AEM Help needed

[elijahcole92]

Hey guys, so just recently got my car back running after finding out the stock ecu went back. I replaced it with a used 30-1042 series 1 version 2 aem ems. Using the provided aem basemap i synced the throttle and ignition and got the car started. However, i'm having two major issues.

1. Once the car runs and gets warmed up it begins to pop and backfire and eventually die, if i let it cool down then i can crank it up and it will run fine for a little while until warm again.

2. My aem wideband 30-4100 is not calibrated correctly between the gauge reading and the ems itself. I originally tried the ground point under the radio, but it was way off even after adjusting the "gain" setting as high as it would go. Then i tried grouding it directly to the battery and the same thing. Then i moved the ground to B2 on the ECU which is "LG2 Chassis Ground" and on this ground it calibrates correctly and reads the right afr and voltage however, it creates noise. I can actually hear it buzzing and it also makes my throttle reading on the aem jump up and down a little.

My car has all the stock grounds as far as i know, do i need to add more or what?

 

[JD Cross]

When it comes to electricity I'm a Neanderthal so I empathize with all the work you've had to do so far with your engine problems.
This may sound stupid but why don't you just get a good replacement OEM ECU, put it in, and drive your car?

 

[elijahcole92]

Well i'm planning on running a used ctsc system i got that came with an fic, but i sold the fic to buy the ems since i had narrowed down my ecu was the problem and i had heard bad things about fic tuning on the 91-94 obd1 setups.

 

[Old Guy]

I don't fiddle with my NSX; however, to satisfy my urge to make things worse than stock, I have a Resto-mod car which I have retrofitted with Megasquirt. The general rule is that both the O2 sensor heater and controller ground (and gauge ground if you have one) should share a common ground point with the ECU and all of its sensors. I don't know where the NSX ECU ground is; but, that would be the primo location for grounding the O2 controller and its peripherals. On my resto-mod I ground all the ECU and O2 stuff on a common stud on the engine intake manifold. Do not ground the O2 controller by tapping into one of the wires from the ECU that goes to the ground connection point. Use a separate wire and ground the O2 stuff directly at the ground point on the body (or engine or wherever the ECU is grounded).

When you say you can hear buzzing, I presume that you mean that the wideband controller is buzzing? That is strange; however, I am using the Innovate product so I can't comment on the AEM stuff. When you say that the throttle reading is jumping up and down, I presume that this is the throttle position measurement that you are reading on your laptop? If by chance you happened to connect your O2 sensor ground into the ground wire for the TPS, the current associated with the O2 controller is coupled into the TPS and will cause the ECU to see voltage changes that are not due to the TPS. This is why it is super critical that every device associated with the fuel injection have its own separate ground wire which runs to a common ground point on the body or engine.

If you have a fuel map for your AEM that you think is fairly good, can you disconnect your wideband controller and see if that improves engine operation (don't go trying anything wild if it does)? I suspect that you will need to update the AEM ECU settings to let it know that you are running without an O2 sensor. The advantage of this is that it allows you to determine whether your engine problems are in the AEM set up or whether the O2 controller is screwing things up. Narrowing down the source of the problem helps. Leaving the ECU in open loop should not be a big deal. Most ECUs are in open loop during start up because they are adding extra fuel to facilitate start up operation and are running below the target AFRs. In fact , it could be that because your engine problems start after the car has warmed up, the problem is occurring when the AEM goes from open loop to closed loop control and the O2 feedback signal is screwing things up good.

As a caveat, I know squat about AEM so take these observations with the appropriate level of caution!

 

[elijahcole92]

Well using the service manual i found most of the cars ground locations, that i cleaned and tightened. Now with the wideband spliced into B2 on the ECU which is "LG2 Chassis Ground" it reads correctly and it doesn't seem to be affecting any of the other sensors, as shown through AEM Pro. I didn't have o2 feedback setup when it did that, but i drove it around a little yesterday and it drove fine for a basemap atleast, though i did do some cruise area fuel tuning.

Does anyone have a ctsc hi boost map they would like to share so i can get started with my ctsc?