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CEL 34 and 35 - 1990 Loyale

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I have a 1990 Loyale, non-turbo. The CEL has come on, giving the codes

34 EGR Solenoid or Circuit

35 Purge Control Solenoid or Circuit

 

I have replaced both of these solenoids, and the EGR valve, and the CEL stays on. I have reset the CEL, both with the connectors under the hood, and by disconnecting the battery. The CEL goes out, and comes back on a few minutes later. The problem started out with just code 34, but now comes up with both codes. I have checked all of the lines, and everything seems connected and in good condition. I'm wondering if there is any other part of the engine that will trigger these codes. I am past due getting it smogged and registered, and would appreciate any help figuring out the problem.

Thanks

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Are the solenoid's good? They are a common failure.

 

You can replace them with a 33 Ohm, 5 watt resistor to fool the computer. You don't need either one for proper engine operation. And once warm you can just hook the two lines together for the EGR and have it operating when you go to get it tested. The solonoid only shuts off the EGR when the engine is cold.

 

GD

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Thanks for the quick response. I've replaced both solenoids a few times with used ones from pick-n-pull. I'm not positive they were all good, but I assumed law of averages that they wouldn't all be bad.

Would the resistors just connect between the two fins on the plug that connects in to the solenoids. Right now, I just want to get the light off and get it to pass smog.

Thanks again for the help.

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Yes - either at the solenoid plug or at the corresponding pins on the ECU. The resistor goes between the ECU pin and ground. One of the two wires to the solenoid is a harness ground so you can just wire up the resistor to the existing plugs. If that doesn't work then you probably have a wireing issue - just cut the wire at the ECU under the dash, run the resistor from that pin to a ground point, and zip tie the resistor up there instead.

 

If you can't get the CEL to go off, pull the cluster and rerout the ground for the CEL to use the same ground as the e-brake indicator. That way the key-on lamp check will still work but the CEL will no longer indicate a fault.

 

GD

Edited by GeneralDisorder

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Since both of the solenoids are having trouble and the error code is for a circuit problem the trouble is most likely with the wiring to the ECU check for power getting to the solenoids, I doubt you are getting any. If not you need to check the wiring back to the ECU connections. The resistor trick won't work obviously if no power is getting to the devices.

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Thanks for all the help so far. The 35 CEL stopped showing up, and it was just 34. I figured out which of the solenoids this is, and wired up a resistor, and it worked. The CEL is off now. Unfortunately, I just took it in to get smogged, and failed. My Hydro Carbons were too high. I'm assuming that this is at least attributable to not having a functioning EGR solenoid. California has a program to help get cars up to emissions standards, so I think I'll be putting it in someone else's hands at this point (after I take of my rigged up resistor). If I find out more on the problem, I'll post it here. Again, thanks for the suggestions.

-Ross

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Guys, I am new here and been reading a lot on all the codes I've gotten in my 91 Loyale.

 

I do have one question regarding Code 34: if you can see the EGR valve working when you blip the throttle, is the solenoid really defective? I ask this because I get the Code 34 CEL, yet I can see the EGR valve work like it's supposed to.

 

Thanks for your input and for the wealth of knowledge that you have accumulated here.

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Guys, I am new here and been reading a lot on all the codes I've gotten in my 91 Loyale.

 

I do have one question regarding Code 34: if you can see the EGR valve working when you blip the throttle, is the solenoid really defective? I ask this because I get the Code 34 CEL, yet I can see the EGR valve work like it's supposed to.

 

Thanks for your input and for the wealth of knowledge that you have accumulated here.

 

 

I have the same problem. A piece of black tape over the light fixed it right up.

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I am going to a Pick-a-part in the morning and get a couple of good Toyota/Honda solenoids and swap the Sooby EGR solenoid. I checked the resistance and it read infinity, so I'm pretty certain that it is defective.

 

If that fails, black tape or resistor it is.

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Update:

 

Got two functioning solenoids from Toyota Corollas. One read 47 ohms and the other 63 ohms. Bought them both for a grand total of $22. Installed the 47 ohm and kept the 63 ohm as back up. Cleared codes and now CEL stays unlit!

 

On a side note, I noticed an improvement in throttle response as well as idling. I also noted that there was no new soot deposits in the tailpipe and the exhaust was a little hotter and didn't smell acrid like it used to. Going to have it smogged in the morning and I know it will pass!

 

Thanks again to everybody!

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i read this thread and i have a couple related questions for our resident SPFI gurus:

 

1. if the purpose of the EGR solenoid is to prevent the EGR from opening while the engine is cold then would i be correct to assume something is less than kosher when the EGR opens even with the engine dead cold?

 

2. what would cause this, a faulty CTS?

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1. I'm no "SPFI guru" but from my experiences this weekend and the troubleshooting leading up to it, I think the car runs richer with a bad EGR solenoid. Looks like the ECU is compensating for the bad EGR by going rich, regardless of motor temp.

 

2. Unsure, but I'm under the impression that CTS function does not correct for a faulty EGR.

 

I am still learning about my '91 Loyale :-\

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Solenoid's can stick open or closed - but that has no bearing on the continuity of the driver coil inside. You have two parts in them that can fail independently - the driver coil (which the ECU can detect and report with a code 34/35), or the valve itself (which the ECU cannot detect). Any and all combinations of driver/valve failure can and do occur resulting in four distinct states that the valve failure can fall into. Not all of them act the same.

 

A faulty CTS that reports warm when the engine is cold could cause the solenoid to function I suppose - but it wouldn't run for beans when cold as it would have no cold enrichment and in any case that can be ruled out with a simple Ohm test of the CTS.

 

EGR failure (either because of the solenoid or the EGR valve) in and of itself should not change mixture settings in the ECU, and it's functioning will not reduce HC's to any great extent. It's pupose is to reduce Nitrogen Oxides (NOx) which contribute to smog. Working or not - it will not change how the engine idles, runs, or drives.

 

Now if the EGR failure or solenoid failure has caused a gigantic vacuum leak - that's another story entirely. That can cause HUGE HC problems at idle as it will cause a severe miss where entire cylinder's of fuel/air are expelled through the exhaust completely unburned.

 

GD

Edited by GeneralDisorder

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Now if the EGR failure or solenoid failure has caused a gigantic vacuum leak - that's another story entirely. That can cause HUGE HC problems at idle as it will cause a severe miss where entire cylinder's of fuel/air are expelled through the exhaust completely unburned.

 

I believe that explains my situation. Did not think that the solenoid can have a vacuum leak, but that's naive of me. Thanks GD.

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I need a little help. I have a 92 4wd Loyale Wagon that I need to smog in. Runs great but the CEL is on.  Just drove 850 miles and got an average of 34mpg.  Hooked the green test cables up on the driver's side in the engine bay and shows a code 34.  I jumped the cables at the EGR solenoid, as described in this forum along with disconnecting the battery to clear the codes. No change, the CEL is still on.  Does this mean the ECU is bad?

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