Timing errors with AEM EMS-4 (crank sensor)
03-23-2013, 04:59 PM
#1
Timing errors with AEM EMS-4 (crank sensor)
Car: 1994 w/ VVT Swap
ECU: AEM EMS-4 Series 2
I'm getting timing errors all over the place and the logs point to the crank sensor picking up teeth that aren't there, this causes a nice jolt as the car misses and has been a pain in my ***. AEM techs have advised me to put a pull-down resistor on the signal wire, and then an RC circuit in an attempt to filter it; however, still getting timing errors and the RC values are getting ridiculous (lol .5 milliseconds).
I am curious if I should just do Abe's NB Crank circuit (Schmitt trigger) and then just **** with the AEM to make it either rising or falling edge. I have a track day that I'm trying to make in 2 weeks, but I've been ******* around with this timing error **** for almost a month.
Fun aside: the IAC also seems to be wrecking havoc (with the IAC plugged in, I get way more timing errors), so I've just unscrewed the idle screw and I'll just let it idle high.
I'll try to post with any requested information.
ECU: AEM EMS-4 Series 2
I'm getting timing errors all over the place and the logs point to the crank sensor picking up teeth that aren't there, this causes a nice jolt as the car misses and has been a pain in my ***. AEM techs have advised me to put a pull-down resistor on the signal wire, and then an RC circuit in an attempt to filter it; however, still getting timing errors and the RC values are getting ridiculous (lol .5 milliseconds).
I am curious if I should just do Abe's NB Crank circuit (Schmitt trigger) and then just **** with the AEM to make it either rising or falling edge. I have a track day that I'm trying to make in 2 weeks, but I've been ******* around with this timing error **** for almost a month.
Fun aside: the IAC also seems to be wrecking havoc (with the IAC plugged in, I get way more timing errors), so I've just unscrewed the idle screw and I'll just let it idle high.
I'll try to post with any requested information.
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03-25-2013, 04:56 PM
#7
Just moved it over to the valve cover, still getting a shitload of timing errors with the IAC plugged in. I do get timing errors with the IAC unplugged; however, it seems like it isn't as violent; I just cranked the idle speed up to 1200rpm on the TB in the mean time.
Right now I'm running 16awg shielded to both the cam and crank from the factory 94 wiring and the shield drain is connected to the valve cover (like I've said about 5 times in this post) currently.
I have some 18awg, 3 twisted pair shielded cable I can use. Tie the +12V and GND on one pair, and then put the signal and a spliced GND to another twisted pair; tie the shield drain back to the valve cover.
Right now I'm running 16awg shielded to both the cam and crank from the factory 94 wiring and the shield drain is connected to the valve cover (like I've said about 5 times in this post) currently.
I have some 18awg, 3 twisted pair shielded cable I can use. Tie the +12V and GND on one pair, and then put the signal and a spliced GND to another twisted pair; tie the shield drain back to the valve cover.
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03-25-2013, 08:59 PM
#13
Isnt one of the sensors that came on VVT engines known to have problems (cam/crank) or was that the 99-00? You have me worring because I just wired mine in, and used the stock NA cas wiring. The NA cas wiring is not shielded and the wire I used to extend the crank sensor wiring isnt either. I didn't think shielding was really required with hall effect sensors.
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03-29-2013, 07:18 AM
#15
I'm battling the exact same issue as you right now! I've been battling the timing issues for a few weeks now. We should compare notes...
I have a 95 car with 99 head and I've spliced in the wires exactly like you did. I used to have a **** ton of timing errors. I flashed my firmware to v24 and it actually got a lot better but I still have timing errors every few seconds. According to my logs the ems seems to be picking up extra crank teeth where there arent any (sharp drops in crank tooth period time). I thhought that might be due to noise so I've been all up and down the chassis searching for faulty grounds or ground loops and I can't find any obvious error. I'm in the process of running shielded wire all the way back to the ecu for cam and crank, but somehow I doubt that will fix it. So far the ems4 seems extremely finicky with these inputs.
What is this Schmidt circuit mod? I may have to try it as well...
I have a 95 car with 99 head and I've spliced in the wires exactly like you did. I used to have a **** ton of timing errors. I flashed my firmware to v24 and it actually got a lot better but I still have timing errors every few seconds. According to my logs the ems seems to be picking up extra crank teeth where there arent any (sharp drops in crank tooth period time). I thhought that might be due to noise so I've been all up and down the chassis searching for faulty grounds or ground loops and I can't find any obvious error. I'm in the process of running shielded wire all the way back to the ecu for cam and crank, but somehow I doubt that will fix it. So far the ems4 seems extremely finicky with these inputs.
What is this Schmidt circuit mod? I may have to try it as well...
Last edited by reddragon128; 03-29-2013 at 07:28 AM.
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