artie b Posted July 20, 2010 Share Posted July 20, 2010 (edited) Hi, I have been lurking and learning from this site. I have 2 1990 Legacy L 5mT's. The one with 190k on it runs very well, until I repaired the AC. Now after 20 or so miles with the AC on, it will miss on one or more cyl. I have traded out the coils, injectors with the other Subie. I installed new plugs and wires. It still misses? I have considered the oxegen sensor, but I have no cel ( check engine light) Thanks for any input, Artie Edited July 20, 2010 by artie b Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted July 21, 2010 Share Posted July 21, 2010 Hi Artie, Can you describe the miss you are experiencing a little more. Does it happen at a specific rpm or engine load? Does the miss go away when you turn off the AC? What diagnostics have you done to determine it's missing on one or more cylinders? What repairs did you make the AC system? Is that the only work you performed? Quote Link to comment Share on other sites More sharing options...
artie b Posted July 21, 2010 Author Share Posted July 21, 2010 The only "repairs" I did was to the AC, when I noticed the miss. I vacuumed and replaced the R134a, right after that is when I noticed the miss I didn't put any other grmblins in it. As soon as I pull over to pull some plug wires, the miss smoothes out. The miss comes on while I'm pulling a grade. I have gotten it to miss without the AC, today. I'm going to replace the fuel filter and Ox2 sensor as soon as it cools off and try to duplicate. The odo shows 191k, and has been running very well hot and cold, until recently. Thanks Legacy777. I have yet to detimine if a OX2 sensor going bad will nOT put a check engine light on. Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted July 21, 2010 Share Posted July 21, 2010 What brand of wires and plugs are you using? I've had really bad luck with Napa Beldon Brand wires, on a variety of cars. Subaru wires and NGK wires seem to work the best, from my experience. Also, I have found Bosch and NGK plugs to be the best. The ac is causing a load on the engine, that makes it work harder, therefore causing more misfires. A bad O2 sensor will sometimes cause a CEL (Check Engine Light), but I have yet to deal with one that causes much more than just the occasional cough. Twitch Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 22, 2010 Share Posted July 22, 2010 When did you last fill up the gas tank? Quote Link to comment Share on other sites More sharing options...
heartless Posted July 22, 2010 Share Posted July 22, 2010 when my O2 went on my 90 Lego it did throw a CEL but only briefly - it came on, it went off - did not come on & stay on - so it is possible that you missed a light...I was looking for a CEL is the only reason I caught mine. And, yes, it was only after the car was fully warmed up - initially 30-40 mins of driving, gradually getting shorter in time to when it would act up. my car ran like crap - cough, spit, sputter, acted like it was only running on 2 cylinders, etc...if yours is only "missing" a little, it may be early stages of failure. might try doing a code read to see if there is anything stored in there. you say you installed new plugs/wires - what kind??? as already mentioned it DOES make a difference. NGK BKR6E-11 plugs gapped at .039 - .043 in, good quality wires - most will tell you Subaru wires, I personally have not had any problems with aftermarkets, but problems have been documented... Quote Link to comment Share on other sites More sharing options...
artie b Posted July 22, 2010 Author Share Posted July 22, 2010 Thanks all, I did use new NGK @.40, old plugs looked good, gap, deposits, color. I traded out with a good running same year, trans Subaru... OX2, 4 Inj., wires, coil, maf, fuel filter, not it. I have tried to eliminate everything that could effect 1 cyl from missing. It does NOT bog, stumble, cut-out. It will miss then before I'm able to stop and check, it smooths out. It seems when it goes into its fit use more fuel? I would think if it was the cold start going rich, I would lose more than 1 cly. and would set a cel? All the wiring appears ok ( in stock looms, etc) and every connector I touched I inspected and cleaned, and greased? I'm ready to cry and use profanity.... Thanks, Artie Quote Link to comment Share on other sites More sharing options...
unibrook Posted July 22, 2010 Share Posted July 22, 2010 my vote is for early stage front 02 sensor failing. does it act up mainly under load? Quote Link to comment Share on other sites More sharing options...
artie b Posted July 22, 2010 Author Share Posted July 22, 2010 only one o2 and it has been changed. I'll keep trying,,,, Thanks, Artie Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted July 22, 2010 Share Posted July 22, 2010 I just had a thought, have you checked and cleaned your throttle position sensor (TPS)? It may be causing you grief. Its possible its sticking when you drive it and causing the intermittent high idle. Twitch Quote Link to comment Share on other sites More sharing options...
