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Pardon the "book" to follow, but after researching many threads I'm still puzzled. So you Sherlocks out there (and others like me with WAY too much time on your hands), thanks for reading!! I could have been more to the point, but with this "long-winded" version I have offered a few things I learned along the way, which may be beneficial to you. So anyway ...
I recently noticed some vibration coming from the front left (between engine and wheel well), on hard acceleration - was "sure" I had destroyed the left wheel bearing during replacement of halfshaft (didn't realize shaft nut was bottomed out on hub, so I kept pounding on it - ouch - don't do that!). Replaced bearing ... to no avail.
My next thought, maybe the new halfshaft (DSS) is out of balance? So I put the original back in as a test (which had been running decent, but had a torn boot). And here's where it gets weird: as soon as I let the car down and start it, the CHECK ENGINE light immediately comes on. Coincidence? Somehow I doubt it: I had all kinds of tools clanging around in there trying to get that stinking DSS shaft out - so I figured I had disturbed a vacuum line or wire ... but the only thing I see in that area are the manual tranny cables? (side note: DSS circlip has SHARP edges, compared with rounded edges on OEM clip - that's what makes the DSS shaft so difficult to remove, so beware).
Well, with the original shaft, the vibration is still there, but I have now pinpointed it to 2600-2800 rpm, regardless of what gear I'm in. A low frequency humming sound/feel, from the left side. I have no problems at idle, and overall it runs great - except that 2600-2800 range.
Regarding the CEL, Autozone found a P0455 (large evap leak), and a P0133 (O2 sensor1 bank1 slow response). I checked the obvious evap stuff - fuel cap / filler neck appears ok. I visually inspected the evap lines from cannister to purge valve to manifold - all seem ok. For a "large" leak, wouldn't I expect to smell gas fumes? Because I don't.
Is it possible that this 2600-2800 rpm thing could be related to the ECU/emissions system? (At first, I was concerned that "pounding" the halfshaft nut (described earlier) may have toasted the tranny output bearings - but that doesn't make sense, because my problem appears to follow ENGINE rpm, versus HALFSHAFT rpm)
Thanks to all of you who have "hung on" to the end! I appreciate any feedback.
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1998 S70 T5, 5-speed, 140k
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Well, still chasing this thing ... to summarize: a somewhat subtle, low frequency, continous humming sound/feel, from the engine area. No problems at idle, and overall it runs great. EXCEPT AT 2600-2800 RPM. Regardless of what gear.
While at the dealer, I went for a test drive with the technician, and unfortunately he had a hard time sensing what I was talking about. It's a subtle vibration that wasn't there before. 70 mph is right smack in the range in 5th - and more noticeable at this speed, as well as during hard acceleration.
They inspected the mounts (Klaus - you suggested), and they checked out ok. The suspension is tight - all new. New wheel bearing. They said the computer shows no problems. In short, they could not find anything.
The spark plugs are intact and show a normal burn. The oem plugs, along with Bosch cap / rotor and Bougicord wires, are less than 15,000 miles old.
Re-reading this thread after some time, I did realize I never checked the vacuum tree Klaus mentioned ... what specifically am I looking for?
Any other ideas are welcomed!
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1998 S70 T5, 5-speed, 145k
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This is a good one, Bill. If it only happens at 2700rpm, regardless of gear, then it has to be engine related and not suspension.
It is time to check all of the vacuum lines for cracking, clean the throttle body, clean the injectors, and anything else you can think of which would have an effect on the timing.
Klaus
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Please answer your responses. We need to know if the advice is good or bad. The 164 has a new home, all I am left with are 2 turbos :)
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Thanks for the replies and ideas.
I checked the spark plugs ... OK, but a bit on the loose side. Re-torqued to 25 N-m. Good suggestion on the cracking.
I did find a leaking hose at the turbocharger inlet area (the hose that runs to the manifold, and enters just below the evap hose). I corrected that, but I still have the roughness at 2600-2800. Will check those other items, Klaus. Thanks.
Here's my new question: How often should the Monitors be re-setting on this car? After Autozone cleared the codes, I have had the following pending Monitors: 1) Catalyst, 2) Evap System, 3) Secondary Air System, 4) Oxygen Sensor, 5) Oxygen Sensor Heater. I have driven the car for weeks and hundreds of miles (and at least 60 warmup cycles); I have no more codes, but then again these monitors have been pending (i.e. not re-setting) the entire time. It will not pass New York State emissions with more than two pending Monitors. Anyone know why they are not re-setting?
Thanks again for any suggestions.
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1998 S70 T5, 5-speed, 140k
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A large leak just means that no vacuum pressure is present, not gas smells. Recheck your vacuum lines and your gas cap.
Put the DSS shaft back on. That is not your problem.
If your vibration is rpm sensitive, check the tranny mount and the engine mounts. Pulling the plugs is an excelent suggestion, they will tell you a lot when you look at them. Also check your throttle body for dirt and any lines hanging from the vacuum tree.
Klaus
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1995 854T and 1998 V70R
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posted by
someone claiming to be Calvin
on
Sat Jun 9 06:58 CST 2007 [ RELATED]
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I read your entire message and think this is an extremely long shot, but I'll offer up an experience I had once with my 96 850 Turbo.
I had a similar symptom in that the engine seemed to be missing or running rough only at a certain engine RPM range. To make a long story short - myself and two or three different shops couldn't pinpoint the problem until I discovered one of the spark plugs was cracked. $2 solution but several weeks of frustration. I had recently had a tune up with new plugs so it never occurred to me that brand new plugs could be causing the problem.
Anyway, doubt if that is your problem but maybe a little moral support will help......
Good luck,
Calvin
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