Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Connect one-on-one with {0} who will answer your question

This answer was rated:

★★★★★

Chevrolet Silverado 2500: 2000 chevy 2500HD silverado

i have a 2000 chevy...

i have a 2000 chevy 2500HD silverado 6.0 gas motor. I have an issue where when i start to go down hill and coast a little bit and let off of the throttle down to about 1/10th throttle the truck down shifts out of overdrive, sometimes i get a p0300 misfire with the engine light flashing. the wierd thing is this only happpens when im going down hill on deceleration. it will kick out of overdrive, sometimes the check engine light comes on sometimes it doesnt. but once at the bottom of the hill the tranny will not shift back into overdrive for atleast a mile or two. this is on the highway around 70 miles per hour. if i stay on the throttle or if im under load it doesnt do it but if i am on the throttle pedal just a little bit and i start to coast then it kicks out of overdrive. if i let off the throttle all together and coast say from 75 to 70 then back on the throttle it wont do it. so i have to speed up and let off all together to prevent this from happening. this is really anoying. i have a air intake, msd coils, hypertech programmer, eldebrock headers.. new plugs, new wires, new throttle position sensor, new fuel pressure regulator, new fuel filter.. I have heard people say crankshaft postion variation relearn procedure could fix this because of slack in the timing chain, i guess that would kinda make sense because that would be about the point that the tension would shift from pull to push or load and no load. please help, thanks

Show Less

Ask Your Own Chevy Question

Answered in 4 hours by:

3/12/2013

Chevy Mechanic: Dave Nova, Chevrolet Technician replied 10 years ago

Dave Nova, Chevrolet Technician

Category: Chevy

Satisfied Customers: 19,453

Experience: ASE Master Certification. GM World Class Certification

Verified

Hello and thank you for trusting me with your question. My name is XXXXX XXXXX I will do my best to help you with your Chevy problem.

Don't Forget, the deposit you placed to ask this question is not used to compensate me until you rate my service! Please remember that when you are asked to give a rating, you are rating My Service, and not this website itself or your vehicle.
.
When the engine downshifts, does rpm go up over 2500 rpm?

Customer reply replied 10 years ago

not always

Chevy Mechanic: Dave Nova, Chevrolet Technician replied 10 years ago

Okay, but the rpm does increase. Because of stretch in the timing chain, the cam and crank sensors will have too much variation in their readings. The computer will interpret this as a misfire. That is why the crankshaft position variation relearn will fix this type of issue. Try driving in 2nd or 3rd gear at a speed where rpm stays around 2500 or more for a distance of a mile or two. If the check engine light comes on and you get a P0300 code, this is a confirmation that timing chain stretch is the issue. You can then have the dealer do the crankshaft position variation relearn. The procedure takes only a few minutes if the engine is at operating temperature.

Customer reply replied 10 years ago

yes the RPM increases because it down shifts, at 73 mph it usually goes from 1800/1900 to 2400 rpms. if i continue to hold my foot on the pedal in the same spot the check engine light will continue to flash but if i completely let off or give it more gas it will stop flashing. also when this happens i dont seem to feel or hear and thing that would sound like a real misfire.. what is your thoughts on the EGR valve would this have any effect?

Chevy Mechanic: Dave Nova, Chevrolet Technician replied 10 years ago

There is no real misfire when this occurs, it is just the fluctuation between the reading of the cam and crank sensors that the computer misinterprets as a misfire. EGR has no effect on this. Your two options are to replace the timing chain or have the crankshaft position variation relearn done.

Dave Nova, Chevrolet Technician

Category: Chevy

Satisfied Customers: 19,453

Experience: ASE Master Certification. GM World Class Certification

Verified

Dave Nova and 87 other Chevy Specialists are ready to help you

Ask your own question now

Customer reply replied 10 years ago

Just had the ECM reflashed and the Crankshaft position variation relearn procedure preformed and took the truck for a test drive and tried to make it do what it always did and it wouldn't. so far so good. I have a long trip on Thursday that is 240 miles round trip so I will find out for sure if that fixed the issue. I will respond back to let everyone know the results for future reference.

