you want to defeat the O2 sensor operation, there's no tuning to do. If you unplug the sensor, then the ECU will stay open loop and any AFC adjustments you've made will be used.

I think it was covered earlier but its worth repeating - you don't want 14.7 for anything other than closed loop.

-Henrik

 

My question was, what is the voltage I want in closed loop (ideally)? Is it 0.5V?

Right now, I do not know if 14.7:1 AFR is equal to 0.5V....I need someone to say yes or no definitively, i.e. 14.7:1 AFR is 0.5V on the O2 Sensor or 14.7:1 AFR is not 0.5V on the O2 Sensor.

 

no one?

 

Narrowband sensor are not very accurate. And you wont get a single voltage, it will be swinging back and forth from lean to rich..about .2 to .8. Averaged over time, yes you want about .5v.

 

thanks.