Thanks OBD
Thread Starter
Race Director
Joined: Aug 2003
Posts: 13,421
Likes: 8
From: Lake Mary Florida
Thanks OBD
Couldn't decide if this should be titled re OBD or Fixing a rough idle...
Anyway the LT-1 has been running fairly decent for a while then about six weeks ago on the way home from beachside, just when I got settled in in the interstate cruising home with cruise set I get a Service Engine Soon light. Last for about 3 min goes out. Wow everything seems fine. Disregard. Couple weeks later same thing just as I get to cruise, SES light still things are running fine except the idle was starting to pick up a miss. Hmm throttle body can't be that dirty so soon. Last week same thing again at cruise SES.
Ok enough is enough pull the codes. Infamous 32, EGR circuit. And now the idle has fully developed a descent miss. Apparently 32 doesn't set until you reach over 50 mph.
So review the diagnostic procedures and identified all the possible suspect components. I order a new EGR, ERG solenoid, vacuum check value, and a new vacuum harness assembly. In case anyone is unsure, the vacuum harness is a vacuum tube assemlby that connects ASR, manifold, solenoid, and EGR all in one plastic assembly. I focus on this because this part has been discontinued. But the bright side Chris at Superior provides a contact to a company that buys up the remaining inventories of these discontinued part.
So all told $90. in parts and an hours time. I now have a new vacuum system, and EGR system.
Results an absolutely perfect idle. And over all performance of the engine improved noticably. Wow what a difference it made. Thanks OBD and GM for making my baby feel better.
Anyway the LT-1 has been running fairly decent for a while then about six weeks ago on the way home from beachside, just when I got settled in in the interstate cruising home with cruise set I get a Service Engine Soon light. Last for about 3 min goes out. Wow everything seems fine. Disregard. Couple weeks later same thing just as I get to cruise, SES light still things are running fine except the idle was starting to pick up a miss. Hmm throttle body can't be that dirty so soon. Last week same thing again at cruise SES.
Ok enough is enough pull the codes. Infamous 32, EGR circuit. And now the idle has fully developed a descent miss. Apparently 32 doesn't set until you reach over 50 mph.
So review the diagnostic procedures and identified all the possible suspect components. I order a new EGR, ERG solenoid, vacuum check value, and a new vacuum harness assembly. In case anyone is unsure, the vacuum harness is a vacuum tube assemlby that connects ASR, manifold, solenoid, and EGR all in one plastic assembly. I focus on this because this part has been discontinued. But the bright side Chris at Superior provides a contact to a company that buys up the remaining inventories of these discontinued part.
So all told $90. in parts and an hours time. I now have a new vacuum system, and EGR system.
Results an absolutely perfect idle. And over all performance of the engine improved noticably. Wow what a difference it made. Thanks OBD and GM for making my baby feel better.
Last edited by 93JetJocky; Jan 16, 2005 at 01:49 PM.
