AEM Ultimate Resource Thread>>>>

[mjannusch]

This year mine was reading voltage on the low side, but I replaced the battery (Optima red-top) and it seems to be a bit better now. I think I'm seeing like high 12V readings on mine now. I was kind of wondering if the MSD was sucking lots of volts out of the battery - it does go down a fair amount during a 1/4 mile pass. I guess the Supra fuel pumps take a lot of amps too, which I'm using.

[xwing]

OK thanks all, at least I know it isn't a normal thing and can chase it down more now.
JT

[slava]

Would appreciate feedback on my second gear pull.
No matter how much fuel i add i am getting knock around 5.5K.
Is it too much timing?
stock 9b/94octane

[mjannusch]

In your log at 5500 rpm your O2 #2 starts reading leaner than O2 #1. By 5691 rpm O2 #1 is 11.78:1 and O2 #2 is 12.12:1, which I would say is too lean for regular pump gas. Right there you get a huge knock spike of 2.9V (which is very high).

Looks like you may have some sort of fuel delivery problem, or your map is too lean at that range. Tough to say without more logging data and the map.

[slava]

Originally Posted by mjannusch

In your log at 5500 rpm your O2 #2 starts reading leaner than O2 #1. By 5691 rpm O2 #1 is 11.78:1 and O2 #2 is 12.12:1, which I would say is too lean for regular pump gas. Right there you get a huge knock spike of 2.9V (which is very high).

Looks like you may have some sort of fuel delivery problem, or your map is too lean at that range. Tough to say without more logging data and the map.

I battle with different o2 reading for a long time, no solution yet. I have supra how wired pump with AEM FPR and 650CC which are running at 50%.
I have 1afr difference event at idle. during normal acceleration the o2reading almost the same and then they are different with firewall o2 being leaner. That how it was with stock pump and FPR , i put supra, how wired, AEM FPR and nothing changed. Here is another log with 2step launch (16psi) where the reading are pretty much the same. You can see sliping clutch situation when speed encreases but RPM not.

[slava]

Anybody run dual WB? are the reading the same all the time?

[mjannusch]

Try logging your O2 #2 Feedback value as well. Something looks to be screwy... Do you have anything set in any of the Inj #xx Fuel Trim tables? (Fuel-> Advanced -> Trims -> Fuel Cylinder Trims)

Which wideband setup are you using?

[slava]

Originally Posted by mjannusch

Try logging your O2 #2 Feedback value as well. Something looks to be screwy... Do you have anything set in any of the Inj #xx Fuel Trim tables? (Fuel-> Advanced -> Trims -> Fuel Cylinder Trims)

Which wideband setup are you using?

Here is my map.
what is O2# feedback provide? never looked at it.

[mjannusch]

O2 Feedback adjusts your fuel settings on-the-fly to hit a target A/F ratio which is defined in the O2 Feedback Target map.

Looking at your map:

O2 #1 Gain is set to 0.98, O2 #2 Gain is set to 0.96. In general, I would expect these two values to be the same. Did you calibrate each of your O2 sensors and set the gain to make the EMS read the same voltage as your sensor controller is sending to the EMS?

Pickup Delay Comp is set to 50 uSec. For your 1997 VR4, it should be set to 130 uSec to properly compensate for the pickup delay of the hall-effect sensors on your car. Changing this will tend to dial in more timing advance though, so you should take out about 5 degrees of timing at higher RPM in your map. You may just want to leave it at 50 uSec, but beware that what the EMS is outputting for timing advance will not match with what you'll get in the real world. You will get less actual advance than what the EMS thinks it has. (Your 27.6 degrees advance at 6500 rpm is probably actually close to my 22 degrees at 6500 in reality).

You are running O2 Feedback with a rather lean target map. Everything below +4 psi is set to 14.7:1. 14.7:1 should be maybe up to -5.32 psi, and then it should linearly ramp to 11.5:1 at loads of say 10.31 psi. Your O2 Feedback is set to be active up to +4 psi and up to 4000 rpm, so anytime you are under that range your car is trying to run 14.7:1 A/F ratio and overriding your fuel adjustments.

I don't see anything immediately obvious as to why your O2's vary by so much. Are you certain that the front O2 sensor (front side of car) is connected to the O2 #1 input on the AEM, and the rear O2 sensor (towards firewall) is connected to the O2 #2 input on the AEM? If those are backwards, you are going to get some really funky A/F problems when O2 Feedback is active.

[slava]

Matt, thanks a lot for looking at the map.
1. The gains are set based on calibration so one was a little highter then the other to get 4v reading.
2. Pickup Delay comp, I thought 50m is what I should have. Though I did test with a timing light setting full ign map to 15 and got it stable through range of rpms ( i need to retest it ) but it this is the case i am good with ign right?
3. I think the lean upto 4psi is good, no issue, good gas mileage , no hesitation.
during cruising i am running 14-16afr.

4. I am pretty sure the front o2 is #1 but i need to verify it to be sure.

I know i had a problem with different reading before and switch channels first and got the same result (even on idle i am getting difference in 1-2afr). Then i actually switched o2sensors and result was the same so i concluded that it has something to do with air flow difference. 1-2RPM big difference in A/F, 2-5 almost identical 5-7 again difference. Weird problem.
I was wondering if somebody ran dual do they see any difference at all? I asked the question in other thread but yet to get a response.