salewit

Wow you know that may just be the best advice I've gotten on any forum anywhere! Thanks so much. It does concern me that the unit doesn't test correctly, but like I said, the car is running like silk, and my emmission stats were about 85% lower than the maximum.

Here we go again. 92 Legacy. Some might remember me from a couple of years ago when my car repeatedly failed smog. The problem was finally fixed, and I went in this year with confidence that the thing would pass easily. It didn't. It actually passed all the emmissions tests, but failed on a technicality. The CEL light was on. I had no idea I would get failed on this. This was illuminated from the problem 2 years ago and I just never bothered to clear it. Or so I thought. I took the car home, disconnected the battery for half a day. Reconnected it, and the CEL is still lit. I checked the code and its 31. Investigated the TPS and I'm getting weird stuff. The idle switch (Pins 1&2) works perfectly. But test 2 which is to backpin #2 and #4 of the connector with ignition on and the connector connected, is not behaving. I get virtually 0 volts (.03) closed, and about .05 wide open. I triple checked my back pins (with an ohmeter) and they're definitely making contact. I tried checking from #4 to ground and I got the same thing. I pulled the connector and then checked #4 to ground and I get about 3.4 volts! It's almost like the TPS is shorting to ground. But then why do I only have 3.4 volts on pin 5? Everything says it should be 5v. Pin 1 to ground by the way *IS* 5.0 volts. The car has been running smooth as silk, and my emmission numbers are excellent. Just need to get the CEL light out. And I assume smog will check to make sure the light comes on with ignition on and off when car starts. So I can't just remove the bulb. Help!

Well Gnuman you nailed it! I popped the hood and wiggled the connectors behind the battery, then went under the dash and wiggled some connectors going into the ECU, and the problem is gone! I knew something was different the second I turned the key as the CEL came on and stayed on. Tomorrow I'll clear the codes and see if the CEL stays off. I was also thinking of unplugging some of the connectors and carefully checking for bad pins and possibly spray them with an electrical cleaner before plugging back in. But it's running just as smooth as silk and I can't thank you enough for the advice. I just wish I had tried this before spending close to $500 on all the above stuff I didn't need. I've been driving my manual with my foot half-way down on the clutch the past 6 months to avoid this bucking. I'll have to learn how to drive again. Thanks again!

Yep... on the list. It's right on. In fact this is the first thing I did as I had a belt that jumped a couple of teeth when I put this engine in a year or so ago. It worked fine and smooth for more than a year after I fixed that problem. No I'm not sure the replacement MAF is good. Where do I get a good one to check it against without buying one for $200+?

No it's on the list only I called it a PVC instead of a PCV. I've heard it referred both ways. Gnuman: Interesting. The battery was loose on the deck and just floating around. I recently (months after the stumbling started) got a tie down kit. I'll look at that in the morning and give you a call.

92 Legacy. Symptoms: Bucking at light acceleration and coasting. Hot or cold. Ok only on heavy acceleration*. Has spasm attacks during idle. Can be idling smooth as silk and then all of the sudden starts trembling, then back to smooth. CEL light flashes on during moderate acceleration then shuts off. Codes are 12, 13, 14, 15, 16, 17 and 31. Cleared memory and same exact codes came back. AFTER this started, replaced plugs, wires, coil, ignition control unit, MAF sensor, cam sensor, TPS, PVC, fuel filter, air filter, oxygen sensor (twice), temp sender (in rear). Tested fuel pressure, fuel pressure regulator, compression, vacuum leaks, valve timing, ignition timing (but couldn't find mark on pulley). I can't find anything else to change or check and I'm stumped. *This week I had a new symptom. During a heavy hill climb, it acted like it was running out of gas... or the engine shut down.... pumped the gas pedal and nothing. Minutes later it recovered and went back to stumbling and bucking but at least it had power again. The only thing I haven't looked at was the ECU, but I can't find it. My book says it's behind the glove compartment or on the floor under the glove compartment. It's not there (hey maybe that's the problem!). Any help would be really appreciated. I'm about ready to park it next to the junker I stripped the MAF out of.

I've got a (still) stumbling 92 Legacy. A few days ago I noticed the CEL come on for just a second and go out. Every day is worse than the last. Stumbling, shuddering, surging. Now all speeds, hot or cold. Today I read in the CEL codes and got 12, 13, 14, 15, 16, 17 and 31. I cleared the memory (confirmed it), drove around the block and saw the the CEL flash on and again checked the memory and got the same exact thing. 12-17 plus 31. I checked the idle control for about 10 minutes running between idle and full throttle both by checking resistance and signal voltage. I moved the throttle slowly, but everything is behaving perfectly. One thing... my manual says signal voltage should be 0.5-1.0 volts with throttle closed and about 4.5 wide open. Mine reacts the exact opposite, so I'm guess that's a type. Closed 4.5 volts down to almost zero full open. Any ideas? Changed air & fuel filter, PVC, plugs, cleaned MAF sensor, checked coolant temp sensor, replaces cam sensor (had a spare). O2 sensor was changed about 6 months ago before problems.

