Intermittent engine cutting out.. ???

[James Scott]

I was passing someone yesterday.. In the middle of the pass, during acceleration, the engine bolted shortly (as if turned off briefly) .. After letting off accelerator.. the engine came back to normal.. ??

From then on.. now every few minutes.. whether going fast (with cruise on or off) or slow.. even parked idling... . The engine suddenly goes dead.. like running outta gas.. or turning key off.. ??

Sometimes when the engine dies while driving.. I can pump the accelerator.. and the engine will start up and work for a while.. Other times, it wont start back up unless I put in N and start.. SOMETIMES, it wont start unless I turn from ON to ACC .. then back ON and to start !!

HeLp!

I have had problems with the gas running out early [engine stops when stopping quickly.. or sometimes when turning left (??).. only after using 12 or 13 gallons of gas (230 miles+], since fuel pump replaced)??? This feels like that.. BUT, plenty of gas in this case (only used 60 miles on new tank)!

Also, when I tried the starter relay MOD.. I had problems with the engine stopping when I put in N or P (with the Cruise MAIN ON)! No good explanation for that.. but I took the relay out.. and now use the old OEM 30 amp circuit. Has been starting really good now (after replacing crazy battery).. So, the intermittent battery short when parked theory for unexpected dead battery is looking like an unecessary explanation .. JUST BAD BATTERY.

This situation is both aggravating .. AND dangerous. This AM I pulled out turning right into high-speed traffic.. only to have the engine mysteriously die .. putting me in a risky situation!

HeLp PlEaSe!

Thanks, Jim

[SURTEESS]

sounds like a faulty coilpack?

[James Scott]

Wouldn't that cause rough running? This just goes SMOOTHLY off.. like running outta gas.. or turning key off.. ??

[icingdeath88]

Sounds like a bad MAF. Try unplugging the MAF before you start the car up and see if it quits doing that. If so, try opening the MAF up and soldering the bad connections back together (search the forums for how to do this) or replace it with a known working one.

[James Scott]

You mean? .. Leave the MAF sensor unplugged while driving the car?? How do I evaluate the MAF.. exactly.. ??

Or do you mean .. just see if it quits at idle.. without the MAF connected?

Thanks, Jim

[Tapani]

http://www.subaru-svx.net/forum/show...t=maf+resolder

Open the pdf in the link on the last posting

Second vote for the MAF.... fixed mine

Tapani

[Mike621]

I would agree that it sounds like a MAF sensor causing the stall, though all of your symptoms/issues do not necessarily point to just one issue.

[James Scott]

So... I should first use MAF cleaner and see ... Then, resolder the three connections inside the MAF (will one appear loose.. ??).. Then ..

I think I'm still using a paper filter .. after my fixup for 2nd smog check 2 years ago .. after failing..

Thanks Y'all! Jim

[icingdeath88]

No just unplug the MAF sensor prior to starting the car next time you drive it, and then drive it normally and see if it still cuts out and stuff. The ECU will use a reference value instead of the MAF signal based on the TPS and RPMs and such. The AFRs will not be as accurate but the car will run and drive normally, just not as efficiently.

The easiest possible way to see if the problem is caused by the MAF or not. Usually cleaning the MAF doesn't accomplish anything when the car has these symptoms because the usual cause is loose connections within the MAF, not a dirty sensor. A dirty sensor would be consistently wonky; loose/broken connections cause the ECU to think there is suddenly no airflow when the signal is lost (ie, sometimes, randomly) and then cuts fuel as a result.

[THE NEW GUY]

Does all the witness lights goes on on the combined instrument when the engine goes off?
Any withness light goes on when the motor goes off?
Normally, when the engine goes off for any reazon while driving, all the witness lights goes on on the conbined instrument... If it does not happen, you may have a contact problem on the main key or main fuse box that simply disconnect power like if you turn the key to the off position.
Does your radio still work when it happens?

[James Scott]

Originally Posted by THE NEW GUY

Does all the witness lights goes on on the combined instrument when the engine goes off? Sometimes power just goes off first, and pumping gas pedal will turn engine back ON
Any withness light goes on when the motor goes off? Often, lights go off too.. then, I try to start (in ON position in NEUTRAL.. or sometimes need to back key to ACC then back ON to START
Normally, when the engine goes off for any reazon while driving, all the witness lights goes on on the conbined instrument... If it does not happen, you may have a contact problem on the main key (replaced about 2-3 years ago.. probably not defective, but I guess it cud be.or main fuse box that simply disconnect power like if you turn the key to the off position.
Does your radio still work when it happens? Yes.

Thanks, Jim

[James Scott]

No just unplug the MAF sensor prior to starting the car next time you drive it, and then drive it normally and see if it still cuts out and stuff. The ECU will use a reference value instead of the MAF signal based on the TPS and RPMs and such. The AFRs will not be as accurate but the car will run and drive normally, just not as efficiently.

Thanks for your very clear .. and complete instructions for a wannabee mechanic .. like myself! I dint know the car wud run without MAF info!

I'll unplug the MAF on my way home from work..

Thanks again! Jim

[THE NEW GUY]

actualy, this car does run if you started it whitouf MAF.
but if you experenced all instruments black out this means no main electric power. This is due to a false contact somewhere. Have your main power circuit checked.

[NikFu S.]

I have the same problem you described, but have just been ignoring it. Seems to get along fine if I tap the throttle before it plummets to zero. I can usually tell if it's going to stall because the tach drops faster than if it retains proper idle.

[James Scott]

Unfortunately... .. . MY CAR WUNT RUN WITH THE MAF DISCONNECTED!

So.. It's still cutting out every few minutes (at the least!).. .

SHOULD I CUT THE TOP OFF THE MAF .. TO RESOLDER ??

Could this be an intermittent failure of the fuel pump? It acts very similar to when my gas gets low .. and then "runs out" early (ever since I replaced the pump 1-2 years ago) .. ?

Thanks, Jim