Starts strongly but dies. MAF dead?

Outshanker · Post by **Outshanker** » Sat May 05, 2012 11:15 am

97 Outback, starts strongly but engine dies after about 3 to 4 seconds. Have checked all vacume related hoses and they all look to be in good condition and connected. Could this mean the MAF sensor has given up?

akpv · Post by **akpv** » Sat May 05, 2012 11:36 am

Outshanker wrote:97 Outback, starts strongly but engine dies after about 3 to 4 seconds. Have checked all vacume related hoses and they all look to be in good condition and connected. Could this mean the MAF sensor has given up?

Any error codes?

Engine should run with the maf disconnected...

Outshanker · Post by **Outshanker** » Sat May 05, 2012 8:35 pm

Ｄｏｎｔ　ｈａｖｅ　the gadget to get error codes but I'd be very interested to get a hold of one. Can you recommend a brand that's not too pricey? By the way where would you plug the thing in to do the testing?

Gannon · Post by **Gannon** » Sat May 05, 2012 10:10 pm

There are 2 pairs of plugs located up somewhere above the clutch or brake pedal that look like this.

Plug the black ones together and turn the ignition to 'ON' but dont start the engine.

Count how many long and short flashes of the 'check engine light' and report back and we should be able to tell you your problem

Outshanker · Post by **Outshanker** » Sun May 06, 2012 9:57 am

Found the 2 black plugs. Connected them and turned the key to the ignition position. Not getting any long followed by short sequence of flashes, just a constantly flashing check engine light. Any ideas about what this means?

akpv · Post by **akpv** » Sun May 06, 2012 10:50 am

That means your ECU has no error codes.

Can you give us some background on how this problem occurred, was it a sudden thing? Have you just bought the car? Does it make any difference if you give it some throttle etc.

The first thing I would be checking from those symptoms is that your fuel pump / system is working ok. Pull off a hose and check the flow.

Gannon · Post by **Gannon** » Sun May 06, 2012 11:01 am

Could be fuel pump related, as it builds pressure before you start the engine, but then once it starts cant keep the supply up, but this seems unlikely.

Im still thinking its air related, seems very much like an air leak. Try unplugging the AFM and starting the car. If it starts, its air leak or AFM related, if it doesnt, it could be fuel. Your CEL should light up and you will be able to read the code for the unplugged AFM.

Outshanker · Post by **Outshanker** » Sun May 06, 2012 11:56 am

Background: Car was driving as per normal when CEL came on about 2 min from home so kept driving. Other than the light being on nothing else was out of the norm. Pulled into the drive way and got out of car to open garage and before I could get back in the car died.
I'm starting to suspect the fuel pump as prior to this I can remember that I use to hear the fuel pump working when the key was in the ignition position. Don't get that sound any more.

akpv · Post by **akpv** » Sun May 06, 2012 12:05 pm

Start with the two tests we have suggested, fuel and afm and see how that goes.

Outshanker · Post by **Outshanker** » Sun May 06, 2012 3:16 pm

Ok. As you know previously I was not getting any error codes but car still refused to run for anything longer than 3 to 4 sec. So went with the following, as suggested. removed the wiring harness conected to the MAF sensor, sits inboard of airbox, and guess what - car starts and runs. Turn car off and from in cabin check for error codes and see that 23 is being reported, again showing the MAF has fallen over. Reconnect MAF, attempt to start but car as before runs briefly and stops. Strange thing is when I now check for an error code only get the quick repeating flashes that mean on code to report. Could this be because the engine did not run long enough before stalling?
What I need to know now is given that the car seems to run well with the MAF disconnected will I be able to drive the car to a garage to get it serviced without having the engine stall on the way? Just by chance the car is going in for HG change TUES.
Thanks for the assist too guys.

akpv · Post by **akpv** » Sun May 06, 2012 3:37 pm

Outshanker wrote:Ok. As you know previously I was not getting any error codes but car still refused to run for anything longer than 3 to 4 sec. So went with the following, as suggested. removed the wiring harness conected to the MAF sensor, sits inboard of airbox, and guess what - car starts and runs. Turn car off and from in cabin check for error codes and see that 23 is being reported, again showing the MAF has fallen over. Reconnect MAF, attempt to start but car as before runs briefly and stops. Strange thing is when I now check for an error code only get the quick repeating flashes that mean on code to report. Could this be because the engine did not run long enough before stalling?
What I need to know now is given that the car seems to run well with the MAF disconnected will I be able to drive the car to a garage to get it serviced without having the engine stall on the way? Just by chance the car is going in for HG change TUES.
Thanks for the assist too guys.

