SHIFT POINTS

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SHIFT POINTS - 10/7/2007 12:54:22 PM    ZR2003   Posts: 9 Joined: 10/5/2007 Status: offline My trans does not like to shift into 2nd when accelerating hard, at wide open throttle. It will hit the rev limiter and the tach bounces a couple of times before it shifts. How abnormal is this? Post #: 1

RE: SHIFT POINTS - 10/7/2007 4:24:43 PM    rriddle3 Posts: 1313 Joined: 12/22/2006 From: Fort Worth,Texas Status: offline quote: ORIGINAL: ZR2003 ...How abnormal is this? Extremely! _____________________________ 2002 Blazer LS 4dr 2WD Auto Trans Hypertech PP III Programmed Flowmaster 50 Series Delta Flow Muffler, C6 Corvette Exhaust Tip TYC Elegante carbon fiber tail lights (in reply to ZR2003) Post #: 2

RE: SHIFT POINTS - 10/8/2007 9:11:28 AM    ZR2003   Posts: 9 Joined: 10/5/2007 Status: offline Any ideas or suggestions? (in reply to rriddle3) Post #: 3

RE: SHIFT POINTS - 10/8/2007 9:35:38 AM    rriddle3 Posts: 1313 Joined: 12/22/2006 From: Fort Worth,Texas Status: offline Don, three things first: 1.I am assuming you have an automatic tranny, correct? 2. Are you throwing any DTC's? 3. In your signature, please give some information on your truck. It makes offering help a lot easier and faster. For example, take a look at my signature on my posts. _____________________________ 2002 Blazer LS 4dr 2WD Auto Trans Hypertech PP III Programmed Flowmaster 50 Series Delta Flow Muffler, C6 Corvette Exhaust Tip TYC Elegante carbon fiber tail lights (in reply to ZR2003) Post #: 4

RE: SHIFT POINTS - 10/8/2007 12:22:18 PM    ZR2003   Posts: 9 Joined: 10/5/2007 Status: offline '03 ZR2 with 4.3 and 4L60E. Everything else seems fine and its not throwing any codes. I'm wondering if a speed sensor or throttle position sensor would cause this? (in reply to rriddle3) Post #: 5

RE: SHIFT POINTS - 10/8/2007 12:24:49 PM    swartlkk Posts: 14308 Joined: 5/1/2005 From: Waterloo, NY Status: offline If you haven't had your vehicle scanned for codes, now would be the time to do so.  However, this may not be something that can be done for free at your local autozone or advanced auto, but try there first and let us know.  If they come up empty, then it may be time to take it to a trans shop and let them have a look at it. _____________________________ Kyle- 2004 Rainier 1970 Chevelle - Resto 1974 K5 Blazer - Resto (in reply to ZR2003) Post #: 6

RE: SHIFT POINTS - 10/8/2007 3:40:35 PM    ZR2003   Posts: 9 Joined: 10/5/2007 Status: offline I've been to a good transmission shop. They changed the fluid and filter and inspected the pan for debris. They said that from what they can tell the transmission is perfectly fine. They also checked for codes and came up empty. They were the ones who suggested the possibility of a bad throttle position sensor. Everyone I've talked to has said that a bad TPS would throw a code, though. I don't know what to do next. On a side note, the problem is more apparent when engaged in 4X4, where it does it almost all the time. In 2wd it only does it occasionally. (in reply to swartlkk) Post #: 7

RE: SHIFT POINTS - 10/14/2007 10:40:42 AM    ZR2003   Posts: 9 Joined: 10/5/2007 Status: offline Nobody else has had any shifting problems similar to this? (in reply to ZR2003) Post #: 8

RE: SHIFT POINTS - 10/14/2007 11:29:35 AM    swartlkk Posts: 14308 Joined: 5/1/2005 From: Waterloo, NY Status: offline I'm not sure that a faulty TPS would cause this, but it may be worth a try.  You can test your TPS with a regular volt meter, but you'll have to probe the wires through the insulation so have some electrical tape ready to seal the holes back up.  I posted about this in a few other threads.  CLICK HERE for some information regarding testing your TPS sensor. The MAF sensor being dirty can also cause various driveability concerns.  Wouldn't hurt to clean it either. _____________________________ Kyle- 2004 Rainier 1970 Chevelle - Resto 1974 K5 Blazer - Resto (in reply to ZR2003) Post #: 9

RE: SHIFT POINTS - 10/14/2007 11:21:12 PM    thegr81 Posts: 2621 Joined: 1/16/2007 From: PHOENIX,AZ Status: offline this is exactly what mine does change out your crankshaft positioning senser if your hasn't thrown a code it will soon my was doing it for a while till it started throwing a code i changed mine and it doesn't do it anymore. _____________________________ 2001 2wd 4.3 vortec v6 "I'm not fat, I'm a minitrucker" (in reply to swartlkk) Post #: 10

RE: SHIFT POINTS - 10/15/2007 5:06:55 AM    swartlkk Posts: 14308 Joined: 5/1/2005 From: Waterloo, NY Status: offline Please be aware that when changing out the CKP, a crank position variation relearn procedure must be done or damage to the engine could occur. _____________________________ Kyle- 2004 Rainier 1970 Chevelle - Resto 1974 K5 Blazer - Resto (in reply to thegr81) Post #: 11

RE: SHIFT POINTS - 10/15/2007 5:10:10 AM    thegr81 Posts: 2621 Joined: 1/16/2007 From: PHOENIX,AZ Status: offline how do you do that im just asking a buddy of mine did mine so i don't know i didn't have the time to do it so i dropped it off at his shop just for those who want to do this on there own _____________________________ 2001 2wd 4.3 vortec v6 "I'm not fat, I'm a minitrucker" (in reply to swartlkk) Post #: 12

RE: SHIFT POINTS - 10/15/2007 5:35:28 AM    swartlkk Posts: 14308 Joined: 5/1/2005 From: Waterloo, NY Status: offline Most all vehicles require the use of a Tech2 or equivalent scan tool.  I know of a procedure that can be performed, but it hasn't been verified so I will not post it here. _____________________________ Kyle- 2004 Rainier 1970 Chevelle - Resto 1974 K5 Blazer - Resto (in reply to thegr81) Post #: 13

RE: SHIFT POINTS - 10/15/2007 5:38:25 AM    thegr81 Posts: 2621 Joined: 1/16/2007 From: PHOENIX,AZ Status: offline ok yea i remember him saying something about Tech2 now that you mention it all i know is that after my crankshaft positioning sensor got replaced by him i haven't had the same problem at all. _____________________________ 2001 2wd 4.3 vortec v6 "I'm not fat, I'm a minitrucker" (in reply to swartlkk) Post #: 14

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