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1998 legacy 250T, EJ25

Flat spot lag

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18 replies to this topic

#1 Peter Wade

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Posted 28 April 2014 - 03:32 PM

Hi everyone, I am new on this site to see if someone can help, hopefully this works.
My 1998 legacy 250T EJ25 wagon has, what I would call a flat spot, or lag even though it's not turbo. It is happening at low revs when I accelerate from lights ect, or just when I want that extra little bit of speed, it does eventually get up and go but just seem to take a while to sort it self out. I took it for a good blow out on the open road and went very well.
The CEL is not coming on. I have replaced the knock sensor, Co2 sensor, spark plugs and leads. Other than this frustrating flat spot, it is going well and idles fine.
Does anyone know of this problem which can point me in the right direction, or should I carry on changing maintenance parts next would be fuel filter??
Or could it be something like TPS, ECU mapping ect...... Which I would have to take to a specialist.
I appreciate any help.
Thanks
Pete.

#2 willwright

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Posted 28 April 2014 - 03:41 PM

OEM wire and NGK plugs I hope and make very sure the wires are snapped onto the plugs, I just went through this myself last week.

#3 Peter Wade

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Posted 28 April 2014 - 03:46 PM

Yes NGK laser platinum plugs and genuine leads from subaru, all looks ok. this issue was happening before I started changing parts, just hasn't fixed the problem yet.
Thanks

#4 willwright

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Posted 28 April 2014 - 03:57 PM

Never hurts to change a fuel filter but man I hate changing parts to fund a problem, I am old school I guess. You can check for vaccum leaks by spraying carb cleaner around intake and check all the vac lunes for cracks . Also I believe the temp senser can cause these issues, however a few posts further down there a thread and it was his injectors needed a good cleaning. Believe it was a thread started by Sir Robert.

#5 Peter Wade

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Posted 28 April 2014 - 04:05 PM

Yes I agree, parts changing is very frustrating.
I will have a look at vac lines ect.. Thanks. Might need to removed injectors and have a look, any tips on removing injectors?

#6 willwright

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Posted 28 April 2014 - 05:01 PM

Make sure you relieve pressure, I dib this usually by removing the fuel pump relay and starting it up or cranking it over for 20 seconds to relieve the pressure., mine is an 03 so I remove furwl rail and then retaining clips to get injectors of it. Again , I'm not real keen on the 98 so I'm assuming pretty much the same.

#7 johnceggleston

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Posted 28 April 2014 - 05:09 PM

my 97 2.5GT has a flat spot in acceleration,

it goes away once i get it above 2000rpm.

 

i have done the tune up, plugs wires, filters, cleaned the MAF, ran some seafoam thru it.

my current guess is a dirty IAC, but it could be a dirty throttle body or EGR pipe. idk.

or it just occurred to me that maybe it was that inexpensive knock sensor from china.....

but lots of folks have installed them with no issues that i have heard.

 

so i'm planning on pulling the intake and cleaning it all up, maybe soon.

 

have you tried disconnecting the battery overnight?

if it drives fine the first time after an ECU reset, it maybe could be the ECU.

i have read one situation where this happened on a 99 outback,

but not on any others.

 

NOTE: my 97 GT has a 96 ej22 swapped into it.



#8 Peter Wade

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Posted 28 April 2014 - 05:47 PM

Hi. Yes mine goes away once it gets the revs up and gets going, it's almost like its thinking about what it doing....
I have also put engine/injector cleaner in it. All parts I changed have been genuine subaru parts.
I forgot to mention that on occasion it did bucker around for a short time while driving at constant speed and low revs, but I haven't noticed it do this since I have made the current repairs.
Intake, you talking about air intake?
I will definitely try and disconnect battery over night.
Sorry, I'm not up with all the short references, MAF, IAC, EGR, could you extend them please?
Thanks.

#9 willwright

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Posted 28 April 2014 - 06:29 PM

Mass air flow, idle air control, Exaughst gas recirculator.

#10 Peter Wade

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Posted 28 April 2014 - 06:35 PM

I see a lot of people using "sea foam" what is this?
Is it another term or brand of injector cleaner?

#11 willwright

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Posted 28 April 2014 - 07:44 PM

Sea foam is a brand of injector / carburetor cleaner. It is good stuff for sure about 12 bucks a can. I run a can every 4 or 6 tanks of gas which is probably overkill to some folks , but sort of figure its like insurance lol, better to have and not need rather than not have and need ;)

#12 Fairtax4me

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Posted 28 April 2014 - 10:23 PM

Fuel filter, air filter, and a new PCV valve would round out the list for a tune-up. Replacing those generally gives you some time under the hood to inspect vacuum hoses, breather and PCV hoses.

Seafoam in the intake does clean alot of buildup out of the intake runners and combustion chambers. It generally makes a difference in bottom end power and throttle response.

#13 Peter Wade

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Posted 28 April 2014 - 10:53 PM

Thanks very much for this, I will definitely try these things.

#14 ocei77

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Posted 28 April 2014 - 11:00 PM

No need to remove fuel relay or crank afterwards. VERY little gas comes out. You'll get a small squirt as you remove the line, but the rest(maybe 1/2 oz if that much) just dribbles. Just elevate the line.

