2000 LGT behaving poorly

Hope some of you folks may be able to help me out with my wife's 00 Legacy. 2.5 4eat. It has always been doggy. If i try to drive it in a spirited manner it will throw a CEL usually related to the downstream O2 sensor. After 2 or 3 trips with my wife driving the light will go out. Lately it began studdering cold at low rpm, but no CEL. I recently removed the IAC, throttle body, and TPS cleaned and reinstalled. At that time I put in a new Fuel filter, and some Fuel system cleaner, it seemed to run better for about a month. I noticed however, that it was acting like it had variable valve timing, would accelerate liesurly to about 3000 rpm, then it seems like it clears and would go like its hair was on fire. Now it chugs and bucks and won't even get to 3000 grand in gear (will rev fine in park/neutral) misses at idle, nearly stalls at idle when the ac compressor cuts in. I have ordered a new fuel pump, and will be installing it since to me if feels fuel related because when it does agree to rev it revs well with no misses. Again no cel lights. If it will run better with the new pump, I will take it to AZ and have the codes read.

 

I am going to search the yards around for a TPS. Wondering also if it could be coil related or crank position sensor. Plugs have about 20K look good no fouling, air cleaner is recent and clear.

 

Hoping somebody might have some insite. I kow studdering is a thing but this has gone to studdering on steroids it is nearly undriveable, and again no CEL.

when driveable is the mpg around the same or is it is a bit down. i sounds like something fuel related to me as well.

 

i have a similar issues on one of my 240sx's and it was due to 2 bad o-ring seals on the top and bottom of 1 injector. basically it was just dumping fuel into the system with no real regulation. i replaced the 8 rings (top and bottom of each injector) and ran some lucas fuel injector cleaner through the system and it ran normal.

Mileage usually runs about 23/4 running around. After I did the cleaning and changed the filter it gained 1 or 2 MPG, last tank was about 22. I think they are sneaking more ethonol in the mix around here cuz my Jetta that usually pulls 30 around town is down about 1 or 2 on the last couple tanks. I will be unhooking the bat when I change the fuel pump so maybe the ecu reset will do some good. If it doesn't I will see if I can get it to AZ to read any codes it may be throwing, but as I said no light so I am a bit stumped. Last time is acted similarly, a plug change did the trick but these are have only 20K on them.

Last time is acted similarly, a plug change did the trick but these are have only 20K on them.

 

What brand of spark plugs did you put in?

Usually when a spark plug is going bad, you'll get as CEL for a misfire.

Dealer did the plugs last, and we did get a missfire light last time around. I don't know what they put in, and I really didn't notice the brand when i checked the one I pulled, but they must be platinim or iridium or unobtanium cause the SOB's charged 12 bucks each for them. (import fees perhaps?????)

Greg, if you don't have any luck here, post over on nasioc.com - there are some very experienced people with NA motors that might be able to help with troubleshooting this.

 

One quick question though, you mentioned the O2 sensor error code, was the sensor replaced? It doesn't sound like that would cause all of the symptoms you've mentioned, but it could contribute. Were the spark plugs wires ever replaced?

The O2's have beeen changed twice but not recently. The car was never reflashed so they are still running on the narrow perameters. As I said I do not trade with either dealership, and I do most maint myself. Wires are original to the car. as is the coil. We also don;t drive the car much as we are both retired and wih the price of gas don't put on a lot of miles. Last time I went in I was told that the O2 cold be changed but it would cost over 400 bucks. When I mentioned the TSB stating sensors could/should be changed at no cost regardless of miles or ownership I was greated with a blank stare. That was at the beginig of summer just before I did the cleaning and changed the fuel filter. I'm sure both local dealerships have decent techs but their front desk people are trained to treat customers like idiots. Their answer to everything is leave it while we drain your checkbook and charge cards.

 

What would you recommend for wires??

I understand the dilemma with dealers and milking you for money, been there several times.

I had a '00 Outback that I pretty much did all the maintenance on, including swapping the head gaskets when that came up. I replaced the plug wires with new ones from Subaru, actually ordered them online from another dealership since I could get them cheaper.

 

Definitely get those codes from AZ when you have a chance, nasioc.com has many posts based on specific error codes and how to fix them. I used that forum many times to diagnose the parts/problem causing CEL codes and was always able to quickly order a new part, etc and fix things myself without simply throwing new parts at a problem like some techs do.

Codes will be good to get. It's always a pain when you have that kind of problem.

 

And I think your fuel consumption is rather high. I get about 27mpg on my NA 2.0 5MT. I would say that you should get about 25 with your, but it also depends on the driving conditions.

 

Just do a fool check and look in all air inlets before and after the air filter to see that there isn't a rat's nest or something else there that is messing up things. Also check all hoses so that they are in good order.

 

Secondary is to check the camshaft timing so it's correct. That's just a bit of dirty work and some time lost. Check the valve clearance too since that can cause some problems.

 

Third step is fuel system, is the injectors OK, fuel pressure OK or is the fuel filter clogged?

 

Most of these can you do yourself, but for the fuel system I would recommend a good mechanic.

 

And also check that the cat is in good order - it may have had a meltdown, in which case you will need a new. But a meltdown is often caused by problems earlier in the chain like bad injectors or uneven distribution of fuel between the injectors which can cause one cylinder to run rich and the others run lean (or the other way around) - in either case it's bad for the cat.