AEM Starting

cmonteiro1

New member
Anyone else have issues starting with an AEM ecu. Car runs great, but for some reason, it takes forever to start. It turns over and turns over and turns over... and then just starts like nothing. Any help is greatly appreciated.
 

Celi-GT4

New member
yes never could figure it out. It helps if you turn to on position and wait for fuel pump to build pressure (listen for it)
 

cmonteiro1

New member
Ive tried that.. It seems like sometimes it works, sometimes it doesnt. I wonder if its just a quirk that has to do with aem. It would be nice to be able to fix it. Do you have issues with your battery running down if you don't run the car in a while? I know two cars with aem that have that problem, and Im wondering if that's the cause.
 

Celi-GT4

New member
I ran a small battery and yes had that problem although I have a 3rd gen with blitz ecu now and have the same problem but it takes twice as long to run down 10days instead of 4. I installed a terminal kill switch from moroso for that purpose and also backup theft prevention.
 

banshee 101

New member
im running the aem and have the same issue with the start, in winter its even worst.
i've looked into it and i dont think their is much we can do, i still love the ecu
 

AvivB

New member
Just a guess: maybe the AEM ECU doesn't ignore the AFM while cranking to enrich the mixture like the OEM ECU does.
It can be tested easily, specially if one of you have open filter instead of the air-box.
Just remove the filter, put your finger to hold the AFM open a bit more that it should open on idle and ask a friend/brother/sister/mom/dad/dog to try and start the engine.
(as soon as it start running, remove your finger.)
If it start quicker than before, I'm right...
If I'm right, I might be able to build a small circuit that will replace your finger (for this use) and fake AFM reading while engine is cranking...

Disclaimer: I don't have and didn't had an AEM ECU, all the above is based on my knowledge on this engine, ECUs in general, knowledge in electronics and the data from this thread.
 

AvivB

New member
Ok, so the AEM ECU use air pressure and temperature to calculate the required fuel...
This will be more tricky to "fake"...
Basically what I suggested in the test is to give the engine rich mixture for starting...
I'll think about that...
 

MWP

New member
Im not familiar with the AEM, but there is only one way i cant think of to trick it into giving you more fuel... by changing the value of the coolant temp sensor while cranking.
So that would mean using a relay to switch over to a set resistor value imitating low coolant temp when the starter is engaged.
Not such a hard thing to do.

Unless its cranking too rich, in which case you should chuck the cold start injector or do the opposite to the above.
 

AvivB

New member
I though about cooling the sensor more... but the difference between 20-30 Celsius to even -10 Celsius will not enrich the mixture enough...
The sensor readings are around 25K ohm at 20 Celsius and 250K ohm at 100 Celsius so cooling/faking it to even 0 ohm will not help...

Sorry for the stupid question, but did anyone of you try calling AEM about that?
I know that when I needed them for the gauges issue they where very responsive...
 

MWP

New member
AvivB":3hs1bzxc said:
I though about cooling the sensor more... but the difference between 20-30 Celsius to even -10 Celsius will not enrich the mixture enough...
The sensor readings are around 25K ohm at 20 Celsius and 250K ohm at 100 Celsius so cooling/faking it to even 0 ohm will not help...

First... temp sensors are not linear, making it read -10degC can be done.
Second... faking -10degC will make a huge difference, youll get something like 20-40% more fuel.
 

vip09

New member
I had an AEM EMS on my Alltrac, and never had starting issues like that. It always cranked right up like a stock car. If you want to look at my map I can email it to you for comparison.
 

klue

New member
Ditto, you guys have issues because something is wrong in your config. Mind you VIP is in alabama, But im in canada, and she starts right up in -10 to +40. There are a few areas that can be checked and tuned to improve start up, Send me your cal files and I ll have a look
 

C-dubb

New member
I have ther same issue. I'm confused as shit now...today i plugged in the laptop to the AEM when and started the car up and it was running fine. I was just looking around at the different maps and parameters and it started to run like garbage after it warmed up. Now it won't start. I'm very confused by tuning.
 

vip09

New member
C-dubb":2auvwuyr said:
I have ther same issue. I'm confused as shit now...today i plugged in the laptop to the AEM when and started the car up and it was running fine. I was just looking around at the different maps and parameters and it started to run like garbage after it warmed up. Now it won't start. I'm very confused by tuning.

It sounds like your warm-up enrichment table might be the culprit?
 
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