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Old 04-15-2010, 03:53 PM   #1
Brydon
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Default Why can the AEM EMS not pick up subaru cam/crank signals correctly?

So I thought I would post this on nasioc since there is a bunch of bright and willing to help people here. All of this is on a AEM EMS plug n play for the 02-05 WRX. I've had the AEM EMS for 4 years now with no issues.

Now my problem, I broke a rod in my car so I rebuilt the engine and added only two things to my setup. 1) AEM injector driver and RC1200 injectors. 2) Aeromotive A1000 pump with all -an lines and a surge tank. Everything else was from the setup before. I've always gave a few of my friends crap because they had this timing waver around 3000rpms and mine was rock solid. But now the car wont even stay running because the cam and crank sensors cannot pickup a correct signal anywhere. TP2ER and Crank time gets more solid above 2000rpms but basically the cam signal is all over the place by jumps of 50000um and the crank moves by about 1000um. Before the 2 additions everything was like a rock.

What I've done:
Changed around cam and crank from rising to falling edges. Every combo of this to see if it gets better. Both rising is the best but still is not good. cam is by far the worst.

Tried sync ignore which sometimes works ok but the timing is not reliable. As verified with a timing light. It sticks to a timing but the AEM will move the timing if you shut the car off then start it again

Changed the air gaps on the cam and crank sensors to see if I could get rid of all this missing. I can make it a little better but problem is still there.

Moved the grounding of the intake manifold to chassis around which helped when the cam/crank ground is on the opposite side of the body then the AEM injector driver. It misses a whole lot less but still is not right.

Changed between 5 different cam and crank sensors. Makes no difference.

Tried V1.11 and V1.19 firmware but there is no difference.

Tuned the stock ECU to idle and run and there is no timing issue and it idles like a rock

The issue is all in the AEM. So why?

My next step is part out because I am sick of screwing around with the AEM EMS. I'm sure a hydra would work better but I'm much more use to the AEM and don't feel like wasting another $2000 to fix a silly problem.

Rough notes from above: AEM EMS has a bad miss do to cam and crank signal errors. Stock ecu does not have the issue. Moving the grounds away from the injector driver helped the most.
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Old 04-17-2010, 09:26 AM   #2
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Aftermarket computers and electronics in general do not have OEM-grade noise filtering. That's why the grounding and shielding are making such a difference. This is not an AEM EMS specific problem, Haltechs are notorious for crank trigger issues.

If you can't figure out the shielding, you need to be suspicious of the injector driver box causing electrical noise. Try removing it and using the AEM's built-in saturated drivers. The RC 1200's are the old pintle style injectors, and they do benefit from peak-and-hold drivers. But that's really not necessary. They will still run ok with saturated drivers, just use a 6 ohm 10 watt resistor in-line http://www.mouser.com/search/Product...key71-RH10-6.0

This is the same resistance as the Mazda OEM resistor box pictured here: . Some people will tell you to run 10 ohm resistors, but this will result in slower injector response, although how much you notice it just depends on the application.

Some older cars came with low impedence injectors and peak-and-hold drivers from the factory, like Jspec 4A-GE Toyota engines. But most older cars with pintle-type low impedence injectors ran them saturated with a resistor box. Cars like that include late 80s Hondas, twin turbo 3000GT/Stealth models, and early fuel injected Rx-7's.

Last edited by arghx7; 04-17-2010 at 11:28 AM.
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Old 04-17-2010, 09:40 AM   #3
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Old 04-17-2010, 10:57 PM   #4
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Thanks for the reply.. Out of everyone I've talked to you have been the most helpful. I'm now super confident that the injector driver is causing enough noise to cause my problem. I borrowed a cheap O'scope and looked at the signals themselves (cam/crank) and they look clean. So I decided to help the AEM out by using 4 gauge wire to ground the fuel pump and injector driver to the chassis. I also made sure all of these grounds are short and not grounded at common points. Making the chassis a filter of sorts. Then I shaved the brackets on the cam and crank down to decrease the signal size which hopefully decreases the noise pickup as well. Then I cleaned every connector with electronic parts cleaner and put dielectric grease on the connectors. This seems to have helped a ton but when I log the issue is still slightly there.