artie b Posted July 22, 2010 Author Share Posted July 22, 2010 no high idle just drops a (one) cylinder for a while, then runs ok?????? still working on it, with some more of your suggestions, Thanks, Artie Quote Link to comment Share on other sites More sharing options...
artie b Posted July 25, 2010 Author Share Posted July 25, 2010 Hi, I still don't know what is causing my miss. I have looked many times for a vacuum leak, which would explain this condition. I would like to know if someone had found an unusual leak, brake booster, something like that? I have done the carb cleaner check for leaks, but I don't know if the IAC would cover this? Please keep me in mind and let me know, Thanks, Artie Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted July 25, 2010 Share Posted July 25, 2010 Just an off the wall question, but how many cans or how much R134a did you charge the system with? From what you are saying it sounds like the problem mainly occurs under load. Is that a correct assessment? Quote Link to comment Share on other sites More sharing options...
artie b Posted August 14, 2010 Author Share Posted August 14, 2010 Thanks, Legacy tri-7, Not just with the AC on, it will miss without AC, takes longer. It happens on 90 F. or higher days it seems. I removed the thermostat and eventually did it again. If I drive above 3200 rpm, no miss, I downshift to 4th and smooths out. If I let it idle it smooths out. I gapped the new NGK plugs at .039. Old plugs read good. I ran dedicated, good ground to the coils. I have run 93 octane to rule out knock sensor. I have replaced spark plugs, plug wires, coils, O2, 4 fuel injectors, Fuel filter, MASS, ECM, gas cap, ECM temp sensor. The operating voltage is 13.8vdc. I have inspected the intake for cracks and bolt tension. HELP!!! If it was a horse it would have 20 or so bullets in it! Thanks for reading and / or replying, Artie Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted August 15, 2010 Share Posted August 15, 2010 Well it sounds like you've replaced all if not all the common components that I think that would cause a miss. Can you describe the miss in more detail. Is it a long pause, or just a short pause? Does the miss repeat more than a couple times in a row....details like that. Only thing else I can suggest is to check all the wiring from the sensors to the ECU. There may be a wire that is worn and may have intermittant connectivity when the engine heats up. My mom had a similar issue with her 90 Toyota truck. The engine wiring harness had an issue with one of the wires where it would cause the engine to shut off. It was heat dependent. Quote Link to comment Share on other sites More sharing options...
artie b Posted August 16, 2010 Author Share Posted August 16, 2010 (edited) EDT EDIT EDIT codeds 21 22 knock sensor..... Looking for it, now Thanks for staying with me Legacy777! I have a Haynes and I have gotten some wrong info on several things, one being how to read codes. After I read the sticky, I found out the right way. I had a code 14 and 16 1 & 3 inj. I read that a IAC would "confuse" the ECM and put a code 14. I cleaned it, now I got 21- coolant temp, 22-knock sensor, 23-air flow sensor, 24-IAC....I have pulled the battery, left it off last night. I will recheck my work and see what codes are stored. IAC wasn't too dirty, It did move easier, after cleaning. I do not have a rotary one, instead it uses a up and down duty cycle. I'll report back with my findings. The miss is very erratic, I have wiggled, tugged, jerked, inspected and cleaned every connection under the hood and ECM. ( all were clean) Gonna replace the fuel regulator, too. The miss I"m figuring may be a partial cylinder and can get worse (either a cyl. drops out all the way or looses another cylinder, which would be, pretty violent on 2 cyl?) I'll take the rope off my neck, get off the wobbly chair and see what I got. Thanks, Artie Edited August 16, 2010 by artie b Quote Link to comment Share on other sites More sharing options...
artie b Posted August 16, 2010 Author Share Posted August 16, 2010 Still have a CEL on. Codes 22 23 Knock sensor. I know where the Haynes says it is, but I don't see it. Quote Link to comment Share on other sites More sharing options...
artie b Posted August 16, 2010 Author Share Posted August 16, 2010 Not so good update.... NO CEL, still has miss... 2 codes stored 22 and 24, I will let it sit overnight to see if they clear. Still misses.... New knock sensor installed. Let me know what yu'a think.... Thanks for viewing and inputing, Artie Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted August 17, 2010 Share Posted August 17, 2010 Artie, I've got all the codes listed and how to check on my site if you want to check it against the haynes manual. http://www.surrealmirage.com/subaru/engine.html I'd suggest trying the active diagnostic with only the green diagnostic connectors and see what shows up. Quote Link to comment Share on other sites More sharing options...
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