i posted this in the safc forum first, but its not frequented enough so i figured i would post it here

okay ..

when i first got my car back from landers it ran great for about 2 days ..
then it would just start up, but die immediately..

just like if you leave the afm unplugged..

found out it was the wires that you hook the safc up to.. the rpm wire and the afm wire

so i got those soldered up good and heat shrinked and everything...

didnt have a problem with the afm wire ever again .... the tach seems to be more finiky .. sometimes it just wont work .. i have to turn the car off and then restart it...

new years eve night, i go to start the car, and it does what it did the first weekend of getting the car back .. starts up then immediatly dies so i start gathering my tools from the hatch to take the kick guard off and jiggle the wires, but before i turn any bolts i try one more time and it starts like normal...

this is starting to **** me off .. thats the first time that the car acted like the afm wire was cut since i soldered them together ..
however the Tach will sometimes not work ... i start the car up, the tach reaches about 400 rpm and then dies .. the car runs fine, but the tach is dead ...

i can usually turn the car off and then restart it and the tach works, but this is just getting annoying ...

has anyone else ever had this problem .. its got to be the safc interferring with the signal, but it just sucks that sometimes it happens and sometimes it doesnt

my battery is really weak right now .. could that cause the safc not to initilize correctly or somthing and cause it to not read the tach wire?

 

I assume you're talking about the dash tach, and not the SAFC tach.

The dash tach is driven off the trailing coil signal. If the trailing coils are dead, or not receiving a signal, the tach will not work. I'd look at the trailing ignition wires coming off the ECU - they may have been damaged by other work done.

-=Russ=-

 

hey Russ,

any idea why the signals would be different? my SAFC sees a signal thats 7-8% lower than my tach reads out. i'm pretty sure the SAFC is the more correct signal as well.

sorry aboot the thread-jacking

 

Mine did teh same, would start for a brief second then die out as if the AFM wire was cut. Only thing is that it never started and ran like yours.
I noticed in the Haynes manual that the AFM has three wires going to the ECU, maybe there is a dsifference in wirelocations on ours and the one that Apexi used as reference when making the diagram.
The SAFC is installed but not hooked up yet(one year and counting).

Anyone knows the solution for our problem ?

 

Recheck the rpm wire connection. The S-AFC's green wire should be tapped into the ECU's blue/yellow wire at the bottom-left corner of the 26-pin plug. This wire sends a signal for the trailing coils to fire, so if the connection has damaged the wire the trailing coil may not fire and hence the tach may not work properly.

Other than that, the S-AFC cannot affect the tach in any way. If the wire connection is okay, you need to look elsewhere.

Only one of those wires is the airflow signal. The Apexi wiring info is correct. Unless you accidently used the S5 diagram for an S4 or vice versa (which would be difficult since the plugs look quite different), it will work.

 

the car runs great ... doesnt run as if the trailing coil isnt firing ..

its just every now and then it seems as though that wire for the RPM signal isnt connected

NEVER did this before the safc install ... it cant be the trailing coil ... unless the trailing coil doesnt work for a split second .. just enough to not allow the tach to work, but then still fire correctly enough to allow the engine to run smooth...

 

No trailing does not have a significant affect on how well the engine runs. Ususally, the method for checking wheter or not it is working is by reading whetehr or not the tach is working. No tach... no trailing spark.

 

Yep, the bulk of the work is done by the leading plugs so if the trailing coils weren't firing you most likely wouldn't feel the difference. You'd just have no tacho. This might simply be a problem with the tacho itself, and the S-AFC install thing is just a coincidence.

 

From what I've read in other threads, the stock tach isn't terribly accurate at high RPM. I haven't had a chance to test this myself though (still waiting to get a SAFC).

-=Russ=-

 

ok .. .well i'll diagnois the trailing coil...

thanks guys!

 

My tach stopped working when the ground wire next to the ecu came loose.