GMC

GMC Troubleshooting Questions? Ask a Mechanic for Answers

Ask an Expert,
Get an Answer ASAP!

GMC

Chevrolet gmc: i have a 2003 gmc 2500 6.0 and get reduced engine

Customer Question
i have a 2003 gmc...
i have a 2003 gmc 2500 6.0 and get reduced engine power at random times, it might happen two times in a row or once and then nothing for weeks or months . i have a check engine light on that says mass air sensor light comes and goes i tried cleaning mass air sensor and didnt help , recently replaced knock sensors harness and intake gaskets ,cleaned throttle body , checked fuel pressure its good drove around with gauge on for awhile trying to get it to do reduced engine power but was unable to get it to do it . i have had scanner on it and throttle body is reading open 9 % at idle and only opens to 87%at wide open throttle not sure if thats correct . if i start it up warm or cold and try to go its sluggish for a couple seconds then is fine also while driving keeping at steady speed can feel it get sluggish and then better again doesnt do it all the time . in all its low on power . it has 170,000 miles on it
Submitted: 2 years ago.Category: GMC
Show More
Show Less
Ask Your Own GMC Question
Customer reply replied 2 years ago
it was doing the reduced engine power before i did the knock sensors and intake if when it does it i have to pull over shut truck off for a couple seconds the start it up and it goes away i have also checked the ground wire on the back of the block .have not put a fuel pump in it since i have owned it bought it with 150000 miles not sure the throttle response seems to not always be there not sure if it could be tps or the throttle body as its electronic .would appreciate any info on where to start . thanks
Answered in 13 hours by:
6/16/2015
GMC Mechanic: Gm Tech (Cam), GMC Mechanic replied 2 years ago
Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1,696
Experience: GM Grand Master Technician 2007. 14 year experience.
Verified
Hi there, I am Cam. I don't suppose you have any codes from the system?
Ask Your Own GMC Question
Customer reply replied 2 years ago
there was one that said mass air sensor i cant remember it exactly at the moment have had this problem for awhile ill go scan it and get back to u
Customer reply replied 2 years ago
it was p0606
Customer reply replied 2 years ago
im going to go scan and see if any others have come up as thats one i had written down
GMC Mechanic: Gm Tech (Cam), GMC Mechanic replied 2 years ago
Ok, the P0606, what module was that stored in?
Ask Your Own GMC Question
Customer reply replied 2 years ago
sry about that the p0606 was a different car the ones that are on the truck are p0101 two times and p1516 and that one is new never had that one before
GMC Mechanic: Gm Tech (Cam), GMC Mechanic replied 2 years ago
These years of trucks with the electric throttle have a couple of very common issues. First and in my experience most common is the ground wire. THe ground runs from the rear harness behind the top of the engine to the rear of the left cylinder head. It is attached at the same bolt as the ground strap at the firewall. I have always been able to find this by pulling on the black wire and see if it gives. The fault has been a conductor broken in the insulation at the crimp. The second issue is the wiring near the throttle body. The wiring tends to break a few inches from the connector. check these out and see. Another common issue is the wiring near the throttle body itself. There are some wires there that can break inside the insulation and cause this. Check the wiring carefully near the throttle and about 6" back.Also check the wiring at the pedal under the dash, micro corrosion in the connectors can cause issues and even unplugging and plugging the connector back in will correct, it so then put some electronics grease on the pins. Finally is a connector in the throttle body itself. It is common for the pins in the connector to fail and cause codes. The repair for this is the pigtail connector for that throttle body.
Ask Your Own GMC Question
Customer reply replied 2 years ago
thanks cam ill have to check them tomorrow was pulling into the driveway coming to a stop and truck went to a really low idle and died on me . did not get a chance to look at it but tried to start it fires,spits and pops a little bit and dies .. hopefully whatever was causing the other problems is whats wrong
GMC Mechanic: Gm Tech (Cam), GMC Mechanic replied 2 years ago
ok
Ask Your Own GMC Question
Customer reply replied 2 years ago
hi cam got truck running again the fuel pump went out ,so now it has new pump have not had reduced engine power yet but engine lights still on and still feels sluggish when accelerating and it still cuts out a little bit at steady throttle going going to check wires on throttle body tomorrow is there any way to test with multi meter? or just inspect wires
GMC Mechanic: Gm Tech (Cam), GMC Mechanic replied 2 years ago
There is no way to really test the throttlebody with a multimeter, anyway if it is not setting any codes then the throttlebody is operating properly. Given the necessity of the throttlebody, it's very sensitive to any fault.
Ask Your Own GMC Question
Ask Gm Tech (Cam) Your Own Question
Gm Tech (Cam)
Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1,696
1,696 Satisfied Customers
Experience: GM Grand Master Technician 2007. 14 year experience.

Gm Tech (Cam) is online now

A new question is answered every 9 seconds

How JustAnswer works:

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

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:

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

He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here.

DianeDallas, TX

< Previous | Next >

Meet the Experts:

Gm Tech (Cam)

Gm Tech (Cam)

GMC Mechanic

1,696 satisfied customers

GM Grand Master Technician 2007. 14 year experience.

