Jump to content

95 1500 5.7 pulsing between 55-65 mph

dzsmith

Recommended Posts

dzsmith Enthusiast

dzsmith

Posted
Posted

so i have a 95 gmc sierra 1500 5.7 on 35s . its got 208,000 miles on the original motor. I had the tranny rebuilt a year and a half ago. about 2 months ago it starting pulsing up and down only between the speed of 55-65 mph. the rpm guage slightly goes up and down but my mph doesnt jump at all. if i am ever driving this it consistently goes up and down. about this time another problem started when i put my truck in reverse it sounds like my truck is going to die and it will if i dont hurry up and back and go back to drive or park. it idles great and runs great in all other speeds. I hate to think this may be a tranny problem, it would be a nightmare, i have replaced the fuel filter, the egr valve, looked over and replaced a few vacuum hoses, cleaned my throttle body up very good, and i have run a can of sea foam in about every other gas tank since thin. i also exchange 1 quart of marvel mystery oil for 1 quart of my engine oil , every time i change my oil. I also replaced my only 02 sensor which is threaded into my exhaust since i dont have cats anymore. i have no check engine lights or anything. I have been thinking of maybe replacing or rebuilding the entire tbi and injectors, which probably needs to be done anyway even if its not the problem. i have a throttle body spacer and an airrade intake but they have been on there long before the problem started. I have noticed that the tbi gets very dirty and gunky quick around the back side of it. I put new plugs, wires, distributor cap, and rotor button on it about 6 months ago, so i dont see why that would be the problem. It doesnt sound like my engine is missing, it just revs up and down and you can feel a slight jerk, but there is no change in mph, only a slight change in rpm.

GMstrong Enthusiast

GMstrong

Posted
Posted

with the motor running pull the connector for the TPS sensor and if the idle doesnt change then its bad.Did you spray the IAC port out that get VERY dirty.Replace the IAC valve to.I suggest going to a u pull it yard.For shits and gigs check the vacuum line on the map sensor.

Wolfmanjohn Enthusiast

Wolfmanjohn

Posted
Posted

Lighten up on the Seafoam and Marvel. I'm not sayin' it's bad, but like alcohol, that stuff is best used in moderation, man!

dzsmith Enthusiast

dzsmith

Posted
  • Author
Posted

so dont use the marvel every oil change, i should space it out more regularly

 

what is the tps sensor?

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • richard wysong
      Gas Prices

      By richard wysong · Posted

      Diesel $5.42 at the truck stop on the hi-way
    • Chuck FB
      Joke Thread

      By Chuck FB · Posted

    • txab
      Gas Prices

      By txab · Posted

      $3.59  
    • needafix
      2019+ Brake failure, it's complicated

      By needafix · Posted

      I'm not sure if this should be a new topic, let me know if it's out of place. This my first post. Thanks 85077522 - AC Delco GM Genuine Parts Brake Master Cylinders. Anyone else had to replace this brake master cylinder yet. I didn't do any brake work, it looks like new parts and I've had the truck for about 4k miles, 119k total miles.  When it started to throw codes I did the calibrations with a bidirectional scanner and got the codes to clear but they came back so I did the routine; base bleed, automated bleed and final base bleed. All that with Bosch ES16-32N fluid (please look it up). That seemed to fix it but 100ish miles later it failed again so I ran the same process but with a pressure bleeder this time and got the same results, fixed for 100ish miles. The original fluid looked bad and I thought I got most of it out, it could've been the wrong fluid. The codes; P25A2, C05B0-00, C2A1B. I can get them to clear but not for long. The C05B0 indicates a leak in the front circuit (which is bone dry) so I'm thinking of doing the bleed process on that front again today and I don't know if that's taboo to just do the front but at this point it seems like it's worth the try anyway. The new master cylinder/module unit is supposed to get here today. But now I'm pretty much convinced this install is over my head. I've called several shops and some mobile guys that I know but this thing is like radio active material, scary wise. I did get 2 local shops say they should be able to do it, one says he has the SPS2 programing capability. And with the battery disconnected is there supposed to be pedal resistance, mine is to the floor, then if I pump it I can get some resistance. I had a panic stop prior to this issue which may have contributed from what I read. And on the first attempt to bleed and hydraulic test the scanner listed things to look for and one was any gaps between the pad and rotors which I did notice on the RF corner and I removed the outer pad (where the gap was) cleaned it and the hardware and didn't see a gap after that but will re-check it. I read that if pushing the caliper pistons back then you're supposed to open the bleeder so as to not push fluid backwards into the abs module or it will damage it. If that's true then that's also a possibility from the previous owner having the brakes changed before I got it. I'm using an XTool ip500 scanner. Any suggestions, questions and comments welcome. 
    • Donstar
      Navigating senior years.

      By Donstar · Posted

      Next Friday will be my 6 week point from my right knee replacement.  The surgeon says it will be fine if I choose to drive after this checkup.  I know I could drive now but best to do as my surgeon (and my wife) tell me.  Richard compared being 62 to 72.  I remember when I was in my early 60's I was experiencing slow but regular decline in my mobility.  Thanks to good medical support,  i continued to fight the speed and spread of this decline. During my 60's I worked on non-surgical methods and just when I turned 70, my orthopedic surgeon recommended joint replacements.  In a little over a year, I had one shoulder and both knees replaced.  This hasn't been a terribly fun experience, but worth the discomfort as my future mobility health trajectory has reversed.  It is a treat to now be watching my mobility. balance and confidence steadily improve!

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...