I would like to keep the injector driver because I will be going to larger injectors after break-in. So unless all else fails then I will be trying to keep it in. In the AEM I set the cam and crank sensors how the WRX wizard sets them up and started the car up. It actually ran and idled better but the cam sensor seems to still jump every once in awhile. I then set the cam to rising edge instead of falling edge and it would idle almost perfect with a small miss every 5 seconds or so. I then set sync ignore to 500 rpms and went for a drive. It drives great and has no issue up to 5000rpms. The car also now falls back down to idle and can idle as low as 700rpms smoothly with 272/272 cams. About 1000rpms seems to be the best for recovery and idle. This is not the best solution, as I wish I could have the cam and crank signals set like factory but it appears that this will be tunable. I can at least break the motor in and get it under some boost.

I will let everyone know my findings. My other option was to remake the whole harness which would probably work the best but the labor would take a long time and I want to get to the track as quick as possible.

Thanks Again
Brydon

Quote:
Originally Posted by arghx7 View Post
Aftermarket computers and electronics in general do not have OEM-grade noise filtering. That's why the grounding and shielding are making such a difference. This is not an AEM EMS specific problem, Haltechs are notorious for crank trigger issues.

If you can't figure out the shielding, you need to be suspicious of the injector driver box causing electrical noise. Try removing it and using the AEM's built-in saturated drivers. The RC 1200's are the old pintle style injectors, and they do benefit from peak-and-hold drivers. But that's really not necessary. They will still run ok with saturated drivers, just use a 6 ohm 10 watt resistor in-line http://www.mouser.com/search/Product...key71-RH10-6.0

This is the same resistance as the Mazda OEM resistor box pictured here: . Some people will tell you to run 10 ohm resistors, but this will result in slower injector response, although how much you notice it just depends on the application.

Some older cars came with low impedence injectors and peak-and-hold drivers from the factory, like Jspec 4A-GE Toyota engines. But most older cars with pintle-type low impedence injectors ran them saturated with a resistor box. Cars like that include late 80s Hondas, twin turbo 3000GT/Stealth models, and early fuel injected Rx-7's.
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Old 04-19-2010, 05:10 PM   #5
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interesting.. i have read about a tendency for timing to drift in other applications at times.

Time to try a Hydra or Vipec perhaps?
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Old 04-19-2010, 08:13 PM   #6
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Quote:
Originally Posted by jigga View Post
interesting.. i have read about a tendency for timing to drift in other applications at times.

Time to try a Hydra or Vipec perhaps?
I've known many people that have a little drift around 3000prms. But generally this can be solved by good grounding and trimming the crank sensor down. My issue was just crazy. Apparently my combination of parts doesn't make the AEM happy.

I've yet to hear of any issues with Hydra and I have no experience with Vipec. I do however prefer the AEM software largely over the Hydra. And at this point dumping another $2000 into EMS seems like a waste.
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Old 04-19-2010, 08:24 PM   #7
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lol....Join my club... I too am mulling over whether to drop another load yet again...

Have you tried adjusting the sensitivity values for the cam sensor in the AEM software?
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Old 04-19-2010, 08:27 PM   #8
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Check Innovative Tuning's blog in the vendor announcements section... they seemed to have someone on there with a RB26 powered BMW who had what appears to be a similar issue as you.. Not sure if it's the same issue though.. Related to triggering and timing moving about.

They had a more drastic solution to the issue though..
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Old 04-19-2010, 10:54 PM   #9
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Originally Posted by jigga View Post
lol....Join my club... I too am mulling over whether to drop another load yet again...

Have you tried adjusting the sensitivity values for the cam sensor in the AEM software?
Yes, if you mean the low/high sensitivity values but it actually runs better on Low sensitivity. I also dropped the tooth min time below the spike I'm seeing in T2PER logs. That makes the timing solid it just straight misses when it spikes. So basically the same effect.

