Stratocaster

So in other words, it can light the cell, but it can't tell you WTF happen after you shut the car down? So you have to have a laptop with you at all times to get the data?

RCR S2

There is a lot of engineering that goes into a stock ECU. They have to design it over wide range of driving styles, conditions, altitude, etc. It's more than just tuning it for fuel, timing, A/F ratios.

Diagnostics is much more advanced with the OEM ECU than you could program into the AEM.

For instance, it will set different DTC's depending on which cylinder is misfiring. It monitors your critical sensors to make sure they are working and will alert you if they aren't and potentially run the car in fail safe mode. AEM would take straight reading from a broken sensor and adjust it's fuel/timing map accordingly unless you know what logic to use and program it in there correctly. For every DTC, there is some logic behind it. Look at how many DTC's are available in the Service Manual.

Another example is long term fuel trim -- it can detect wear of sensors and automatically adjust over long periods of time.

700+s2000

I found out about the water temp today the hard way. i will be replacing the head gasket in a couple of weeks whe it arrives. So modefries is the only thing available at the moment to read the temp through the ems


Nick

Scorpion

OK my turn to add my understanding of the EMS.

The Temp gauge issue. The EMS has an output to drive the LED gauge, however the voltage that EMS puts out is not compatible with the temp gauge. Meaning (and these are just numbers..may not be actual values) to light 3 bars at 190* you need 250mV but at 190* the EMS is outputing 500mV. Modifers ECT driver corrects the voltage mismatch.

The self-tuning. Yes the ems has closed loop O2, but you have to have a good base tune to use it. It will not correct a 15:1 AF to a 12.5:1 AF. All it will do is add or remove fuel to a percentage you set. IE richen or lean the cell 5%. If your target AF is outside the perentage you set the EMS to correct for than you are not going to get it.
Knock control. If you trust the factory knock senors to tune then your car should be taken away from you. It is nothing more than a microphone that listens for detinitation, takes a db level and converts it to a voltage that is sent to the ECU/EMS. I have seen loud exhaustes throw a knock sensor out of wack.

These are the things that bug me about the EMS.

1. The calabrations for most of the factor sensors are off. AIT in a 100* garage read 60*...yeah right. The coolant temp is another taht is off. I thought I was overheating for the first week I put the thing in my car.

2. Lack of decent manuals and instuctions. It took me two months and a lot of searching on the EMS forums just to find out how to get control of the radiator fans. It should not be that hard.

3. Boost control. You have to set the wastegate duty cycle...how in the hell do you figure that out? Why not just set a desired boost pressure like every other EBC out there?!?!

OK so mine are what it can't do but they are just complaints. I still like the EMS and wouldn't ditch it for anything else.

AusS2000

I never understand posts like this. Yes it is the only thing available, and before it was the only thing there was nothing, and I doubt there will be anything else as it doess the job admirably.

Except of course you could just use an external gauge.

AusS2000

The instrument cluster expects a frequency not a voltage. I suspect when AEM (actually GEM in the UK) were making the 'S2000 specific EMS' they got to the ECT gauge and thought 'too hard'.

Prior to some saintly S2ki member instigating the ECT project there was no solution other than external gauges and setting the CEL to light at a certain temp.

AusS2000

LOL, I've been trying to nut out what a 'wastegate duty cycle' is myself. I'd love to see an AEM boost control for dummies thread.

Slows2k

:Cough: Aus :Cough:

AusS2000

I guess some credit should go to Modifry too.

Stratocaster

Now we just need to get him (Modifry) to make and interface that delviers ODBII