trouble code 34 on spfi'ed ea81

[mountaingoatgruff]

hopefully this time i've got an intelligent enough question to avoid the routine condescension around here...

 

my 84 hatch is running remarkably well after it's spfi conversion, but it's check engine light was on and the o2 monitor was throwing a code even as i was barely ironing out the kinks in my ignition system.

 

i went through the "read memory" and "d-check" modes, following the procedures outlined in the fsm. both checks showed code 34:

 

"egr solenoid valve continuously in on or off position, or clooged egr line for ca models"

 

i then followed the fsm procedure for addressing the trouble code and according to the flow chart, the problem is in either the harness or the ecu.

 

i physically followed the LR wire from the fourth terminal on the ecu connector through the round connector between the body and engine harnesses to the egr solenoid valve connector itself and found nothing wrong so that theoretically eliminates fault in the harness.

 

i performed the voltage and resistance checks outlined further along in the flow chart and found nothing wrong with the ecu.

 

my question is whether the voltage and resistance checks for the ecu would show proper values even if the ecu is faulty.

 

also, under what conditions should the egr solenoid valve be open/closed?

 

to cover the simple stuff: the heads have been replaced with rebuilt ones and in the process all the vacuum lines were replaced as well, the egr valve itself appears to operate as it should (opens when i goose the throttle, so apparently the egr solenoid valve is staying open).

 

also, even though my spfi parts were off a co car and so the code wouldn't refer to clogged lines, the egr valve and pipe were cleaned before installation and i bead blasted my intake, including the egr ports, and verified all media was cleared from the mainfold before final cleaning.

 

i don't think that how i have all my vacuum lines routed would affect this, but i can provide that information if needed.

 

the car runs great and has much more power than i expected (which may be because of how poorly it performed in it's previous carb'ed life with small valve heads). i can't ignore the problem, though, because i need to take my car in to the smog nazi's asap.

 

thanks in advance

[Cougar]

Have you verified that the voltages at the valve end are the same as at the ECU end?

[mountaingoatgruff]

good idea, cougar - i'll do that after work tonight.

[mountaingoatgruff]

checked voltage at egr solenoid valve connector and tests out okay.

 

here's something to complicate things...

 

i didn't think of it earlier, but my spfi parts all came off a 92 loyale from co, fed smog equipped. but to avoid having to rig a clutch pedal switch in addition to a neutral switch i got an 89 spfi ecu from a car in a local wrecking yard, ca smog equipped.

 

the 89 ecu was in the car when i got the code. the fsm explanation says that on ca cars code 34 may indicate a clogged egr passage, so knowing my passages are clean i thought maybe it was just sensing a discrepancy between the two sets of smog equipment.

 

i know the difference in ca and fed cars is just the egr temp sensor. i kept waiting for a code 55 meaning an open or shorted erg temp sensor circuit, but it never happened. i then figured i just see what happened if i put in the fed car's ecu.

 

it gave no codes for quite a few minutes and even through d-check mode. then after i shut the car off, actually bolted the ecu to the column and restarted it gave just code 34.

 

i ran read memory mode on each ecu to check the vehicle specification codes and both the silver ecu from co and the black ecu from ca gave a 5, manual fed/can emissions car. maybe the 89's ecu was replaced...

 

i'm done messing with it for tonight, but i'm wondering if anybody has ever had issues with an ecu grounding or something else like this.

 

i'll try insulating the case of the ecu against grounding and remounting it tomorrow. if it goes through all check modes without codes and doesn't throw a code after driving a couple days i'll figure that the problem was in grounding the ecu case, despite how much sense that doesn't seem to make.

 

i'm still wondering what conditions determine when the egr solenoid valve should be open or closed if anybody knows for sure.

[Cougar]

I think the EGR valve control from the ECU is dependent on various things that are happening at the time. Engine temp, throttle position, O2 sensor feeback, and possibly other things.

 

Is the valve staying open or closed all the time? Can you tell us what the voltage readings are at the valve?

[Gloyale]

Have you checked that the valve is normally closed? Can't blow through?

 

Have you tried blowing through the solenoid, with 12v applied to see if it opens or is stuck/clogged?

 

Have you tested the resistance of the solenoid valve?

 

Have you tried using a different solenoid valve?

 

 

 

 

As a last resort a 33 ohm resistor(5 Watt IIRC) soldered in place of the solenoid should shut off the CEL. If you do this, plumb the vac lines to the solenoid toghether so the EGR valve always get's vaccuum. This could cause a bit of power loss under heavy throttle until warmed up. (That is the job of the solenoid, to halt EGR function until engine is warmed up to temp. The old ones used a thermovalve instead of being switched on by the ECU via the solenoid)

[mountaingoatgruff]

the first thing i checked was whether the ecu would throw the code again after unbolting it and leaving the battery disconnected last night, just for curiosity's sake. of course, no code.

