HELP! check engine light/knocking

[Joshua R. Abel]

Hello, I'm very glad to see a forum with other SVX enthusiasts. At last, people who appriciate the SVX as much as I do.

This will be the first of many questions I will have about my 92 AWD black/black LSL.

I have had mine for about a year and a half or so now, and haven't had any real major problems yet. Just the battery, alternator, power steering pump, and rear wheel bearings. With 113,000 miles on it now I expected to run in to a few things. I fixed all of the aforementioned problems myself with little or no difficulty.

But now I have run into a problem that I am having some trouble diagnosing; When driving at highway speeds especially up an incline, (any hill requiring more than 3000 RPM) my engine starts knocking pretty badly. I'm not sure if it's a miss or a fuel related problem or something vaccuum related. If the car stays around, or a little below, 3000 RPM for an extended period of time, the check engine light comes on. Normally this only happens when climbing a hill. Most of the time, after I reach the crest of the hill and start the decline down the hill the check engine light goes off. But the knocking has me a little worried. It is kind of like a hiccup at a steady, higher RPM. If I let off the gas or give more gas, it temporarily stops. Sometimes the check engine light comes on even if I can make it up a long hill without the car knocking.

But driving around town at low speeds and low RPMs the car runs perfectly. No check engine light, no knocking. Could this be as simple as new plugs. I haven't changed them since I owned the car, and I don't know when the previous owner had them done. I should probably change them reguardless of whether this solves my problem. But this looks to be a VERY difficult, time consuming tune up. Any advice on plugs would be helpful too, I use NGK Iridium in my RX7. Do these work well on SVXs too?

I'm not sure if a simple misfire would produce a knock this bad and if so, if it would trigger a check engine light. And why the light would then turn off after the engine gets a little 1500 - 2000 RPM rest coasting down a hill. Any help on this problem would be very much appriciated.

Thanks SVXers

[Aredubjay]

First of all, WELCOME! You've found the grand nest of all SVX enthusiasts!

You'll need to run the C/E light self diagnosis to see what's causing the light to come on. If your car is knocking, I'd almost be willing to bet, it's the knock sensors being set off. But, run the diagnostic and see what it says. Instructions are in the "How To" (see link at top of page) locker.

A plug change is not as daunting as it looks. You just have to take your time. There should also be a how-to in the "How To" locker . If not, I've written one I'll post for you.

The knock sounds like a "bad gas" knock. What octane are you running and have you always made sure you use 92 or above.

I see you're in Pittsburgh, so you have an excellent support group in your area. You may want to plan on attending the Reading, PA meet in April. You'll see around 60 of us whackos all in one place, plus, you'll get lots of tips on how to maintain your baby.

Again, welcome. Come often, and have fun.

[Mr. Pockets]

Josh, welcome to the site, and I hope we can be of some help. As Randy said, follow the self-check procedure for reading the codes that the ECU is storing. I think there's also a list of those codes in the how-to folder so you can find out what they mean.

Some people say, 'bah, changing the plugs isn't so bad,' but I rate changing the plugs on my own SVX as one of the most irritating repairs I've ever done on a car. For a point of reference, I've replaced my own transmission. That may have been a weekend-long job, but at least each of the hundred or so steps went smoothly.

Anyway, the OEM plugs on the SVX are platinum, and the maintenance schedule says to replace them every 100k. Mine had 133k on them when I replaced them (probably why I had such a hard time with it) and they were still gapped within spec and just a little dirty. Amazing car...

...anyway, get yourself an inspection mirror and a set of picks from Sears. There are rubber boots that cover the connection between each plug and its coil. Four out of six boots stuck on the plugs on my car and I had to dig them out. Much swearing was involved.

Good luck and let us know what the self-check reveals.

HI--I am down in Morgantown and the exact same thing started in my 92 just as the really cold weather hit. I will check my codes this weekend but I think it might be related to the winterized gas. I changed my plugs at 95000 miles and it was tedious but not hard. The key was finding the exact length extension--3" that wasnt too long or too short. Also, a ratcheting wrench to take the bolt our of the coil is a real aid.

[Aredubjay]

Originally posted by wvsvx
HI--I am down in Morgantown and the exact same thing started in my 92 just as the really cold weather hit. I will check my codes this weekend but I think it might be related to the winterized gas. I changed my plugs at 95000 miles and it was tedious but not hard. The key was finding the exact length extension--3" that wasnt too long or too short. Also, a ratcheting wrench to take the bolt our of the coil is a real aid.

I hadn't even thought about the "winterized" gas. That does seem to be a problem with some cars. Luckily, we don't have that problem here. We run the same juice winter, summer, spring and fall.

[Joshua R. Abel]

Thank you to everyone assisting me with my problem. I hope someday I can also be of assistance to you.

I attempted a self diagnostics check on the car. (Held in AUTO and OFF on the climate control while turning the ignition on.) Because this seemed to be the easiest way I have read that it can be done.

