For whatever reason, when I use the external signal harness with the Greddy Profec E-01 and the voltage table provided by the AEM Wideband O2 installation instructions, the lowest A/F ratio that the Profec reports is 11.2.

The AEM installation instructions show something like this:

11.00 = 0.500
11.25 = 0.625
11.50 = 0.750
.
.
.
16.75 = 3.375

So I have the Profec programmed to be 10.00 at 0v up to 16.75 at 3.375 volts. However, as stated above, the lowest I see is 11.2 on the Profec even when the A/F level is pegged below 11.0 on the gauge itself.

I'm pretty sure others (Sharif?) have said that they are able to see values below 11.0 on the Profec so perhaps something is wrong on my end.

Any ideas?

--Steve

 

When you are datalogging A/F from the AEM gauge onto the profec E-01 there are a couple of things to remember. The AEM gauge is a non-linear graph, and the E-01 can only show a linear graph. So you can only be accurate between a certain ranges of A/F. Mostly between 10.5-13 (or something like that I can't remember exactly). I do not remember the numbers I entered on the profec to graph the A/F from the aem. If you don't get the correct figures tonight I can post mine tomorrow.

 

I would love it if someone would post the numbers. On my instructions (page 9 of the AEM install guide), the numbers look pretty darn linear, i.e. exactly 0.125 for every 0.25 AFR from 11.00 to 16.75.

--Steve

 

I did the scaling on the PROFEC and it matches perfectly...across the board. I dont know how or why...but it works perfectly.

You need to use the other page of values zimbo. I think it's like 0 volts is 9.7AF and 5volts is 17.9. Dont quote me on those numbers...they are not exactly accurate. But there is another page of conversion values in the instruction book...use those...not the ones you are refering to. I wish I had my car back from the shop, so I could read the values right off the Profec.

Hth,

Sharif

 

Dang!

I have the instruction manual right here in front of me and there's only one chart showing values. It's on page 9, right beneath a graph showing AFR versus Lambda. The odd thing is that when I go WOT, the analog value (reading the voltage of the white wire from the AEM gauge) drops down to 0.525 or something like that by about 4000 rpms and stays there until redline when I am pretty darn sure my A/F isn't *exactly* 11.2 from 4000 rpms to 7000 rpms.

The rest of the time, the AFR numbers on the Profec seem to correspond pretty closely to the numbers on the AEM gauge itself.

--Steve

 

So what is the coversion factor that you used.

0 Volts = ?
5 Volts = ?

 

anyone anser gq here? im curious as well

 

I would love to know the answer as well. If I ever get the AEM wideband I ordered 2 months ago I'm going to build an analog alarm circuit to let me know when my A/F is too lean, since my guage will be mounted out of sight. I would hate to blow up another engine.....

Kevin
www.KPtechnologies.net

 

Well, after much testing I decided to use 0.525 volts as 11.00 and then go in 0.125 volt increments per 0.25 of A/F. Something like that. The Profec and the gauge itself are always within 0.1 of each other (though it's hard to sweep my eyes immediately from one to the other).

--Steve

 

You will reconsider that Kevin, as every time your car is decelerating you will hear that alarm unless you enable the alarm only if you have positive boost via engine management.

 

I was thinking for of a visual alarm, like two 3mm LED mounted in the Apillar. I know it won't be perfect, but under WOT I can monitor them and under normal circumstances I can ignore them. The boost sense is a good idea. I should have bought an electronic boost guage instead of a mechanical.

Kevin
www.KPtechnologies.net