2003 impala 3800 misfire on cylinder 4 - Chevy Impala Forums

It appears you have not yet registered with our community. To register please click here...

Chevy Impala Forums

Go Back   Chevy Impala Forums > Performance and Technical > Chevy Impala 7th Gen Discussion

Chevy Impala 7th Gen Discussion W-Body 2000-2005. Discuss all Chevy Impala 7th Generation Performance and Technical Discussion here.

Reply
 
LinkBack Thread Tools Display Modes
Old 11-17-2012, 09:07 AM   #1 (permalink)
Junior Member
 
mjluard's Avatar
 
Join Date: Nov 2012
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Exclamation 2003 impala 3800 misfire on cylinder 4

New to the forum so i would like to say thanks in advance for any and all help

my car is a 2003 impala with a 3800 . my cel is on with dtc p0300 i have a genesys scanner and watching the live data only cylinder 4 is missing .
now i have checked every thing i can think of and the miss is still there it only misses at idle if u bring the rpm upto roughly 1500 or more no miss.

things i have checked

1. new spark plugs (acdelco)
2. new wires (off name)
3. looked for vacume leaks with carb cleaner
4. swapped coils
5. swapped plugs
6.swapped wires
7. used a noid light to check injector circuit
8. swapped injectors
9.swapped ignition module with a known good one
10. car has a new cat. converter less tha month old
11. relearned crank position sensor


as u can see I could use a little help STUMPED
monday will be checking compression (although no abnormal engine noise can be heard) , also will recheck for a vacume leak with a smoke machine.

also as u can see i have access to most tools that could be needed

again any help would be greatly appreciated

mjluard is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 11-19-2012, 07:09 AM   #2 (permalink)
Junior Member
 
mjluard's Avatar
 
Join Date: Nov 2012
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
compression test

cyl. 2,5,6 175psi
cyl. 1,3 170psi
cyl. 4 145 psi

well figured that was enough compression being that it is suppose to not be more than 70 % less than the highest cylinder witch would have to been 122.5 or less

y lack of compression figured could have been caused by the bad Cat. causing a build up of carbon on the valves

i ran two bottles of top engine cleaner through the car and wouldn't u know it miss gone

mjluard is offline   Reply With Quote Quick reply to this message
Old 11-19-2012, 08:08 AM   #3 (permalink)
Back in Black
 
12ltz's Avatar
 
Join Date: Apr 2012
Location: Manassas or Suffolk,Va
Posts: 3,979
Thanks: 76
Thanked 167 Times in 129 Posts
Good find glad you were able to get it fixed. I usually do top engine cleaner about every 60,000 miles but with the 2012 direct injection might change that 40,000.

__________________
_________________________

2012 Impala LTZ
2002 Buick Regal LS 365,000 miles
2000 Buick Regal LS 195,000 miles
1998 Olds Silhouette 3.4V6 177,000 miles
1996 Olds Cutlas 3.1V6 350,000milesXXX RIP

Too many freaks, not enough circuses.
12ltz is offline   Reply With Quote Quick reply to this message
Old 11-19-2012, 11:47 AM   #4 (permalink)
8th Gen Antagonist
 
kingnutin's Avatar
 
Join Date: Mar 2009
Location: Vancouver , WA
Posts: 13,661
Thanks: 516
Thanked 1,191 Times in 787 Posts
145 is NOT ok when the others are 170-175, looks like carbon on the valve seat was the issue though. Glad it's fixed!

__________________
1978 Caprice Classic Landau
350 2-bolt, stock 4bbl
Stock rebuilt TH350
Edelbrock performer cam + intake
Dual 2 1/2" Flowmaster exhuast (waiting to be installed)
Edelbrock IAS Classic shocks
95 9C1 3.08 posi
4 wheel disc brakes!
16x8 American Racing Baja's with 225/60/16 Pirelli P4's

kingnutin is offline   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 Chevy Impala 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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
2003 3.4L #3 cylinder misfire Firefighter Z Chevy Impala 7th Gen Discussion 13 04-13-2014 01:44 AM
Cylinder 1 misfire on 2005 Chevy Impala biglo Mechanical and Electrical Problems 2 03-27-2014 12:09 PM
3.4 problems p0481 and misfire cylinder #5 meandmycar Chevy Impala 7th Gen Discussion 3 05-12-2012 01:03 AM
1" lowering spring..Now feel vibration. #4 cylinder misfire and Reprogram pcm??? Weaver412 7th Gen Engine Performance 2 08-03-2010 06:38 AM
Misfire in cylinder 1 tt455 Chevy Impala 8th Gen Discussion 3 08-17-2009 08:22 PM




Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0 ©2011, Crawlability, Inc.
This site is not affiliated nor endorsed by General Motors Corp. Chevy Impala and related trademarks are the property of General Motors Corp.