Hard/Rough Start Fixed – Not Your Typical Culprit - The Saab Link Forums

Go Back   The Saab Link Forums > Saab NG900 '94-'98 and 9-3 '99-'02 Forum > Car Problems? NG900 or old 9-3 Only

Car Problems? NG900 or old 9-3 Only If you're experiencing problems with your NG900 or 9-3, post your question in here. CEL Code or GTFO!

SaabLink.net is the premier Saab Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 02-11-2008, 01:32 PM   #1
ERP
Flirting With TSL Addiction
 
ERP's Avatar
 
Join Date: Jan 2004
Location: Colorado Springs
Posts: 546
Send a message via AIM to ERP
Hard/Rough Start Fixed – Not Your Typical Culprit

This problem came up after my 2.3L swap, but it could happen to anyone with a NG900/9-3. I had a hard time starting the engine and it took me a while to figure out. Cold starts would take 3-5 attempts to get the engine to catch and idle. It would idle high then come down to 1000 rpm after a few seconds. Power was down for the first 30-60 seconds, then the engine would pick up and drive great. Gas mileage was good too, only down a few points from average. But what made this different than typical hard starts was that it was worse when the engine was hot. It would take even more cranks to get the engine to start. I tried all the standard fixes first. I cleaned the IAC, I swapped in a spare Fuel Pressure Regulator, I swapped in a spare Throttle Position Sensor, I swapped in a spare Crank Positions Sensor, I changed the fuel pump and check valves(upgraded to the Walbro) and I replaced my alternator (old one was going out and my battery was less than a year old). Nothing made any difference.

I swapped in a crushed FPR and it did help a little, but did not fix the hard starts. I pulled the vacuum line from the FPR and it richened up idle and helped the starts, but was dangerously lean under boost, don't try this without a wideband O2 sensor. I also re-flashed my ECU since I was running a 2.0L on a 2.3L engine. I could see on my wide-band that my air/fuel was lean 16-17 at idle, but nice and rich under boost. For two months my Saab was hard to start but I never saw any check engine light.

The solution appeared when I hooked up my laptop to the OBD2 port and checked out all the sensors. The coolant temp sensor showed -40F. This is parked in the garage and there was no change in temp after a few minutes of idling. At first I thought it was just my reader having a problem interpreting the ECU, since my coolant gauge was working fine and I replaced the coolant sensor about a year ago. Then I talked to JZW and he reminded me there are two coolant sensors. I could have hit my head on the wall. Two months of hard starts and all the time I spent trying to fix it and my ECU coolant sensor was simply unplugged. I plugged it in and the engine starts great now. So if you are having problems starting cold and hot, check the coolant sensor in the intake manifold.
__________________
2008 Turbo X 19T JZW Stg 4, 415 hp, 532 tq
2006 Lotus Elise - Supercharged, 6.9 lbs/hp
2005 9-2x Aero Stg 2
1996 900 'Aero' 2.3t Sold -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ERP is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 02-11-2008, 01:39 PM   #2
Elder
 
Moonracer's Avatar
 
Join Date: Nov 2006
Location: Meyer Iowa
Posts: 2,451
didn't it set a CEL with that unplugged? It should have.
Moonracer is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 01:44 PM   #3
ERP
Flirting With TSL Addiction
 
ERP's Avatar
 
Join Date: Jan 2004
Location: Colorado Springs
Posts: 546
Send a message via AIM to ERP
Nope, never got a CEL though all of it. I wish I had, it would have made it easier to figure out.
__________________
2008 Turbo X 19T JZW Stg 4, 415 hp, 532 tq
2006 Lotus Elise - Supercharged, 6.9 lbs/hp
2005 9-2x Aero Stg 2
1996 900 'Aero' 2.3t Sold -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ERP is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
 
Old 02-11-2008, 01:47 PM   #4
Elder
 
Moonracer's Avatar
 
Join Date: Nov 2006
Location: Meyer Iowa
Posts: 2,451
strange?
Moonracer is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 03:12 PM   #5
Moderator
Elder
 
DeLorean's Avatar
 
Join Date: Nov 2003
Location: In a compound on a hill
Posts: 7,595
Send a message via AIM to DeLorean
you won't get a CEL from an un plugged NCT sensor, the ECU just assumes the value of 0 ohms resistance is correct (and that it's -40 outside). If you are having running issues, checking all the sensor outputs would be the first thing I'd check. on the Megatune screen, you can pull up the realtime display and check all the sensor outputs at a glance.

