Engine hesitation/flat spot (Liberty 2.0R)

Posts specific to the 2.0 litre NA engine

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Sun Sep 15, 2019 9:20 pm

Thanks for the reply and the link to the grounding fix. I spent most of today working on the engine bay ground wiring connections. Also removed the ECU (Subaru PCM) to make sure that it was well grounded. It seemed to improve or fix the hesitation problems but I think I have another problem related to the AT fluid level because it started to play up when the engine/AT was hot. Also found and fixed a small cooling system leak. The knock sensor is a single wire connection so the signal to the ECU is dependant on the engine earth bonding.

I'll check the AT fluid level tomorrow. Also need to check the battery voltage because I saw a reading of 9V on the monitor.

btw, there's no MAF on this model + no inlet manifold leaks, I've checked for that. Exhaust not sure. My monitoring cable/software does not support logging/charting.
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Sun Sep 15, 2019 10:53 pm

Right so your car is this one, '98, April — '00, June???

How is the atmo sensor, reliability-wise?
http://opposedforces.com/parts/legacy/e ... tration_1/

Potentially has some sort of EGR, or is it fuel purge?
http://opposedforces.com/parts/legacy/e ... ntrol_egr/

Pcv system, note TSB.
http://opposedforces.com/parts/legacy/e ... ntrol_pcv/

Ah yes the air box, I have to say the info here is all over the place as there’s air sensors as well as mass airflow sensors.
Maybe post a pic of the engine bay?
http://opposedforces.com/parts/legacy/e ... d_element/

Anyway my point is, air sensors and a/f sensors are good for around 100k klm, then replace with oem parts.
I’ll take a peek at the FSM too.

I guess that goes for MAP equipped cars as much as MAF cars.
https://www.subaruoutback.org/threads/m ... back.9865/

And take a look here: map sensors get dirty causing lean condition.
Weren’t you increasing octane to combat knock?
https://www.subaruoutback.org/threads/m ... tion.6157/

And of course, how is/are the cat/s?
Inspection with a probe is a good idea.
Some say remove the nearest sensor bung and hit the cats with uec.

You have uec’d the car thoroughly, eg inlet, fuel and oil flushes?
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Mon Sep 16, 2019 8:50 pm

Replies :-
Manufacture date 05/00
Model BH9BKBR, engine EJ251NXBVE, transmission TZ1A4ZFABA
MAP sensor has been replaced, pressure and temp ECU readings OK
No EGR or air assist valve. Only fuel tank canister purge valve and PCV
There are no sensors on the air box side
MAP has been cleaned. Cat and O2 sensors have been swapped out

Another day working on the car:-
Checked the ECU battery voltage reading – 12 to 14V
Removed after market additional AT oil cooler
Checked AT oil level – it seemed very high so I drained oil
Went for test drive – really bad, no acceleration from standing start
Used jump leads to ground inlet manifold and bell housing – no improvement
Performed Torque Converter stall tests – stalled at ~ 1,200 rpm with knock correction reading -10.5

The Subaru tech note ref: SIB-T-002-2007 says this is abnormal
“Maximum Knock Correction Stall speed if AT Comment
Up to –4 Degrees Up to 2400 RPM Engine is performing normally
-9 and greater (-10, -11, etc) 1900RPM and less Report via FPRS to Subaru (Aust.)Technical Dept.”

Unbolt and tie back knock sensor again
Test drive results were better but still bad, hesitation and surging
Allowed engine/AT to cool and checked AT oil level – still to high
Drained more oil went for test drive - seemed to improve
Performed Torque Converter stall test again – stalled speed ~ 1,800 rpm

I’m starting to think that the lack of acceleration from a standing start could be a torque converter/AT problem. I’ll try again tomorrow
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Tue Sep 17, 2019 5:02 am

Been through the fuel system including FSM fault testing on the fuel purge?
Iirc faulty purge = inlet leak.
Dying or improper fuel pump install = issues.
That’s everything including FPR, fuel pump control module, filter etc.
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Tue Sep 17, 2019 5:07 am

Bear in mind all grounding upgrades must have fresh & shiny bare metal contact points.

I’ll ask my Subaru mechanic, George at RB Autotek in Richmond about your issues.
They resurrect many sick Subies including full engine reco’s.
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Tue Sep 17, 2019 2:08 pm

Reply:-
The Subaru guys checked the fuel pump and filter, also pressure tested

Another day working on the car:-
The problem with the AT fluid level was me. I was trying to check the level without the engine running so the high level readings were wrong. It’s really hard to get a repeatable reading.
After more test runs and torque converter stall tests I’ve noticed that torque stall speed is sometimes around 1,000 rpm and at other times at least 1,800 rpm. The lack of acceleration from a standing start happens when the stall speed is 1,000 rpm. The engine power is almost zero when this happens. If I push the accelerator to the floor with the brakes on the torque from the engine fails to raise the car. This must be a major clue to my problem. I monitored the ECU parameters during this condition and I’ve noticed that the “Torque Permission Signal” which is normally On turns Off when I try to increase the engine revs.
Any thoughts on this one ?
Thanks
Attachments
Normal.jpg
Normal.jpg (220.08 KiB) Viewed 2643 times
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Tue Sep 17, 2019 4:58 pm

Indeed.
Some of these issues remind me of neutral position switch issues.
If you can see that in freessm, if not, your FSM will have the diagnostic table, link in my signature.

