SaturnFans.com
saturnfans.com - classifieds - forums


Go Back   SaturnFans.com Forums > Models > Saturn S-Series > S-Series Tech

Reply
 
Thread Tools Display Modes
Old 02-21-2012, 10:37 PM   #1
Decaf
Junior Member
Decaf is on a distinguished road
 
Join Date: Jan 2012
Location: Northern IL
Posts: 30

2000 SL1
Default Rough Idle In D, Voltage/RPM Drop

It only does this once the engine is warm periodically and is remedied by putting the car in neutral.
RPM goes to ~1600 at start and takes about 5-10seconds to drop to 1200 on cold start.
RPM at idle is 1200 cold start, 750 after about 10min, 600-650 warm and will drop to 500 at lowest when at a stoplight.
ECTS has been replaced, stant thermostat, new WP, new dexcool, new IAT, cleaned TB/IAC/TPS, new ngk plugs (iirc), new delco wires, clean air filter, 3000m diligent oil changes, cleaned EGR. 130k miles.

I have no gotten a compression test, I'm not sure about tensioner/idler pulley but there is some noise coming from that area. Not sure how to check if motor mounts are good.

Tons of city driving so I get 20-25mpg and I take it easy.

Any ideas besides letting a mechanic try to diagnose?
Decaf is offline   Reply With Quote
SaturnFans.com Sponsored Links
Old 02-22-2012, 04:34 AM   #2
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 45,648
 

2003 L-Series 3.0L Sedan
Default Re: Rough Idle In D, Voltage/RPM Drop

Simple belt/tensioner test; if you can deflect the belt with just your fingers then the tensioner is worn out. Most tensioners that wear out allow the belt to squeal in early morning starts until the belt warms up from friction. If the belt tensioner is worn out, replace the tensioner, idler pulley and belt, all at the same time. Good belt tensioners won't allow belt deflection with fingers.
...
VCX NANO
fdryer is offline   Reply With Quote
Old 02-22-2012, 09:09 AM   #3
Puck head
Member
Puck head is on a distinguished road
 
Join Date: Jan 2012
Location: Dallas Texas
Posts: 95

1997 SC2
Default Re: Rough Idle In D, Voltage/RPM Drop

Mine was doing the same thing. I changed the fuel injectors starting problem solved. Surging rPm. Fuel pressure regulator another problem solved. Easy to do too. Ok the Injectors were a bit tricky but no that bad.
Puck head is offline   Reply With Quote
Old 02-22-2012, 12:04 PM   #4
Decaf
Junior Member
Decaf is on a distinguished road
 
Join Date: Jan 2012
Location: Northern IL
Posts: 30

2000 SL1
Default Re: Rough Idle In D, Voltage/RPM Drop

Quote:
Originally Posted by fdryer View Post
Simple belt/tensioner test; if you can deflect the belt with just your fingers then the tensioner is worn out. Most tensioners that wear out allow the belt to squeal in early morning starts until the belt warms up from friction. If the belt tensioner is worn out, replace the tensioner, idler pulley and belt, all at the same time. Good belt tensioners won't allow belt deflection with fingers.
Yes i have the classic bird chirping sound in the cold morning starts. I'll go check that out today. To my untrained ears it sounds like its drive belt related or where the timing chain is under the valve cover/power steering pump.
Decaf is offline   Reply With Quote
Old 02-22-2012, 11:37 PM   #5
ssewall
Senior Member
ssewall is on a distinguished road
 
Join Date: Jun 2011
Location: Maine
Posts: 1,088

2002 SL2
Default Re: Rough Idle In D, Voltage/RPM Drop

Testing the top mount depends on what type you have.



For the type on the right you put a straight edge on the surface where the valve cover meets the head, then measure up to it from the base of the mount. It should measure > 39mm. You'll need a straight edge to put on the top of the head to measure up to. It makes more sense when you look at it.

The frowny is measured by sticking a hex key in it's mouth A 2mm key should fit.
ssewall is offline   Reply With Quote
Old 02-23-2012, 12:31 AM   #6
Decaf
Junior Member
Decaf is on a distinguished road
 
Join Date: Jan 2012
Location: Northern IL
Posts: 30

2000 SL1
Default Re: Rough Idle In D, Voltage/RPM Drop

Quote:
Originally Posted by ssewall View Post
Testing the top mount depends on what type you have.



For the type on the right you put a straight edge on the surface where the valve cover meets the head, then measure up to it from the base of the mount. It should measure > 39mm. You'll need a straight edge to put on the top of the head to measure up to. It makes more sense when you look at it.

The frowny is measured by sticking a hex key in it's mouth A 2mm key should fit.
Why am I measuring it? Pardon my lack of knowledge.


When you say "deflect" does that mean i the belt should have no give when tugged anywhere on the belt?
Decaf is offline   Reply With Quote
Old 02-23-2012, 12:49 AM   #7
ssewall
Senior Member
ssewall is on a distinguished road
 
Join Date: Jun 2011
Location: Maine
Posts: 1,088

2002 SL2
Default Re: Rough Idle In D, Voltage/RPM Drop

You're measuring how much the mount has sagged from when it was new. The measurements I gave you are what the FSM authors have determined are likely to cause problems such as idle vibration.
ssewall is offline   Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Has anyone experienced voltage drop in closed loop? mgordon1100 S-Series Tech 19 10-27-2010 11:59 PM
SL1 RPMs drop, Rough Idle What's the problem? SL1Guy S-Series Tech 1 10-08-2009 11:14 AM
SL1 RPMs drop, Rough Idle What's the problem? SL1Guy S-Series General 2 10-07-2009 09:19 AM
Depressing clutch causes voltage drop kornphlake S-Series Tech 18 07-20-2006 02:34 AM
rough idle, rough sluggish pickup, 97slw smiles233 S-Series General 7 10-14-2005 04:28 PM


All times are GMT -4. The time now is 12:04 PM.

Advanced Forum Search | Advanced Photo Search


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
SaturnFans.com. The Saturn Enthusiasts Site.