It will run poorly but should be driveable. Not sure if the non-turbo subis have limp mode?

I don't have much experience with any thing other then the gen 1 liberties so take this with a grain of salt. From memory some error codes are stored in the ECU and will show up any time after the event has occured (until you reset ecu) and some error codes will only show up if the ecu is getting an odd signal at the time you do the check.

ajbuwalda · Post by **ajbuwalda** » Sun May 06, 2012 6:19 pm

No water in oil? Due to a head problem, i had the same problem and just found it was because the heads.

pitrack_1 · Post by **pitrack_1** » Sun May 06, 2012 10:56 pm

Outshanker wrote:Ok. As you know previously I was not getting any error codes but car still refused to run for anything longer than 3 to 4 sec. So went with the following, as suggested. removed the wiring harness conected to the MAF sensor, sits inboard of airbox, and guess what - car starts and runs. Turn car off and from in cabin check for error codes and see that 23 is being reported, again showing the MAF has fallen over. Reconnect MAF, attempt to start but car as before runs briefly and stops. Strange thing is when I now check for an error code only get the quick repeating flashes that mean on code to report. Could this be because the engine did not run long enough before stalling?

Hi Outshanker,

Assuming the MAF sensor is the problem:

Do you (someone else out there, guys?) know if it's a hot-wire type. If it is, you may be able to backprobe with a multimeter to check if it's gone open-circuit (need a circuit diagram, also be careful of what the multimeter may put on it). Otherwise a system readout tool may let you know what values it's returning- you'll need specifications to compare.

If you have a film or other type which returns a frequency reading, a 'tap' test is apparently helpful.

Also, MAF sensors have been known to become contaminated, for example through the use of oil-impregnated air filters- the oil will coat the sensor giving erroneous readings on a hot-wire. They can usually be cleaned with an appropriate product, an online search may help. So if you've got an aftermarket oilable filter, a good clean may be the fix if a glob of oil's interfered.

Gannon · Post by **Gannon** » Mon May 07, 2012 6:25 am

All Subaru's have hotwire air flow meters, and it definately sounds like its rooted. Have do you know somebody else who has a Gen1 or Gen2 Subaru with a 'green sticker' AFM you could swap in to test?

d_generate · Post by **d_generate** » Tue May 08, 2012 5:58 pm

Get some AFM or Contact cleaner and give it a really good hosing with it, leave for 5min to dry and see how you go, common problem & cure, if not see if you can borrow or at least try the one you buy first, Subaru wants a fortune for them so go 2nd hand, usually $50-$150 and clean it before you use it......Hope you are not running a K&N pod filter, they eat them.

Outshanker · Post by **Outshanker** » Wed May 09, 2012 12:04 am

Have tried cleaning the MAF with a CRC product that comes recommend for the job but no joy. Ordered a new one from the US today after Subaru quoted me $800 for one. If the one from the US works I might order at least 1 more to keep on the shelf.

d_generate · Post by **d_generate** » Wed May 09, 2012 1:35 am

Don't bother wasting your money, they are generally pretty reliable provided you keep them clean, maybe find someone wrecking a car and pick one up for $50 as a spare, that's the same price for the one for my STI motor, MY99/00 WRX ones are only about $250 because they are rubbish so Subi had to drop the price.

Rip your old one apart, you'll be surprised how complicated they are inside.

Outshanker · Post by **Outshanker** » Tue May 22, 2012 8:58 pm

Installed the new MAF last night and car now runs like a new one. Makes me feel even better knowing the MAF, sourced in the USA, only cost me about $70 all up delivered to my door while the Subaru item was quoted by Subaru to be $800. Certainly seem like a bit more than a gentle nudge to trade up to a new model. Now just need to keep an eye on the HG.

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Starts strongly but dies. MAF dead?

Starts strongly but dies. MAF dead?

Probable MAF sensor issue