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Ea82t bogging at 4-5000 rpm


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Hello all. I am brand new to this forum but a very happy owner of a 1987 subaru GL-10 in its middle stage of decomposition. After second gear i cant seem to wind the motor past maybe 4300rpm and while its there its gutless and acts like a lack of fuel. The fuel pump is in good working order and the motor runs cool. Any help would be appreciated.

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Its the 5 speed with turbo. Ive also replaced the fuel filter and plugs. The engine has high miles but i dont know how many. The odometer doesnt work correctly so it safe to assume over 200,000. However it runs cool, and doesnt burn oil or coolant.

Its the multi port fuel injection.

Edited by snowscoob
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Fuel pump is in good working order ...based on what info ? The only way I have been able to correctly test these efi fuel pumps is T piece in a gauge and run it on a "dyno" and find it is usually or always lower down the revs that its pressure drops off, not near 4300rpm. Needs to be ~ 36 psi, seen EA82T bog down at 10 psi just when you want some power about 2200 when turbo starts to spool up. Just because it pumps fuel don't mean it is healthy - it is correct pressure, so, what about fuel pressure regulator and its vacuum supply hose ?Maybe some injector cleaner? in fuel? Air filter element healthy ?

 

It is efi - could be a few things you won't be able to put your finger on until swap bits in and out ....

 

coil, or leads?

Edited by jono
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+1

Define "good working order".

 

Might not be the pump,but,go there first.

Pump needs to maintain 43 psi at full boost,full throttle.Does it?

 

You can put 7 psi on the regulator(full boost) w/a bicycle pump and then check the fuel pressure and volume after hot wiring the pump if a road test is out of the question.

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I will test the fuel pump out as suggested as soon as I can. I have a fully equiped shop available to me at different times so this shouldnt be a problem. I recently drove the car 2000 miles with a broken axle.....quite scary. Not to mention it started in -50 North Dakota! But the subaru pulled through. It has been maintained as best as I can manage. The plugs... air filter.... and cap are new. Maybe the oxygen sensor could be the culprit? I pulled the plugs today and they were white, making me think lean. Im out of my element with fuel injection, Im a carb guy.

Can anyone point out where the the fuel pressure regulator and fuel pump are located?

Edited by snowscoob
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The turbo engines have knock retard. So if there's a problem with that it will pull all the timing and the power will fall flat. I'm not sure if 87 still had the separate knock module or if it had been integrated into the ecu by then. Check the knock sensor and its wires too.

 

really ? is this comment from theory land or experience? The only reason it is theoretically pulling timing back (step-by-step) is that things are at max power producing before detonation and I have seen my knock boxed system in midst of its retardation by monitoring the output of the otherwise not connectd terminal near the coil on 85/86 models and seen it run up to about 4.0V and not felt any falling flat.

 

If the knock sensor circuit is suspected, does the 4plug ECU have a test point like 3plug ECU;s with separate knock control module?

 

What  ECU have you got ? Flapper MAF or hotwire ? Sounds like you may have 4 plug and hotwire ....

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Well in my mystical theory land, I have seen newer cars run terrible under load due to a partially failed knock sensor that was putting out a false signal but still not pop a code for it even with much better self diagnostics than any EA82 ecu has. Knock retard doesn't necessarily mean that the engine is detonating. It's just an output based on inputs and if the sensor, wiring, or circuitry is failing you can get false retard and a massive loss of power. I'd also ask that you'd watch your tone when calling BS on a suggestion any other member here may offer.

 

Fuel pressure and the ignition coil/wires would also be the first place I'd look, followed by a restricted exhaust. But beyond that you have to look at timing.

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i used to have an 87 gl-10 turbo wag, ive dealt with all kinds of issues.

 

3 major problems that pop up with that motor are 1 coolant temp sensor, 2 intake boot leaking, and 3 maf.

 

all of those will cause stutters and stumbles..

 

another thing that i dealt with is a little stumble due to a bad cap and rotor. but i think i read that you replaced that.

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Yes cap and rotor are new. Exaust has been gone through, MAF cleaned, and I checked all the vaccum lines yesterday and failed to find leaks though I wasnt to complete. I did see however, that the wire leading to the oxygen sensor was crimped at the base. I moved the wire a bit to get a better look and the car wouldnt start. Moved it back and she fired. So i think i found my culprit.

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You can check to see whether your timing is advancing at higher rpms by hooking up a timing light and put a tic of white off paint on the correct idle advance setting on your flywheel. Then with light hooked up, you can spool up the engine to see whether the timing is advancing by watching your white tic mark on the flywheel.

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then you can tap the engine block with say a 1/2" extension bar to effect a knock to be sensed by the knock sensor, watch the voltage from the test wire near coil if it is Series 1 3 plug ECU to see if it spikes from its happy running 1.7V up to 4.5V and see if timing retards and returns to previous seen timing - can be done at idle. A no BS calling comment as per usual, in light text, tone is adjusted to bold if I get excited. Sorry if you tok insult WoodsWagon, none intended

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I new I liked Subaru. I have been watching many other forums of vehicles that hold my interest, but none have the kind of loyal and helpful fans the almighty scooby does!

Allright.....I have much to think about. I put in a new Oxygen sensor because i cant stand having exposed wires, but as I am the tinkering type I will go through the motions and see what I come up with. Thank you all who chimed in for your help. I'm sure I will need more advice in the future.

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