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EA81 SPFI MAF details


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33 replies to this topic

#1 tweety

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Posted 05 September 2013 - 04:24 AM

My recent conversion of my EA81 to SPFI has gone well.  The only symptoms now that are an issue is about 60% power...down 40%.  Runs smooth etc.

 

Took it to a guy that specialise sin injector systems. Bare in mind we never had the SPFI system her ein Oz, in any Subaru.

 

He checked the conversion and found all items like fuel pump location, pressure and timing to be ok.  He diagnosed (95% certain) a faulty MAF.  The MAF was very slow to react and isnt operating correctly according to his experience.

 

Have purchased a secondhand one form your neck of the woods.  Can anyone tell me how to test it?  what are the operating details of a correctly operating unit?  I've been told that people that test these usually tst a new one and have those details on them whenever a unit comes in for inspection- allowing them a benchmark to go by.  But in Oz, this isnt possible as there are none around.

 

Any help appreciated.



#2 ivans imports

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Posted 05 September 2013 - 09:56 AM

The maff dosent open it weighs the air coming in by how fast it moves bad maff no idle no revup flooding ect lacking power not a maff thing timing ? feul delivery ? leaks after maff on vacume sestem or timing diagnostic conector pluged in.



#3 jono

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Posted 05 September 2013 - 05:40 PM

Has anyone got a link to a genuine workshop manual test procedure. I think Tweety has just three wires to test on his spfi air flow meter. Surely Subaru did a nice flow chart for testing the input and output of these wires ?



#4 naru

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Posted 05 September 2013 - 07:01 PM

Not much info in the FSM.

 

Check for 12V on the power lead.

Check the ground lead is grounded.

Check that the signal wire has 0.1-0.5V w/key on,engine off.

Check that the signal voltage increases w/you blow thru the maf.

No other info provided.

 

Logic says it should respond quickly.

 

I would look at O2 sensor voltage for mixture abnormalities and test the TPS too.



#5 tweety

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Posted 05 September 2013 - 07:40 PM

thanks.   O2 sensor was new and installed about 8 inches form the engine exit.  all vacuum was checked and ok.  timing was out just a little and adjusted.  does idle now although just a little on the low side and IAS adjustment doesnt make it idle faster. will do some voltage and ground checks.  other than that will see when the used one hits our shores.



#6 Crazyeights

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Posted 05 September 2013 - 11:40 PM

If engine and gaskets are 100% solid, perhaps try bumping up the base timing as far as 28 degrees and see if it helps.



#7 pressingonward

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Posted 06 September 2013 - 01:03 AM

I've seen a couple bad MAFs on older Subarus. I assume he tried cleaning the MAF that's on the car?

 

If you get the new MAF and have more issues let me know and I can get you sensor values off my SPFI EA-81. I'd rather not take the time to log sensor values unless you really need them though.



#8 tweety

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Posted 06 September 2013 - 05:00 AM

well thankyou pressingonward, really appreciate the offer. Will see if the next MAF makes any difference. if it doesnt then I have two options- buy a new one or likely my issue is from a different source.  We will see soon. should have the unit here in a few days.

 

while we are waiting...here is the trike on youtube with over 25,000 hits. its when it had the weber carb before the supercharger. It's filmed in Strathbogie Victoria Australia.....down under!

 


Edited by tweety, 06 September 2013 - 05:04 AM.


#9 ivans imports

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Posted 06 September 2013 - 09:43 AM

Is the green test mode timing conectors unpluged also the black single wire ones unpluged if its still pluged in timing will not be right

#10 tweety

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Posted 06 September 2013 - 05:20 PM

yes, all unplugged.



#11 ivans imports

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Posted 07 September 2013 - 10:38 AM

Diamiter and length of intake boot from the mass to the engine is it stock ? some tuning can be done by changing size and length of intake plumbing but that may be all you can get from a ea 81 is still a fairly small engine.



#12 tweety

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Posted 07 September 2013 - 03:43 PM

yeh intake is stock.  MAF was cleaned.  should get the other MAF in couple days to try out.  Like the Fuel injector guy said, and I tend to agree, that the engine runs perfectly in all aspects excepts power output. its smooth, easy starting, economical etc etc just its like 2 thirds throttle.


Edited by tweety, 07 September 2013 - 03:44 PM.


