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Old 10-09-2018, 12:01 PM   #1
comatosellama
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Default 2003 obs having engine woes. Worth saving?

Just got word back from the dealer. Iíve got a bad catalytic converter, possibly bad rear o2, and am leaking oil from cam carrier, oil pump, and valve cover (just replaced valve covers, not sure what I did wrong). Car is worth around $5000, has newish (30k) head gaskets and clutch. 100% rust free which is unheard of in Michigan, and is already lifted. Dealer wants $4700ish, which isnít gonna happen. My main issue was getting very low mileage (14-15mpg), I can live with the car eating some oil.

Right now Iím thinking Iíll get a tsudo hi flow cat and an o2 sensor and o2 sensor fooler since the high flow will trip the p0420. This should clear out the MPG issue. It doesnít seem like fixing those leak points is too hard (Iíve done clutch work and a lot of stuff on my brat, Iím comfortable doing anything besides engine/trans internals). Do you guys think itís worth it? My only real hesitation is the engine has a nasty piston slap.

 Thanks, CL
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Old 10-09-2018, 01:09 PM   #2
Charlie-III
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Do you have CEL codes? If so, what?
Yes, clogged CAT can kill mileage and power.
So can bad plugs, wires, dirty airfilters, bad O2 sensors, soft tires, larger diameter tires (odo and speedo off, so calculations are off), dragging brakes, etc.

Valve cover gaskets, unless I have detailed info, I at least make sure I use RTV in any "corner" of the gasket to mating surface. This may mean where the gasket goes from the head to around the front cam bearing support.

I have a highflow CAT, headers, no antifouler, no CAT code. Headers are a more common issue possibly needing an antifouler.

How many miles per quart of oil are you going? If 1500-2000 miles/qt., just keep checking, add as needed.
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Old 10-09-2018, 01:43 PM   #3
comatosellama
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Default 2003 obs having engine woes. Worth saving?

Quote:
Originally Posted by Charlie-III View Post
Do you have CEL codes? If so, what?
Yes, clogged CAT can kill mileage and power.
So can bad plugs, wires, dirty airfilters, bad O2 sensors, soft tires, larger diameter tires (odo and speedo off, so calculations are off), dragging brakes, etc.

Valve cover gaskets, unless I have detailed info, I at least make sure I use RTV in any "corner" of the gasket to mating surface. This may mean where the gasket goes from the head to around the front cam bearing support.

I have a highflow CAT, headers, no antifouler, no CAT code. Headers are a more common issue possibly needing an antifouler.

How many miles per quart of oil are you going? If 1500-2000 miles/qt., just keep checking, add as needed.


P0420 code. New plugs wires recent air filter and a new Bosch front o2 sensor. Around 1.5quarts per 1000 miles. Oil consumption isnít my main concern, just wanna get MPG up. Car is FXT strut lifted and has 25Ē-27Ē tires depending on the weather.

Have any videos of your exhaust? Iíve got uel headers too, and an n1 weld on.
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Old 10-09-2018, 02:18 PM   #4
Charlie-III
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I have an early COBB coated EL header with their (RandomTech?) high flow CAT and full SS CATback (first on my generation Legacy wagon).

How are you figuring mileage? Big tires throws off the Odometer and speedometer. The system counts revs based on stock diameter tires. If you go bigger diameter tires, then you cover more ground than the odo and speedo reads, thus mileage drops off and you're going faster than indicated.

Maybe figure out what you're doing with big tires, then adjust your mileage calculation.

BTW, bigger tires hurt acceleration which also hurts mileage. It affects the total gearing in the drivetrain.
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Old 10-09-2018, 02:27 PM   #5
comatosellama
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Quote:
Originally Posted by Charlie-III View Post
I have an early COBB coated EL header with their (RandomTech?) high flow CAT and full SS CATback (first on my generation Legacy wagon).



How are you figuring mileage? Big tires throws off the Odometer and speedometer. The system counts revs based on stock diameter tires. If you go bigger diameter tires, then you cover more ground than the odo and speedo reads, thus mileage drops off and you're going faster than indicated.



Maybe figure out what you're doing with big tires, then adjust your mileage calculation.



BTW, bigger tires hurt acceleration which also hurts mileage. It affects the total gearing in the drivetrain.


4.2% difference on summer tires which leaves me at 18.6mpg, still 6-8 mpg short. This is with all roof rack stuff removed and fuel efficient tires
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Old 10-11-2018, 05:24 PM   #6
Ethan Riccio
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It's worth saving if it holds value to you, and taking the hit of selling it with issues + the hassle of buying/inspecting/registering a new car is valued at more than the cost of repairs. I have "totaled" my 98 OBS at least twice ($800 purchase price) but I'd rather have the issues I know about than the issues I'd have unknown on a different $800 dollar car.
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Old 10-11-2018, 09:03 PM   #7
wtdash
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Quote:
Originally Posted by Ethan Riccio View Post
but I'd rather have the issues I know about than the issues I'd have unknown on a different...car.
Quoted 'for truth' right there.
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Old 10-11-2018, 10:09 PM   #8
Charlie-III
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Quote:
Originally Posted by comatosellama View Post
4.2% difference on summer tires which leaves me at 18.6mpg, still 6-8 mpg short. This is with all roof rack stuff removed and fuel efficient tires
Did you check the other things I listed above in earlier post? Tuneup, brakes, etc?
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Old 10-11-2018, 10:15 PM   #9
comatosellama
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Quote:
Originally Posted by Charlie-III View Post
Did you check the other things I listed above in earlier post? Tuneup, brakes, etc?

