OB99W
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Everything posted by OB99W
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If the condenser/capacitor became electrically leaky, it could draw additional current beyond what the grid draws and cause more of a voltage drop than normal (you can expect there to be some drop). If that were the case, the capacitor would become warm or hot (under normal conditions it should be at ambient temp). Given its circuit placement, if the capacitor failed ''open circuit'', all you'd probably notice is a ''pop'' in the audio when the defroster was switched. Checking voltage drop across the relay contacts is still a good idea.
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Can we assume that you meant to say ''engine on''? (Otherwise, a 13.7 volt reading at the battery doesn't make sense.) Typically, to suppress an arc the capacitor would be placed across the switch (relay) contacts, not across the load (defroster grid). Placing it across the grid would tend to minimize the switching arc being ''broadcasted'' (causing RF interference), since the grid can act as a transmitting antenna for the transient.
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Yes, it's possible for a disconnected FPR vacuum hose to trigger P0420. The lack of vacuum will cause excessive fuel pressure, which can lead to an overly rich mixture. That, in turn, can raise emissions beyond what the cat can handle, resulting in changes at the rear O2 sensor that the ECU interprets as a bad cat. As has already been suggested, reconnecting the hose, clearing the code, and then seeing if it returns is the easiest way to verify whether that was the problem.
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While it could be that the oil was underfilled at the last change, there are other possible explanations. You mentioned going over your usual oil change interval -- maybe you'd been ''using'' oil before, but the level didn't get low enough by change time to cause problems until you went further than you had previously. Oil consumption can be so gradual that it doesn't show up as obvious smoke at the tailpipe. The oil warning light is initiated by low pressure, not level. If there's enough oil for the pump to build pressure, even if the amount is quite low, the oil light will remain unlit. As long as you keep tabs on the oil level, you'll probably be okay. Obviously, I'd suggest checking more frequently, especially since the cause of the level drop hasn't been determined. You're welcome, I'm glad to help.
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If the ECU ''thinks'' the engine is hot, it won't set up the proper conditions (rich mixture, etc.) needed for a cold start. The engine coolant temp sensor is mounted to the coolant pipe -- follow the upper radiator hose to that metal casting, then look under the intake manifold in the vacinity of the cylinder #3 runner. Unfortunately, it's kind of buried. Be sure you replace the sensor that has two terminals (the one with a single terminal is for the temp gauge).
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They're more of a ''defogger'' than a ''defroster'', although eventually they'll melt ice. You should be able to just measure the voltage on the conducting traces on the window. Put one meter probe on a conductor as close as possible to the trim on one side, and the other probe similarly placed on the opposite side. (It might require two people.) Obviously, try to not damage the conductors. If the wiring, etc., is okay, the voltage should measure only slightly less than the approximately 14 volts measured at the battery.
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If, as Fairtax4me suggested, the plug wires are properly seated at both ends, then do see if reinstalling the originals makes a difference. The two cylinders that are misfiring (#1 & #2) are ''wasted spark'' paired -- they share the same coil in the pack. A problem with that coil or either plug wire could cause misfire on both of those cylinders. Once you get back to us after checking the ignition wires, we can offer other ideas if needed.
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An ECU tends to be one of the most reliable parts, and would rarely be the cause of multiple codes. I'd suggest reinstalling the original one and see if the engine will start. With so many seemingly unrelated circuit problems, the common factor tends to be power or ground issues. A failing main relay, for example, could cause what you're experiencing.
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That's because, in simple terms, the voltage at the primary of the coil has to be ''pulsed'', not constant. Naturally, for the spark to occur at the correct part of the engine cycle for each cylinder, those pulses have to be correctly timed. The used distributor isn't necessarily good. EDIT: I suggest that you go to the AutoZone website, and register. Enter the data for your car (year, make, etc.), and then go to the repair guides. Under ''Engine Electrical'', select ''Electronic Distributor Ignition System''. Go through that ''tree'' -- there's diagnostic info.
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I had mentioned the neutral switch earlier. A new post (#56) in http://www.ultimatesubaru.org/forum/showthread.php?t=85794&page=6 might be worth reading. EDIT: Just to verify my suspicions, I did a bit of searching and came across http://bbs.scoobynet.com/general-technical-10/491306-misfire.html . The OP's problem might not be the switch, but investigating it is probably justified.
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Welcome to the forum. I agree that the problem could be caused by something not being sensed correctly, and that the ECU then defaults to some fail-safe (''limping'') mode. Unfortunately, there are several possible causes. Having the code(s) in the form Pxxxx (where the x's are numbers) would be helpful. Having said that, one thing that can be intermittent and cause erratic fuel delivery is if the ECU doesn't know whether the car is in gear or not. The neutral switch could be intermittent. If one of the codes is P1507, see http://endwrench.com/images/pdfs/DiagTroubSum04.pdf . Otherwise, let us know what turns up.
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Welcome to the forum. Flashing of that light indicates the cruise control has been disabled. That's done whenever a problem significant enough develops that the computer determines it can't adequately control things. Misfiring and/or unstable idle speed would certainly qualify. As already mentioned, getting the trouble code(s) read (for free at most larger automotive stores ) would be helpful -- please let us know what you determine in the form Pxxxx (where the x's are numbers), not the code definition(s).
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With proper timing and no carbon buildup on the piston crown or the head, 180-185 psi is typical (especially with the non-interference engines). I assume that both banks are now correctly timed, so perhaps one head got shaved a bit. I wouldn't suggest intentionally mistiming in an attempt to equalize the readings -- the 10% difference isn't particularly significant, and it's likely that the engine will perform better with proper timing than with it changed just to equalize compression at cranking speed.
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I suggested that thread because it showed that the voltage reading didn't indicate a fault. Some generic OBD-II scanners don't read certain A/F sensors correctly, or the data is misinterpreted. (By the way, that's true in particular for wideband type.) Pep Boys might have suggested the dealer because they would use the Subaru Select Monitor instead of a generic scan tool. P0420 can have several causes (besides the cat itself being bad) -- do a search here for that code, and it should turn up threads with more info. Here's a link to some: http://www.catalyticconverter.org/news/news_page.cfm?Key=catalytic_converter-&News=120 .