Recent Topics
Craftsman Tractor Doesn't Shut Off Immediately
by mez
10/25/14 05:45 PM
Found Ultra 0w20...go for it?
by BTLew81
10/25/14 05:43 PM
Anyone still have a VCR?
by chiefsfan1
10/25/14 05:14 PM
Time for OEM battery change?
by chiefsfan1
10/25/14 05:09 PM
Bought the wrong oil filter.
by joegreen
10/25/14 04:42 PM
Air Filtration - Lawn Mower Engines
by lawnguy
10/25/14 03:46 PM
Berryman Chem-dip and B-12 Chemtool.
by GreeCguy
10/25/14 03:33 PM
It's Not About The Nail
by JerryBob
10/25/14 01:27 PM
Windows Scripting Tool?
by sleddriver
10/25/14 01:10 PM
calcium sulfonate quiz
by miro
10/25/14 12:50 PM
BATTERY QUESTION
by lucerne06
10/25/14 12:42 PM
Motor Brushes
by Vikas
10/25/14 12:39 PM
Newest Members
PhxAZ, Miramonte, Rotario, ignat, aahull
51695 Registered Users
Who's Online
76 registered (3800Series, 97f150, 901Memphis, 69P, 9 invisible), 1600 Guests and 219 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
51695 Members
64 Forums
221195 Topics
3497314 Posts

Max Online: 2862 @ 07/07/14 03:10 PM
Donate to BITOG

Topic Options
#3468612 - 08/29/14 04:27 PM Rough idle on cold start
Falcon_LS Offline


Registered: 10/03/08
Posts: 3516
Loc: Kuwait
Weird issue with my Envoy (4.2L L6) the last two days. On cold starts first thing in the morning, the engine idles rough (like a single cylinder misfire) for about a minute then returns to normal. If you rev the engine whilst it idles rough, it revs smooth as glass. No codes are stored in the PCM.

Worth noting, same thing happened this evening after the truck was sat for 12 hours and I had no cruise control. Pulled over, killed the ignition and fired her back up again and I had my cruise control back. Possible throttle body issue? Thanks!
_________________________
99 Mustang: M1 0W-40/FL820S
00 Pajero: M1 0W-40/26300-35503
01 Marquis: M1 ESP Formula 5W-30/FL820S
05 Envoy: M1 ESP Formula 5W-30/51522XP

Top
#3468614 - 08/29/14 04:31 PM Re: Rough idle on cold start [Re: Falcon_LS]
Skid Offline


Registered: 06/10/11
Posts: 199
Loc: USA - Southern California
If I had to guess, water temp sensor.

Top
#3468617 - 08/29/14 04:33 PM Re: Rough idle on cold start [Re: Falcon_LS]
Char Baby Offline


Registered: 05/25/05
Posts: 7319
Loc: Rochester NY
Possibly the throttle body needs to be cleaned or the(if this engine has one), the Idle Air Control Valve(IACV).

Research will help you fine where the IACV is!
Cleaning the T-Body with the proper cleaner may also aid in this idle issue.

Also, check for vacuum leaks!

This is just a start. Others will chime in with more helpfull information.

CB
_________________________
"Finally Retired"!

1980 Firebird FORMULA V8-NEW
2001 Lexus RX-300 V6-NEW
2004 Nissan Altima 2.5S-NEW
2006 Mazda 3i 2.0L-PreOwned

Top
#3468623 - 08/29/14 04:40 PM Re: Rough idle on cold start [Re: Char Baby]
Bud_One Offline


Registered: 04/19/14
Posts: 326
Loc: Spring,Texas
Originally Posted By: Char Baby
Possibly the throttle body needs to be cleaned


+1

Co-worker of mine has a 2004 Trailblazer with the 4.2 and had the same issue but never went away warm or cold. Throttle body was caked full of black goo. Cleaned it up and it ran great.
_________________________
2005 Chevy 2500HD -Amsoil SSO 5w30, Fram XG3675
2003 Vibe - Formula Shell 5W30 w/MOS2, Fram PH4967
1997 Accord Wagon - Pennzoil HM 5w30, Fram XG3593A

