Positive (10) ltft all rpm
I have a pain of a problem with my 06 subaru forester 2.0 116kw/158hp manual transmition. European model.
Like i said in the title my car shows around 10-13 ltft at idle and all higher steady rpm. Under load/driving it will zero out or will be compensated by the stft.
So far i checked for vacuum and exhaust leaks.(but at higher rpm shouldn't get better?)
I replaced front o2 sensor.
Cleaned maf and replaced briefly with one that died in 2 days. (at higher rpm shouldn't get worse)
Checked and cleaned pcv valve.
When i bought the car it had no compression on cylinder 3. Because of no lash on an exhaust valve. And the previous owner drove the car for a short while in this condition. So maybe the cat is on his way. But i don't have any codes. And shouldn't request for more air? Thus negative fuel trim?
It seems to me that it doesn't look like a big issue that can do damage.
But what annoys me is the stumble when i drive off from still. It has a little lag when it has to decide what fuel trim it wants to use at that point.
Please give me some advice!
What should i check next? Or should i recheck?
Thank you!
Also thank you Paul for your videos! I learned a lot from them and i can say that i think i know more that the mechanics i asked around here.
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Check you IAC. A dirty IAC that is not operating properly will act like a vacuum leak. If its clean, check to make sure its opening and closing smoothly. I'm suspecting that its not closing all the way. That exhaust valve may still be causing problems as well.
You cannot replace parts based on codes and replacing 02's 90+ percent of the time does not fix the problem. There are checks you could have done to the 02's before replacing and save time and money.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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I took apart the engine and rebuild the heads. Adjusted the valve lash and took a compresion test afterwards.
And i cleaned the throtle body back then. That was a year ago.
These symptoms are present since the engine rebuild.
I don't know if they were prior to that because the engine run on 3 cylinders.
I will clean again the throtle body. It's electronical throtle body so the iacv it's the throtle body itself.
Today i finally found the egr valve )). On the internet it's shown in other places. On european model it's hidden under the intake manifolt right behind the alternator.
I will clean the egr valve and check if it's closing shut.
Also on the internet i read that jdm didn't have the egr. Only usdm. So i thought mine doesn't have one too.
I really hope it's either a dirty throtle body or egr.
I replaced the o2 sensor because i used an adroid app and bt obd adapter that has a slow refresh rate so i thought the o2 sensor is slow to respond to vacuum leak i produced.
Thank you again.
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Also check your MAP sensor.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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I have a cool software developed by subaru enthusiasts that can do two way tests. It's called fressm. I'm not sure it has the option for the throtle plate/iacv. But it has for 20+ number of solenoid type agregates.
Also the maf looks ok. It shows 2.6-3.0 on idle and volts around 1.06.
Edit: I saw you said map not maf. What should i check? It shows 32-36 psi at idle.
Thank you!
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you can only clean as you did... bad design by Subaru. Older years had the IAC on the outside where you could change and clean.
If your bi-directional software can activate the IAC at least you know the wiring is OK.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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Edit: I saw you said map not maf. What should i check? It shows 32-36 psi at idle.
32-36 psi represents 65 + inHG which is not typical of your MAP Sensor.
Using Scan Data are you able to tell :
1. BARO PID, what is the value?
2. MAP Pid value, at idle, and WOT?
To get a reading in the intake manifold you would see on a gauge we would take BARO-MAP( or Absolute MAP).
So in your case at idle, depending on your elevation from sea level, you want to see your MAP PID read a very low number.
eg, BARO = 29.9; MAP=7.4; Therefore there is 29.9-7.4=22 inHG of vacuum in the Intake Manifold.
***BUT*** at WOT you want to see the MAP value raise substantially up to 1.5 in hg within the BARO reading. Anything greater than 1.5-2 inHG from BARO at WOT represents an airflow restriction in the motor. So you want to see for example 27+ inHG at WOT.
OR. your MAP isn't functioning properly!
This one sensor can cause your positive trims across the board.
Never stop Learning.
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vladislav
with the KOEO what are the following readings
BARO kpa
MAP kpa
MAP voltage
also with the engine running and hot, what is the throttle position angle % at idle
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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I meant 32-34 kpa at idle. So 9.44959 inHg.
I'm have trouble at work and i was busy fixing some bugs on a new website that we launched early because of someone else's ambition.
And i didn't receive a notification for whatever reason for you replys.
I attached a screenshot at idle. Here's a gdrive link in case the photo it's not uploaded photos.app.goo.gl/978ZLHvWNyPDtBtH9
And this photos.app.goo.gl/Y7sQgi99Ykv6a3oB9 is a screen recording while driving. Maybe you can see something that is obvious to you.
I will sneak today and do a reading of map at wot.
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They weren't that dirty.
Throtle position got from 11.4 to10.6 at idle.
And egr doesn't leak vacuum.
Also fixed a heatshield that was rattling and caused ignition time pulling.
I reset the ecu and still fuel trim at idle is 10-14.
Map reading at wot is exact same as atmosferic pressure.
I'm out of ideas.
Here are some screen shots
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I know you checked, but I would recheck for a vacuum leak. I would do a smoke test at this time. The leak might be small and hard to find.
Also check your fuel pressure readings. At idle and WOT. Do a snap throttle test, the pressure should increase approx 10% then drop back to idle pressure. Also check the pressure after you turn off the engine. Does the pressure stay or drop. Watch the pressure for 15min. Does the pressure drop and if so, how much.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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I don't think it's somenthing wrong with fuel pressure. Fuel trim should increase with rpm.
Also vacuum leak should get better with rpm increase. Even to be totaly ignored at 4500 rpm.
Nobody even herd here about smoke machine. I tried with a pump and a cigar in the inlet hole. And i didn't hear any whisling or see smoke.
It's a strange behaviour and i can't figure it out. And anybody i asked.
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At idle you should have around 43psi and at WOT around 50psi. After checking pressure, let the system sit with the gauge attached and check pressure after 10min.
The 02 you replaced, is it a wide band (air fuel sensor) or a narrow band 02 sensor.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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Your Intake Pressure is 25 kpa @ 4488 rpm, this is NOT good, it should be 1-2 kpa close to WOT.
This clearly shows the Intake Manifold pressure is not dropping like it should when the throttle plate is opened. Only 2 things can cause this, Intake Restriction or an Exhaust Restriction.
You need to monitor three PIDS O2, Calc Load, and MAP.
@ WOT
Rich O2>Low Calc. Load>High Map>>>>>Restricted Exhaust
Rich O2>Low Calc. Load>Low Map >>>>>Restricted Intake
Lean O2>Low Calc. Load >>>>> Air Measurement Issue
Lean O2>High Calc. Load>>>>> Fuel Delivery Issue
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he originally had an issue with an exhaust valve... maybe that valve timing is still off causing additional intake pressure. Vacuum reading at idle is showing -68. Should be 17-21.
vladislav,
you might want to check compression and leak down in that cylinder with the repaired exhaust valve.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
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I don't have a fuel pressure tester. I will ask my mechanic. It's not a very popular tool here. Mechanics here are replacers of new parts )
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I will do the tests you mentioned.
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I did a compression test after i repaired the valve and it was in the same range as the others. Around 11 bar (i hope is the correct unit). I didn't have the tools to do a leakdown test. Neither my mechanic.
And i did the clear flood test and the engine crank sounds continous.
Also i was very carefull when i set the timing.
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