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Guest Message by DevFuse
 

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Hello Subaru lovers, question for you!

loss of power on low rpm

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28 replies to this topic

#1 suby2001

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Posted 10 April 2014 - 10:42 PM

I'm a new guy here, can't find any rules or tips how and when to post, I'm getting really frustrated, Please, I need some help!

Here's the problem,

I've got Subaru
Legacy L 2001 Automatic, bought it three month ago, the car was having issues
with a radiator cap, I replaced it and started to drive. In a couple days CEL
popped out, misfire cyl 2, misfire cyl 4, some vacuum leak, and Map sensor.
Here's what I did:
Put new NGK spark

plugs with a proper GAP, new NGK wires, new coil pack. Changed the oil, and
filter. After that we erased the codes, after 10 or so CEL code - misfire and
MAP sensor. Next thing what we did, checked for the Fuel pressure, which was
good, and cylinders pressure two of them were around 120 and two of them around
95-100, which I think is Okay.. Next thing, got the MAP sensor from ebay used
one,installed and cleared the codes after, drove around didn't feel any
difference, CEL is on again - MAP sensor. GOT new knock sensor with a TPS
sensor, installed it today and cleared the codes, and no difference. Ordered
the MAP sensor from ebay again, but they send the wrong one, doesn't fit on
mine, it's more for 2004 legacy or others, so had to send it back. Mine part is
Bosch 0261230013, and of course autozone or advancedAutoParts don't have it.
Ebay has it but for Hyundai which is okay I think? So I'm planning to get that
one.

 

Here's what the car is doing: start's up and RPM are going to 2500 right away, then slowly goes
back to 900-1000 , and shakes; sometimes badly and sometimes not really
noticeable. After 7 min of warming up I'm trying to drive but there's no way I
can, the car is in the stage of a "hitting a wall" or "loss of
power" and hesitating. And only happens under load, doesn't happen in
neutral. I had to stop and put emergency lights on, because the car wasn't
moving faster than 2 miles per hour and it doesn't matter how much you pushing
on the pedal. However sometimes It's getting better(pushing on the pedal and
sounds like the air stuck somewhere, with a sound of misfire-very rarely but it
happens) Here's the tricky part, after 2500-3000 rpm it takes a second breath
and drives like crazy, no issues, no hesitation, a lot of power, until it goes
back to low rpm, and becoming badly again, sometimes even dying. On the parking
works great, responds great. Tranny shifts good, around 2500-3000 rpm Also,
when I pulled the MAP sensor it was all oily, and inside of manifold looks
kinda oilish? Don't know if that's okay?

 

I would appreciate
any suggestions.

 

Thanks


 

 


 



#2 johnceggleston

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Posted 11 April 2014 - 10:13 AM

check the timing.

misfires and low compression on 2 & 4 (same head / cam) could mean the timing is off.

pull the driver side cam timing cover and pop the access plug on the passenger side ,

and rotate the engine by hand until the timing marks are at 12 oclock.

if left and right sides do not line up, your timing is off.

 

plus, compression should higher and equal.

but lower numbers could be due to an improper test.

it should be done with engine warm, all plugs removed, and WOT (wide open throttle).

 

but if one side is lower than the other,

this is probably timing .



#3 MR_Loyale

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Posted 11 April 2014 - 04:23 PM

If the ECU is reporting a sensor is bad and you have replaced the sensor, check the wiring harness for continuity between the sensor and the ECU. That is my suggestion.



#4 MilesFox

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Posted 11 April 2014 - 08:22 PM

If you have oil in the intake, replace the PCV valve. on later models it is molded inside of the rubber hose, but otherwise should be on the back of the manifold near the throttle body.

 

Ypu may have poor fitment withthe spark plug wires, i was fooled by thm once with similar symptoms. You did right by using NGK wires and plugs. for auto zone and chain stores that show 'listed, but not available', forget them and try ordering thru napa if you have one local. don't trust the economy brand parts at chain stores, and places like that who have a premium brand will be available as the middle brand at napa, for less cost, usually.