Chevy Mechanic: Dave Nova, Chevrolet Technician replied 10 years ago

Sounds great. Thank you for the update and I would love to hear how it does on the trip. If you need anything in the future, feel free to ask for me by name.

Dave Nova

Customer reply replied 10 years ago

well I have tried to make it do what it was doing and after the dealership reflashed the ECM and did the Crankshaft position variation relearn procedure I have not had any issue. that solved the problem.

Chevy Mechanic: Dave Nova, Chevrolet Technician replied 10 years ago

That's great news. Thanks for updating me again.

David

Was this answer helpful?

Yes

How JustAnswer works

Describe your issueThe assistant will guide you

Chat 1:1 with a chevy mechanicLicensed Experts are available 24/7

100% satisfaction guaranteeGet all the answers you need

Related Chevy Questions

2000 chevy silverado 5.3L. Trans 4160e I have a new/rebuilt

2000 chevy silverado 5.3L . Trans 4160eI have a new/rebuilt transmission rebuilt with heavy duty transmission parts.After about 1500 miles on the trans I feel what seems like a sputter, or hesitation.… read more

David Craig

OWNER/MECHANIC

Associates

16,316 satisfied customers

1992 K3500, 4l80e All was good until I had to kick down from

1992 K3500, 4l80e All was good until I had to kick down from overdrive to pass. Would not go back into overdrive. Went to get gas and back on the highway, went into overdrive for about 70 miles. Had t… read more

HDGENE

11,310 satisfied customers

1999 astro van when getting on hiway and it down shifts to

1999 astro van when getting on hiway and it down shifts to go faster then after it shifts into over drive it hesitates and engine light flashes and then engine light stays on steady when i let off gas… read more

GM Tech (Cam)

Owner/Technician

Vocational, Technical or Trade Scho

28,685 satisfied customers

I have a 383 stroker motor that I need to put in my 1990

I have a 383 stroker motor that I need to put in my 1990 K2500. It is carbuerated so I need to know what I need to do to convert it to from the EFI. … read more

Mike S.

Chevy Mechanic

Vocational, Technical or Trade Scho

2,417 satisfied customers

94 Chevy: with a 6.5 DIESEL, automatic tranny..neutral

Im working on a 94 Chevy with a 6.5 DIESEL, automatic tranny. I have acc pedal response in neutral or park... If I put it in gear, foot on the brake, I get no response...its like I didnt even touch th… read more

Shannon Martin

retired

Vocational, Technical or Trade Scho

572 satisfied customers

2000 Sonoma: the gas pedal to shift..shifts fine..overdrive..MPH.

My 2000 Sonoma's transmission started acting up. I have to let of the gas pedal to shift from first to second. But if i coast down hill it shifts fine all the way through overdrive and will coast 70 M… read more

Tim's Auto Repair

mechanic

High School or GED

9,755 satisfied customers

1991 chevrolet p30: step van..gas pedal..throttle position..thermostat

i have a 1991 chevrolet p30 step van, with a 6.2 diesel in it, when i first got it if it didnt go into overdrive i would stop shut it off an restart it an it would go into overdrive. 2 weeks ago it st… read more

Tim's Auto Repair

mechanic

High School or GED

9,755 satisfied customers

2005 GMC Canyon: automatic transmission..cruise control..freeway..hill

I have a 2005 GMC Canyon I5 3.5 engine w/automatic transmission (4sp+OD). When in cruise control at 70-75mph (freeway limit in Montana), when starting up a hill, the transmission will often shift down… read more

BOBBYSS

Automotive Repair/Damage Investigator

Associate Degree

14,739 satisfied customers

05 LS: 4x4..silverado..overdrive..hills, it would be in OD..rpms

i have an '05 LS 4x4 crew cab silverado. My wife n I were headed off to our honeymoon yesterday and my truck started jumping in and out of overdrive with no load. It would down shift coasting down hil… read more