Top
#3468626 - 08/29/14 04:47 PM Re: Rough idle on cold start [Re: Falcon_LS]
Falcon_LS Offline


Registered: 10/03/08
Posts: 3516
Loc: Kuwait
Thanks for the input! The throttle body was cleaned roughly 3,000 miles ago and even then, barely needed any cleaning. It was almost spotless (engine's fed Euro V gas).

I monitor ECT constantly with my ScanGauge-II - at cold start ECT matches ambient temp and fluctuates between 190-195 F at operating temp - I guess that rules out the ECT sensor?
_________________________
99 Mustang: M1 0W-40/FL820S
00 Pajero: M1 0W-40/26300-35503
01 Marquis: M1 ESP Formula 5W-30/FL820S
05 Envoy: M1 ESP Formula 5W-30/51522XP

Top
#3468660 - 08/29/14 05:31 PM Re: Rough idle on cold start [Re: Falcon_LS]
Whimsey Online   content


Registered: 12/22/02
Posts: 3072
Loc: The Garden State
Originally Posted By: Falcon_LS
Thanks for the input! The throttle body was cleaned roughly 3,000 miles ago and even then, barely needed any cleaning. It was almost spotless (engine's fed Euro V gas).

I monitor ECT constantly with my ScanGauge-II - at cold start ECT matches ambient temp and fluctuates between 190-195 F at operating temp - I guess that rules out the ECT sensor?

This may sound dumb but were they only looking at the throttle body on the visible outside of the throttle plate. My 1996 Ford Contour which burns no oil in 8500-9000 mile Oci's was clean on the visible front of the throttle body. Behind the throttle plate had black build up. After I cleaned it, it idles much better. Does it smooth up after it warms up? Mine now runs fairly stable idle, it only idles rough for a few seconds while still warming up, it only happens on the first stop after starting up. I'm sure my IAC valve should be cleaned but it's a PIA to get to so I'll live with less than perfect idle, but acceptable idle from a 4 cyl. I had no codes.

Whimsey

Top
#3468687 - 08/29/14 06:11 PM Re: Rough idle on cold start [Re: Falcon_LS]
Trav Offline


Registered: 11/20/06
Posts: 9987
Loc: MA, Mittelfranken.de
Originally Posted By: Falcon_LS
I monitor ECT constantly with my ScanGauge-II

Try unplugging that and see what happens. Start with the simple stuff.
_________________________
ASE L1, Master. Deutsch Meisterbrief.

Top
#3468717 - 08/29/14 06:51 PM Re: Rough idle on cold start [Re: Falcon_LS]
Merkava_4 Offline


Registered: 01/30/07
Posts: 9384
Loc: Clovis, CA
Originally Posted By: Falcon_LS
The throttle body was cleaned roughly 3,000 miles ago and even then, barely needed any cleaning. It was almost spotless (engine's fed Euro V gas).


Ah..........but are you just looking at it from the air side? I think you'll find that the throttle body looks quite different on the engine side. The engine side is what regurgitates all the combustion byproducts and oily PCV fumes onto the throttle body.

Top
#3468751 - 08/29/14 07:34 PM Re: Rough idle on cold start [Re: Bud_One]
01_celica_gt Offline


Registered: 07/29/13
Posts: 847
Loc: St. Louis, MO
Originally Posted By: Bud_One
Originally Posted By: Char Baby
Possibly the throttle body needs to be cleaned


+1

Co-worker of mine has a 2004 Trailblazer with the 4.2 and had the same issue but never went away warm or cold. Throttle body was caked full of black goo. Cleaned it up and it ran great.


