Strange power loss at speed (Gen 1 Liberty)

WagonJunkie · Post by **WagonJunkie** » Thu May 28, 2015 4:51 pm

G'Day,
I have a strange problem with my '93 Liberty & I'm hoping someone might have some ideas about the cause...?
(I'll admit I haven't searched the forums much because the problem is so strange and specific I doubt there will a post with the same scenario / problem...)

The car is an AWD '93 Lib. wagon with the EJ22E & and a 4EAT auto.
It has about 185,000 on the clock and is our daily driver / family bus.

The engine is strong and the AWD system works well.
The car drives fine and accelerates smoothly under almost all circumstances and any speed....except the following....

There is a hill near our place heading out of town. It's quite steep and it's looong. Like over a kilometre long. The speed limit is 110 km/h and it's a real car killer. You start from the red light at the bottom and just as you're getting to about 100km/h with your foot down, the gradient really starts to kick-in. Half way up and the tranny is now back in third (and sometimes screaming in second) and the engine is pulling around 4000 rpm to maintain about 100 km/h. This is normal. Your right foot is pretty deep into the pedal. It's the same for any car, it's a long hill that sorts out the slugs from the rockets. For the drive-train it is a combination of high fuel demand, high load and high speed.

At around 2/3rd 's to 3/4 of the way up my engine starts to lose power quite quickly. At first it seems to slow a little so you push the pedal even further, but within about 100 meters the revs are falling quickly and the speed is dropping rapidly. The engine seems a little rough but there's no weird noises or vibrations.
All I can do is pull over (it will literally slow to a stall if you don't, I've pushed it to complete failure once) and restart the car. It then drives away normally.
The worst part is, it doesn't do it every time we go up that hill.
The problem cannot be replicated anywhere else or under any other circumstances....and we live on a steep hill that the car goes up & down every day.

It doesn't throw an ECU or TCU fault code when it happens either.

I have replaced the fuel pump with a new unit but has not solved the problem (although it seemed to go up the hill a little better at first....)

My thoughts are:
1. Fuel pressure regulator is leaking vacuum and not pulling open enough at high fuel demand...??

2. Air Flow Meter signal breaking down...? (but why no fault code generated?)

3. Spark integrity breaking down at constant high load...? (I replaced the plugs, leads and coil about 10 - 15,000 kms ago...)

Sorry for the long post, but it's a very specific problem and I wanted to give as much info as I could.

Many thanks.

WagonJunkie · Post by **WagonJunkie** » Fri May 29, 2015 2:03 pm

I have been doing some more reading....and there is plenty of posts out there in "internet land" that describe this issue and failed O2 sensors and toasted cat. converters....
I put a new O2 sensor in the car about 25000 kms ago (doesn't mean it hasn't failed...)
Does anyone have any experience with failed cat converters? Can they produce THAT much back pressure to actually cause the car to come to a complete stop...?
I'm going to get under there & check for rattly internals this weekend too...

Proton mouse · Post by **Proton mouse** » Fri May 29, 2015 3:21 pm

My first thought is of fuel starvation.
Due to the steepness of the hill, something might be moving around and blocking either the pick up in the tank or within the fuel filter(s).
When you stop, the pressure/suction in the fuel system drops and lets go of the sludge/crud etc so it then drives off normally.
I don't think that would produce a fault code??
Just a theory

John

WagonJunkie · Post by **WagonJunkie** » Sat May 30, 2015 12:12 pm

Thanks Proton.
Yeah my first instinct was fuel starvation too.
After I fitted the new fuel pump (and filter) I thought I had solved it because it flew up the hill the first time. It wasn't until a few days later that the power loss returned, the second time I was heading out of town.
I'm tempted to give it to the exhaust shop for a new cat. converter & 02 sensor.....but I really don't want to spend the $$$ and then have the problem return.

Post by **TOONGA** » Sat May 30, 2015 2:01 pm

Has the fuel filter been changed?

If the O2 sensor has been changed and ins't throwing a code changing it again won't make any difference.

Go to a wrecker or find someone wrecking your model and buy the exhaust parts you need that way you can save money.

TOONGA

WagonJunkie · Post by **WagonJunkie** » Sat May 30, 2015 2:26 pm

Yeah fuel filter changed. Old one was only about 10,000 kms anyway.
....and new fuel pump fitted.

