I have heard lot of people recommend getting a new engine harness when using A AEM EMS, They say i got rid of a lot of issues with tuning. Has anyone had success with their old stock harness or should i just bit the bullet and buy a new one from tweek'd performance?
Do I need a new engine harness for my 7MGTE AEM EMS v1
- Thread starter 8T7supra
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Depends if your old one is in good shape or not. Especially the shielded wires to the CPS and knock sensors.
I have some log files from from my car would anyone be able to tell if their was an issue with the harness? I got my car tuned a few years back and it made 430 wheel but it never seem to run perfect all the time. some time it would run great but other its seemed like it was dropping a cylinder and would build boost very slowly and I am wonder if it could be an issue with the harness. i would just like to make sure its the harness before I drop $1000 on a new one.
Check to see if you are recording lots of timing sync errors, and check the knock data for big anomalies (the knock control on the V1 is pretty crap anyways though) Also make sure you are not using the stock igniter - see my writeup on using the DH61. It also helps to ground the case of the AEM ECU to the ground wires in the engine hardness to reduce interference.
When the car was tuned it had the stock ignitor but last summer i switched over to the DH61 and followed your write up. I am sure that I wired it correctly I triple checked it and made sure I didn't mix up the C2 and C3 wires. The car revs fine when its in neutral under no load but when their is a high load like in 5th gear in low RPM's in the 2000-3000 area it misses like crazy it wont even accelerate. I am wondering if that it due to noise from the cps or knock wires or if it just because it was tuned with multiplex and the tuner was trying compensate for it. I did read that grounding the case will help but i have not tried that yet and I am in the process of swapping the engine into a new shell that I got and am trying to decide if I need a new harness or not because now would be the time to do it. I am also wondering if its possible to just replace the knock sensor and cps wires on my current harness because those are really the only wires that should give me trouble. Here are some screen shots of my log files.
Turn off knock control temporarily and see if it goes away, and log timing sync errors to see if they are accumulating. having an error once in awhile (like 1 every minute or two) is normal. If that doesn't fix it (and you don't get lots of timing errors) it is not the harness. As long as you completely followed my software setup instructions, any fiddling from the multiplex setup was overwritten by the new dwell setup, and if it is firing on all cylinders the wiring is correct. I had an issue similar to what you are describing and narrowed it down to grounding issues.
Try grounding the EMS case to the grounding wires in the harness (just use a fork terminal under one of the screws) - that cleared up a lot of problems for me.
Try grounding the EMS case to the grounding wires in the harness (just use a fork terminal under one of the screws) - that cleared up a lot of problems for me.
OK thanks for the help. I plan on grounding everything when I swap the motor into my new shell so I am hoping that clear up a lot of issues. If it is the cps or knock sensor do you think replace the wires including the pins in the clips would solve the problem?