X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 25 May 2007 08:03:14 -0400 Message-ID: X-Original-Return-Path: Received: from vms040pub.verizon.net ([206.46.252.40] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2066686 for lml@lancaironline.net; Fri, 25 May 2007 03:42:46 -0400 Received: from jacky0da39824a ([71.97.245.199]) by vms040.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JIL00GZE6R3E6W5@vms040.mailsrvcs.net> for lml@lancaironline.net; Fri, 25 May 2007 02:42:42 -0500 (CDT) X-Original-Date: Fri, 25 May 2007 00:42:32 -0700 From: "Tom Gourley" Subject: Re: [LML] LIVP Oil Pressure Question (TSIO550E)...Fluctuations Noted X-Original-To: "Lancair Mailing List" Reply-to: "Tom Gourley" X-Original-Message-id: <004501c79ea0$418c05c0$650610ac@jacky0da39824a> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Mailer: Microsoft Outlook Express 6.00.2900.3028 Content-type: multipart/alternative; boundary="----=_NextPart_000_0042_01C79E65.94863F60" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. ------=_NextPart_000_0042_01C79E65.94863F60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable LIVP Oil Pressure Question (TSIO550E)...Fluctuations NotedMy first = suspicion would be an electrical problem with or around the oil pressure = sensor. You mentioned that you rigged a ground wire. Depeding on how = it's hooked up it may or may not affect the problem. I've seen some = engine sensors read erratically because of where the ground lead from = the engine interface box (the box all of the engine sensors are wired = to) was physically attached. The problem may affect multiple sensors, = or only one. For example on a Legacy using a JPI engine monitor the = installation manual said to attach the ground wire from the engine = interace box to the engine block. We first tried an unused stud (it was = real convenient) on the back of the engine where the vacuum pump would = be, if it had a vacuum pump. The tach reading jumped all over the = place. We removed the ground wire from that stud and attached it to the = large ground stud running through the firewall to the engine. The tach = worked fine after that. After thinking about it I suspect attaching the = ground wire to the vacuum pump pad created a secondary return path from = the engine back to the rest of the system that was in parallel with the = primary return path (a "ground loop"). Bad. =20 What type of oil pressure sensor do you have? Is it a 4-wire sensor? A = 3-wire sensor? Single wire sensor? If it's a multi-wire sensor does = its ground wire run back to the engine interface box? If it's a = single-wire sensor, and the sensor case isn't attached to the engine, = then the case of the sensor should probably have a wire running back to = the same ground as the engine interface box. Does the installation = manual specify how to ground the sensor? Tom Gourley ------=_NextPart_000_0042_01C79E65.94863F60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable LIVP Oil Pressure Question (TSIO550E)...Fluctuations = Noted
My first suspicion would be an = electrical problem=20 with or around the oil pressure sensor.  You mentioned that you = rigged a=20 ground wire.  Depeding on how it's hooked up it may or may not = affect the=20 problem.  I've seen some engine sensors read erratically because of = where=20 the ground lead from the engine interface box (the box all of the = engine=20 sensors are wired to) was physically attached.  The = problem may=20 affect multiple sensors, or only one.  For example on a Legacy = using a JPI=20 engine monitor the installation manual said to attach the ground wire = from the=20 engine interace box to the engine block.  We first tried = an unused=20 stud (it was real convenient) on the back of the engine where = the=20 vacuum pump would be, if it had a vacuum pump.  The tach = reading=20 jumped all over the place.  We removed the ground wire from that = stud and=20 attached it to the large ground stud running through the firewall to the = engine.  The tach worked fine after that.  After thinking = about it I=20 suspect attaching the ground wire to the vacuum pump pad created a=20 secondary return path from the engine back to the rest of the = system that=20 was in parallel with the primary return path (a "ground loop").  = Bad. =20
 
What type of oil pressure sensor do you = have? =20 Is it a 4-wire sensor?  A 3-wire sensor?  Single wire = sensor?  If=20 it's a multi-wire sensor does its ground wire run back to the engine = interface=20 box?  If it's a single-wire sensor, and the sensor case isn't = attached to=20 the engine, then the case of the sensor should probably have a wire = running=20 back to the same ground as the engine interface box.  Does the = installation=20 manual specify how to ground the sensor?
 
Tom Gourley
 
------=_NextPart_000_0042_01C79E65.94863F60--