Vanguard

Thanks for the link. Looks like the same article that I read awhile ago when I decided to check for the codes (when the check engine light came on). I don't recall the numeric code that I got back but, I think, it was for the oxygen sensor. I'll have to run through the procedure again to see what code it reports. The dealer and car shop tried retrieving the code(s), they were using their equipment which presumably would know how to read the basic and advanced codes (I've heard that the above procedure only gets basic codes and there are advanced codes, too). When I managed to get a code reported using the above procedure, it only reported a code once out of 6 attempts on different days and after clearing out the ECU and waiting for the error to reappear. So it is like the ECU is setting off the engine check light but won't report any codes for it. Maybe the ECU is defective and why no one can get codes reported from it.

I don't recall seeing an *engine" temperature sensor, just the coolant temperature sensor. I'll have to check the diagrams again. I had not thought about the knock sensor. I haven't yet tracked down where it is. Since the car shop and dealer couldn't find the source of the problem after taking in 5 times, I suspect that I'll end up piecemealing the sucker by replacing parts one-at-a-time until the problem goes away: oxygen sensor ($85), knock sensor ($66), purge valve ($86), PCV ($8), and the computer last ($???). ----- Regarding the engine computer, I figured it would cost $400. But a search at car-part.com turned up the following: 1- Ignition Cont, (center of firewall), w/o turbo; AT 2- Ignition Cont, (center of firewall), w/turbo 3- Ignition Cont, (center of firewall), w/o turbo; MT 4- Elec Cont Unit (ECU), (behind left side of dash), w/turbo, thru 9/91 5- Elec Cont Unit (ECU), (behind left side of dash), w/turbo, from 10/91 6- Elec Cont Unit (ECU), (behind left side of dash), w/o turbo; LHD 7- Elec Cont Unit (ECU), (behind left side of dash), w/o turbo; RHD; thru 8/91 8- Elec Cont Unit (ECU), (behind left side of dash), w/o turbo; RHD; from 9/91 With a price of $30 (salvage price) if I selected the 8th item. However, I'm not sure which to pick. LHD? RHD? It is non-turbo and referred to in the diagrams as the ECU (don't know what they mean by "Ignition Cont[roller]"). I was a bit surprised the ECU would only cost $30 even for a used one.

Vehicle info: '92 Subaru Legacy L wagon 4WD non-turbo Sometimes when I start my car, the exhaust is far too rich and detonates back in the catalytic converter. When it happens seems sporadic. The weather could be cold or hot, humid or dry, and the car may have been sitting for several days or only for 4 to 8 hours since the last time it ran. I can compensate by shifting manually to keep the RPMs way up. When the problem arises, I have to keep the RPM up to around 2500 when at a stoplight (so it doesn't peter out). When I take off, I'll put it in first gear and shift manually to keep the RPMs up high; otherwise, it will hesitate on acceleration and I hear the detonation in the exhaust system. Even after the temperature guage shows normal level, it is only after it has been at normal for about 15 minutes before the over-rich problem fades away. It only runs overly rich occasionally. The other problem is that the "Check Engine" light comes on sometimes. I've had it in the shop 4 times to have them read the codes. The first 3 times, they got no error code. On the 4th time, they got no error code but when I started my car to leave then the "check engine" light came on and they hooked up while the car was running. I don't remember what was the code but it didn't make sense at the time and the mechanic said it was wrong. When the "check engine" light comes on is *not* when I have the first-startup overly rich mixture problem. They seem to be independent symptoms but maybe not. I suppose the "Check Engine" light might not be coming on but the computer is still screwing up the mixture when the car is started. So my choices (that I can figure out) is to replace the engine computer and/or the oxygen sensor. I replaced my exhaust system about 4 to 5 years ago but they reused the original oxygen sensor (they were going to replace it but couldn't get one at that time). As I recall, this sensor check how much oxygen is in the exhaust and recirculates a portion of the exhaust if the oxygen is too low. Well, if it is running overly rich then wouldn't the oxygen level would be low? Any opinions if it is more likely the computer or the oxygen sensor screwing up the mixture (so it is sometimes too rich on startup)? Might it be something else? Besides the 4 times to take it into the shop to see if they can nail the cause of the "check engine" light coming on (but never finding anything), I've even left my car at their shop over the weekend to let them start it cold to see if the over-rich problem crops up, but it never failed when they had my car.