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Old 08-29-2003, 06:26 AM   #1
SubeDonC
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Default why am i getting hesitaion

Only once in a while my car will feel like it wants to stall and this is a new thing. Im approaching 60k miles. I changed the plugs thinking it might be that but its still there, now assuming its a fuel problem. I changed the fuel filter at 35k but i dont think its that cause id have hesitaion at high end power. It only happens when cruising between 2k and 3k rpm's but goes away if i romp the pedal or down shift, somethimes even after i down shift to slow down it happens.

I have a 98 DOHC with CAI, Bruelen header and cat, stromung midpipe and muffler, Bosch platnium plugs, and a zex n2o system that i havent used since last year.

What could it be?
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Old 08-29-2003, 06:33 AM   #2
BAN SUVS
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Ditch the platinums for a set of NGK coppers. They give better spark. Try replacing your wires with something better too.
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Old 08-29-2003, 10:44 AM   #3
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Have you done the single point grounding mod? This has cured the hesitation problem for many, many people.

Your o2 sensor might be on its way out. When they get old they dont read as well and make the ecu have issues.

I agree with Ban SUVS about the copper spark plugs, coppers do provide a better spark, they dont last as long as platinums though.
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Old 08-29-2003, 11:27 AM   #4
BAN SUVS
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O2 sensor is also a possibility of course, and grounding helps some but not others. (I think it always helps, just some people can't really tell.) And you have to change the coppers every 20,000 miles or so. I do them every spring, just like Peaty. He;s the man.
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Old 08-29-2003, 12:26 PM   #5
SubeDonC
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i did the 02's not to long ago... im also running a s-afc and it was tunned on a dyno. Also my a/f meter says im running kinda close to lean when i never was before but its stil in the stoich area. Sounds to be bad 02 just not reading.
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Old 08-29-2003, 06:20 PM   #6
IggDawg
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get the heck rid of those plugs. I bet at least one (more likely 2 or more) are fouled. they will NOT tolerate a turbo Subaru engine, and they don't like NA subies that much either. the electrode design is very poor. the center electrode is almost recessed in the insulator and has a tendancy to get fouled really easily. I would strongly reccommend you get some NGKs. hesitation was killing my legacy turbo and I thought it was so many other things. I changed out the plugs and the problem 100% vanished.

I think those plugs really like very clean engines. subaru engines are clean, but are dirty relative to other types of engines. for example, a little oil will usually build up in the bottom side of the cylinders since it's a flat engine, and that causes a little puff of somke on start-up sometimes. they're also a little more carbon-happy than some other engines.

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Old 08-29-2003, 06:23 PM   #7
SubeDonC
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i was running Zex tri-tip non platinum plugs when this happened. The Bosch plugs i just put in, i JUST put in.
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Old 08-30-2003, 06:16 PM   #8
Yotsuya
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I just got over this problem, and it was pretty severe. First change your plugs and see if that'll fix it (you can get four good NGKs for about $10 or less). If that doesn't fix the problem check the plug wires; mine went at about 70K and I had an arcing spark coming out of the coil from my number 1 wire.

If those are settled, try the front oxygen sensor. It turned out that was my car's problem. If you're throwing a CEL, have it checked and look up the code. The more I read your symptoms the more it sounds like this.

To test: try holding you accelerator at a low (1000) RPM rate for about ten seconds. With a bad front sensor, my engine would lean out, sputter, and nearly die, even with consistant pressure onthe gas. With a new sensor; it can run at 1000 consistantly.
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