Engine starts, then revs drop and stalls
 

Hey guys,

My 1999 Forester GT is having an issue where I start the car normally, a second later the check engine light will come on, over the next couple seconds the engine will rev up to around 1.5k (a few hundred higher than when first turning the car on), then will fall off over the next few seconds until the car stalls.

I had been having some issues with the car sputtering while driving, and I decided to pull out the MAF and gave it a clean with some contact cleaner and put it back in. After doing that the car seemed to stop sputtering and run fine as I took it around the block for 5-10 minutes, but coming back to it this morning the car has been giving me the issue described above.

Anyone have any ideas on what could possibly be causing the issue? Let me know if more details are required.

[QUOTE=Huddo;813447]Hey guys,

My 1999 Forester GT is having an issue where I start the car normally, a second later the check engine light will come on, over the next couple seconds the engine will rev up to around 1.5k (a few hundred higher than when first turning the car on), then will fall off over the next few seconds until the car stalls.

I had been having some issues with the car sputtering while driving, and I decided to pull out the MAF and gave it a clean with some contact cleaner and put it back in. After doing that the car seemed to stop sputtering and run fine as I took it around the block for 5-10 minutes, but coming back to it this morning the car has been giving me the issue described above.

Anyone have any ideas on what could possibly be causing the issue? Let me know if more details are required.[/QUOTE]

If and engine light has come on take it into a shop or find someone to check the CEL code.

go from there, there's a multitude of causes for what you have described. but considering you messed with the MAF and it drove ok. I'd say yours may be faulty.

It would be handy to get the code that the ECU is coming up with. Willing to try plugging two connectors together under the dash to see if you can get the fault codes? It's not hard to do, "Rossco" posted a thread here on Perth WRX on how to do it (and I think there are pictures too!)

On the topic, I've had a similar idle problem pop up recently with a MY99/00 WRX, although not as bad as yours. With mine, when coming to a set of lights, or stop sign, the revs drop to about 500rpm and then slowly creep up to 750-800 rpm. Happens 50% of the time. No starting issues. The check engine light comes on when coasting in gear, down hill. The code for mine is 24 - Idle air control valve.

People who know Subarus well tell me this is a very common problem. It might be what you're experiencing too?

Try google but do be careful because some posts will suggest everything from airflow meter, to throttle position sensor, to the speedo not sending a speed signal to the ECU. Next thing, you're at the doctor because you think the red lump on your testicles is herpes.

All right, so it seems first thing to do will be to check the fault code and go from there. Probably wont have time to check it out until the weekend with Christmas shopping and work taking up the majority of my time.

Will update once I get the chance to rad the code this weekend.

Thanks for the help guys!

Here is how to read codes in pre 2001 models.

[URL]http://www.perth-wrx.com/vb/stock-ecu-discussion/30024-how-read-subaru-cel-gc8-stock-engine-control-unit-only.html[/URL]

Check your spark plugs, and ensure all inter-cooler piping is secured.

chances are you afm is stuffed, often cleaning them will fix them for a little while with the problem returning, did the car ever have an oiled k&n filter on it? they are a know cause for killing afms ;)

i would replace the afm first thing as they are relatively cheap for your model

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My money is on AFM.

My WRX tuner posted on FB about this the other day, he said (as others here have) it will generally either be AFM or possibly the O2 sensor requiring replacement - figured it would apply to the GT too.

Might be best that we all wait until he pulls the CEL code?