blitz

Crashton, how long have you had the ceramic pads on? Are your rotors wearing faster?

The only problem is that I believe insertion of the fuse relies on duty solenoid C to supply 2WD operation via hydraulic pressure.

If it were mine, I'd probably try a change of tranny fluid. There's a remote possibility that the wrong stuff was put in, or that it may have been topped up with something that's causing the frictional coefficient to be different from what specs call for. I've been using Mobil 1 with good results, although there may be something better available. Not sure.

Thanks Tim and Cookie. The corrosion thing is a sore spot with me. Auto manufacturers ignored the obvious body-metal and exhaust rot issue for decades and they seriously need to quit pretending that it's not happening to brakes as well. It's like way past time that manufacturers begin to incorporate corrosion resitant materials on disk brake assemblies. It really sucks that after two winters, noticable corrosion has begun, and after 4 winters, irreversable damage is well underway. Anyone that drives on salted roads knows what I'm talking about. I got three Michigan winters on my OBS and the brakes are rusting away, and the heat-shields are all rotting off. Sounds like a hunk-O-crap going down the road.

IMO, the aversion to dirt is an age-related phenom. In years gone by I accepted and welcomed massive greasiness and associated it with great accomplishment. As I get older I realize that cleanliness is analogous to precision on most operations. In short, I get progressively less fond of auto-repair grime as time passes.

No prob legacy2.5, I do understand your point about the tank pressure. I just wanted to clarify about high system (pump) pressure needing to be bled down before pulling any filter hoses. It was the following quote that concerned me on account of not being entirely clear on this. I just was worried someone might misunderstand and end up with a faceful of fuel.

I just got finished doing some searches on the thermoquiet pads and the manufacturer's claim (Federal-Mogul) is that the construction technique used, eliminates the need for the normal "anti-squeal" shims. Interesting concept. Question: When you put these in your Sube, did you include the factory shims, or did you leave them out? I'm kinda interested in trying these, but I'm wondering what to do with the shims. I've got two, a thin stainless-steel one, and a thicker mild steel one with a rubber coating. I'd be afraid that leaving them out asks the piston to extend appreciably further.

Any tank pressure is a result of thermal expansion such as might be caused by bringing a vehicle into a heated service bay from a frozen parking lot, or by mid-day heat following a cool night. Understandably, removing the cap would allow this pressure to escape. My question is; how does removing the cap relieve the 40 PSI (or thereabouts) of system pressure forward of the pump (i.e. at the fuel filter and associated lines)?

legacy2.5, Clarification please. Are you suggesting that the entire fuel tank is being pressurized by the fuel pump as a part of normal operation?

I second the idea of using a lube to help with getting the hoses off and on, but I'd stick to something petroleum based. Errant silicone finding it's way into the combustion stream is the number one failure/contamination mechanism of 02 sensors.

Are these "gradual downhills" actually mountain grade descents where several thousand feet are lost after being gained? If so. I'd have a look at things that are affected by changes in atmospheric pressure, like the gas cap, evaporative emmision system, atmospheric pressure sensor, and possibly the fuel pressure regulator.

Another thought; if you get a chance, pull your PCV valve and have a look see. If it's gunked up and not moving freely, it could be sticking partially open and giving a vaccum leak.

Oops, about the codes; yeah there are EGR codes but I'm not sure on the specifics (OBD-I for yours I believe). The codes are pretty good but they're not foolproof.

That would be the proceedure for checking the diaphram which opens the valve to make sure it is not punctured or torn, but my concern was more one of a possible pitting of the valve face and seat or an accumuation of coke on the plunger shaft. Both would prevent full closure resulting in some EGR at idle and there shouldn't be any EGR at idle. You should be able to visually inspect both by removing the EGR valve. Most strong toluene-smelling carb/injector cleaners in a spray can work great for cleaning a crudded-up EGR system. Just don't spray any of the solvent on the diaphram tho. Amsoil's great stuff, but lordy expensive. Unless you're doing extended intervals, you'd be wasting dough ...DOH!!!. IMO the best summer oil for a Sube with some mileage is a 15W-40 fleet oil. Mobil 1 works great in the winter.