Gary

Gary

ASE Certified Technician

1,542 satisfied customers

GCM master tech over 25 years

Dave Nova

Dave Nova

GMC Technician

929 satisfied customers

ASE Master Certification. GM World Class Certification

Chris (aka-Moose)

Chris (aka-Moose)

GMC Technician

563 satisfied customers

16 years of experience

Ron Z.

Ron Z.

- GMC Tech -

255 satisfied customers

18+yrs experience. State Inspector & GMC Diagnostics/Repair

George H.

George H.

ASE MasterTechnician

225 satisfied customers

15+ Years ASE Master Technician with Level 1 Certification

Don - Mo Lurch

Don - Mo Lurch

ASE Certified Technician

216 satisfied customers

GM, GMC, Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics

< Previous | Next >

Related GMC Questions
I am trying to remove the engine cover on a 2017 gmc sierra
I am trying to remove the engine cover on a 2017 gmc sierra denali 6.2L ecotec 4wd. There is a bolt or clip holding the back next to the firewall Steve… read more
GM Bob
GM Bob
Automobile Technician
High School or GED
989 satisfied customers
06 envoy cranks but no start engine light is on and stays on
06 envoy cranks but no start engine light is on and stays on solid no security lights and fuel pump is on when key is turned to start cranclk speed … read more
AMEDEE
AMEDEE
AUTOMOTIVE TECHNICIAN
Vocational, Technical or Trade Scho
9,105 satisfied customers
06 envoy cranck no start no security light engine light
06 envoy cranck no start no security light engine light stays on solid ran great started right up this am but after it started as I was pulling my arm back to release key my sleeve got caught on key a… read more
Gunvir Singh
Gunvir Singh
1,712 satisfied customers
I have a 2006 gmc sierra with 5.3 engine is it normal for
I have a 2006 gmc sierra with 5.3 engine is it normal for the coolant fans to kick on when temp is over 210 with a.c. off … read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
I have a 2007 GMC acadia the check engine light came on i
I have a 2007 GMC acadia the check engine light came on i scanned it and it gave me the codes p0016 p0017 i changed the crank shaft sensor 1 were is the second one located i cant find it… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
My check engine light flashing car losing speed. It stayed
it stayed on at first replaced water pump an heater hoses. … read more
baddad1
baddad1
technician
High School or GED
5 satisfied customers
Truck will not remote start and check engine light on.
Truck will not remote start and check engine light on. Advance Diagoned: Getting code P0674 GP cyl 4 issue, U0101 TCCM no comm, and code C0550 … read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
Engine turns over but wont start. Trouble codes as follows
ok trouble codes as follows PO 301, PO 69E , PO 25A , PO 606...WHERE DO I START? … read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
4,012 satisfied customers
My stepvan utilimaster gas engine Gmc Workhorse is cranking
My stepvan utilimaster gas engine Gmc Workhorse is cranking but not starting. Seems like the ECM isn't getting power. … read more
roy
roy
Associate Degree
3 satisfied customers
I'm having engine surging problems too. ~160k, Automatic.
I've cleaned and reassembled the Mass Air flow sensor, made sure there were not leaks in the pipe … read more
ricardo hohl
ricardo hohl
automotive instructor
Associate Degree
1,818 satisfied customers
With the engine running an turn the headlight switch on the
with the engine running an turn the headlight switch on the engine goes into reduced power mode. If you pull the dimmer the engine dies. … read more
roy
roy
Associate Degree
3 satisfied customers
Creplacet the engine and the instrument cluster does not
creplacet the engine and the instrument cluster does not operate at all now … read more
AMEDEE
AMEDEE
AUTOMOTIVE TECHNICIAN
Vocational, Technical or Trade Scho
9,105 satisfied customers
Traction control light on reduced engine power, No i was
No i was just driving home and power reduced and engine and traction control light came on just happened ten minutes ago no stores open … read more
eauto
eauto
self employed
High School or GED
74 satisfied customers
On the 2012 gmc sierra 1500 the engine harness ends with the
on the 2012 gmc sierra 1500 the engine harness ends with the ecm/pcm, fuse block, throttle control module transmission module what are other two connection ends for… read more
Marvin the Mechanic
Marvin the Mechanic
82 satisfied customers
Engine suddenly stopped when driving and will not even turn
Engine suddenly stopped when driving and will not even turn over … read more
Jerry Newton
Jerry Newton
Vocational, Technical or Trade Scho
2,066 satisfied customers
Check engine light is on, onstar tells me it is an air
check engine light is on, onstar tells me it is an air filter, yet engine is now sluggish and wont stay on … read more
baddad1
baddad1
technician
High School or GED
5 satisfied customers
Aveo 2009: replaced engine. Engine starts but shuts off with
Aveo 2009: replaced engine. Engine starts but shuts off with in 2 or 3 seconds. Any suggestions … read more
Jerry Newton
Jerry Newton
Vocational, Technical or Trade Scho
2,066 satisfied customers
The reduced engine power symbol is on but with no arrow.
The reduced engine power symbol is on but with no arrow. Have not experienced any change in engine performance since I noticed it today. What does this usually indicate? … read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
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.

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.

Show MoreShow Less

Ask Your Question

x