 

O.



#15 Peter Wade

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Posted 28 April 2014 - 11:18 PM

Do you simply just put the sea foam into the air intake at the engine where the intake hose connects to the engine?
Sorry, I do have mechanical knowledge but I am learning as I go with this car:)

Edited by Peter Wade, 28 April 2014 - 11:20 PM.


#16 willwright

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Posted 29 April 2014 - 07:46 AM

Good morning Pete, lots of films do it differently but if you goto YouTube.com there are lots of good videos by good Subaru techs that have put up videos on just about everything on subies. I am always glad to see someone as yourself take the bill by the horns and learn to do things on their own. My number is 719-238-0917 and anyone can call me anytime and if I can help I surely will. I'm not a mechanic by trade but been to school and been working on cars and tractors since I was old enough to know what a screwdriver is. Another thing I've always done is by a Haynes manual from tjw auto parts store for every car I've ever owned. For 20 bucks and the excellent help from forums like this one, a person would be hard pressed to screw anything up that couldn't be fixed. My dad always said, the only dumb question is the one you don't ask lol, man , how true was that I have come to learn. I tell you another product I swear by is MMO ( marvel mystery oil) I run it in my gas as well every tank , in my subie and in my diesels. Knock on wood , I have never had injector problems. Before every 3rd oil change, I pour a at in engine oil and let it run 10 minutes, keeps everything nice and clean inside engine.

#17 Rooster2

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Posted 29 April 2014 - 11:17 AM

Good morning Pete, lots of films do it differently but if you goto YouTube.com there are lots of good videos by good Subaru techs that have put up videos on just about everything on subies. I am always glad to see someone as yourself take the bill by the horns and learn to do things on their own. My number is 719-238-0917 and anyone can call me anytime and if I can help I surely will. I'm not a mechanic by trade but been to school and been working on cars and tractors since I was old enough to know what a screwdriver is. Another thing I've always done is by a Haynes manual from tjw auto parts store for every car I've ever owned. For 20 bucks and the excellent help from forums like this one, a person would be hard pressed to screw anything up that couldn't be fixed. My dad always said, the only dumb question is the one you don't ask lol, man , how true was that I have come to learn. I tell you another product I swear by is MMO ( marvel mystery oil) I run it in my gas as well every tank , in my subie and in my diesels. Knock on wood , I have never had injector problems. Before every 3rd oil change, I pour a at in engine oil and let it run 10 minutes, keeps everything nice and clean inside engine.

How much MMO do you pour into the crankcase, run for 10 minutes, before changing oil? Also, how much added to the gas tank? I have used MMO before, but not on a continual basis. What you say makes a lot of sense. I should be using MMO more often. Thanks foe an informative post. Think I will also repost this question as a new topic too.



#18 willwright

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Posted 29 April 2014 - 01:41 PM

1/2 qaurt in my outback crankcase is plenty, I figure since its only a 4.2 quart system the last thing I want is to thin it out too much and soon a bearing. If your using 10-40 then not as big a chance but 5-20 I would err on the side of caution , these motors run very clean anyways so unless you've bought a car severely neglected , doing this every 3 or 4 oil changes just helps insure those oil drain holes at the oil control rings don't get carboned up and plugged. In gas tank I run 1/2 qtevery fill up without fail. I'm not advertising here lol, I just stick to what I know has worked as long as my dad has showed me what a wrench was. Would get an old tractor or car back in the day and that thing would be smoking like a tar kettle. After a good flushing with mmo and he usually would let it sit overnight , after running it a but, then he would start it the next morning and let it warm up and then drain change it all out. 9 times out of ten the oil rings would clean up and not smoke or use oil near as bad. Run through the gas would clean up those carbs just like you had soaked them in carb cleaner after a few tanks of gas. I'm sure there are many products as good and some may claim better, but for a gallon of MMO for 12 bucks at Walmart I can treat 8 tanks compared to the same 12 bucks for a can of seafoam.

#19 Peter Wade

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Posted 17 May 2014 - 02:24 AM

Hi willwright.
Thank you very much for the great support, and thank you to everyone else who replied to my post, it is all very much appreciated, it's a good feeling when there is plenty of support out there when you have a problem.
Just to inform everyone out there that I have fixed the problem of my legacy having that flat spot, poor performance issue.
As I've said, I replaced co2 sensor, knock sensor, plugs, leads. After putting my issue on this forum, as suggested, I then replaced PCV valve, Cleaned MAF sensor, put foam through intake, it's like driving another car, performing very well. After taking the PCV valve out it was obvious that it was quite gummed up and needed replacing, I would say that was the problem. I would advise to everyone with a subaru around the same age to just replace this valve, it only cost me $40 genuine subaru, and took 5 minutes to replace, it was the easiest and cheapest part to replace and am very surprised more people don't recommend to just replace it.
I have certainly learnt a lot by doing all of this, and found out a lot of information on this web site.
Again thank you very much to all of you that helped, it was the advise from you guys that got me there.




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