Yeah, if it's cruising OK, that rules out an injector problem. Checking for vaccum leaks is a great idea. Also you might want to have a look at the EGR (if you've got one) to make sure it's closing completely. If it's sticking open, that'll give a rough idle. As far as the coil arcing goes, it may not necessarily be a critical deal. My last car had the corona type arcing on the coil pack for almost 100k miles, but never seemed to affect the spark reaching the plugs for some reason. The first time I noticed it, I freaked and called the dealer for a price on a coil, but after hearing the price decided to wait for an actual misfire. It never happened, but I did remove the coil and wash contamination off the surface with soapwater and used a little MEK sovent to try and remove any carbon tracking.

Possibly a fuel problem depending on the type of fuel injection, although you didn't name your specific vehicle or model year. Newer SFI F/I uses four separate circuits to fire the injectors sequentially, whereas the previous MPI system used only two circuits to fire the left bank and right bank alternately. If your vehicle employs MPI F/I, one bank may not be receiving fuel. Therefore no change when removing the spark from that bank. It's possible that an injector coil has shorted, or that the driver for that bank has failed, or possibly both. First measure the injector resistance of the good side and compare it against the published spec to get a baseline, then measure the other two. Make sure the injectors are in spec before replacing the driver (to avoid burning out the replacement driver). I'm not sure if the ECU drives the injectors directly, or if there is a separate buffer/driver.

The "learning" capability of the Sube ECU has reached mythical proportions over the years. :^) ECU's are bound to become much more powerful in the near future, but other than stored fault codes and the "limp-home" modes that sometimes accompany them, the only parameter that's learned to the best of my knowledge is the closed-loop fuel trim (adaptive lambda target, which in itself is a reasonably mild adjustment function). The ignition timing derives from a fixed load v.s. RPM map (tempered by real-time atmospheric temperature and pressure data) and is only variable in any major way through temporary corrective retard on account of knock sensor activity. After the knock ceases, the timing moves back to the map. I'm with subyluvr2212 on the carbon issue. To take it further, it's my belief that the extremely oversquare bore/stroke ratio makes the Sube motor more sensitive to carbon buildup with regards to octane requirement.

Here's a quote from the Ford link given above: "In 1996-on vehicles, the switch rate of the rear sensors is compared to the switch on the front. It follows that if the catalyst is efficient it will be removing HC and HO and the rear sensor will show a slow switch rate compared with the front. By dividing the number of downstream switches with those of the upstream gives a catalyst switch ratio, and a typical threshold is 75%, above which a DTC will be recorded." End quote. So the front sensor must be switching at a rate substantially more vigorously than the rear sensor. The ECU measures the switch rate of both sensors and calculates a ratio. If the ratio falls below a pre-determined minimum, cat-efficiency code is displayed. This switching ratio can be adversely affected by a slowing of the switch rate of the front sensor (leaky exhaust, contaminated front sensor), an increase in the switch rate of the rear sensor (contaminated cat), or both. I'm sure there's a fair amount more to it, but that's the basics of the "efficiency" mechanism as I understand it.

Thanks for doing that Skip.

Be aware that the Redline "where to find" database is out of date. In my case (metro Detroit) I was directed to locations that ceased to exist 6 years ago. :-p

Another possibility that comes to mind would be a contaminated/lazy front O2 sensor. Might wanna see if there's a service record on whether the sensor's ever been changed. A lazy sensor's gonna result in a richer-than-normal average fuel mixture (poor fuel mileage) but leaner than optimal part-throttle acceleration mixture (spark-knock/downshifting). It's also gonna reduce the crossing count of the front sensor relative to the rear sensor (crossing ratio) and trigger a cat-efficiency code.

The Subaru factory filter is made by Purolator and HAS a anti-drainback valve as also does the PureOne. The Premium plus 14460 however does not have the ADBV. Having said that, the non-valved filter is the one I use. In fact, if you live near a Pep-Boyz, you can get it for even a buck cheaper as the house brand "Pro-Line PPL-14460".

Cookie explained it: gravity. One bank has the thrust side of the piston facing down while the opposite bank has it facing up.

LOL Thanks.