#13 Gloyale

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Posted 07 September 2013 - 03:59 PM

Red wire at MAF should have 12v key on/eng off

 

Black wire should have full continuity to ground, less than 10ohms.

 

White wire is signal output.

 

Testing between Black and White wire should show 0.1-0.5 volts.   while blowing though MAF this voltage should increase.



#14 tweety

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Posted 07 September 2013 - 06:24 PM

thanks Gloyale. much appreciated.



#15 ivans imports

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Posted 08 September 2013 - 10:32 AM

is a 90-94 harness ? mine is a 86-87 harness has inline resistor on injector curcit think it runs ritcher the ea81s i did in loyales always seemed under powered somthing to do with 90and up wire harness



#16 tweety

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Posted 08 September 2013 - 04:35 PM

is the earlier harness.  harness was modified before I got it...like a kit.  had resister on it already. dizzy modified etc.



#17 tweety

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Posted 09 September 2013 - 03:03 AM

Well what a saga this is turning out to be.

 

Ordered the used MAF sensor. advertsied on Ebay as a 1985-1994 unit.  Numbers stamped on it the same- identical to mine being 86-94 SUBARU MASS AIR FLOW METER 22680 AA100 AFH38-01

 

Got it in the mail today in Oz.  Not the same.  above the letters ABC and D near the connector mount is the number "2".  mine has the number "1".  there appears to be at least two types.  Almost identical in size the purchase don has a slightly larger cylindrical area that fits into the alloy mount and a larger base on that area so it wont fit in. tried grinding the plastic away and no good. 

 

So, not really the sellers fault as you'd think they were all the same.  now am hunting for my version. looks like only one with the alloy mount can be purchased. ho hum.

 

purchased one on the left.see the larger plastic base bit

 

 

This next pic...you can see the number 2 inside the indentation. my original one has the number 1- the ONLY difference in numbers.

 



#18 TomRhere

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Posted 09 September 2013 - 03:46 AM

Fairly sure the #1 on yours, and the #2 on the "new" one is just the cavity ID numbers of a multi-cavity mold for the plastic of the housing.

 

No idea on the other difference of them.



#19 tweety

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Posted 09 September 2013 - 05:01 AM

mmmm. would make sense. they look otherwise identical. means if I can grind the extra plastic off the 'new' one and make it fit, providing it seals ok (bit of silicone if needed) then I might be able to use it. otherwise have to track down the same number 1 type or the number 2 type with the alloy housing piece as a unit



#20 tweety

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Posted 09 September 2013 - 07:58 AM

ok, so there are at least 3 types of sensor and they all have slightly different matching bases.  So have to seek out a MAF for a Loyale 86-87 model with alloy housing in good nick.

 

A later one would be ok 88-92 if the alloy housing is together with it.

 

Anyone list a junkyard for me they know has these in USA? if so please post the details  most web sites that advertise them have "listing ended" on them.



#21 ivans imports

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Posted 09 September 2013 - 09:16 AM

i have never pulled one apart like that always keep it part of aluminum body it may get damaged taking it apart as far as i know they all work the same i will look at the part # on my 81 brat and see what one it uses



#22 tweety

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Posted 10 September 2013 - 03:16 AM

yeh Ivans imports, they are all the same, certainly need to order them with the alloy body. found some on the net, used of course. prices range from $40 to $550. We will know more after sunday as a friend and I are going to do some testing.



#23 TomRhere

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Posted 10 September 2013 - 04:01 AM

I have an extra MAF (complete unit)  hanging out in the garage. Not sure what year it's from, but I can swap it into the Wagon and make sure it's a good one.



#24 tweety

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Posted 10 September 2013 - 06:56 AM

I have just ordered one from www.rockauto.com lol. Thanks anyway TomRhere :)  also ordered a coolant temp gauge as I believe they cause similar issues.

 

The symptom of the trouble is purely low power output.  the engine starts perfectly (best starting engine I've had), runs smooth, economical etc. But power is down about 30%. Idle was a little low but since the timing was set correctly with green test plugs in it has idled better. The MAF is the only thing my technician thinks is suspect.



#25 ivans imports

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Posted 10 September 2013 - 08:51 AM

What years is the engine ? 80-84 or 84 and up ? as the internals are different on early ea81 vs late ea81 mine is 81 ea81 came with smaller valves ports and soilid lifter cam it may be why i noticed sutch a power change on mine






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