How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Ken Your Own Question

Ken
Ken, ASE Certified Technician
Category: Chevy
Satisfied Customers: 754
Experience:  GM Certified Technician, 25 Years Automotive Experience
16282319
Type Your Chevy Question Here...
Ken is online now
A new question is answered every 9 seconds

Chevrolet trailblazer LT I have a cylinder 6 misfire on a

Customer Question

I have a cylinder 6 misfire on a 03 Chevy trailblazer . I have changed all 6 coils spark plugs and # XXXXX injector check engine light still on . Computer was reset and came back on what do I go ?
Submitted: 3 years ago.
Category: Chevy
Expert:  Ken replied 3 years ago.
Now you need to do a cylinder leak down test to see if you have a valve problem. This motor is known for valve seat problems. Most of the time it is a miss fire at idle only at first, if driven on too long it becomes a miss fire all the time. Ken
Customer: replied 3 years ago.
Had diagnostic from dealer compression is good in # XXXXX and 6 did node test no open or shorts found
Expert:  Ken replied 3 years ago.
#)

Subject:P0300 DTC and Engine Misfire at Idle - Possible Leaking Intake Valves

Models:2004 - 2006 Buick Rainier
2002 - 2006 Chevrolet Trail Blazer
2002 - 2006 GMC Envoy
2002 - 2004 Oldsmobile Bravada
2005 - 2006 Saab 97x
with 4.2L Engine (VIN S - RPO LL8)

 



Condition/Concern:

On rare occasions, a SES light and P0300 DTC may be encountered as a result of single cylinder misfires only at idle. These misfires may or may not be felt and they will disappear off of idle. If the engine misfires do not occur at idle, this PI does not apply.

Recommendation/Instructions:

If the SI diagnostics do not isolate a cause for this concern, perform a cylinder leakage test as outlined in the "Cylinder Leakage Test" procedure in SI and document all leakage rates on the repair order. When performing the cylinder leakage test, it is very important to hold the crankshaft with the related piston at top dead center to ensure that the valves are fully closed or inaccurate results may be obtained. If an aftermarket leakdown tester is used, the instructions of the aftermarket tester should also be referenced because with some aftermarket testers, it may be necessary to limit the air pressure to 50 PSI in order to obtain accurate test results.

If a leaking intake valve is found, replace the cylinder head and valves.

Expert:  Ken replied 3 years ago.
If the miss fire is only at idle you will only find it with a leak down test. Compression test will pass. Ken
Customer: replied 3 years ago.
It's not a misfire during idle
Expert:  Ken replied 3 years ago.
when do you feel it then?
Customer: replied 3 years ago.
Sluggish going pass 40mph check engine light starts to flash when above 50 it 60 mph
Expert:  Ken replied 3 years ago.
Its only #6 what fault code is setting?
Customer: replied 3 years ago.
P306
Expert:  Ken replied 3 years ago.

does it just lack power or do you feel a bucking miss fire

 

Customer: replied 3 years ago.
Lacks power . Stepping on gas pedal harder to gain speed hills are worse
Expert:  Ken replied 3 years ago.
Do a back pressure test on the cat. If the cat is partly plugged it will cause a lack of power and can pick on one cylinder. Check the fuel pressure. Low fuel pressure can cause problems and #6 is the last one on that fuel rail. that is what i would check next. Ken
Customer: replied 3 years ago.
Could a fuel filter cause low fuel pressure ? Or is that just from fuel pump ?
Expert:  Ken replied 3 years ago.
Yes !! It acts just like a bad fuel pump or a plugged cat !! All 3 feel the same when driving down the road. Ken
Customer: replied 3 years ago.
So a cloged fuel filter can cause a #6 misfire ?
Expert:  Ken replied 3 years ago.
Yes, on that motor more than others because #6 is the last on on the fuel rail. This would cause a lean miss fire and most likely under a load when more fuel is needed. If you can see the mis fire counter on a scan tool. you will see a lot on miss fire on #6 and some on others. #6 is missing the most. Ken

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6870
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    5404
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1912
    18+yrs experience. State Inspector and Chevy Diagnostics
 
 
 
Chat Now With A Chevy Mechanic
Ken
Ken
GM Auto Tech.
380 Satisfied Customers
GM Certified Technician, 25 Years Automotive Experience