ilib11 wrote:Re upper engine clean - I cannot tell if it was actually done. I saw stories on Whirlpool about subi services which just do not do that to save time/effort and throw out these upper clean chemicals cans. Where would you connect in 2.5T intake to do the upper engine clean?
Re spark plugs torque - may I kindly ask on how the spark plugs torque make a rough idle? On any other cars I had I did not have any problems by just screwing in spark plugs hard enough. These engines were not boxers though.
ilib11 wrote:Hi All,
After a number of investigations I can now say what it is NOT:
- spark Plugs (new NGK)
- ignition coils (new OEM)
- MAF (new OEM)
- first O2sensor (new OEM)
- PSV valve (cleaned, checked)
- throttle body unit (cleaned, swapped to another one used OEM)
- air filter (new)
- battery (new)
- any rubber pipes etc I can touch without taking off the intake manifold
- electricity noise or problems (oscilloscope shows stable supply with no noise mostly at 14.2-14.4 v)
- oil cap
Other checks:
- Fuel
51 psi with vacuum disconnected
41 psi with vacuum connected and AC off
42 psi with vacuum connected and AC on
39 psi-> 40 psi -> 41 psi when engine is off
- Intake vacuum
20 mm Hg with A/C off
17 mm Hg with A/C on
(measured at brake buster pipe)
- Cylinder compression with open throttle :
1 cylinder - 9 bar (130 psi)
2 cylinder - 10 bar (145 psi)
3 cylinder - 9.5 bar (138 psi)
4 cylinder - 10 bar (145 psi)
Unfortunately I still cannot fix the original issue and I am practically out of ideas what else could be a reason for it, that drives me nuts. Only the following two left in my mind:
a) something strange with injectors which makes uneven fuel supply at low rpm
b) banjo bolts are blocked with some gunk so it is not enough oil pressure for AVCS etc at low rpm
Are there any ideas for the next steps?
Please share, I would appreciate your input, thank you!
ilib11
ilib11 wrote:Hi All,
The next update on the problem in case you are interested....
The car is no better so I decided to fire a small parts cannon and also did some extra tests.
1)I took an oscilloscope and checked voltage from the alternator - all stable, no noise, dropping or other obvious abnormalities.
2) Measured cylinder compression with open throttle :
1 cylinder - 9 bar (130 psi)
2 cylinder - 10 bar (145 psi)
3 cylinder - 9.5 bar (138 psi)
4 cylinder - 10 bar (145 psi)
3) Changed the plugs to new NGK Ruthenium HX LFR6BHX. The old ones from the dealership were NGK SILFR6B8 (no Subaru marking or other identification), but looked good to me. There was a sort of silver grease on their threads, looks like it was an anti - seize.
4) Changed ignition coils on the cylinders 3 and 4 to new Subaru genuine ones. (Did not change them on 1 and 2 as it was a small parts cannon and I already cleaned coils earlier for cylinders 1 and 2 and swapped them from 1 to 2 and vice versa with no positive effect). Old coils were dirty with some white residue at the spark plug side.
And the results are as follows:
- Idle got smoother for sure
- acceleration (I think) is better too and it has a more delicate or smooth sound
- the initial problem with shaking under load did not go but become reasonably better. And I was able to reduce the rpm upping from +200 to + 150 rpm.
I think I will continue with replacing the other two ignition coils and see what happens.
The compression difference of 1 bar across cylinders - is that too bad or within normal limits?
Thanks and regards, ilib11
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