zoltan944

I got my AEM wideband installed in the 85 928 with the edition of the X-pipe. Upon start up the gauge will give me readings in the 15.2-16.8 range at idle. When i start going it will bounce around the 14.2-15.5 mark kinda. After getting out of my subdivision to get on it a bit, it goes high 16-17 then pegged lean. It will hardly ever from that point come back out of pegged on lean.
So, if i take my widebands 0-1v output and hook it into the my green lead to the computer and disconnect the standard O2 the car runs the same, but wont come out of lean.
Now if the computer was doing its job it should be adding more fuel to bring the car out of lean right? So even if my gauge is wrong (off) then the computer should still add fuel. At WOT it should ignore this reading anyway and i should be at better #s no?
Im gonna go pull a plug right now, this is all driver side bank readings

zoltan944

here is a pic of a plug, the 4 driver looks identical to this one and so does the one pass i pulled

zoltan944

i guess i have a feeling its perhaps the gauge itself... if i disconnect the 02 wire and reconnect it, there is a clear obvious differnece in sound in the car and should be a differnece in AF but my gauge doen't show it... I may have to try to find someone witha spare to test against mine to see if i need to buy a new gauge

John Speake

I agree with your reasoning.....I assume for the first tests you had the standard O2 sensor feeding the LH, with a WB sensor plugged into another port on the X ?

You may be able to reprogram the simulated NB ouput from your WB unit and move the output law around a bit to explore what is going on.

Did you do a free air calibration of the WBO2 system ?

tv

Before I added my rrfpr's I was running lean and never had any pre-detonation or anything other than running warm. I think MK has talked about running lean a few times so yes it is possible but I am an open loop and you are not. To me your plug looks good, not yellowed or anything else. There are some websites that list pictures of plugs and their causes.

SwayBar

Your plug indicates that your car is running lean as the wide-band suggests.

Are you using the stock O2 sensor to drive the car's fuel-computer and the wide-band O2 sensor driving the it's unit?

If you have the wide-band driving the car's fuel-computer, I would remove the wide-band O2 sensor and reinstall the original stock O2 sensor and hook it back up to the fuel-computer. Next, take the car somewhere where they can weld a new bung into the exhaust system for the wide-band O2 sensor, preferably after the X pipe, and use that to drive the wide-band unit.

As John suggests, make sure you do a free-air calibration.

John Speake

"When i start going it will bounce around the 14.2-15.5 mark kinda..."

This suggests that when at cruise the loop is keeping the mixture reasonably under control, it will always hunt from high to low of the range of the NB O2 loop. But you do appear to have a lean running off the O2 loop.

This could be MAF low, injectors not flowing fully etc. The X pipe might lean things out a little also.

blown 87

A miss fire will also make them show very lean, as will any exhaust leak. But I think you are more than likley right as far as the gauge being bad.
I do not know about the one you have, but with the Innovate the grounds are picky.

mark kibort

disconnect the o2 sensor input to the computer but leave it connected to the fuel air meter.
this way, the system is not moduating the fuel air mixture and it runs as if it is WOT all the time, even part throttle. it should run in the 12.5 :1 or 13:1 range. (the rich area of the meter)

Mk

zoltan944

A normal 3 wire 02 is running the computer while i look at the AF readings, but i have switched it to AEMs output as well looking for change.
As far as free air calibration, can someone with an AEM confirm that my directions said there is some laser doohikee that self calibrates itself?
Also anychance that the power/ground of the regular 02 is maybe shooting juice across the pipe??(that sounds stupid)
Also, i am going to be putting another bung in for the 02, where should i put it? where the X meets or it its on 1 of the pipes past the X the mixture will still be good?

hacker-pschorr

Just curious, how do you know?

zoltan944

you know this really is strange cause i just went back out again, and it read and the car did what it was supposed to. so i go down a side street and floor it in 2nd and then it peggs lean, and driving normal all the way home i can't get it unpegged

tv

I'll answer all possibles;

Leaness- I knew from my failed emissions test where the NOX was sky high also when i went to tune on the dyno before i adjusted the RRFPR, it was very lean.

Warm- I knew it was running warm from the temp guage and aux fan

Pre-detonation- I was referring to knocking or pinging. I never had any of that even when I first bought mine. It performed well, no hesitation, no unusual audible sounds or roughness.

All parts of the system had been changed before the RRFPR's got installed IIRC. Plug wires, plugs, dist.s, coils, temp and other sensors, brains. Plus vacumn leak tests.

Then I installed the RRFPR's (2) and tuned it on a dyno with a wideband in front of the cats (hi-flo). Got it mostly perfect. Subsequent emissions confirmed 0 nox and just 6% of allowable CO on an open loop euro.

I am now running considerably more than stock pressure, my MAF which is new, is set at 700 on a 0-1000 scale. My euro and others incl. DR's as was mentioned were lean runners. Now it is running perfectly.

Ian928

I your car is running on only 7 cylinders, the last one will pump air into your exhaust and disturb the readings. I would try to pull the last 3 plugs and maybe hook up a timing lamp to all of the plug wires to check if there is sign of a misfire

Ian

zoltan944

good call... I actually replaced all of these plugs like 150 miles ago and have the old ones, they all kinda seem fine. How else would i be able to tell if i was running on 7 cylinders or not?