Jump to content

Suburban accelerates when put in gear

Marty T
 Share

Recommended Posts

Marty T Enthusiast

Marty T

Posted
Posted

I have a 2005 Suburban 1500 LT 5.3 with 161,000 miles. Runs drives and shifts real well. I have had diagnosed twice now but have been given much to go on. Problem is it idles fine at approximately 600 rpm in neutral but when put in reverse or drive it pulls. The throttle plate opens from 4% to 14% open and the vehicle will accelerate almost to the point of shifting into 2nd gear without touching the gas pedal. A Chevy service facility recalibrated my throttle body and then replaced it with a known good on from another vehicle….same problem. I then got a new ecm and they reprogrammed it….same problem. After some time on the phone with their tech people they decided it was something transmission related…maybe torque converter related. I then took it to a reputable trans shop where they had better equipment to diagnose transmissions. They said the vehicle definitely had an issue that needed to be fixed but the trans checked out great and there were no problems there. Their tech people said the only other thing that could throw a load would be the mass airflow sensor. Not wanting to spend a lot at this point I took the vehicle home and replaced the maf with a used part from a local yard….same problem. The vehicle shows no codes and has a 4L60E trans. I am in need of some help from someone who may have encountered this problem before or has any ideas. Thanks so much for the help.

swathdiver Senior Enthusiast

swathdiver

Posted
Posted

I would also check for a vacuum leak.  When the throttle body was replaced with the donor, was the truck driven around long enough for the computer to relearn, maybe 20-50 miles?

 

It is my understanding that 14% is way too much, should not really be more than 10% which would indicate a dirty plate and normal about 5%.

Marty T Enthusiast

Marty T

Posted
  • Author
Posted

I do not believe it was driven after the TB was replaced but it was calibrated. I'm not real aware of what needs to be done but was assured the TB was ruled out as suspect, It had this acceleration problem when I bought it and could see someone had put a new aftermarket TB on it and was extremely clean inside. My Chevy service tech is saying trans and my trans guy said MAF, which I ruled out. Stumped. Thank you for your reply.

Marty T Enthusiast

Marty T

Posted
  • Author
Posted

I will see if it has an IAC. Anyone out there know if it has and if so would it relate to the problem I am having? What may be a test for it?

SierraHD17 Senior Enthusiast

SierraHD17

Posted
Posted

You won't have an IAC as your truck is drive by wire.  Has anyone paid attention or swapped the TAC module on the firewall?  It's the communication link between the pedal and the throttle body.  Otherwise something has to be loading the truck somewhere.

  • Thanks 1
Marty T Enthusiast

Marty T

Posted
  • Author
Posted

The TAC is something that has not been done. Can it be tested or just change it out?. Could you please describe this part and the full name so I might understand it better and I can do some research. Sounds like a possibility if it's a critical component between the TB and Pedal. Thanks for the help.

SierraHD17 Senior Enthusiast

SierraHD17

Posted
Posted

Throttle actuator control.  It's the brains of your throttle circuit and also handles cruise control.  It's a box on the firewall right beside the brake booster.  For tests.. just swap it with a known working one for simplicity.

Marty T Enthusiast

Marty T

Posted
  • Author
Posted

Thank you. I will try it. This seems to be leading to a torque converter clutch issue I think. Any way I can test this? I'm trying all the simpler and cheaper suggestions first but I think a new trans and torque converter is in the future. Just hard to go that direction when the shop says everything is fine with the trans with their diagnostic tools.

  • 3 years later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • GMCustomerService
      Damaged Left Rear Bumper & Left Rear Quarter Panel - Repair Questions

      By GMCustomerService · Posted

      Having bumper and other body damages can be very frustrating, especially as a result of a parking lot collision/bump. Our team wants to learn more about the damages to your truck so we can look into ways we might be able to help. When you get the chance, please fill out our support form with more details: https://s.gmc.com/support-request . A member of our team will follow up with you as soon as next available. We want to get you enjoying your truck to the fullest again. 
    • PhilB
      Gas Prices

      By PhilB · Posted

      Did you even read this article?   Even the title of the article says "U.S.-Iran Deal Doesn’t Mean a Swift Return of Oil and Gas Flows"   Remember, crude oil prices are based on FUTURE purchases by the oil companies.  Gas prices are based on FUTURE purchases by the station.  This article stated that many of the oil producing nations have to restart their processes to get the oil produced.  Then the oil has to be shipped to wherever.  And it doesn't get there overnight.  And most of that oil is not coming here. Check out this site:  https://afdc.energy.gov/data/10621   A graph will pop up to show where the US imports their oil from.  Notice that there isn't a lot of import from OPEC and Iraq.  Most of the US import comes from Canada. The US oil produces are selling their oil on the open market, which is why the US fuel costs went up.  So you're correct, the US oil companies are going to slow walk the price downward.
    • GMCustomerService
      Tranmission stays in Low

      By GMCustomerService · Posted

      Having codes and an engine light with no hints on what might be causing it is nothing short of frustrating. How long have these concerns been present? We want to know more so we can look into ways we might be able to help you. When you get the chance, please fill out our support form with additional details on your experience so far. A member of our team will follow up with you as soon as next available: https://s.gmc.com/support-request 
    • GMCustomerService
      Defective Brake Pad Wear Sensor?

      By GMCustomerService · Posted

      Knowing the life of your brakes is a highly important status to keep track of. If you suspect your brake sensors need attention, please fill out our support form with additional details on your experience. When did you last take it in for inspection? Our team will follow up with next steps as soon as next available. Please include your username and GM Trucks Forum in the form as well. Support Form: https://s.chevy.com/support-request 
    • teamjnz
      Stabilitrak conversion to Z71

      By teamjnz · Posted

      I just purchased a 2004 Tahoe with 148,******. I used to have a 2006 Suburban that had the push button Auto 4X, 2Hi, 4Hi and 4Lo. When checking out this truck I noticed it had push button but didn’t focus on it. After the purchase when driving home, this is when I noticed it was different and after a little research found out it has the AWD stabilitrak system. I don’t live in an area that requires AWD. I bought the truck to start a new adventure in life with off roading, now that the kids are all grown up. I purchased the truck knowing it didn’t have the G80 rearend but plan on re-gearing to drive on 33s or 35s and upgrade with a rear locker and still be able to tow when needed. Blah Blah Blah Anyway I know am thinking about converting the stabilitrak  to Z71. I know I will have to replace the transfer case. So now the information gathering stage is happening to see if it is worth it. Is the front AWD stabilitrak differential different when compared to a non-AWD front diff? Will I need a completely different front differential or can it be converted? What else should I be considering? I did see something in a video for GMT900 platform with removing the ABS fuse that disables the stabilitrak and turns the truck into a 2 wheel drive. Would that work in the GMT800 platform?

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...