Fried ECU

[Rampage]

I thought the fuel pressure is supposed to be 36.3 psi. Am I wrong?

[idosubaru]

11 hours ago, davepak said:

 replaced the fuel pressure regulator with an aftermarket one with a gauge. I set it to  (+/-) 65 psi based

 

 

What's going on with those units - the red units look like they're labeled as metric, not PSI, but those metric numbers aren't the right order of magnitude if that's the case.  What are we looking at in terms of units? 

[davepak]

10 hours ago, el_freddo said:

I once did an MPFI conversion on my L series before I found forums and saw the light in the EJ conversion world. 

Mine would surge sometimes when accelerating, other times it would pull like an EA82 freight train. Didn’t matter about the load or throttle position, sometimes it happened, sometimes it didn’t. 

I recall that if I took my foot off the throttle and back on when this was happening it would clear up. I never found out what the issue was but I suspect it had something to do with the smaller carb fuel return line that my conversion inherited (this was swapped out when I did the EJ conversion). 

It could be worth removing the fuel cap and blowing compressed air back to the tank through the fuel return line to remove any restrictions in the system. 

The other thought is that it’s some solenoid that’s sticking - probably one to do with the fuel tank ventilation system, definitely in the emissions control stuff! 

Shame you cancelled the inspection, I was hoping it would be there to pass and live on, even if it limped over hills for now... 

Cheers 

Bennie

Well @el_freddo I haven't declared it dead. But I thought I'd give it more time and adjustments to see if I can pinpoint something else now that I fitted a new fuel pressure regulator. Ill clean up the MAF again.Oh and regarding those fuel lines...I had taken them all out and blew compressed air on all of them including that weird fuel separator! On that note, Im curious to see if I run the car without the fuel cap and check whether there is hesitation under load or not then... Hmm 

[davepak]

2 hours ago, idosubaru said:

 

What's going on with those units - the red units look like they're labeled as metric, not PSI, but those metric numbers aren't the right order of magnitude if that's the case.  What are we looking at in terms of units? 

You are right @idosubaru these are metric and as pointed out by Bennie, the regulator is set at 60psi give or take. And as per the FSM it should be 36.3 psi. HOWEVER, I had it low at 40 psi and the engine immediately bogged down just about to die. So I wonder what's the deal here, I can say that I heard a bit less of the whining of the pump than before, as if it was restricted so badly by the regulator that the pressure made such a horrible whining noise. I'm heading to the garage and check some of these things now.

[idosubaru]

2 hours ago, davepak said:

You are right @idosubaru these are metric and as pointed out by Bennie, the regulator is set at 60psi give or take. And as per the FSM it should be 36.3 psi. HOWEVER, I had it low at 40 psi and the engine immediately bogged down just about to die. So I wonder what's the deal here, I can say that I heard a bit less of the whining of the pump than before, as if it was restricted so badly by the regulator that the pressure made such a horrible whining noise. I'm heading to the garage and check some of these things now.

Okay, I still don't understand.  You'll probably clear that up after you go check things out this time.  The gauge seems way off...although I can't see which metric units it is in either. 

[1 Lucky Texan]

is this car also prone to having the fuel lines reversed like some folks accidentally do in newer cars?

 

I dunno, I'm really out of my element here lol!

[davepak]

34 minutes ago, idosubaru said:

Okay, I still don't understand.  You'll probably clear that up after you go check things out this time.  The gauge seems way off...although I can't see which metric units it is in either. 

It is in metric. And it was showing 60psi. Which should be way higher than what the FSM details for the fuel pressure regulator. 

I lower it at about 40 psi with the adjustment screw. And it seems OK there. However.. Same issues when I drive it. On Park or neutral I rev it up and it goes up fine with minor sputtering. But when engaged in D and launching forward, then it boggs down. RPMs down to 500 and this time it died. 

[davepak]

1 minute ago, 1 Lucky Texan said:

is this car also prone to having the fuel lines reversed like some folks accidentally do in newer cars?

 

I dunno, I'm really out of my element here lol!

That's a very interesting point. It might be possible.. I'll review the fuel lines on the FSM it could be that the return line is acting as the fuel inlet and the fuel inlet as return... I can just swap then and see what happens 

[Rampage]

Looking at the picture you posted, is this pressure regulator connected to the fuel filter that comes from the fuel pump? That would work if the return line to the tank is blocked off. It would be harder on the pump though.