#5 heartless

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Posted 12 April 2014 - 06:39 AM

when I pulled the MAP sensor it was all oily, and inside of manifold looks kinda oilish? Don't know if that's okay?

 

No, that is not ok. As Miles has already said - replace the PCV valve and clean out the hoses as best you can. Also try to clean out as much of the oily residue in the intake as you can.

 

Buying stuff from ebay can be kind of a crap shoot sometimes. perhaps you should try Rockauto.com - they usually have very good prices and fast shipping - I think they even have a warehouse in Ohio...

 

There are also several Subaru parts dealers online with fair pricing... I have used both of these with good results...

 

https://www.subaruge..._parts_cat.html

 

http://www.parksubar...m?siteid=215943



#6 jarl

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Posted 12 April 2014 - 10:13 AM

First thing that comes to mind is to buy a USB vag-com adapter from ebay and download FreeSSM and see what's going on :)

#7 Fairtax4me

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Posted 12 April 2014 - 10:24 AM

Inside the manifold will appear oily because of the vapors from the PCV/breather system. This is normal, But there is a point where it becomes excessive.

With repeat codes for the MAP sensor, there is likely a wiring issue for that sensor. These MAP sensors rarely fail.

Low compression numbers and power loss at low RPM, points to a timing belt issue.
Did you do the compression test the way John described above?

#8 suby2001

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Posted 12 April 2014 - 06:18 PM

Thank you so much guys for the advices and suggestions, I didn't expect that I'll the answers that quick! Tomorrow planning to check the wiring and the timing belt. Today when I was driving the CEL started to blink, and also it feels like something is stuck in the catback system or exhaus system. When I'm driving on low RPM it's like a vacuum bubble or something, then RPM's go higher the car awakes and the bubbly "something stuck" noise disappears. Maybe the cat is clogged? Also, I can take the video and post it in youtube if that would be helpful?! 

Thank you again guys, I appreciate your help!



#9 Gloyale

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Posted 13 April 2014 - 11:05 AM

It may not be electrical......it may be something wrong mechanically putting the Intake pressure out of range of normal.

 

I would suggest spraying starting fluid around the base of the intake to check for vac leaks at idle.....

 

And then I would suggest verifying that the timing is dead on......your "bubbling" sound could be valve timing one or 2 teeth off......and if the T-belt lets go on that engine the valves are toast.



#10 suby2001

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Posted 14 April 2014 - 08:49 PM

Okay, so here's what we discovered:

Took off the timing belt cover, and just like you guys said, found that the belt was off time by 2.5 or even 3 tooth! Fixed that, started to drive and didn't feel any changes. Erased the codes, drives like a new car. 30 min later CEL is back, 2 calls: PO302, PO304  (cylinder 2,4 misfire :(   ) We checked for the vacuum leaks, didn't find anything. Wires and plugs were replaced 200 miles ago, coil doesn't seem bad.

Bad headers?



#11 MilesFox

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Posted 14 April 2014 - 08:58 PM

If the timing was off by 3 marks, it may be off again. It can only be off by having a failed tensioner. So you correct it, and it fails again if the tensioner is failed.

 

It is unusual that the timing would be off as a random occurrence unless it was installed wrong in the first place. Suggest replacing the tensioner based on your circumstance.

 

If it slips more than that, It can crash the vales. Be careful!



#12 suby2001

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Posted 14 April 2014 - 09:04 PM

The thing is that the engine runs great now, didn't drove much around 30 min, but doesn't seem like it has any issues even with the CEL on. I'll try to drive more, maybe something else will pop up.



#13 Fairtax4me

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Posted 14 April 2014 - 09:09 PM

Timig could have jumped again.
The tensioners in those fail often and don't keep proper tension on the belt which allows it to skip.

Recheck timing. You know it at least runs well now, so of the timing skipped again order a full timing kit with new tensioner and water pump.

#14 suby2001

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Posted 15 April 2014 - 12:34 AM

Oh forgot to say, the timing belt and pulleys looked brand new, I don't think the previous owner did a good job on changing the timing belt. 



