Hey guys,

I've had some experience sorting through spark issues.

-testing power @ the pump when cranking
-checking for pulses in lines when cranking
-testing the fuel pump relay
-jumpering the yellow plug to see if injectors click
-holding the plug and wire @ the shock tower and cranking to check for spark
-etc.

So I yet again found my car not starting the other day. I figured it was just flooded out from me driving it all day pretty hard and then coming home and letting it sit. I figured it was acting bitchy b/c it does every so often in a blue moon and with the weather getting hotter it just seemed right.

-pulled plugs, replaced them (i needed new ones anyway)
-pulled EGI fuse and cranked it
-deflooded it several times

still not firing up. She spins over, smells like fuel and doesn't crank. So I tried holding the plug and wire connected to the shock tower while cranking and it doesn't spark and ground out.

So, smells like fuel in the exhaust... obviously getting fuel. So I unplug the AFM for ***** and giggles after I replaced w/ one that I thought was good and it didn't work plugged in and she fires right up.

So I understand they go bad... but my question is. If I replaced it w/ one that was used, and thought to be good and it by chance was bad and didn't work. By me unplugging the AFM and it firing up every time and running as it should for a couple of seconds and then dying;

Can I just call it at that and start looking for a known good S4 TII afm? I have some things bookmarked just in case but this is just screaming bad afm. What do you guys think?

-Allen G.

 

Might be bad, might not. IF a AFM has an internal elect problem, it's possible it could kill the 5vdc ref voltage the ECU uses for just about everything on God's green earth.

First you should know the fuel is not controlled by the afm DURING Start. Only after 500 rpms has been reached does the afm play a role. UNLESS the original starter wiring has been bypassed on some home made fashion, then the afm is used for start fuel

RX have a internal fuel Start map for the start cycle IF the ECU sees the start voltage from the start signal wiring.

I've no idea why your car does not start and run. Just guessing. I do know a RX should start without a afm connected up. Just won't stay running.

 

exactly... it starts up and doesn't stay running when the afm is unplugged. when I plug in either of them, it doesn't fire up. its getting fuel. just no spark.

 

The only other thing I can remember causing me problem like yours...........is I left a very large intake hose off the intake. Duh. Starts up but wouldn't stay running. I think it was on my turbo car and I left the *blowoff valve* disconnected from the turbo intake duct. So check for some LARGE DUCT /hose left off. Not small vacuum hoses but larger hose.

 

I think your mis-informed about what I'm actually talking about. I'm saying that I think I've narrowed it down to a bad afm as to why I'm not getting spark. I don't have a vacuum leak.

 

anyone else have any input?