Fuel filter, plugs, wires, PCV, front o2 sensor are all new. Air filter and brakes are all very recent.
Not sure how to check for a dragging brake? Guess Iíll take it on a drive and temp gun all the breaks and check for unusual heat?
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Old 10-11-2018, 10:28 PM   #10
Charlie-III
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Quote:
Originally Posted by comatosellama View Post
Fuel filter, plugs, wires, PCV, front o2 sensor are all new. Air filter and brakes are all very recent.
Not sure how to check for a dragging brake? Guess Iíll take it on a drive and temp gun all the brakes and check for unusual heat?
You could do a temp gun.
I have a highway nearby, 65MPH limit, that has a long uphill. I run a few miles (5-8?) at speed, going up the hill I get in the slow lane near the top and then coast to a stop near the top.
Park car, put hand on center of each wheel. The distance run, speed, coasting to a stop should basically have wheel centers at about ambient.
A warm wheel is a dragging brake more than likely.

Tire pressures also have a bearing on MPG. Low tire, slightly dragging brake, other little issue can all lower gas mileage.
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Old 10-11-2018, 10:46 PM   #11
2slofouru
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All of the wheels will get warm with normal driving and braking, a dragging brake wheel will be HOT. I have one dragging now and have to check for a dragging caliper or ebrake, all of the caliper pins are good and none of the pistons stick.

But anyway, it's cheaper to keep her. Being a non rust vehicle and having relatively minor issues you described, I'd keep her. Just deal with the ones that sap the most money first.

Taking care of the cat and/or air/fuel sensor issue will improve your mileage, which will save fuel money. Mine felt way too slow and was getting the same crap mileage you describe, I'm running 06 wrw wheels and tires though. Mine turned out to be a front air/fuel sensor. I don't remember having a code, but installing a new one immediately brought mileage back up to 18+ in town and it even feels like it has more power.

Then focus on the oil leaks, you just don't want so much leaking that it catches you off guard and you kill a bearing from not checking level often enough.

Last edited by 2slofouru; 10-11-2018 at 10:51 PM.
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Old 10-11-2018, 11:04 PM   #12
comatosellama
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Quote:
Originally Posted by 2slofouru View Post
All of the wheels will get warm with normal driving and braking, a dragging brake wheel will be HOT. I have one dragging now and have to check for a dragging caliper or ebrake, all of the caliper pins are good and none of the pistons stick.

But anyway, it's cheaper to keep her. Being a non rust vehicle and having relatively minor issues you described, I'd keep her. Just deal with the ones that sap the most money first.

Taking care of the cat and/or air/fuel sensor issue will improve your mileage, which will save fuel money. Mine felt way too slow and was getting the same crap mileage you describe, I'm running 06 wrw wheels and tires though. Mine turned out to be a front air/fuel sensor. I don't remember having a code, but installing a new one immediately brought mileage back up to 18+ in town and it even feels like it has more power.

Then focus on the oil leaks, you just don't want so much leaking that it catches you off guard and you kill a bearing from not checking level often enough.


The front o2 has been bothering me. Iíve got a BOSCH, as rockauto lists them as OEM, but apparently denso is OEM. Not sure what to do about it, might check the voltage and see if itís working right, but I noticed no improvement when I replaced the original with the Bosch.
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Old 10-11-2018, 11:12 PM   #13
2slofouru
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I don't buy from Rockauto, but do buy aftermarket for some parts. Mine is a denso, but it's not oem. I figured for how cheap the sensor was compared to oem, it was worth a shot. Yours being from rockauto doesn't mean it's crap, but I'd rather an aftermarket denso over an aftermarket bosch. My oem sensor gave no indication it was failing, but replacing it made an instant difference.

Your p0420 could be a few things. The exhaust gaskets anywhere from the head ports to the one ahead of the second sensor could have a tiny leak, affecting readings. The cat efficiency could be too low, possibly from oil burning or running rich for a long while. You could also have a faulty reading fron a/f sensor or rear O2 sensor.

Since you've replaced the front, I'd buy a set of oem exhaust gaskets from the head to the front of the second sensor, since it obviously can't read anything after the second sensor.
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Old 10-12-2018, 12:28 AM   #14
Charlie-III
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Quote:
Originally Posted by 2slofouru View Post
All of the wheels will get warm with normal driving and braking, a dragging brake wheel will be HOT. I have one dragging now and have to check for a dragging caliper or ebrake, all of the caliper pins are good and none of the pistons stick.
While true on regular driving heats things up, my route is putt putting along at 25MPH of less until the highway, so no real heat.
Then, highway run and a coast uphill. This route was on my way to work, so maybe 6 miles of local roads, then highway.
It was very easy to find tight pads or dragging calipers.
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Old 10-12-2018, 01:58 PM   #15
yarrgh
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How's the knock sensor? It can also affect fueling. Although it tends to throw a code easier than an oxygen sensor.
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Old 10-12-2018, 07:38 PM   #16
comatosellama
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Originally Posted by yarrgh View Post
How's the knock sensor? It can also affect fueling. Although it tends to throw a code easier than an oxygen sensor.

I mean it looks good but Iím sure itís original. For $12 I may as well pick up a new one.
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Old 10-12-2018, 07:39 PM   #17
comatosellama
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Just installed the new cat and rear o2. Car seems much much happier, revs better and pulls better at low rpm. Weíll see if mpg gets better. I also narrowed down the oil leaks, need to pull timing covers soon and order parts.
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