#15 heartless

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Posted 15 April 2014 - 07:50 PM

i second fairtax's comment about rechecking the timing - the tensioner may be bad and is allowing it to jump time quite easily...



#16 johnceggleston

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Posted 16 April 2014 - 07:32 AM

the tensioner is expensive.

they could have replaced everything else and not that to save the money.

 

check the timing,

if it is off, replace the tensioner.

 

plus looks are deceiving.

unless you KNOW when it was changed

and what exactly was changed,

you are at risk.

but usually it is not the belt that fails.

the toothed idler and the tensioner are the most common the failure points.

and usually because they are not replaced when the belt is.


Edited by johnceggleston, 16 April 2014 - 07:37 AM.


#17 ivans imports

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Posted 16 April 2014 - 09:36 AM

Change front AF sensor have had 15 with this exact problem in last 6 months also check ex valve guides for droping down. The AF sensor shorts full lean and cause's grief



#18 1 Lucky Texan

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Posted 16 April 2014 - 11:52 AM

I think someone reported running the engine with the covers off, you could see excessive movement of the tensioner. as mentioned above, if the work was done cheaply, the old tensioner may have been compressed too quickly and destroyed.

#19 suby2001

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Posted 02 May 2014 - 09:04 PM

Hi guys, sorry it took me so long. I'm graduating and it was my final week, so had to study a lot.

 

I checked the timing, took off the covers. Timing is perfect, didn't moved at all, and "0" at the middle pulley. On CEL had 4 calls:

 

P1142 No DTC Definition Found.

P0507 Idle Air Control system Revolutions Per Minute Higher than expected.

P0302 Cylinder 2 Misfire

P0304 Cylinder 4 Misfire

 

Talked with a mechanic, he said it might be the heads. Because the Timing belt is new, which means it was replaced; and if it broked when they were driving - they messed up the heads. 

 

Don't know what else I can do, Subaru dealership?

 

Please, any suggestions would be really appreciated. 

 

Thank you.



#20 willwright

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Posted 02 May 2014 - 09:59 PM

Pressure test each cylinder, roll where both valves are supposed to be closed and see if they will hold pressure or if they will hold at all. If not, either bent valves, burnt valves or head gasket. That would let you rules out valve or head gasket issues. I would do a valve adjustment first then pressure check each cylinder like I said.

#21 suby2001

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Posted 02 May 2014 - 10:44 PM

Thank you! How to do the valves adjustment?



#22 willwright

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Posted 02 May 2014 - 11:09 PM

Turn the crank so when both valves are suppose to be closed on compression stroke and adjust intake and Exaughst , tighten lock nut and move to next cylinder.if this is the 2.5 I set my intake at 0.008 and Exaughst at 0.010

#23 willwright

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Posted 02 May 2014 - 11:16 PM

Do the number 1 cylinder first at top dead center, and your timing mark should be I'm its correct position. Both valves should be closed , adjust those and then move to cylinder 3 and do it same way, followed by cylinder 2 and last 4. Your basically adjusting them in their firing order . Once all adjusted, pressurize the cylinders one at a time in same order and see if they hold.

#24 Fairtax4me

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Posted 02 May 2014 - 11:38 PM

Code:
P1142
Make:
Subaru
Description:
Throttle position sensor circuit range/performance problem (Low)

This could also cause the idle control code to set if the ECU is trying to adjust idle speed while you're cruising under light throttle.
Check the voltage on the center pin of the TPS with the engine idling. Should be around 0.50v. Use a paper clip or needle to back-probe the connector through the rubber boot.

Could also be a poor connection in the harness connector on the bell-housing.

#25 suby2001

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Posted 03 May 2014 - 05:25 PM

Checked everything today, adjusted the TPS, cleaned the idle control. Now it's working how it supposed to be. However, still has a misfire :( Tomorrow planning to open the heads and look at the valves. Does any of you guys have a DIY with pictures for that kind of job?

 

Thank you.






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