The display read 88 with some symbol thing in front of it for a few sec. then displayed a code 13.
I'm guessing the 88 thing is of no relevance. But the code 13, according to the code locker is a "Cam position sensor/circuit" problem. Wich would certainly explain the knocking.

I don't think the bad gas idea is accurate because I have only used EXXON 93 SUPREME (the best gas available here) since I bought the car. I use it in all my cars and have never had a problem.

Now, does anybody know where the cam position sensor/s is/are located? I would think they would be close to the firewall in the engine bay by the cam cover. But that is a guess I have absolutely no idea.

Are there any other things that this could be? A relay, fuse, or cracked wire insulation maybe. Any further assistance would be very helpful. Thanks again everybody.

[Aredubjay]

Originally posted by Joshua R. Abel
Thank you to everyone assisting me with my problem. I hope someday I can also be of assistance to you.

I attempted a self diagnostics check on the car. (Held in AUTO and OFF on the climate control while turning the ignition on.) Because this seemed to be the easiest way I have read that it can be done.

Any further assistance would be very helpful. Thanks again everybody.

Congratulations! You've just diagnosed the climate control!


To diagnose the C/E light, you have to remove the plastic kick panel in the driver's footwell, under the A-Piller (and under the fuse block). Once opened, you'll see a bunch of wires and a couple of connectors (a big black one, and a small black one). The small black one is the one you'll need. You'll also see a couple of blue wires. THey will have connectors on the ends of them and be stuck up into the tape that surrounds the rest of the bunch of wires. Take one of those blue wires (doesn't matter which one) and plug it into the second hole of the small black connector. The connector should be facing "notch side" up. Once that's done, get in the car and turn the ignition on and watch the flashing of the C/E light (long blinks tens, short blinks ones -- IOW - two longs and one short is a code 21). If there's only one code it will repeat over and over. There may be multiple codes so, watch closely. When finished, turn the ignition into the off position. Take the other blue wire and plug it into hole #1 beside the other blue wire and then, turn the ignition to the ON position -- then, OFF again. This will clear the codes. Remove the blue wires from the connector, return them to their position in the tape, push the connectors back into the A-Piller and re-affix the kick panel. Then, go check the number of the code you got with the blinks of the C/E lights. You can find the sensor positions here:http://reaper450128.homeftp.net/servicecd.htm

Good luck.

[Joshua R. Abel]

Hey, thanks. Now at least I know I can diagnose any climate control problems.

Now that I feel like an idiot I went and did the Check Engine test to get the correct code.

It had three long flashes then two short ones. Then just repeated itself a bunch of times.

I'm thinking this is a code 32. But as you already know, I'm far from a genius.

In checking the codes in this site, it appears to be an Oxygen sensor/circuit. On the right side.

Is this correct? If so which is the right side? If you are in front of the car or behind the car. Driver's side or passenger side would be more informative.

Or should I just change both of them, to be safe? If one side needs to be replaced, the other one probably isn't too far behind. Or are they ridiculously expensive like many of the other SVX parts?

Is this what could be causing the knocking? Maybe too lean a mixture? Does each O2 sensor read 3 sets of cylinders? Or is there a primary and secondary sensor?

Thanks again for any help you can contribute.

[Aredubjay]

Joshua,
I certainly didn't want to make you feel like an idiot. You're, at least trying to do it yourself.

Directions are normally given from the perspective of the driver's seat. Therefore the right hand O2 sensor would be on the passenger's side. When one of mine dies, I just replace both of them. I've used the aftermarket sensors from http://www.oxygensensors.com with success. You can either order the "splicable" or the "OE Conncetor." Splicing is a pain in the butt, but, they're less expensive and consideably less expensive than OE. I would've used OE, but, our good friend Beav (whom I trust implicitly) gave the okay to use A/M. Check out this thread for the whole scoop:

http://www.subaru-svx.net/forum/show...Oxygen+Sensors

And, yes, if your sensors are sending the wrong signals to the ECU, you could experience "pre-ignition" also known as "knocking."

Again, best of luck.

[Joshua R. Abel]

Thanks for all of your info on the O2 sensors. It is very much appriciated.

I checked the local Advance Auto Parts to get prices on the sensors, they were about $90 ea. for the OE Bosch repl.

Oxygen Sensors.com has Walker sensors for $69.50 ea. But they look different, they look like they only have 2 wires in the pictue. It does say they are compatible with Bosch #13419 wich work.

I was under the impression the OE had 3 or 4 wires. Do you know if this is correct? It's cold and wet out now, I don't really want to check mine. I guess as long as the harnesses are the same and they plug in and work they should be OK right?

Thanks again

[want-a-fast-svx]

pretty sure there are only 2 wires for the sensors.

[Aredubjay]

Originally posted by want-a-fast-svx
pretty sure there are only 2 wires for the sensors.

Actually, there are three: Pos, Neg, Heater. If you look at the pic of the sensor I posted, you'll see that the instructions are quite complete. Of course, if you get the OE plug-in type, there'll be no worries.