 

i tried bolting the ecu into place while the car was running to see if i could get it to happen...nothing.

 

so before busting out the multi-meter i checked the valve itself as gloyale suggested. it was closed with the car off.

 

i then applied 12v and i had to play with the wire to get it to open (i thought maybe i wasn't getting decent conduction).

 

after getting it to open, i removed current and it failed to close - i couldn't get it to close at all.

 

so i removed the valve and noticed the black plastic housing has split down the one side. now its off to the wrecker to find another.

 

good call guys, and thanks for the help. i love my subaru but crap like this really makes me appreciate the simplicity of my old mopars.

[Cougar]

It sounds like you will be in good shape after you replace the defective unit. You are welcome for the help and thanks for the feedback.

[mountaingoatgruff]

i have a few things i need to go to the wrecker for, and i plan on finally making it there on saturday. i'll try to remember to post whether a working valve solves the issue.

[Gloyale]

i have a few things i need to go to the wrecker for, and i plan on finally making it there on saturday. i'll try to remember to post whether a working valve solves the issue.

 

Vaccum Solenoids off of other vehichles will work if you have trouble finding an intact, functioning replacement.

 

I like the ones from Isuzu troopers, and Hondas. You'll have to swap connectors, and make sure you get one with the same functions (off closed, on open)

[DaveT]

i'm still wondering what conditions determine when the egr solenoid valve should be open or closed if anybody knows for sure.

 

The EGR solenoid is set up to disable the EGR valve during warm up. When the engine temp sensor (not the one on the temp gauge) gets up to operating temperature, the computer de energizes the coil of the solenoid, allowing the EGR valve to get vacuum. In disable - mode, the EGR valve is routed to a tiny air filter so it closes. The ECU does not have any sensors to verify the operation of any of this - except it can tell if the coil in the solenoid is open.

 

My solution to the always failing OEM solenoids:

http://home.comcast.net/~davidtief/solenoid.html

[mountaingoatgruff]

okay, so i take it isuzu, honda, and toyota solenoids are more reliable than the hitachi ones used by subaru?

 

i have to go digging through late 80's nissan maximas to look for an ecu (for a family member - i'd never buy one of those stupid 3.0 cars).

 

do nissans use respectable solenoids?

[Gloyale]

okay, so i take it isuzu, honda, and toyota solenoids are more reliable than the hitachi ones used by subaru?

 

 

No, not really. Most of them are Hitachi or Denso. The difference is later vehichles, like 90-96 Troopers and Amigos, Toyotas, and Hondas have several solenoids a piece. And they are newer. Also, at least the Toyotas and Hondas have a better change of having NOT been driven hard or abused in the snow/mud like a subie.

[Gloyale]

do nissans use respectable solenoids?

 

 

Hmmm.... I would try for something from a newer vehichle. 90s not 80s. Nissan probably has the same or similar solenoids. Which means if they are a similar age, they could be shot too. You're trying to find one that's 10-15 years old, not 20-25.

[mountaingoatgruff]

yeah, i suppose that whole 10 years older thing might be something to consider while looking. all the asian imports are spread out along the back of the yard i go to, i was just thinking of saving time is all. i definitely don't mind the extra time to find a good part rather than go through this again in the near future.

[DaveT]

yeah, i suppose that whole 10 years older thing might be something to consider while looking.

 

All I can say is the Toyota ones (from a junkyard) I put in almost 20 years ago still work. Moved them from car to car, even. Back when I did that mod, the Subaru ones always failed. Out of the 6 EA82 wagons I have / had, I have only a few of the OEM solenoids.

[mountaingoatgruff]

so i got a solenoid off a 91 toyota corolla that is closed when off, has the same plug, and is mfd by nippondenso:

 

 

the writing says the port with the hose attached is the vacuum supply (so i hooked that to the tb) and the other would go the the egr. i plugged it in and let the hatch come to temp.

 

while cold the egr wouldn't open and it idles much smoother so we're okay there now.

 

but after warm-up the egr still wouldn't open and the code 34 comes back (this is with the ecu on the floor not grounded, so you guys are right - that's obviously not the problem).

 

i removed the solenoid and was going to try seeing if i could get it to open when i realized i didn't really know how i would do that in the first place.

 

does the mount of the solenoid need to be grounded? which wire receives 12v or is it both?

 

i tried messing with it a bit but i don't wanna fry it... it may be a $3 part but the gas to get me there is $3.70/gal out here!

 

i need to know how to test this thing so i can verify that its okay and then rule that out.

