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Last seen: 9 months 3 weeks ago
Joined: 08/08/2019 - 07:52
AEM EMS V1 reading buzzing sensor values



In process of tuning my Honda S200 TTS Supercharged with an experimented S2000 tuner, I am having a strange issue : the AEM EMS V1 is reading very buzzing values on all the sensors/inputs !

My car setup is:
Honda S2000 AP1 MY 2002 UK RHD
F20C MY2004 engine
AEM EMS Series 1 (30-1052U)
TTS Performance C30-94 kit
RC Engineering 750 cc injectors (SH4-0750 - 12 ohm)
Walbro 255 fuel pump (oem wiring)
Fresh NGK BKR8E-11 spark plugs (resistor) with oem coils
AEM UEGO 30-4110 with LSU 4.9 - 0-5v output of the UEGO gauge connected to the Lambda#2 pin of the AEM EMS
Prosport oil temperature + pressure gauges (sensors on sandwich plate; sensors grounded in engine bay)
Those 3 gauges are powered by the "ing on" free pin on the fusebox, with a 10amp fuse, and grounded to the existing ground point near the fusebox where already several things are grounded

Now, the facts:

  1. Before installing all this stuff, my car had no visible electrical problem. But I had no EMS to see if values were buzzing or not...
  2. Now with all that stuff:
    1. values in EMS are constantly buzzing/jumping
    2. when driving the car, I sometimes have CELs flashing: the green key and the orange engine. See this vid: https://www.youtube.com/watch?time_continue=28&v=9bhlNgQnrRc
      In the tune, the LS10 output (engine CEL) is configured to light above 205F: with values buzzing, this can be a reason for it to light... (I saw sometimes 205+ values in the logs due to buzzing).

      But for the green key, I have no idea! What is the output LS number ?

  3. All that parts (SC kit, EMS, walbro, injectors) were, 1 year ago, installed on another S2000 AP1 MY03 UK , except:
    1. spark plugs that were different (don't know the model),
    2. UEGO gauge output that was not connected to the EMS,
    3. oil sensors that were not installed (but gauges were... useless  ).
    4. The EMS tune was different: it was made by a french tuner. Now the actual one is completely new and being made by the new tuner.
  4. I drove this previous car for about 1 month and I freduently noticed those same CELs flashing , sometimes at WOT, sometimes cruising on highway at 85mph 6th gear... never in the same conditions in fact.
    I did not connect to EMS on this previous car so I can't say if values were buzzing.

Does anybody have any idea of what can be happening ? 

We have thought of electrical Gremlins, but the fact that CELs were already flashing on the previous car makes me think it is not a ground problem on my car.
To be sure of that:

  • I will change the (fresh new) spark plugs for my old NGK PFR7G just to check if the new ones are not creating gremlins.
  • I will remove all my gauges power and ground wirings, just to check if the new ones are not creating gremlins.

And the question I really fear : do you think the problem can be inside my EMS ? 

For information, here is an example of my buzzing logs during a pull:

Thanks for your help !

Last seen: 9 months 3 weeks ago
Joined: 08/08/2019 - 07:52
Here is a video of what is

Here is a video of what is happening. First only with ignition on, and then with engine started.
We can see values like battery, throttle, boost, air temp or coolant temp constantly changing.

Last seen: 9 months 3 weeks ago
Joined: 08/08/2019 - 07:52
News: I tried to put mys EMS

News: I tried to put mys EMS v1 in another s2000: the values are still buzzing. I tried to put another EMS v2 in my s2000: the values are not buzzing, or very very very little, like throttle changing of 0,1% which I think is normal. It really looks like my EMS is the problem then... AEM staff? Have you ever heard of such a problem? Any idea? A component inside the EMS could be damaged ? Thanks