Yeah they were done post crudiness. Sure there's junkyards all over, but I didn't think they'd ever take a part back. Especially an electrical part. But I'll check it out.

Yes that's me again! Actually this is the first thing I checked when this problem started getting worse. The valve timing is right on. On the plus side I can now get to my timing belt in about 7 minutes flat! What's weird is when I changed all the basic "tune-up" things noted above, the car smoothed out considerably... for a few days... and then went back to its bad habits. Getting worse almost daily. But absolutely no problem with heavy acceleration or climbing hills. Doesn't miss a beat. I haven't had any new CEL messages since I cleared it during my smog fiasco last year. The smog test numbers from what I remember were excellent once the O2 sensor wires were connected properly. The car wasn't scoped. Manual transmission. Can't find my book.... what and where is the IAC valve? I'd love to try swapping out the MAF sensor, but that's a $300 gamble. Is there any way to test the sensor with a multimeter? The plugs I used I think were NGK gapped to .044". As far as getting it diagnosed at a shop... I know I'm being stubborn, but I just have such a bad taste in my mouth from the shop I took it to during my bad smog test that diagnosed it as a bad cat. It turned out to be the sensor connected improperly. This shop was very highly recommended... Valuestar and all that. Not saying that this is a smart move for me to be fumbling around here, but I suspect a lot of you know where I'm coming from on this. Kind of like going to a prostitute.

92 Legacy. Car bucks or surges in ALL conditions except heavy acceleration. Doesn't matter if engine is cold or hot. From idle to highway speed. Most noticeable when steady on the pedal at about 30MPH it'll surge then hesitate. Problem seems to be getting worse. At idle, my tach will sit at about 800RPM, then all of the sudden the engine will shudder for about 3 seconds and the RPM dips to 400-500, then other times it will race up to 1500 RPM. Hot or cold. I've done a lot of searching here and found LOTS of people with the same situation. The problem is everyone has a different "opinion" on what is wrong. I've read injectors, fuel pump, MAF sensor, temperature sensor, plugs, wires, coil, O2 sensor, crank sensor, etc. I don't have the money to just change things left and right and some things I changed a few months ago during a different problem (failed smog). I'm wondering if anyone can recommend a sequence of things to diagnose to help me find out what the problem is. I've recently changed: Plugs, PVC, air filter, fuel filter, oil and filter. Approximately 3-6 months ago I replaced: cam sensor, temperature sensor, O2 sensor and visually inspected inside of catalyic convertor, tested throttle position sensor with ohmeter. Thanks

What I do is take a straight pin and stick it in there between the wire and the connector and probe the pin. If you don't have a pin, a safety pin, or possibly an uncoiled paper clip might fit in there. The connectors on my 92 Legacy would not allow a probe the size of my multimeter in there. No way!

I hate to bring this old thing back to the top, but I just wanted to thank everyone that helped me out with this beast. The car finally passed smog! The culprit was apparently the mis-wired O2 sensor. Cat didn't need changing either. The numbers were all below average. The car is running unbelievably well. Thanks again for all the help!

OB: I don't think I let the engine get fully up to temperature, so I'm thinking the CTS is probably about right on. Alright I just put the old O2 sensor back in with the white from the harness connected to the black on the Bosch replacement and stuck a pin in the connector on this signal wire. The engine had fully cooled at this point. The cat was cold. I started it up, and put my voltmeter on it right away and it was jumping all over the place from .1 - .9 volts. From what I understand this is what is supposed to happen after two minutes or so. I never got the "open loop" mode of just .1-.2V. I have one muffler strap I missed, so when it cools down, I'm going to fix that strap, test it again cold, and maybe go for a spin. Then what? Smog test?

Well I think I'm going to run out and get a new one. I measures the resistance between the heater wires and got 4 ohms. My book says it should be 30. What's $40 after spending hundreds?

Hmmmm you know I think I do have this O2 sensor installed wrong. I disconnected the connector, and measured 12V on the black and red with the engine cooled. So the question is did I fry the sensor or should I try connecting it properly? How would I know if it's good? Also, could this have ruined my cats? If so, which one if not both?