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My Engine Light -- clogged EGR passages in engine!


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10 replies to this topic

#1 Hank Roberts

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Posted 07 April 2005 - 06:08 PM

Edited 5/2 changing the title -- current best guess, it was the passageways/ports that carry the exhaust gas from the exhaust side to the valve, and from the valve back to the combustion chamber, that were packed solid with crud. They're now being cleaned out. Hoping ...

----

Well, I _almost_ got it home before the Check Engine light came on again.

Maybe this is a clue -- I'd been at the highway standard 65-75 speed til everyone came 'round a curve and saw stopped traffic, bridge work going on. Sudden stop, then creeping along at 2 to 4 miles an hour for a while, then a stretch of a mile or so at 25, then everything cleared out, I sped up to 65, and the Check Engine light came on.

And it's stayed on -- I let the car rest overnight, started and stopped the engine five times to see if that'd change anything -- when the key is turned right to the running position but the engine hasn't turned over, I can hear the fuel pump and some relay under the steering wheel clicking and the Check Engine light flashes. As soon as the engine starts up, no more flashing or clicking.

Suggest anything to anyone?

I know where the leads are (under the hood in front of the driver, for the 1988 SPFI) and how to take down the codes, so I'll do that this weekend. I know grounding may help, and I know how to test resistance and will do that across whatever sensors I find. And I know the reports that the EGR relay coil was fabricated with no solder connecting the leads, apparently trusting the plastic coating to maintain contact and that these do corrode over time and the resistance goes up -- so assuming I can find that relay coil I can check it.

And I know a lot of questions to ask the mechanic over at the other end of the Bay who thought this problem had been fixed before I bought the car yesterday. I may have to take it back to him before doing anything since he does warranty his work - but I'd sure like to know if he is doing it right.

Wish I had the ability to really work on this myself, I don't, so beyond trying to understand and check things, I may be looking for a mechanic in Berkeley a lot sooner than I thought.

#2 hooziewhatsit

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Posted 07 April 2005 - 07:01 PM

The relay clicking and fuel pump running are most likely because the green connectors are connected.

What code does it throw? 34 for the EGR solenoid?

#3 Hank Roberts

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Posted 07 April 2005 - 07:13 PM

The relay clicking and fuel pump running are most likely because the green connectors are connected.

What code does it throw? 34 for the EGR solenoid?


No, it ran fine most of the way home -- and when I looked under the hood, the green connectors are not connected. But the light stayed on once it came on while driving, and comes on as soon as I turn the key now.

I will be able to look at codes tomorrow or this weekend - I just had time to look under the hood to locate the connectors and try starting it a few times this morning, and call the mechanic who'd worked on it to tell them the problem hadn't really gone away after all, or had come back.

Unfortunately the mechanic didn't write down the code numbers on the paperwork. The problem they claimed was that the computer ECU wasn't sending a proper signal to the EGR valve, replaced the valve, then replaced he ECU saying they'd found it had an internal short.

Since it wasn't my car at the time, I figured, better they fix it before I take title -- which I thought had happened. Now, it's mine -- and I'm hoping they warranty their expensive work done four days ago!

#4 calebz

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Posted 07 April 2005 - 07:15 PM

With the key on and motor off, you should hear the fuel pump come on for just a second or 2. This is the fuel system pressurizing. If it comes on and off every second and a half or so, its because the D-check connectors are connected.

Check the codes and see what you come up with.

And don't overthink it.. For the most part, those plactic connector covers do their jobs. The only real exception I have seen to that are on the coolant temp sensor (on turbo motors) and the knock sensor.

#5 calebz

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Posted 07 April 2005 - 07:17 PM

Unfortunately the mechanic didn't write down the code numbers on the paperwork. The problem they claimed was that the computer ECU wasn't sending a proper signal to the EGR valve, replaced the valve, then replaced he ECU saying they'd found it had an internal short.


If he was getting an EGR code, replacing the valve won't do anything. Its the solenoid that causes the code.

#6 Hank Roberts

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Posted 11 April 2005 - 06:00 PM

OK, got a 3-long, 4-short code flashing with the key in the 'run' position -- this is with the under-hood connectors disconnected.

EGR solenoid -- no surprise there.

Now my only real question is, do I risk more if I take it back to the mechanic an hour and a half away, who replaced the EGR valve and then the ECU (a $700+ part) but not the EGR solenoid, proclaimed it fixed, and sent it out -- then my old friend sold it to me and I drove it off, as noted.


Or do I risk more if I take it to a local Subaru mechanic (in Berkeley, there are 2 shops that come very well recommended for the old generation Subarus)? They ought to know what to do.

But if they find the newly-installed ECU is bad, who do I blame?

(Well, that's easy, I blame myself, I never owned a Subaru, and didn't have the opportunity to do the research before I bought this one at a distance.)

I am guessing just replacing the EGR solenoid is what it needs.

I am worst-case afraid that the new ECU failed in the first few hours of use for some other reason, computers do burn in and fail sometimes. In which case, I guess I'd be better off going back to the mechanic that installed it.

Or -- bad mechanics cover up bad work sometimes -- maybe I consider that a a sunk cost, forget about it, and find a better mechanic close to home.

