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Juddery under acceleration and thirsty as F***


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Hi guys, new on here, so i hope you can help, just bought a 1999 Subaru Forester S turbo, love the old girl, just a few little niggles i'd like to sort out.....MPG.....horrendous, approx 15mpg, plus the car feels juddery when accelerating, starts fine, bit of smoke first thing. Oil changed, oil filter changed, plugs changed, fuel filter changed, had a knock sensor CEL, so changed that also, running on premium, ECU reset, had OBD check, no faults showing up, so im thinking either the engine is knackerd, though it pulls lovely with loads of power, or maybe it could be the O2 sensor, i've been reading other forums which mention the O2 sensor, but wondered if anyone has had the same issues before i go spending another ton plus on something that doesnt change the juddering.

Forgot to mention. its done 170000miles.

I'm looking forward to your reply guys......unless its bad bad news.

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All I can tell you is what I've learned from my recent experiences with my two month old purchase.

From cold, mine was okay, but after a bit of driving the judder pulling away from junctions and in traffic was getting pretty bad. Replacing the clutch & heavily worn flywheel helped but it also turned out my gearbox was also FUBAR. :(

I'm guessing this is probably a worst case scenario & most definitely not the reply you want to hear. Fingers crossed yours isn't as bad as mine was!

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Hi & welcome, if the engine was shot you'd here a horrible knocking sound above 3k.

Google subaru rod knock for an idea

When you say judder is it across the entire rev range or only at ertian points ? May be a hole in one of the vac lines or poor fuel delivery

15 mpg does sound very low, could be a number of things but your O2 sensor could be dead and over fueling and causing the stutter too

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I would be checking maf, tps switch, general hoses & connectors, fuel pressure, fuel injectors for jet leak/drip/flow rate etc. what do spark plugs look like ? do a pic ...

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could be a few things, sounds like over fueling is causing the juddering

 

is there a rolling road near you, might be worth having a health check done, it will be cheaper than buying random parts and hoping it solves the problem

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Hi all, as far as i know theres no rolling road around here, defo not rod knock, no knocking at all, just hesitant through all rev ranges, still goes like stink, just not as smoothly as i'd assumed, and as its sooooo juicy im thinking over fueling from a faulty 02 sensor.

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O2 is narrow band so unlikely be issue, I would be looking at maf with multimeter checks & perhaps a clean if readings show nothing out of spec. tps needs looking at to with multimeter for checks.

Being a 99 it should have obd2 style diagnostics so will work with ssm diagnostics so you can run O2 sensor tests & view/log live sensor data & see if anything amiss .

plumbing in fuel gauge to test line pressure & regulator function would be good. If over fuelling your spark plugs should show evidence of this. Compression test would be smart just get quick idea of engine health.

injector test would be good if nothing else shows up.

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^ for you the bit near bottom on 1999 to 2002 is relevant, if your car a EU model & has the 99 on style OBD2 plug you got better diagnostic options purely as more support for that protocol system.

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Great info there [emoji106]

I'm not great with computers, I would need a list of you need to buy this cable, plug it in like this, download this software, then an explanation of how to do it and what to look for [emoji17]

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