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The mkiv Supra Owners Club

how to test/diagnose AEM ecu. CODE 31


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i want to check a local customers car tomorrow is there a guide on how to check the AEM ecu..

 

i know people here have had issues with AEM..

 

so all i want to check is to see if the unit is faulty..

 

if the unit is OK then i can move onto other things to check with his car..

 

code 31 is for MAF but this car is JDM auto with big single turbo.

 

 

thanks

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I didnt think the aem stored fault codes, the only way to test the ecu is either fit it into another car(obviously loading the other cars map) or fitting a known good ecu into the suspect car. What problem are you getting anyway?.

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I didnt think the aem stored fault codes, the only way to test the ecu is either fit it into another car(obviously loading the other cars map) or fitting a known good ecu into the suspect car. What problem are you getting anyway?.

 

sorry the code is from the Diagnostics port ECU will still show faults this way ?,. the history that i know from car is that car has been starting some days and then some days it wont...

 

runs pig rich and cold start is really bad on it way too rich(no idea who mapped it) been in uk a good few years now..

 

but now the car wont start..

 

we swapped the plugs just before we closed and still the same..

 

so i did ecu diagnostics and code 31 showed up.

 

but i recall dangerous brian on here having an issue with a AEM ecu capicator coming loose so the car wont start and eventually failed.

 

so i just wanting to check if the ecu was now faulty, car has single turbo and auto (all of my cars are 6 speed).

 

will a normal auto tt ecu fire it up on 850cc injectors to eliminate ?

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Mine has emanage ultimate and stock ecu atm and it had the code 31 before i went NA-T.

had a SAFC (gen1) fitted tho when it was Na-T (SAFC with those adjustable knobs)

the SAFC was in the car when i bought it and by then it didnt have code 31.

 

 

Not so long ago I did a datalog on cold startup and went for a drive. What i noticed was that the injector duration was 6,6ms on cold startup and during driving itwent to 12.5ms. also the map sensor sees positive pressure, is this possible?

when lifting off the throttle the rpms go down to 400 and then jump to 900 and then down to 500 and then 900 slowly regaining a steady idle.

 

i set the emanage jumpers on factory settings except for jumper 8 which i set to 12V instead of 5V for ignition ouput.

 

My toughts on this would be the map sensor being faulty as i diagnosed the car and error code 31 came up (map sensor faulty or short in circuit). Maybe the lambda died aswell but i highly doubt it as its not even 1 year old.

 

my setup:

2jzge-t

emanage ultimate + 3bar map sensor (voltage clamped stock map @ 4.3V on every rpm)

3'' midpipe

nur spec S backbox

XTD stage 3 6puck ebay clutch :p

One sided FMIC

T61 (mark @ clubna-T's turbo)

NGR Type S boV

innovate LC1 wideband (took a crap on me, is dead as we speak...)

4runner dizzy cap

adjustable cam gears

OBX R 40mm WG

NGK3330's

Edited by Ricardod (see edit history)
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Hi Jurgen / Ricardod

 

Im interested to see if you both managed to eliminate the error 31 code as mine has also started to display the 31 code, albeit Im using an Apexi Neo SAFC not AEM FIC. Ive tried swapping out the map sensor with a someone elses known - working item, but problem still persists. Car runs very rich, floods plugs, misfires like crazy, which is a shame as its ran like a beaut for passed 6 years of ownership, now this error shows up :/

 

TIA

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OK, thanks Jurgen. Ive been doing a bit of googling, and found a thread on here from a few years back, which relates to a faulty TRL FCD or something inside the unit having a habit of becoming disconnected, thus throwing the error 31. Worth a peek I reckon.

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