View Full Version : aem ems series 2 and ignition drift

08-19-2010, 10:56 PM
i have a series 2 aem ems(6620) on a s14 blacktop and i am having ignition drift when trying to sync the ignition. i have the replacement disc from aem and engine runs fine so it seems. but im getting an odd lean condition after about 30minutes of driving. no parameter is pulling fuel at all!! i can key-off and key-on and the problem goes away for about 5 minutes and returns. its gets so bad that i cant even drive it under light cruise its so lean.

if i rev the engine with the ignition locked at 15* timing , the timing still increases with rpm via the timing light and crank pully marks. i have even set my entire vaccum part of the ignition map to 15 degrees thinking it may be a software issue but the timing still increases with rpm. i have the timing light hooked up to the timing loop coming off the coil harness towards the back of the cylinder head.

so do you think its a bad CAS? are s13/s14/s15 CAS sensors the same? Could it be EMF causing a dirty cas signal in the harness?

things i have tried - cleaning the cas sensor with rubbing alcohol as well as the disc. verifing ignition/cas settings with other maps. checked for loose pins/bare wires in the harness. reloaded firmware(1v17) with aemtuner 2.0.

here is my cal file and a log of the lean issue that leads me think its a cas problem. trouble7-log shows the problem in action , trouble8-log was taken after the key was cycled after immediately after trouble7-log and the problem eventually comes back after a while of sitting parked and revving the engine.

i also have replaced fuel pumps too and its not a fuel delivery problem ,(mechanically)

here is a link to AEMs forum so that you can download my cal and log files.


08-23-2010, 08:26 AM
flip the ignition pickup lead over. you'll get indicated timing drift if you have the pickup lead on wrong.

go to ignition phasing options and increase/decrease pickup delay comp until you have no more drift. ONLY AFTER YOU try both directions on the ignition pickup during timing check. if that doesnt do anything, change the jumper inside the box for whatever coil output youre using. look for JPC # and change the jumper setting. ive had cars run but have horrible timing drift and the coil edge triggers (jpc ) were setup wrong

08-23-2010, 03:25 PM
the drift is pretty significant and its linear with rpm. it can go as high (guesstimating) 30-40 degrees. i tried changing the ignition settings in the software to leading too training and vice-verse but it stays the same. ill try the pick up again. also gonna out a plug wire in the coil and try it that way too.

Do the jumpers have to be changed in the box if the box is application specific? IE its not a universal ems, but one made specifically for the s14 blacktop?

08-23-2010, 09:24 PM
maybe the factory got it wrong or its a used box and you didnt know it. i'd call henry at aem electronics support and ask factory jumper settings for your box.

i can tell you for a fact that just today i got a used 1040 box for a honda that was on one of our customers cars sold to another customer without telling me. baddddd timing drift with stock distributor. jumpers were setup wrong on coil1. changed to factory default and whalla

i try to stay away from aem questions when it involves lack of tuning knowledge. but i think you are in a hardware problem. check those and let me/us know. or i could be wrong since it is on the internets

08-24-2010, 07:57 PM
well the AEM box is a series 2 box. I pre-ordered it from AEM months before release and its the 5th one made serial number 6620-0005. i hope no has used it previously. thanks for the reply by the way. i have no replies on AEMS forum. i really appreciate the help.

The tech at AEM just said its possibly a bad CAS if it has ignition drift.

just started back to school so time is tight.