BigBlock434

Technician

High School or GED

288 satisfied customers

Tahoe: the brakes it will kick out of overdrive..throttle..wheel drive

doesn,t always shift into overdrive if you have to slam on the brakes it will kick out of overdrive. if i,m going down hill and let go of the throttle it will shift into overdrive. 99XXXXXtahoe… read more

stin1974

Mechanic/Technician

High School or GED

758 satisfied customers

Chevy suburban: 700R4 auto trans rebuilt..vibration..Runs great

I have a 1985 K20 Chev Suburban with 350 ci M code engine, 700R4 auto trans rebuilt by AAMCO. The problem is a lack of power and vibration when going up a steep hill. Runs great on the flat. The Roche… read more

Ivan

Automotive Instructor

Bachelor's Degree

4,857 satisfied customers

1993 GMC Yukon: steering column..jerks..shift through all gears..hill

I have a 1993 GMC Yukon and it shudders rather violently "you can feel it shake the steering column" when it downshifts from overdrive to drive. It just jerks a little at lower speeds and is much more… read more

michael

High School or GED

667 satisfied customers

mountains: 5th wheel..Silverado ( 07 2500 hd duramax..steep hills

I travel in the mountains towing a 5th wheel. ... and I''m new to the Silverado (''07 2500HD Duramax) and I''d like to know how the tow/haul mode should be used going up the steep hills and down the o… read more

goodwrench9124

ASE Certified Technician

Vocational, Technical or Trade Scho

2,045 satisfied customers

Camaro: overdrive at 60 mph and about 2200 rpms..trans..throttle

I have a 2001 Z28 Camaro and I am losing overdrive at 60 mph and about 2200 rpm''s. The trans seems to down shift and the rpm''s go to about 5,000 and the car seems to lose all power. If I shift into … read more

michael

High School or GED

667 satisfied customers

95 Chevy Monte Carlo Z34: overdrive..car has been driven..kick..slip

My 95 Chevy Monte Carlo Z34 automatic trans will not shift into overdrive everytime. Gets worse after car has been driven for about an hour and I stop to do something for a short time and then go agai… read more

Ted G.

Owner

Vocational, Technical or Trade Scho

5,692 satisfied customers

2002 Chevy Impala: Automatic..55k,..it shifted into overdrive

2002 Chevy Impala Automatic, 55K, sometimes I really have to floor it to get it shifted into overdrive.… read more

autodoc_2000

Automotive Technician/Asst Service Manag

Vocational, Technical or Trade Scho

2,556 satisfied customers

1992 Chevy: shifts..overdrive and seems to go to neutral..upshift

1992 Chevy K1500 shifts from overdrive and seems to go to neutral. When I let off the gas it kicks back into gear and works great. It also happens on the upshift a times. Wondering if this is soleniod… read more

Dean @ TransLab

design engineer

currently working on Masters (M.Div

94 satisfied customers

Silverado 1500: 4x4..trailer..cruise control..overdrive into 2nd gear

I have an 06 Silverado 1500, 5.3, auto, 4x4, w/3:73 rears. I typically pull a loaded 5500 lb trailer w/an off-road truck loaded on it in the tow/haul mode with the cruise control set between 70 and 75… read more

Matt

Shop Owner / Technician

Vocational, Technical or Trade Scho

44 satisfied customers

Disclaimer: Information in questions answers, and Show Less

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

JustAnswer in the News:

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 LRochester 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!!!!
AlexLos 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.
GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.
JustinKernersville, 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.
EstherWoodstock, 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.
RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Tim's Auto Repair

mechanic

9,755 satisfied customers

Have owned a repair shop for 25 yrs.

Gary

Chevy Technician

9,659 satisfied customers

15 years GM master tech

Dave Nova

Chevrolet Technician

19,453 satisfied customers

ASE Master Certification. GM World Class Certification

Chris (aka-Moose)

Technician

4,008 satisfied customers

24 years of experience diagnosing & repairing

Jerry Newton

Chevy Technician

2,804 satisfied customers

ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.

Mike S.

Chevy Mechanic

2,417 satisfied customers

ASE Certified Master Technician

goodwrench9124

ASE Certified Technician

2,045 satisfied customers

Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified

< Previous | Next >

Show MoreShow Less