 

thanks

 

edit: just thought i'd mention - after lookind at dave's pic, the toyota solenoids we have look the same. mine had the black cylinder on the port its on now and the other two were hooked up to rubber lines. it wasn't an egr solenoid in it's original life but i didn't think that'd matter. also, i looked at hondas but those cars were a mess at this yard and it was too hard to find anything in that area...engines and transaxles strewn about...doors and hoods piled between cars...those ricer guys are hacks.

[DaveT]

but after warm-up the egr still wouldn't open and the code 34 comes back (this is with the ecu on the floor not grounded, so you guys are right - that's obviously not the problem).

 

i removed the solenoid and was going to try seeing if i could get it to open when i realized i didn't really know how i would do that in the first place.

 

does the mount of the solenoid need to be grounded? which wire receives 12v or is it both?

 

To test the solenoid, apply 12VDC to the 2 wires. + on one, - on the other. The 2 wires are not supposed to be connected to the frame / mounting bracket. You should hear the solenoid click when you connect the 12V. If you blow air - (use a clean piece of hose & blow into it) you will find one way, the air goes through with no power, another port will only allow flow with power, and the 3rd will always let air flow, but which of the 2 other ports the air comes out of will be decided by power / no power. These are low pressure, don't use more than 10PSI if you use a compressor.

 

The 34 code shows up for an open circuit on the EGR solenoid coil. It could also be along the harness from the ECU. I'm not sure if it can sense shorts. It is also possible the sense circuit or the driver is bad in the ECU. I have only had bad (open circuit) solenoids. Have you checked that the wire to the solenoid goes to 12V after warm up?

 

The Toyota ones were much nicer to get from the donor cars. They use about 4-5 of them in each car, it makes no difference what the original function was, as long as it has 3 ports.

[GeneralDisorder]

Wire a 33 Ohm, 5 watt resistor (ceramic, flame-proof) into the solenoid wires and forget about the solenoids. Do that for both the EGR and the Purge solenoid. If you still get the code, wire them directly to the ECU with a 12v fused supply under the dash. Actually it might be good to do that and leave the dead solenoids under the hood for show.

 

When you go to have it tested, warm up the rig then connect the EGR vacuum line. Disconnect it when you have passed. EGR only opens under load, at about 1500 RPM and higher. Purge is uneccesary - it will not affect their tests.

 

GD

[mountaingoatgruff]

first off, i'm definitely not going to be doing anything to circumvent any emmissions equipment. as it is i'm not too sure how much trouble i'll have smogging this thing and if i do have trouble i want to know everything is working as it should.

 

i tested the solenoid by stripping a bit of each wire, clamping one between the battery terminal and it's cable clamp and touching the other wire to the other terminal. no signs of life - it didn't click/open. testing this way would provide enough conduction wouldn't it - it shoulda opened?

 

checked voltage at solenoid connector on car after warmup and my multimeter showed 13.45volts. i reconnected the solenoid and noticed when you goose the throttle the egr diaphragm opens slightly and immediately recloses. when you quickly rev to and hold high rpm's it doesn't open at all.

 

i checked the operation of the egr before installing and it opened smoothly without too much effort then.

 

sounds to me like i just replaced a bad solenoid with another bad solenoid...

[DaveT]

 

A-

i tested the solenoid by stripping a bit of each wire, clamping one between the battery terminal and it's cable clamp and touching the other wire to the other terminal. no signs of life - it didn't click/open. testing this way would provide enough conduction wouldn't it - it shoulda opened?

 

B-

checked voltage at solenoid connector on car after warmup and my multimeter showed 13.45volts. i reconnected the solenoid and noticed when you goose the throttle the egr diaphragm opens slightly and immediately recloses. when you quickly rev to and hold high rpm's it doesn't open at all.

.

 

A- One wire of the solenoid to one battery terminal, other to the other, yes it should click. Stupid electrons! It does sound like you found a bad one.

 

You can also use the ohm meter to check the solenoid coil. Bring it with you to the junkyard.

 

 

B- Did you check it before warmup, - point being to see that it changed state?

During my first hunt to solve the 34 code, I hooked up a test LED with a 1200 ohm resistro and a few feet of wire. The resistor lead would slip into the back of the ECU conector along side the pin I wanted to monitor. The other end of the resistor has a length of wire to the LED, other end of the LED length of wire to ground. Tape the LED on the dashboard, watch it go on / off to know the ECU is changing state of the pin.

 

I also have a vacuume test gauge (NAPA or whatever parts store is around) Put a Tee in whatever vacuume line, run the hose into the car to the gauge.

 

The EGR valve might not open much under no load conditions. I don't remeber the curve.

[GeneralDisorder]

first off, i'm definitely not going to be doing anything to circumvent any emmissions equipment. as it is i'm not too sure how much trouble i'll have smogging this thing and if i do have trouble i want to know everything is working as it should....