How many hose connections are on this regulator?

If it is 2 then it should be piped in to replace the original pressure regulator from the fuel rail to the return line.

Then 36 - 40 psi should work fine.

[el_freddo]

Reversed fuel lines is a good suggestion. 

Quick way to check is to disconnect the fuel hose from the filter in the engine bay, put a container under each hose and prime the fuel lines. 

Which ever container has fuel in it is the direction the fuel is flowing from. It should be coming from the filter  

Cheers 

Bennie

[davepak]

Ongoing tests. Update @idosubaru @Rampage  @el_freddo @1 Grumpy @john in KY

So the tests continue. I fitted that aftermarket fuel pressure regulator and with that I have realized that the fuel pump was always whining badly before, regardless of which one ( I have 3 fuel pumps to use) when it had the stock fuel pressure regulator. On setting the pressure at about 39 psi give or take I have noticed that the fuel pump STOPS whining (hey, but not always). And realize this should be the normal operation of it. When the fuel pressure regulator was set at 60 psi or more (I know it was a lot!) it would whine. So my conclusion is that the stock regulator was not working fine. Also, there HAS to be some issues related to fuel delivery as I have noticed the changes with the new regulator set at about those 39psi. As if the car is smooth and steady. Nevertheless, it is not near ready, as when I believe the pressure is fine, I still notice some inconsistencies when ramming the gas pedal. There is some sputtering still.

Also, I have checked the fuel lines, they all check with their order: delivery, return, evaporation and vacuum. The fuel filter is like the third in line when the car has rolled less than 500 miles due to this sputtering issues.

Additionally, I have seen 2 distinct behaviours regarding the fuel pressure: sometimes the needle on the gauge remains totally solid and even lower than the previously set pressure of 39psi. Other times, the needle oscillates but never going further than say 40 psi, nor lower than 36 psi. This makes me suspect some unexpected issues with the fuel pump's electric circuit.. I recall when placing the aftermarket fuel pump, that if its body would touch ground, I would see a tiny spark, almost like a tiny short circuit, but it wouldn't affect much the pump's operation (or so I think) And given the fact that the wiring has TWO wires for ground, I did not think on grounding the pump's body.

 

So what I think I will do now is work on achieving that sweet spot with the pressure regulator. Set the idle at the infamous 800 rpm for AT and review the ignition timing yet again at those 25 degrees BTDC. This car is like adjusting the Large Hadron Collider!! So many sweet spots at the same time for a lousy 71 odd BHP !

[el_freddo]

Are you sure it’s 25 degrees before TDC? I remember my MPFI being 20 degrees BTDC. 

Might be worth adjusting and seeing if the behaviour changes. 

Cheers 

Bennie

[el_freddo]

Also, any play in the distributor shaft? 

Cheers 

Bennie

[davepak]

7 minutes ago, el_freddo said:

Are you sure it’s 25 degrees before TDC? I remember my MPFI being 20 degrees BTDC. 

Might be worth adjusting and seeing if the behaviour changes. 

Cheers 

Bennie

You know.. I just had a moment of realization.. 

So the FSM indicates that ignition timing is 25 degrees BTDC for a Turbo MPFI AT. 

But now, my car is NO LONGER turbo. I removed the Turbo, I overhauled the engine with the right pistons to make it a non Turbo Car... An EA82 MPFI Naturally Aspirated. So I'm thinking... Should I then set the timing all the way back to 6 degrees BTDC in this case!!?? 

[1 Lucky Texan]

could need a wider plug gap too.

[subaru1988]

1 hour ago, davepak said:

 I overhauled the engine with the right pistons to make it a non Turbo Car... An EA82 MPFI Naturally Aspirated. So I'm thinking... Should I then set the timing all the way back to 6 degrees BTDC in this case!!?? 

 

I've learned the hard way with these cars that timing that is too far advanced will make your car run and idle poorly. At least that was certainly true with my '88 SPFI Wagon. The whole "computer" in these cars complicates it some, at least between the ears, for those of us used to carbs, points, etc. I say that about the computer because in old cars, a vacuum can for a high performance car is different than one for a base car, and so is the total mechanical timing curve.

One would think the settings would be different for timing, etc from car model to car model and ECU to ECU since the "computer" supposedly controls ignition advance, at least from what I've read on here. In other words, are you forcing a Turbo ECU to work with a non-Turbo engine? If so, does it really make any difference at any setting, including at idle when you connect the green connectors? Just throwing that out there since timing CAN obviously cause driveability issues.