Last edited by DeLorean; 02-11-2008 at 03:42 PM.
DeLorean is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 03:17 PM   #6
Elder
 
NickTurbo900's Avatar
 
Join Date: Sep 2005
Location: Greater Burlington, Vermont
Posts: 4,023
Quote:
Originally Posted by ERP View Post

The solution appeared when I hooked up my laptop to the OBD2 port and checked out all the sensors. The coolant temp sensor showed -40F.
Drool. I would like to have this ability. Can someone point me in the direction of the required hardware/software???


Congrats on the fix ERP. Only a swedish car could believe it was -40F for days on end.
NickTurbo900 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 03:19 PM   #7
Elder
 
drewz airflow se's Avatar
 
Join Date: Dec 2004
Location: OHIO
Posts: 8,107
Send a message via AIM to drewz airflow se
I just wish my car was OBD2
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

^CLICK ME^
drewz airflow se is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 03:41 PM   #8
HNNLIC
Elder
 
Blaque's Avatar
 
Join Date: Oct 2003
Location: Washington, D.C. / Kansas City
Posts: 4,209
Send a message via ICQ to Blaque Send a message via AIM to Blaque Send a message via MSN to Blaque Send a message via Yahoo to Blaque
This is really informative. I've been dealing with the same issue for quite a while. Good info Eric.
__________________
Virtualization FTW. IT 4 Life.

“Brothers and sisters… and friends…and I see some enemies. In fact, I think we’d be fooling ourselves if we had an audience this large, and didn’t realize that there were.. some enemies present.” –Malcolm X


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Blaque is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 04:16 PM   #9
ERP
Flirting With TSL Addiction
 
ERP's Avatar
 
Join Date: Jan 2004
Location: Colorado Springs
Posts: 546
Send a message via AIM to ERP
Quote:
Originally Posted by NickTurbo900 View Post
Drool. I would like to have this ability. Can someone point me in the direction of the required hardware/software???

Congrats on the fix ERP. Only a swedish car could believe it was -40F for days on end.
Yea, but even a Swedish car should realize that after 2 hours of driving the coolant temp should get above -40F.

The hardware/software that I used to hook up to my OBD2 was Digimoto, http://www.digimoto.com/shop/ It comes in handy for sensor reading, CELs and turning them off, and data logging.
__________________
2008 Turbo X 19T JZW Stg 4, 415 hp, 532 tq
2006 Lotus Elise - Supercharged, 6.9 lbs/hp
2005 9-2x Aero Stg 2
1996 900 'Aero' 2.3t Sold -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ERP is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Old 02-11-2008, 04:20 PM   #10
Elder
 
NickTurbo900's Avatar
 
Join Date: Sep 2005
Location: Greater Burlington, Vermont
Posts: 4,023
OMG. Eric Thank you. Thank you. Thank you.

This is wunderful. Thank you!

Thank you so much! I cannot believe how inexpensive this is. Sorry guys but my FS posts will continue to fill up the forum til I have this amazing tool in my hands!
NickTurbo900 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the The Saab Link Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Vehicle Info.
Enter your vehicle information (year, model, mods)
Insurance
Please select your insurance company (Optional)

Log-in


Thread Tools

Posting Rules
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 03:53 AM.


Powered by vBulletin® Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Friendly URLs by vBSEO 3.5.2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
All content is copyright © The Saab Link and it's original authors.


 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.