I'll learn my way around this thing, but -- having been a Subaru owner for less than 4 days now (when do I quit counting the days?) -- I need it working reliably as a baseline. And I need to make a backcountry mountain trip in a week to see a Forest Service guy about a big prescribed burn ....

---> Yes, I'd just pull the EGR solenoid out myself and put in another one, but with the carpal tunnel even this little thing's a bit chancy for dropping and screwing up parts.

---> I have an ohmmeter, can measure resistance if I find the points

---> I think I've found the EGR solenoid itself -- way down under the air intake hoses, sitting on um er a a big engine part.

---> I could try, but -- if that didn't fix it, the question becomes who would my dear wife blame. I'd rather it were a mechanic (grin).

Urgh. Well, that's the news from here, now.

I suppose I can also clear the code -- I've got the decision tree for that, connect, rev, turn off, hold the accelerator a particular way, go drive with RPMs above a certain level, see if the light comes back on (this is from memory, really, I do have the list to follow)..

And see how long it takes to come back. I dunno.

I hate computers. Did I mention that? I've worked with them since the 1960s IBM 1620, which had a small hallway right through the middle of it, and less capability than my current wristwatch ....

#7 Hank Roberts

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Posted 23 April 2005 - 06:16 PM

Wellll .... took it to the Berkeley shop (SOS Subaru) that's been well spoken of. They agreed a code 34 is the EGR solenoid, and replaced that. They also found one vacuum line hooked up wrong and the rest sort of scrambled, sorted those out and replaced some bad ones, and off I went.

I got 197 miles, filled the gas tank, went back on the highway, got up to 60 and blink, CHECK ENGINE light on again. Code 3-4 again. EGR solenoid.

Duh.

It did get me up into the mountains, I had my chance to walk the 40 acre swith the expert Forest Service guy and talk about forest fire, prescribed burning, what works when, what looks safe -- and come mid-December after the rains, now have some patches of brush I know can be burned safely. Subaru did OK getting me there and back, which is why I bought it.

Other than, um, popping out of first gear when I tried to use engine braking on the very steep (more than 10 percent) downgrade stretch, though once I got back to 7 percent grade that didn't happen again. But that may be another topic if it happens again.

And back to the shop Monday morning. Now that it's had new EGR valve, new EGR solenoid, new ECU computer, and new vacuum lines, I suppose it's time to ... um ... I dunno. The guy there has been working on these things for a long while, seemed to know what he was doing, although he didn't know about the factory design defect in the EGR solenoid (the coil wires not being soldered internally but just wrapped and shrinkwrapped). I gave him the alt.autos.subaru printout on that bit.

I dunno. I'd checked the wiring and grounding as best I knew how, but I suppose that's the last thing remaining. Unless one of the parts already swapped in is bad intermittently.

The gas cap's good and tight, but I'm suspicious that it's something connected with the fillup -- or with the stop then start and go up to highway speed -- kicking this light on.

Danged carpal tunnel, I wish I could still do tool work without dropping everything. I'd just rip-and-swap myself. Now I have to think, instead.

Any thoughts welcome.

#8 erik litchy

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Posted 23 April 2005 - 06:34 PM

popping out of first is definatly not normal. is that the only gear that does that?

#9 Hank Roberts

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Posted 23 April 2005 - 08:33 PM

I'll make a thread for gearshift stuff if I don't find one active and follow that up there. Should've done that first.

Meanwhile --- can anyone suggest anything -besides- the wiring to look at, for the Code 34 (EGR solenoid) coming back with all new parts installed?

#10 Hank Roberts

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Posted 28 April 2005 - 05:28 PM

Aha.

Dang.

So after checking everything else, the mechanic in Berkeley started rechecking the work done for the previous owner just before I took title.

They'd replaced the EGR valve saying it was clogged, then the ECU, then said exhaust port (that leads combustion gases back to the EGR valve) was completely clogged up, and cleaned that out.

Well, they apparently didn't do a very good job on that.

-- The exhaust port is open but dirty, still needs cleaning, and
-- The INTAKE port (from the EGR valve back to the combustion chamber) is plugged -- completely -- solid.

Now the previous owner had been running for months with the Check light on, and using the cheapest gas he could buy, and at least the rubber tube that connects the EGR valve replaced by some chunk of hose that was crimped and clogged.

So, I am hoping, this will sort things out.

Now, what octane rating (and brand?) are you California old-stock-engine Subaru folks using? If there's a thread for that I've missed, please point me there.

And I'll add more news here if I can contribute anything useful.

I don't recall any mention elsewhere about cleaning out these EGR ports, so maybe this isn't all that common.

#11 Hank Roberts

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Posted 17 July 2005 - 06:21 PM

So the good news is -- after 3 months, there has been no further problem with the engine check light related to the EGR. Cleaning out the actual clogged ports in the engine (that lead gas from the exhaust side back into the combustion side to reduce level of oxygen in the mix, when the valve opens) solved that problem.

Took two mechanics (first in Palo Alto, second in Berkeley) to find and clean both ports! You'd think that when there's an "in" side on a valve it would suggest also looking for an "out" side. But, apparently not at the first mechanic's shop. They'd carefully cleaned out only half of the path the gas travels through and left the other half plugged solid with carbon.

That's one thing the second place did correctly.

So, something to check if you have that code and swapping parts doesn't help. It can be a physical obstruction.




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