Excessive AEM uego sweep

[Turbo Cary]

I've been having some issues as of late with my AEM gauge sweeping a bit. Here is my current setup

 

88 secondary injector now as primary

12800cc secondary

Maf Translator

SAFC2

Stock ignition system

Mazda TPS conversion

TD06 16G turbo

2 1/4" hard pipes

4" intercooler

3" dp back exhaust

 

My wideband seems to sweep from 13.5-16 while cruising or at idle. I have the wideband set to P04 and wired into the factory ECU to mimic the factory sensor

 

At wot it is fine. On the rich side around 10.2-10.8 but I haven't had a chance to get it on a dyno to really tune wot.

 

Also it is a new O2 sensor I just put in a few days ago. The old one I suspected of being bad so I went ahead and got a new one.

 

Anyone have any thoughts? Every AEM I have seen tends to sweep only .2-.5 on the gauge and not rapidly like a narrow band

[scott87star]

It's supposed to sweep that much in closed loop, but you shouldn't be in closed loop at idle. Check the nose switch, likely its ground signal isn't making it to the ECU to tell the ECU that it should be idling. But again the sweep in cruise is normal, since the old narrow band sensors were only accurate at stoich or 14.7 AFR the ECU keeps sweeping the mixture rich and lean centered on stoich. It was the only accurate control scheme.

[Turbo Cary]

Hey dude thanks a lot. I checked continuity at the MPS and there was none. I tried to adjust the sas and see if there was a difference (I rebuilt my throttle body a while ago) but it didn't change.

 

I had to wind the throttle spring one more turn which made it keep tension against the sas. After that I had continuity every time the throttle contacted idle.

 

Did the idle learn/tps reset and now it slowly fluctuates between 14.3-15.3 at idle.

[StarquestRescue]

If you are not running a cat, i would just disconnect the narrow band input to the ecu. Then you can tune the afr where you want it and be rid of the wide swings. The problem is that the ecu does not know your primary is 80% bigger and appiys the same 02 correction it would for the stock injectors and over corrects.

 

Winter is not user freindy to air flow correction tuning. I would lean mine out 10-15 percent before start up, and then put the fuel back as needed.

 

Under moderate acceleration the stock system will stay in closed loop to about 800 hz of airflow. Or about 3 -4 psi. A set up like yours could stay in closed loop to maybe 8 psi, Another reason to eliminate the wide afr swings.

[speedyquest]

Starquest, you really suggest not running an A/F signal to the ecu? What exactly is the reason for that? I would have assumed that would be used in some kind of calculations for the car. How else would it know what is going on fuel wise?

 

EDIT: I re-read the thread again and I see what you mean about the size of injector. But still I'm not sure I'm fully understanding how getting rid of the O2 input would be good.

Edited November 12, 2015 by speedyquest

[Turbo Cary]

Starquest, you really suggest not running an A/F signal to the ecu? What exactly is the reason for that? I would have assumed that would be used in some kind of calculations for the car. How else would it know what is going on fuel wise?

 

EDIT: I re-read the thread again and I see what you mean about the size of injector. But still I'm not sure I'm fully understanding how getting rid of the O2 input would be good.

 

I had the same question but think of it this way. The ECU in open loop runs on specific parameters. If you eliminate the O2 input it keeps the ecu in open loop. Basically I would just have to tune my car based on the stock programming and not ECU compensation.

[speedyquest]

Its an interesting thought... but doesn't that open you up to issues with stepping much further and further from what that base maps does and assumes to control the engine? I mean maybe my thought is wrong but I've always looked at open loop as a bit of an idle "tune" and closed loop as a dynamic "tune". Definitely correct me if I'm wrong because frankly this kind of pushes into other aspects of modifications I was contemplating with my car.

[Turbo Cary]

Speedy, I am running a SAFC 2 which allows me three modes of modifying. You actually only adjust two but the third is calculated when adjusting those. You have your low, mid and high adjustments. You set your throttle point as to where you want that stage of map to begin and end.

 

For example my low is set at 20%. Anything below 20% follows the low adjustments. My high is set at 32% so anything above 32% follows the high map. The mid is the halfway point between the two so between 20 and 32% it is the mid range.

 

By having the ecu not receive a O2 signal it will stay in open loop. Then I'd have to tune it out starting with low range. Its gonna run stupid rich cause the ecu doesn't know what's going on. Then after it is settled I'd run my wot tuning. Why skip the mid? Unless I'm starting to tip lean on wot acceleration I can easily readjust the low to compensate.

 

Of course this is gonna make things a little more difficult with temp changes outside. With the ecu reading the O2 it corrects in real time. I'd have to make tuning adjustments on a more regular basis not using an O2 input to the ECU.

 

I also have a Maf Translator which is basically baseline settings. Running without an O2 input to the ECU running just a translator is pretty much impossible. You can't get the fine tuning adjustments needed.

[TexasQuest]

This may not have much relevance to your situation but I've heard in the past that TBI cars usually have an excessive amount of wideband gauge movement.