Anyone running the AEM EMS-4 on their 4efte/5efte with the stock ignition?


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Good day all,

Is anyone running the AEM EMS-4 on their 4efte/5efte with the stock ignition (dizzy/distributor)? I am asking because I seem to have "noise" on the cam input which cause the car to sputter & jerk between 3k-4k rpm. Once you clear this area, the car is smooth. I logged and reviewed and it's not lean in the specified area.

I've read you can use resistor to clean this up so the car can rev out clean but I have not seen a write up or pics on how to do this. Have anyone installed this EMS before? If yes, did you all have similar problem and how did you solve it.

Any information would be appreciated.

Kind regards,



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Alot of ECU's struggle with the factory reluctor triggers due to the low voltage they put out - this is why if you look at an rpm vs time plot the data line is never a nice straight line and does dither a fair bit. I've got examples somewhere. Most ecus can filter and smooth these out but some are terrible at it. Personally I'd be looking at the arming voltages and making sure the threshold isn't too high through the 3-4k range for starters, ie the ecu is ignoring part of the trigger signal because the reluctor output voltage is right on or partially lower than the threshold. Link ecu's have an internal scope so its easy to check this, unsure if AEM EMS have that ability as I'm not a fan of them. As an example of the threshold voltages, a common issue i've come across in various reluctor based setups is hard starting due to having say a 0.5v threshold for the 0-500rpm range - ie the ecu ignores any reluctor output voltage less than 0.5v. If the triggering wheel is old or dirty etc I've had to set these down to 0.2v to get them to start. Worth looking at for starters anyway. Good luck.

I've not tried resistors, but i'd be interested to know if that works as it would lower voltage which would make the issue worse?


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Aplogies to thread jack people, but thought @Stu- maybe able to help with a similar issue I'm having. I recently fitted a ME221 ECU to my GT. However after trying 4 different base maps, I simply can't get the car to start.

After doing a bit of research online, I saw that it could be caused by a trigger/dizzy issue?


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I haven't used their software but I'm downloading it now so will have a look.
Can you attach your base tune to here for me to look at?
Is it a new ecu or come from a running car?

Ive loaded the software, have to used the scope to check your getting trigger signals?
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Thanks a lot. I bought it used and was previously running on a hybrid ct9 setup.
I can't seem to attach the base maps here on the site. Can I email them over to you or send them via facebook?

ME contacted me earlier this evening and said:

please check the hardware install guide. The distributors can give a noisy signal which is known about across a lot of systems but there is a workaround. The map that was sent above assumes that you have done this mod."

Sorry STu, I'm a noob at this. How would I check to see if I am getting trigger signals, would it come up on the laptop screen as I'm trying to start the car?
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Im away at the moment and don't have my laptop to look at the software, but I did see a trigger scope so best bet is to start the scope up and crank the engine over and you should see the wave form produced.