 

And I told you EXACTLY how to do that. You are either not listening, or you don't understand how these two systems work. The EGR code can be eliminated with the resistor, and the EGR can still be enabled by connecting it directly to it's vacuum source. The solenoid only DISABLES the EGR durring warm up - it actually functions as a "de-emissioning" device by turning off the EGR till the engine warms. Removeing the solenoid and plumbing the EGR directly does not bypass any emissions equipment whatsoever.

 

The Purge solenoid functions to pull the evap gasses from the charcoal canistor into the intake. It's a purely passive system, and cannot be tested by the "police". It does not affect tail-pipe emissions except to potentially increase them slightly as evap gasses would enrich the mixture.

 

Installing resistors and leaving the "dead" solenoids in place will be impossible for them to detect in any way, and will eliminate your code, and your CEL, which would automatically fail you..... I don't see a problem here besides your lack of understanding.

 

GD

[Gloyale]

And I told you EXACTLY how to do that. You are either not listening, or you don't understand how these two systems work. The EGR code can be eliminated with the resistor, and the EGR can still be enabled by connecting it directly to it's vacuum source. The solenoid only DISABLES the EGR durring warm up - it actually functions as a "de-emissioning" device by turning off the EGR till the engine warms. Removeing the solenoid and plumbing the EGR directly does not bypass any emissions equipment whatsoever.

 

The Purge solenoid functions to pull the evap gasses from the charcoal canistor into the intake. It's a purely passive system, and cannot be tested by the "police". It does not affect tail-pipe emissions except to potentially increase them slightly as evap gasses would enrich the mixture.

 

Installing resistors and leaving the "dead" solenoids in place will be impossible for them to detect in any way, and will eliminate your code, and your CEL, which would automatically fail you..... I don't see a problem here besides your lack of understanding.

 

GD

 

I wouldn't say it quite the same way.......but..... he's right. Wire the resistor correct, and plumb the EGR directly to it's vacuum sorce.

 

You can have you're cake(no CEL) and eat it too (functional EGR)

[mountaingoatgruff]

And I told you EXACTLY how to do that. You are either not listening, or you don't understand how these two systems work. The EGR code can be eliminated with the resistor, and the EGR can still be enabled by connecting it directly to it's vacuum source. The solenoid only DISABLES the EGR durring warm up - it actually functions as a "de-emissioning" device by turning off the EGR till the engine warms. Removeing the solenoid and plumbing the EGR directly does not bypass any emissions equipment whatsoever.

 

The Purge solenoid functions to pull the evap gasses from the charcoal canistor into the intake. It's a purely passive system, and cannot be tested by the "police". It does not affect tail-pipe emissions except to potentially increase them slightly as evap gasses would enrich the mixture.

 

Installing resistors and leaving the "dead" solenoids in place will be impossible for them to detect in any way, and will eliminate your code, and your CEL, which would automatically fail you..... I don't see a problem here besides your lack of understanding.

 

GD

 

the problem here is that i said "as it should." bypassing the solenoids may allow the system to operate in a way that satisfies their requirements but not mine. i am going to repair the defects in my car to allow it to work properly - i'm not going to modify it further to just get it to work. that is not solving the root cause of the problem, its just circumventing it.

 

i understand these systems just fine and what i don't know i'm learning. i really don't appreciate the way you insult my intelligence. if i wasn't interested in going that route when gloyale suggested what makes you think i'd suddenly want to do it after you browbeat me like that?

 

the way you go on about the evap/purge system makes it obvious that you're the one lacking understanding here. can you use your awesome konwledge and rhetoric to explain to me how disabling the purge solenoid allows the system to operate "as it should?"

 

why don't you just stick to correspondence with the portion of the usmb crowd that worships you and doesn't seem to mind when you crap on them?

[mountaingoatgruff]

I wouldn't say it quite the same way.......but..... he's right. Wire the resistor correct, and plumb the EGR directly to it's vacuum sorce.

 

You can have you're cake(no CEL) and eat it too (functional EGR)

 

 

like i said, i'm making an educated decision to decline performing this proceedure. i just want to do it properly, regardless of the possibilities.

 

the fact is what i'm doing to my car is illegal in ca under normal circumstances. i expect to have issues when i take my car in to be smogged and i expect to have to request that a referee allow me to smog my car as an 84 gl with a 92 engine or as a 92 car (same test).

 

the visual inspection will probably catch that i did all sorts of other things to the car, like chop off the asv's and weld the pipes. those sorts of modifications may cause further issues that i am not interested in dealing with so i'm trying to limit how much is modified (like for the asv pipes i've got one flange w/out a port and i'm trying to find another). i want everything related to and used by the fuel injection system to be working as it should, which is as it would from the factory or as close as it is possible to get it. this means i wont bypass or modify systems/components/parts where proper repair can be made.

 

i'm choosing to have issues with the car now, before the gov't is involved, so that once they are i can hope things will be as painless as possible.