The car is still returning OK fuel mileage on the highway (I keep a log of this) which would indicate the 02 sensor is OK.

The Gen 1 liberty has a fairly unique exhaust design where the cat conv. is also the three-way junction aft of the two cylinder heads. This makes the cat. con. replacement less straight forward.
Later model Lib's have the two pipes from the manifolds joining before a single entry/exit cat con.
The exhaust shop said they would just get rid of the original design & make up a regular junction and straight cat. conv.
This is all fine and good.....if that is the problem! But if it's not, I've dusted circa $400 chasing the wrong gremlin...

Anyway, it seems from this forum (and another) that this is not a simple "....everyone knows how to fix that famous issue with old Subaru's..."
....so I'll need to do more of my own trouble-shooting & eliminating.

Many thanks for your replies nonetheless.

Post by **TOONGA** » Mon Jun 01, 2015 11:12 am

there are a few options for exhausts for your car. Im not sure what you are being told, but the factory Gen 1 liberty exhaust is the same from 1989 to 1994. all you need to do is match the parts you have with parts from a car at the wreckers.

What colour is the transmission fluid? (not the front differential)

When was the last time the 4EAT was serviced ? (EG 8.5 lt of trans oil and gasket kit)

TOONGA

WagonJunkie · Post by **WagonJunkie** » Mon Jun 01, 2015 1:54 pm

Yeah, I could replace the exhaust parts with stuff from the wreckers....but I would be fitting a cat. conv. with unknown mileage / abuse ...?
I'll probably order a new 02 sensor anyway if I decide it's definitely an exhaust related problem. (Last time I found an online price for a new Bosch sensor for under $100).

In my humble opinion the standard Gen 1 exhaust design is not good (maybe why it was changed after '94?) because the cat conv. is also the three-way junction - it looks pretty restrictive to me....and it also means that a standard replacement / generic cat conv. at every exhaust shop in the known universe will not fit.

I have changed the transmission fluid twice in the last 2.5 years. These were not full flush changes where you purge every drop (i.e. - the fluid left in the converter etc)...just a workshop floor change with the pan off. I did NOT replace the filter at either interval (I know, I should have)....but I did re-do the pan gasket with a good qual. gasket-in-a-tube.
The first change was because I hadn't owned the car long and I didn't know how long it had been in service. The second change was when I disassembled the centre transfer housing to replace the AWD duty solenoid and check the clutch pack.
Both times the fluid looked (and smelled) perfect.

WagonJunkie · Post by **WagonJunkie** » Mon Jun 01, 2015 1:56 pm

Thanks for your thoughts so far guys...

I drove the car up the hill three times yesterday. My plan was to disconnect the O2 sensor after the first run.
.....but it drove up PERFECTLY three times. So if I had disconnected the O2 sensor it would have proved nothing (at least yesterday anyway...)

Currently searching FleaBay for a straight jacket.

Subydoug · Post by **Subydoug** » Mon Jun 01, 2015 6:47 pm

From your description I would say fuel pump is knackered. How old is the pump? During high load the fpr will not bypass as much fuel. If the pump is worn out and it cannot keep up the pressure will start to drop in the rail. When you back off and pull over the pressure shoots back up and you can take off again. Perhaps the pump is right on the edge of being able to flow enough fuel as you go up the hill. Could be intermittent from day to day because of battery load or fuel tank level. I would certainly either just replace the pump if its old, check it gets a healthy voltage while running (idle is fine, the pump still pumps the same amount of fuel) or monitor the fuel rail pressure while going up the hill.

Regards

Doug

vincentvega · Post by **vincentvega** » Mon Jun 01, 2015 10:14 pm

try replacing the FPR. i have heard of this fault before and I carry a spare FPR for this reason.

WagonJunkie · Post by **WagonJunkie** » Tue Jun 02, 2015 8:53 am

WagonJunkie wrote: I have replaced the fuel pump with a new unit but has not solved the problem (although it seemed to go up the hill a little better at first....)

My thoughts are:
1. Fuel pressure regulator is leaking vacuum and not pulling open enough at high fuel demand...??

WagonJunkie · Post by **WagonJunkie** » Tue Jun 02, 2015 8:56 am

vincentvega wrote:try replacing the FPR. i have heard of this fault before and I carry a spare FPR for this reason.

