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Why delete the EGR valve?


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26 replies to this topic

#1 Jes1991

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Posted 17 March 2018 - 10:49 AM

When I bought my 91 Loyale the check engine light would come on after about 2 minutes of driving. The guy I bought it from said that it was because of a malfunctioning EGR valve and the person that owned it before him had disconnected the little vacuum hose going to it and put a stopper in the hose. The wagon ran fine (except a dirty fuel filter that I replaced) and so I didn't think much of it. So yesterday I had a little time on my hands and was tightening the throttle cable and noticed metal sticking out behind the EGR. The guy had taken a soup can lid and completely blocked off both ports with the lid. I pulled the valve off and checked it out. It still could hold a vacuume, so I figured it wasn't "bad". I took the soup can lot off and there was a perfectly good gasket under it. I slapped the valve back in, reconnected the vacuume hose and drove it for a bit. I didn't notice any difference at all (maybe the exhaust was a bit softer) even the check engine light came back on exactly as it used to. So what was the point I wonder? Any ideas? I bought the car a year ago so it would be a bit awkward to call him up after all this time.

Edited by Jes1991, 17 March 2018 - 10:52 AM.


#2 Gloyale

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Posted 17 March 2018 - 11:09 AM

there really isn't a point.  EGR helps keep cyl temps lower and reduce NOx emissions 

 

And the code isn't related to the valve actually, but the solenoid that keeps it inoperarble until engine warmed up.  These old ECUs have no way of knowing if the EGR is opening or not.  The ECU just sees a faulty resistance from the dead solenoid and throws the code.

 

you are better off with it the valve restored.  It may or may not be operating depending on wether the solenoid is fail closed (non-op) or open (EGR cold or warm) but either way I will bet that it was leaking exhaust from the soup can.



#3 naru

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Posted 17 March 2018 - 11:27 AM

Hard to understand where the code came from.

If the solenoid is bad,it was bad before you hooked up the vacuum.

Should have triggered the check engine light earlier as well.

What is the code??

 

EGRs can be bad in other ways.

Sometimes the valve does not seat resulting in a poor idle.

 

Or,some people get silly about "removing all that emissions crap" whether the reults are detrimental or not.

An inoperative EGR messes up ignition timing at cruise.



#4 Jes1991

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Posted 17 March 2018 - 02:57 PM

That's the second part of this crazy story. It's not throwing any codes. At least not any that an obd1 scanner can see.

#5 Gloyale

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Posted 17 March 2018 - 03:23 PM

That's the second part of this crazy story. It's not throwing any codes. At least not any that an obd1 scanner can see.

 

CEL will light if you leave the test connectors hooked up.

 

Disconnect the green test connectors and the black (or white)read mode connector.



#6 jono

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Posted 17 March 2018 - 04:05 PM

Keeps combustion temperatures down...when and by how much and for how long?

#7 DaveT

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Posted 17 March 2018 - 04:16 PM

The cel comes on because the solenoid coil is open, in all of the cases I've seen on my ea82s. The code is read by viewing a red led in the ECU which is under the steering column. You have to remove the plastic trim panel that is under there to see it. You can count the blinks of the red led while the car is on and the CEL is lit. It goes slow blinks then fast blinks to indicate a 2 digit number.

#8 Jes1991

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Posted 17 March 2018 - 04:17 PM

That's what the mechanic said. I unhooked both of them and now the check engine light comes on quicker and still no codes... maybe a bad ECU?

#9 DaveT

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Posted 17 March 2018 - 05:10 PM

You unhook the solenoids? Yes, that will cause the cel quicker.

The only way I know to read the codes on these old models is the led I described previously. The simplest method is to stop when the cel lights, put in in park, count the blinks.

#10 DaveT

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Posted 17 March 2018 - 05:11 PM

It is normal for an open egr solenoid coil to not light the cel immediately. The egr is not activated until the engine is up to temperature, so it's condition is not checked.

#11 jono

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Posted 18 March 2018 - 12:41 AM

Could be a change in the resistance values inside the solenoid coil that causes a delay in the light

You could find another solenoid of any kind, that is in a working condition and hook it up electrically to check result.

If you were to use another solenoid to work the egr you may need to check its actions, workings etc to see if it needs to bleed off, totaslly shut off or bypass vacuum

#12 Gloyale

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Posted 18 March 2018 - 01:14 AM

You unhook the solenoids? Yes, that will cause the cel quicker.
 

I think he meant he unhooked the test and read connectors

 

And since he did, and the CEL is on there is a code.  If it's 34 (3 long, 4 short) it's the EGR code for a faulted solenoid.  