Just in general principle, I'd start at 6 BTDC and go up from there. You'll find the sweet spot with some trial, error, and logging your changes.

Edited January 22, 2021 by subaru1988

[Rampage]

Try 8 degrees like the carb.

Looking at the valve timing The Turbo cams have the valves open for less duration that the MPFI non-turbo.

The valves are open longer with the non-turbo cams.

The Turbo forces air into the cylinder so the valves do not have to be open very long. The NA uses the piston to pull air into the cylinder so the valves are open longer.

The ECU controls the injectors as to how much fuel is added to the air going in.

It kind of makes sense that at higher rpms the pistons cannot pull in enough air and fuel to get a good burn. Or, am I over thinking it.

Back in the day, to get more horsepower we used cams ground to open the valve quick and hold it open as long as possible, then close it quick.

[idosubaru]

I’m no expert on timing but definitely time it to non turbo fuel injection specs if they differ. 

Ive had a 1987 turbo XT for years that I converted to nonturbo.  Dropped in a nonturbo engine and nonturbo ECU.  It has never run well. Barely drivable. I’ve driven it 30 miles once and that’s it.  Bogs and stutters bad.

I never figured out if it was a mechanical issue or swap issue. Maybe some Briton isn’t happy with the swap or maybe the gas tank is full of rust. Who knows. But I always suspected some of the wiring or ECU wasn’t happy with me converting it to nonturbo.  

I wonder if:

A: the Turbo ECU isn’t happy with something

B: if you swapped ECUs - If the ECU you choose is compatible with the wiring in the vehicle. 

between carb spfi mpfi flapper and MAF and disty changes jr seems like getting mismatched wiring or ECU is a possibility. 

[el_freddo]

13 hours ago, davepak said:

But now, my car is NO LONGER turbo. I removed the Turbo, I overhauled the engine with the right pistons to make it a non Turbo Car... An EA82 MPFI Naturally Aspirated

Ooh, this changes things! 

The vacuum advance device in the distributor is different between NA and Turbo on the old flapper AFM units. This is to take into account when on boost. 

As stated, cam profiles are different and the mapping of the ECU will be different, especially when it expects boost and it’s not getting it. I’m not sure if these RCUs were that advanced or if they just threw more fuel into the cylinder when it expects boost to be present. 

Switching to the NA ECU probably won’t work either as wires maybe different and there is most likely more wiring for the turbo ECU for the knock sensor and boost readings. 

Why was the turbo removed anyway? With the NA compression and modern high octane fuels you should be ok running the factory boost on those pistons if you can go back to the original boosted setup. 

Cheers 

Bennie

[davepak]

Works continue. 

But the actual fix does not. 

The problem has to do with fuel delivery once again. But I can't tell what the problem is. I've seen fluctuation in fuel pressure by the pump's operation, and I wonder whether the ECU is not doing it right. On suspicion of lacking a "ground control" I placed an already spliced ground cable to the chassis to notice a surge of voltage from 8.32 to about 9.40V on idle and subsequently up to 10 plus volts when revved up. But with the addition of the ground cable the pump seems to whine a lot. (like before) 

The videos show the oscillation on the gauge, like a wave from the fuel pump happening on its own at idle and then the increasing voltage for the fuel pump when hitting the gas pedal. 

Edited February 2, 2021 by davepak

[davepak]

**Updates**

calling out at @idosubaru @el_freddo @DaveT @naru2 @john in KY @subaru1988 @Rampage

I took the car for a ride. And it did. I can see that all systems work but it all goes down to one thing: FUEL PUMP POWER.

The stock fuel pump seems to work better of the three pumps I have. It has a fuel damper and I believe it makes a positive difference on flow and pressure. (It was placed there by Subaru anyhow). But the problem is the actual power that the pumps receives and the subsequent behavior after that.

I have seen voltage as low as 8.32 and as fine as 12.03 volts. Why? 

This suggest a lack of fuel delivery and the car sputtering then dying, this must be the very problem this car has had all along. It fails to deliver the required fuel and when demands increase, it fails to meet them. The pump used to whine a lot, now I have a set pressure out of a pump that is close to the actual requirements (around 40 psi of pressure) and I have noticed a quieter operation.