Whilst you’re at it, test or replace the reverse sensor.
On a gen4 at least, the tightarse fixes are to shave a few thou off the washer in the sensor seat.

Neutral position switch issues, eg fail or intermittent cause quite a few undiagnosable issues.

Likewise the easy way to spot fuelling issues is to temporarily, safely tee a fuel pressure gauge before the FPR and mount it temporarily to eg the rhs wiper whilst road testing the car.

Is freessm something you can watch live?
Or is it stored values?
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Wed Sep 18, 2019 5:49 pm

Another random tip: nps^ and safety switch.
Iirc the latter is associated with the inhibitor switch or circuit.

https://www.google.com.au/search?q=suba ... ent=safari

On later models there certainly a CEL/DTC for that...
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Wed Sep 18, 2019 9:31 pm

Replies:-
I can monitor the ECU Neutral Position Switch state, it’s On in Neutral and Park so OK
freessm supports real time monitoring with min/max values but no logging or charting

Re Neutral Position Switch – I spent a couple of hours reading the Subaru FSM ? manuals for clues but now realise that the AT is a rather complex beast. The ECU generates the Torque Permission Signal to the Transmission Control Module that is some function of the gear shift position and ignition switch position. The TCM generates 3 Torque Control Signals to the ECU which if I understand it correctly, controls the torque output of the engine but I can’t see how it can do that without shutting down the fuel injectors and I have not seen any evidence of that.
The Neutral Position Switch (or gear lever position switch on the AT) provides important signals to the TCM that controls the AT.

Another day working on the car:-
Added Nulon head gasket fix to the cooling system because I was still losing a small quantity of water. This seems to have fixed the remaining leak because the pressure in the top hose is a higher now.
After lots of test drives and monitoring I’m now convinced that the lack of acceleration from a standing start is related to the ECU Torque Permission Signal. The problem only shows itself after driving for about 10km, it’s then quite persistent which makes the car dangerous to drive because you cannot rely on it when pulling out into traffic.
If I perform the AT stall tests when it’s in this state and monitor the ECU/TCM parameters the state of the Torque Permission Signal changes from On to Off and the revs stop at about 1200 rpm. I’ve tried moving the gear lever and ignition switch to see it clears the problem but no luck. I also tried disconnecting the knock sensor but no change.
At other times, when it’s working properly, the Torque Permission Signal changes remains On and the engine revs to about 2000 rpm.
I think I’ll have to phone Subaru to see if they can tell me more about tech note ref: SIB-T-002-2007
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Thu Sep 19, 2019 5:21 am

Yeah you want to make sure NPS, RPS is not active or intermittent in gear.

Since issues also kick in after warmup, lookup IACV issues and fixes.
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Thu Sep 19, 2019 6:49 pm

After 2 weeks working on this I think it’s going to beat me. The IACV is good, I’ve changed it several times. More AT stall tests today and I no longer think it’s the Torque Permission Signal because I’ve seen it in the Off state during a good stall test, 2,000 rpm. I changed the AT oil filter but no change. The engine just fails to generate power when the stall test limits at 1,300 rpm.
I’m now looking to buy another Subaru, I think the old one is destined for the scrap yard. Screen captures are during Idle, Bad Stall Test and Good Stall Test. See Current values.
Attachments
AT Stall Test 2.jpg
AT Good Stall Test
AT Stall Test 2.jpg (112.41 KiB) Viewed 2609 times
AT Stall Test 1.jpg
AT Bad Stall Test
AT Stall Test 1.jpg (112.39 KiB) Viewed 2609 times
AT at Idle.jpg
AT at Idle
AT at Idle.jpg (112.3 KiB) Viewed 2609 times
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Fri Sep 20, 2019 12:32 am

paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Fri Sep 20, 2019 1:46 pm

Well, I guess that was too easy because all of the brake lights are working. I performed the AT stall tests according to the Subaru diagnostic procedure this time. The first set of results were 1,900 rpm for 2nd, R and D. The second set of results were 1,500-1,900 for 2nd, 1,400 for R and 1,400-1,900 for D. The manual says anything under 2,100 is below spec and the causes could be – throttle not fully open, erroneous engine operation or torque converter one way clutch slipping but I don't think that helps.

Thinking of the basics - how can an engine that revs well in idle lack power when in drive if it obviously has fuel, air and sparks ?
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby bigBADbenny » Fri Sep 20, 2019 3:11 pm

Is idle 100% ok?
If it is, can you see fuel pump duty in free ssm?
User avatar
bigBADbenny
 
Posts: 9255
Joined: Tue Oct 04, 2011 6:36 pm
Location: Collingwood, Melbourne
Car: MY07 GT-B 6MT OBP Wagon
Real name: Ben Richards
Profile URL: http://tinyurl.com/agvbzop

Re: Engine hesitation/flat spot (Liberty 2.0R)

Postby paulc » Fri Sep 20, 2019 4:55 pm

Idle is smooth, no probs
I can see the injector times + fuel pump on/off, it's always on
No misfiring but the engine noise changes when there is no power
My guess is the timing gets severely retarded so low power
I have a timing light so I can try to test that
Thanks
paulc
 
Posts: 12
Joined: Sat Sep 14, 2019 10:32 pm
Car: Subaru Outback 2.5l 2000

PreviousNext

Return to 2.0R engine specific

Who is online

Users browsing this forum: No registered users and 1 guest