#13 idosubaru

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Posted 18 March 2018 - 01:01 PM

Follow the check engine light and symptomatic leads and ignore what a previous owner did.

Maybe they were guessing, or given bad advice
from a neighbors friends oil change guy, or had an EGR code due to some battery issue or prior work and misdiagnosed it....theres no telling. Making assumptions or decisions on that could be pointless if nothing else else is known.

#14 idosubaru

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Posted 18 March 2018 - 01:03 PM

List the current symptoms and codes.

Why were you tightening the throttle cable? Any issues?

Why bother with the EGR if it was running right? Are you looking for a reason as lost people do and chasing a suspicion of issues?

#15 Jes1991

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Posted 18 March 2018 - 06:43 PM

Yes I unhooked the 2 tester cables. And now the light comes on instantly after startup. Still no codes or flashes. He even unhooked the maf sensor to try to throw a code and STILL no codes. I can't see any broken or chewed wires...
I was tightening the throttle cable because over its 27 years of life, it was stretched and I had a 2" dead spot before I got any throttle. And I like everything hooked up in my car unless it actually improves it's preformance. I'll try to get a solenoid and test it.

#16 idosubaru

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Posted 18 March 2018 - 07:56 PM

Check engine light is on and there are no codes?
It has the stock engine in it right?
How are you checking for codes?

What do you mean an “OBD1” code reader? These don’t require a code reader though it seems like you know how to look for the flashes.

#17 Jes1991

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Posted 19 March 2018 - 01:44 PM

Stock motor (I don't know if it's original) and the On Board Diagnosis plug. It's a whitish yellow plug under the hood near the fuel pump.

#18 Gloyale

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Posted 19 March 2018 - 02:34 PM

Stock motor (I don't know if it's original) and the On Board Diagnosis plug. It's a whitish yellow plug under the hood near the fuel pump.

 

Are you looking for the CEL to blink?  Because that's not how to read codes.

 

Got to look at the LED light inside the ECU, visible through small hole in the front of ECU if you drop the lower dash cover.

 

Don't connect either test or read connectors. 

 

Just look at the LED while the engine is running with a lit CEL.


Edited by Gloyale, 19 March 2018 - 02:35 PM.


#19 DaveT

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Posted 19 March 2018 - 03:29 PM

+1 what Gloyale wrote.

#20 jono

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Posted 19 March 2018 - 05:12 PM

You have a fuel pump up front and an ECU?

 

All I have seen with ECU are mpfi NA and turbo and fuel pump is just forward of the fuel tank. Is yours spfi ? Do spfi have front fuel pumps? Or ECU with a carb ?



#21 Jes1991

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Posted 20 March 2018 - 11:48 AM

Fuel filter. Sorry my bad. It's on the upper drivers side under the hood. I'll double check the light on THE ECU tonight if it's not raining too hard

#22 st33lix

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Posted 21 March 2018 - 05:16 AM

Hi Jes1991,

 

on my Subaru Leone Superstation Turbo (1987) with EA82T Engine i have a green (2 Pin-TEST-mode) connector and a black (1 Pin READ-mode) connector under the steering wheel.

 

"Reading mode" is activated if the green one is disconnected and the black one is connected.

 

Error-Blink-Code is visible on the LED light inside the ECU with Key-Switch ON and Engine OFF.

If there is no error code saved on the ECO the led will blink you the car specification.

 

greetings

Franz



#23 idosubaru

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Posted 21 March 2018 - 07:47 AM

Reread what Gloyale said - don’t use any connectors.

Count the LED flashes on the ECU.

How are you using that diagnostic plug? What are you doing with it or hooking up tonit and where are you getting instructions to do this?

#24 st33lix

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Posted 21 March 2018 - 02:02 PM

Gloyale, DaveT and Idosubaru are absolutely right !

I just wanted to add, that without any connector the LED on the ECU is showing the error why the CEL is on at the moment.
With the black 1 Pin reading connector the LED shows also error codes from the past that are saved on the ECU.

greetings
Franz

#25 jono

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Posted 21 March 2018 - 06:43 PM

The blinking red LED on my 85 GLTA was my first intro to successful diagnostics of ECU trouble codes back in 2006.

 

The code was a "solenoid stick to open or stick to shut"

 

and indeed it was the EGR solenoid, whch I replaced with one that worked from a carbed EA82, problem solved.

Most lately n my NA Mongrel EA82 completely stopped egr and its solenoid from any duties and now have sweetest tune, best regular fuel economy ever had - consistently ! :D






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