Innovative Tuning seemed to have a similar problem on several cars but I didn't see the solution to them. Maybe I missed it. The funny thing about there o'scope findings are that really there is nothing wrong with the signal. Nothing that should cause a 60 degree jump. I think the issue is related to high frequency noise in the AEM but I'm not sure a good way to filter it. i think I would need more information from AEM about how there system works. Or I can always open up the box and start looking around.
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Old 04-20-2010, 09:13 AM   #10
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Quote:
Originally Posted by Brydon View Post
Yes, if you mean the low/high sensitivity values but it actually runs better on Low sensitivity. I also dropped the tooth min time below the spike I'm seeing in T2PER logs. That makes the timing solid it just straight misses when it spikes. So basically the same effect.

Innovative Tuning seemed to have a similar problem on several cars but I didn't see the solution to them. Maybe I missed it. The funny thing about there o'scope findings are that really there is nothing wrong with the signal. Nothing that should cause a 60 degree jump. I think the issue is related to high frequency noise in the AEM but I'm not sure a good way to filter it. i think I would need more information from AEM about how there system works. Or I can always open up the box and start looking around.
Solution in the case of the BMW was to swap to a Vipec ems. Seems to have worked.

Perhaps AEM themselves might have a few ideas for you? The thing I don't like about the AEM is how finicky it can be at times. If the map isn't getting corrupted, it's the EMS itself that isn't happy about something. Very picky customers...

Or perhaps send it in to get checked over?

How do you plan on proceeding?
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Old 04-20-2010, 11:19 PM   #11
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Quote:
Originally Posted by jigga View Post
Solution in the case of the BMW was to swap to a Vipec ems. Seems to have worked.

Perhaps AEM themselves might have a few ideas for you? The thing I don't like about the AEM is how finicky it can be at times. If the map isn't getting corrupted, it's the EMS itself that isn't happy about something. Very picky customers...

Or perhaps send it in to get checked over?

How do you plan on proceeding?
AEM seems to refuse that there is an issue with the AEM even though there is dozens of cars with the same issue. I however have not called them directly about the issue. But many have with no success. It appears that any re-engineering will have to be done by the end user.

Luckily I have two cars that run WRX engines so I popped the AEM in my daily driver and the car runs great. No missing. But the AEM literally ran great for 4 years in this car before I decided to change a few things.

As for proceeding, I think I will break the car in first before making any major decisions. After re grounding and shaving the sensors and some software magic it appears to run without missing or timing drift so I hope I can run the car like this but if I can then I will probably redesign the entire wiring harness and see if that solves the issue. If all that fails then I'll move onto a Hydra or ViPec (not sure of cost of that) but I would really like to avoid having a $2000 paper weight laying around.
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Old 04-21-2010, 02:39 AM   #12
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Quote:
I would like to keep the injector driver because I will be going to larger injectors after break-in. So unless all else fails then I will be trying to keep it in.
In non-Subaru applications I have run 160lb/1680cc Bosch injectors with saturated drivers and 6 ohm resistors. It's not as big of a deal as you would think. But you did pay money for that box and I understand that you want to try and make it work.

also, I believe the new v2 AEM box has built-in peak-and-hold drivers

Last edited by arghx7; 04-21-2010 at 02:44 AM.
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Old 04-21-2010, 05:34 AM   #13
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Quote:
Originally Posted by arghx7 View Post
In non-Subaru applications I have run 160lb/1680cc Bosch injectors with saturated drivers and 6 ohm resistors. It's not as big of a deal as you would think. But you did pay money for that box and I understand that you want to try and make it work.

also, I believe the new v2 AEM box has built-in peak-and-hold drivers
The AEM V1 doesn't drive those injectors very well at all with a resistor pack in tow.

WOT is fine, but for anything requiring finesse, they are rather jerky in operation with respect to driveability.

So yes, while it technically does work, if you are anal about driveability, it will drive you nuts.
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Old 04-21-2010, 09:21 AM   #14
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Quote:
Originally Posted by jigga View Post
The AEM V1 doesn't drive those injectors very well at all with a resistor pack in tow.

WOT is fine, but for anything requiring finesse, they are rather jerky in operation with respect to driveability.

So yes, while it technically does work, if you are anal about driveability, it will drive you nuts.
Agreed idle and cruise on cars with resistor packs is less than perfect.

Besides I have to get my 25mpg cruising or what is the point of having a gt40r.
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Old 04-21-2010, 11:58 AM   #15
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Quote:
Originally Posted by jigga View Post
The AEM V1 doesn't drive those injectors very well at all with a resistor pack in tow.

