Hi comp with ITBs on AEM EMS 4 by ethergore2

6 minute(s) of a 30 minute read

I'm using expandable tubing. I'm not sure how well it does yet since the car is not driving. It's been fairly easy to work with and I think it looks great. I can't recall the temp rating on it but since its got holes in it I'm not relying in it doing much other than hold wires together. You should be able to find it at any electronics store.

6-2-2013

Everything works and the engine is running ok but I could really use some kind of base fuel map. 

Do you know of anywhere that I could download a base map from ?

I don't have one to give you at the moment since mine isn't done. Is your setup even similar? If your car is running that might be as close as my map may gets you anyways.

5-20-2015

So its been forever since I have added to this thread but my build continues. To make a long story short the AEM EMS-4 never worked out. The signal that the 4agze CAS puts out is too dirty for this "simpler" ecu. Some of their higher end ecus have filtering to help get meaningful data from the CAS but not this one. I could have kept the EMS-4 and used a crank mounted trigger wheel but I really wanted to keep the CAS. In order to do this I ended up switching ECUs and using VEMS to run my car. My choice for this ecu was due to convenience since Grant, the guy helping me with wiring, was comfortable with this setup. In addition, Grant is friends with one of the developers of VEMS so we had some good help when needed.

To get the trigger working even on the VEMS we had to add some filtering to clean up the system. With that said we could have possibly got this to work with the AEM but I doubt it. According to their tech support, the EMS-4 really wants to see the more modern square wave versus the older sinusoidal (curved) wave that the 4agze CAS puts out. Another benefit to the VEMS is that is can use rising edge or falling edge signal so there is no need to rewire the CAS.

Despite getting a good trigger signal we still had lots of trouble getting a good setup. We originally tried to run speed density instead of alpha N due to its ease of setup and adaptability to small changes if needed. We tried really hard to get this to work and spent a lot of time trying to change things to get it to run right. Ultimately there is no real good way to get a motor with large cams and ITBs to run on speed density. MegaSquirt comes close by using their ITB mode which is a blend of Alpha N and Speed density and, in retrospect, would be my recommendation to anyone running ITBs with large cams.

A little more about speed density with this setup is that it could work if there was a software developed to run it on MegaSquirt or any other system. I'm writing it here because no one else would listen to me on the Vems site and MegaSquirt already has their own method and I am not a member of their forum. The problem with running speed density with large cams and ITBs is the fact that it cannot compensate for barometric (altitude) change. There is barometric correction on vems and MegaSquirt but it is designed to be used with Alpha N. What is does is add a fixed amount of additional fuel based on the altitude change. It basically works exactly like warmup enrichment. With speed density what is needed is a correction to load settings. As the car increases in altitude the map value decreases. This places you in a lower load cell row and causes you to run lean, even with a small change in altitude (like 2 kpa). A simple fix would be to correct this value as the kpa drops. This would keep you in the correct load/rpm cells and the car would run correctly. This is proven to work as you correct the base kpa in ecu calibrations. 

So when my car was tuned well at sea level, it would run great at sea level. As soon as I got the car back to my house (4 kpa higher than sea level) the car would be lean to the point it could not run. This was a big shock as I found this out taking it off the trailer after a long drive. For a temporary fix I simply added 4 kpa to the calibration of the sensor. This put the car back into the correct load cell and the car ran perfect. This shows that a load based baro correction could have cured the problem. Theoretically there would still need to be additional fuel enrichment on top of this but that could be done along with the load correction.

Again, I know this may not be the correct audience for this information but I am hoping those familiar with tuning can understand and have some input to my idea. Maybe someone familiar with MegaSquirt will even attempt this which would be awesome.

Since I could not get speed density to work we ended up switching to Alpha N. We switched the settings and the car fired right up from the old speed density settings. From there we used auto tune and backed off the timing. At that point the car basically tuned itself. Baro correction is still needed for altitude change but it works well. At this point my car is scheduled to go to the dyno this Saturday. That is why I was motivated to post again. Sorry for the long winded post but it really helps me keep motivated on a project that has been going on this long. At times I really wanted to give up but when I look back I am amazed about how much I have learned about fuel management systems.

I will put up some dyno numbers after this Saturday if everything goes to plan. Ill also add some video too.

With that said, who can guess what my HP/Tq will be? To jog your memory the motor is:

High comp

Decked block/head

TRD thin head gasket

Most badass headers (YSPL) (K1 Motors)

Silvertop ITBs with ITG filter

Crower 280 degree cams

3 angle valve job

.5 over pistons

Light weight drive train (fly and drive shaft)

I'm hoping 150 to the wheel minimum. Your thoughts?