Time to play "Which sensor's broken?"!!!

SVX10 · #1 04-03-2009, 03:23 PM

Howdy everybody. I've been having issues getting my SVX to run properly after letting it sit for probably 6-10 months. I'm having a new issue with some pretty unique characteristics that I'm hoping somebody can ID the cause of.

The car starts every time...better than it has in a while thanks to a new battery and clean terminals all around. It idles pretty well when it's cold, also...a bit rough but I think that's related to my 5MT mount more than anything else.

The problem starts as the engine gets warm. The idle slowly drops and drops and drops until it's just barely running (400-500RPM). If I blip the throttle it'll come back to life, then slowly settle lower and lower and lower. Eventually it will stall. Sometimes when I blip the throttle it just dies immediately.

I pulled the diagnostic connector to see what codes I have, and this is when it got a bit more interesting. As I held the engine at 3000 RPM it would stay there no prob for about 15-20 seconds, then it would completely cut power, RPM would drop, and no response from the a-pedal to revive it. About 1-2 seconds later if I was still on the gas it would respond again for about .5sec, rev up, and then cut out again. If I keep my foot in the gas it'll keep cutting in and out in this sequence seemingly indefinitely. If I let my foot off the gas it will stall.

I've been digging through old threads and the closest thing I can find is the Cam Position Sensor. Is that a valid match to these symptoms?

I have a small crack at the base of one of the vacuum hose connections coming out of the end of the main air intake tubing on the driver's side, but I can't believe that would cause the cutout and stalling. It seems like a definite sudden ECU action of cutting all power for 2 seconds, then giving it back for .5 sec, then cutting it, giving it back, etc. A definite limp mode.

Your help is very much appreciated!

bheinen74 · #2 04-03-2009, 03:28 PM

alternator?

SVX10 · #3 04-03-2009, 05:18 PM

interesting you say that because i have other odd things going on in connection to the alternator. Why was that your thought?

Here's another thing that happens that points at the alternator:

When I disconnect my alternator wiring mod, everything goes dead. My car needs the alternator wiring mod's alternator + to battery + wire in order to function.

redlightningsvx · #4 04-03-2009, 06:30 PM

I would check your alternator grounds then if it only works when doing the wire mod.

AUSVX · #5 04-03-2009, 08:42 PM

I have a simple little thought that may help

If you have a car battery charger, charge the battery right up and then re connect the battery to the car and see what happens, if everything's cool for a couple of hours and then gets all screwy it's probably the alternator.

In the next month or so, I'm changing, the crank, cam and cam sensors, my car idles pretty low with no stalling but with other issues, will let you know what happens.

SVX10 · #6 04-04-2009, 03:05 AM

I've checked the alternator output, and it's @ 14.4V, so it seems healthy, but I could watch it when the engine cuts out and see if anything is changing.

Also, where are the cam position sensors?

The frustrating part is that I can't rev it long enough to pull codes. I may just give up and take it to Subaru.

what would cause a full engine power cut like I'm seeing? Seems like the ECU is trying to protect something.

SVX10 · #7 09-26-2009, 01:42 PM

checked the cam and crank sensors and connectors. found 2.7k ohms resistance across rhe sensors and .87k ohms across the connectors. i know i can`t really test the sensors by resistance but i did anyway =) swapped the position of the 2 sensors that are the same and wrapped electrical tape around where the wire insulation was broken @ the connector for the sensor on the side of the engine. still stalls when warm. starts again no prob though. runs for a few sec then stalls. ugh