WOT is fine, but for anything requiring finesse, they are rather jerky in operation with respect to driveability.

So yes, while it technically does work, if you are anal about driveability, it will drive you nuts.
What resistance value have you used? It makes a difference. I've dealt with this on Rx-7's with saturated drivers. The injectors are staged and too much resistance cause the secondary injectors to come online late, resulting in a lean hesitation around 4000rpm. It also helps to adjust your injector latency values.

It's not that I think saturated drivers are better. But If I had to choose between reliable crank/cam signal and a peak-and-hold drivers, you know what I'm going to pick. Saturated injector drivers don't damage engines. I've seen too many blown motors from these kinds of noisy signals.
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Old 04-21-2010, 12:19 PM   #16
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Originally Posted by arghx7 View Post
What resistance value have you used? It makes a difference. I've dealt with this on Rx-7's with saturated drivers. The injectors are staged and too much resistance cause the secondary injectors to come online late, resulting in a lean hesitation around 4000rpm. It also helps to adjust your injector latency values.

It's not that I think saturated drivers are better. But If I had to choose between reliable crank/cam signal and a peak-and-hold drivers, you know what I'm going to pick. Saturated injector drivers don't damage engines. I've seen too many blown motors from these kinds of noisy signals.
lol Don't get me wrong, you can use them in a pinch. It's just that you will notice that you aren't driving a stock car, that's all.

It was a DSM resistor pack that was used. Latency values were those provided in the AEM wizard. Made for a rather odd looking fuel map actually.
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Old 04-26-2010, 10:44 PM   #17
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A little update for anyone that cares. So after all of my playing around the car seems to run alright. I took it out and did some road tuning on it and the car performs very smoothly and runs great. I've had it up to 7000rpms with no miss.

The car is still using sync ignore and the cam sensor still has a problem picking up the signal all the time. But with sync ignore the crank sensor now appears to have no issue and no timing drift, as far as I can tell. When I get it on the dyno I will be watching the timing to see if there is any movement. But according to the logs it is not having any issue.

For anyone that is interested here is my setup. It is a 1993 L with complete 04 WRX harness and dash swap. I've been running it since 2005. Let me know if you see where else I might have a problem:

Engine:
EJ257 Block
Wiseco forged pistons
Eagle Rods
WRX heads setup shimless
DPR STGIII cams (272in/272ex)
Supertech daul valve springs
Supertech Titanium retainers
Supertech Valves
Gates Kevlar Timing Belt
Everything was balanced better than stock including clutch,rods,pistons,balancer,crank, line bore mains and rods, 3 angle valve grind, decked, etc
2005 RS Intake manifold with PCV/EGR delete and then smoothed
Port matched intake manifold
gt4088r with .95ex by precision/ also have a .85ex garrett
Custom Twin-Scroll setup for T4 flange
RC 1200cc injectors
Aeromotive Fuel Rails
Aeromotive Fuel Pump A1000
Aeromotive FPR A1000-6
Surge tank with -6an lines from and to the stock fuel tank
-10an lines to the Aeromotive Fuel Pump
-8an fuel lines to and from everything else
Dual 44mm Tial wastegates
Huge FMIC core made for and EVO
custom IC pipes and intake pipe by me
Invidia catback
Mishimoto Radiator
Oil cooler with -10an lines and fittings
Remote Oil filter

TRANSMISSION:
AWD conversion
05 STI 6-speed with hub swap
05 STI Rear Diff
STI short throw shifter
Redline tranny fluid
Exedy triple plate clutch 900ft.lbs or something stupid

ELECTRONICS:
AEM EMS with tuning by me!
5bar Map sensor from AEM
AEM Injector Driver for Low Impedance Injectors
PLX wideband hooked to AEM EMS
Blitz EBC
AEM oil pressure gauge
AEM Fuel pressure gauge
AEM oil temp gauge
Alpine head unit some number fancy thing who cares it plays music!
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Old 04-27-2010, 04:41 PM   #18
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I'm having the same problems that you are having with the aem on my 04 sti. I have BC stage 2 cams and I had to put the sync ignore to 400 rpm and now i dont have much problems.
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