+1 just finished a 98 corolla with throttle body full of oil. Took off the throttle body and IACV, cleaned them both as they were both full of oil. Afterwards idle went from a constant 1400 to 750 rpm normal now. I did do an oil consumption fix, now I can barely hear the engine running and its revs REALLY smoothly.


Edited by 01_celica_gt (08/29/14 07:36 PM)
_________________________
01 Celica GT 1ZZ-FED(Rebuilt @ 186) Auto @ 203k
00 Celica GT-S 2ZZ-GE(Rebuilt @ 164k) Auto @ 171k
2ZZ-GE: CelicaBlend 0w20(3.0qt) + 0w40(2.0qt) = 5.0 qt

Top
#3468762 - 08/29/14 07:48 PM Re: Rough idle on cold start [Re: Falcon_LS]
Kuato Offline


Registered: 10/23/05
Posts: 3139
Loc: Northeastern MT
How is your battery? If it's not in good shape it could cause a miss. I've had 2 different vehicles over the years that acted as yours does. Losing the cruise control was the tip off.
_________________________
Amsoil


88 Dodge D150, 318 2wd MT 176k
04 Jeep Wrangler 2.4 MT 186k
13 F150 5.0 4x4 24k

Top
#3468800 - 08/29/14 08:27 PM Re: Rough idle on cold start [Re: Falcon_LS]
toneydoc Offline


Registered: 12/16/11
Posts: 1012
Loc: War Eagle
Have you checked for any corrosion at the distributor cap and coils and spark plug connections. Have had rough running and misfiring in the past due to corrosion and buildup at some of the connectors on wiring.
_________________________
1994 Jeep 136k Nextgen 5w30HM
2014 Camry 1k Toyo 5w20
2010 Sebring 32k NextGen5w30
2014 HD Ultra 2k HD20w50
2012 Toyota Rav4 13k Toyo 5w20

Top
#3469019 - 08/30/14 06:39 AM Re: Rough idle on cold start [Re: toneydoc]
Falcon_LS Offline


Registered: 10/03/08
Posts: 3516
Loc: Kuwait
Found the culprit - we've been having some extremely humid weather of late and there was moisture in the coil in cylinder 1. Not sure how it got in, given I've generously applied dialectic grease when I did the plugs 25,000 miles ago, but I took this opportunity to pull the plugs out for inspection and reapply DG to all coil boots after blowing them clean with a compressed air gun.

That being said, I always clean my throttle body off the vehicle. In this case, it's drive by wire so I don't want to be messing with the plate. Removing it and generously spraying it with throttle body cleaner or brake cleaner does the trick, but it's always been clean with the gas I'm using.
_________________________
99 Mustang: M1 0W-40/FL820S
00 Pajero: M1 0W-40/26300-35503
01 Marquis: M1 ESP Formula 5W-30/FL820S
05 Envoy: M1 ESP Formula 5W-30/51522XP

Top
#3469050 - 08/30/14 07:50 AM Re: Rough idle on cold start [Re: Falcon_LS]
Char Baby Offline


Registered: 05/25/05
Posts: 7319
Loc: Rochester NY
Originally Posted By: Falcon_LS
Found the culprit - we've been having some extremely humid weather of late and there was moisture in the coil in cylinder 1. Not sure how it got in, given I've generously applied dialectic grease when I did the plugs 25,000 miles ago, but I took this opportunity to pull the plugs out for inspection and reapply DG to all coil boots after blowing them clean with a compressed air gun.

That being said, I always clean my throttle body off the vehicle. In this case, it's drive by wire so I don't want to be messing with the plate. Removing it and generously spraying it with throttle body cleaner or brake cleaner does the trick, but it's always been clean with the gas I'm using.


Well done!
Thanks for keeping us posted on the results!

smile
CB
_________________________
"Finally Retired"!

1980 Firebird FORMULA V8-NEW
2001 Lexus RX-300 V6-NEW
2004 Nissan Altima 2.5S-NEW
2006 Mazda 3i 2.0L-PreOwned

Top