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 Chevy expert Your Own Question

Chevy expert
Chevy expert, ASE Certified Technician
Category: Chevy
Satisfied Customers: 10370
Experience:  30 yrs experience ase cetified tech shop owner
Type Your Chevy Question Here...
Chevy expert is online now
A new question is answered every 9 seconds

1997 Chevy: misfires..distributor cap..corroded..rotor cap and it

Customer Question

I have a 1997 Chevy Silverado with a 5.0L engine. I been getting P0300, multiple/random misfires. The distributor cap posts are severely corroded so I replace the distributor and rotor cap and it works for a short time. I've had it in 2 shops and all they did was replace the same parts as I did with the same results. They said it was because I used aftermarket parts and if they replaced it with OEM parts it would be OK.

I did have an anti-freeze leak several years ago at the back of the head (close to the distributor) but I fixed it and can not find any evidence of anti-freeze in the area now.

My question is what is the source of the problem and how could I repair it permanently? If there isn't a definate answer what should I test?

Thanks,

Dan
Submitted: 4 years ago.
Category: Chevy
Expert:  ZZDaryl replied 4 years ago.
Usually if there is a misfire it is either caused by spark problem (old or bad, cap, rotor, wires or coil) or by a fuse issue (injectors, vacuum leak, low or high fuel pressure) it seems that the spark issue has been covered so I would start by looking at the fuel issue, since there seems not to be any other codes I would start by getting the fuel injectors professionally cleaned to see if it helps, looking for vacuum leaks should also be done.
Customer: replied 4 years ago.
Relist: Answer quality.
If the problem is with fuel injectors or a vacuum leak why would changing the distributor cap and rotor fix the problem temporarily until the distributor cap posts corroded again.

Another piece of information that I should have included in the first question is that the truck runs good when accelerating but misfires when I let off the gas pedal.
Expert:  Chevy expert replied 4 years ago.

This is very common problem , the root cause is the spark is jumping too large a gap as an rotor comes around to meet the post inside the distributor . This happens due to a variety of problems most commonly someone has installed the distributor incorrectly and even though it's a two phase or two off the spark will jump a very large gap and that's what builds up the corrosion and eats away at the cap . If the distributor has not been removed or installed then this is a very good sign of a Worn distributor gear , Faulty distributor , Wrong cam sensor , Or just a miss adjusted distributor

 

Install a scanner and look at the cam retard value with the engine at 1200 RPM in park. The factory specification is 0 degrees plus or minus 2 degrees.

If not in specification, turn the distributor slightly, then bring the engine over 1,200 RPM again and the value should update. Repeat this process until 0, plus or minus 2, is achieved.

If the distributor has been replaced, verify the correct distributor has been installed. Remove the rotor and check for an "8" stamped on the cam position sensor shutter blade/rotor plate if equipped with 8 cylinder engine and "6" if equipped with a 6 cylinder engine.

Chevy expert, ASE Certified Technician
Category: Chevy
Satisfied Customers: 10370
Experience: 30 yrs experience ase cetified tech shop owner
Chevy expert and other Chevy Specialists are ready to help you
Expert:  ZZDaryl replied 4 years ago.
Sean is most likely right please accept his answer, I misread your question and was thinking you were just having a misfire problem.

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