Hmm....yeah I think I'm going to fit a new one just to eliminate it.

(By the way, nice photo!!)

Subydoug · Post by **Subydoug** » Tue Jun 02, 2015 9:21 pm

Opps

.

Best of luck then!

Doug

ekuidas · Post by **ekuidas** » Sun Jun 14, 2015 4:55 pm

My 93 Liberty AWD 2.2L Wagon had a VERY similar issue (if not the same!) but I kept driving it until it got worse and would occur when travelling even mild speeds of 60KM/hr. It started off at a higher speed, 110KM/hr, then 80KM/hr, then 60... It was often used in short trips, sometimes where the engine wouldn't have had time to properly warm up (so things would gunk up easy).

I ended up changing everything you have mentioned so far minus the CAT as well as a lot more since they were mostly original parts, here's a full list of what I went through BEFORE I found the real issue:
* Full timing belt kit (replaced 6 months before things got worse)
* Spark Plugs (NGK's, the old type as specified in the service manual)
* Spark Plug cables
* PCV Valve
* Air Filter
* Mass Air Flow Sensor
* Fuel Filter
* Fuel pump
* Nulon Oil Flush & Oil Change + Oil Filter
* Knock Sensor (old one was cracked)
* O2 sensor
* Ignition/Fuel Pump Relay
* Accessory belts
* Crankshaft Pulley
* Greased up the Vehicle Speed Sensor cable (it was rough sounding)

... and the issue was still there, but at least the car was running with some nice new parts, and I did all the work myself. (Here's a great link to the fuel pump relay if you want to try it - showthread.php?t=19809 )

The ECU and TCU weren't throwing any codes either, except if I stalled the car out when it was running rough and it was in gear, the TCU would throw a false Speed Sensor code that'd go away next start up.

Anyway, what worked for me in the end was a combination of:
1. Remove and carefully clean the Crank/CAM Sensors so that they are shiny clean. Be careful not to damage the cable or the sensor itself, they're $800 or something new EACH from Subaru, so don't break them! - My Crank sensor was gunked underneath with carbon so it could've been actually misreading the crank angle at higher speeds.
2. Run a full can of Nulon foaming air intake spray (since we don't get Seafoam in Australia) into the intake manifold from the small vacuum loop hose (not the PCV valve) on the drivers side and watch it clean everything out.

I hope your issue is easier to find and you don't end up having to chase too many gremlins like me. If you do replace the CAT, post some pictures as I'm thinking of replacing mine or the entire exhaust itself. IF the CAT is at fault you won't even be able to rev it hard when the car is sitting still.

Edit: vincentvega, I read you were looking at making some fuel sender PCB's, did you ever make a replacement for our Gen1 AWD Wagons? I'm in need of some

WagonJunkie · Post by **WagonJunkie** » Mon Jun 15, 2015 1:17 pm

Thanks for the info ekuidas, very helpful post....

Some of the same parts (and tasks) you mentioned have been replaced and carried out on my car too.

So once you cleaned the CAS and the intake manifold, the problems never returned...?
...ever...?

I would be pretty stoked if either of these simple tips work on my car - I will definitely try both.

I haven't been able to replicate the problem since my initial post a couple of weeks ago though...

WagonJunkie · Post by **WagonJunkie** » Mon Jun 15, 2015 1:19 pm

....although lately the fuel economy seems a little off (haven't crunched the numbers, just a gut feeling because I used to log it religiously for about 2 years)

ekuidas · Post by **ekuidas** » Mon Jun 15, 2015 2:28 pm

Yeah the problem has been gone for a good 3 months now and it's my daily driver, I've even taken it out to some 110km/hr roads for the first time in a while, hasn't missed a beat.

Mind you before I fixed it, it was bad to the point that even if I'd warmed the car to working temp and then got it to a higher speed (60-80km/hr) it would start to stumble about. It would only happen once in that day until the engine was cold again. That being said, it's not like it magically went away for no reason, one of those two things I did last fixed it (CAS or Intake clean).

When your engine is stumbling about, if you have a chance, leave it in neutral and pop the bonnet, does it sound as if it's "unbalanced"? That's how mine was, and it was probably the CAS mostly in my case, since it can cause the ECU to incorrectly adjust ignition/fuel timing and throw it off balance.