I can only imagine some issues with the wiring feeding the pump.  As far as I know, the ECU will supply a ground to actuate the pump "fuel pump ground control". So there must be an issue with this wiring system. But how, why and how can I test it accurately?

I am planning to run a live wire with 12v and a chassis ground and see if there is an improvement on the pump's attitude.

Any thoughts?

The videos show:

-The test drive, it reached 3100 RPMs at 40 something miles (I ran out of raod)

- Voltage fluctuations at the fuel pump. At one point its around 10 volts, at another around 11 volts even when revved up.

 

It is as if the ECU "forgot" about the fuel pump and it lets it slowly died. I've seen hoe the pressure starts to drop from 40, to 30, 20 psi until the car can no longer run, stalls and dies.

Edited February 2, 2021 by davepak
content added

[el_freddo]

Running a switchable and fused wire to the fuel pump would be a good test. 

If that proves successful, I would keep those new wires and put a new relay in that’s activated by the ECU ground wire. Pull the positive voltage from a known good source, or if it’s 5v, find and use the corresponding ECU positive wire. See if that setup works. 

Sounds like you’re onto a good thing there though! 

Cheers 

Bennie

[idosubaru]

Excellent.

1. Did voltage ever drop to zero? 
2. how many times did the voltage “drop”?  once or was it swinging around wildly?
3. Was there an obvious correlation of ‘voltage lowering’ to ‘performance decrease’ every time the voltage dropped. 

test the fuel pump relay.  

tracing and repairing would be ideal but that’s tiring. 

im not familiar enough with the pump electronic circuit to comment specifically. I’d be tempted to start replacing nonfused legs first and ensure the ECU is protected  

One of the connectors by the ECU puts the car into a test mode that cycles the fuel pump on and off I think. It’s the green ones.  That may help for testing purposes.

[idosubaru]

This is weird - I have an XT Turbo I converted to non turbo and it had fuel problems.

so I ran a direct switched power wire as el_freddo said.  During my longest run with it - about 40 miles it shorted and started smoking. Made it home but never found the culprit or fixed it and still have the car. 

XT Turbo, converted to nonturbo, fuel pump powering issue - That’s uncanny similarity to yours.  

coincidence?  

Or could there be something  different between the turbo and non? Seems unlikely  though.

I don’t have good internet access but Ill try to look up my old posts and see if I ever mentioned it hear  

 

[davepak]

3 hours ago, idosubaru said:

Excellent.

1. Did voltage ever drop to zero? 
2. how many times did the voltage “drop”?  once or was it swinging around wildly?
3. Was there an obvious correlation of ‘voltage lowering’ to ‘performance decrease’ every time the voltage dropped. 

test the fuel pump relay.  

tracing and repairing would be ideal but that’s tiring. 

im not familiar enough with the pump electronic circuit to comment specifically. I’d be tempted to start replacing nonfused legs first and ensure the ECU is protected  

One of the connectors by the ECU puts the car into a test mode that cycles the fuel pump on and off I think. It’s the green ones.  That may help for testing purposes.

Hi @idosubaru !

1. The voltage never dropped to zero.

2. The voltage started this time at 11.90 volts up to 11.98 volts, no pump whining, pressure at 42 psi. I did a voltage drop test: 0.86  and 0.64 volts in both positive and negative leads of the fuel pump. Also, a super smooth engine's operation and a responsive "driveway" test, it lurched forward nice and strong.

3. There was a drop in voltage and a subsequent change in the pump's operation: the voltage dropped down to 10.34 volts, the pump was in an operational "wave", up and down pressure and whining and less whining, just like a wave, pressure oscillated between 36 to 42 psi. There was no significant voltage drop: 0.34 volts in both leads to the fuel pump. I did not let the car run further, I know after a while the engine's operation diminishes.

4. There is something else here, this change in voltage (drop) seems to happen when the radiator fans turn on, more like, when the engine is warm at operating temperature. AS IF the hotter engine might have something to do with the pump's voltage reception. AS IF the ECU senses a hotter temperature and drops the voltage to the pump? As if that infamous water thermosensor (which is new) is tricking (for no reason) the ECU. (This last part is a total baseless conjecture, more like finding a culprit when I don't know what is causing the problem) 

I had a suspicion of a voltage drop particularly on the negative (ground) side to the pump. Especially because the ECU uses a grounding signal to operate the pump. However, the voltage drop is not significant and in fact corresponds to less than a volt on each lead.