Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

question on MAP sensor

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BrianDamage, Aug 12, 2002.

  1. BrianDamage

    BrianDamage 1/2 ton status

    Joined:
    May 14, 2001
    Posts:
    753
    Likes Received:
    0
    Location:
    Alabama
    hey yall

    got a ? about my '87 TBI 350 Blazer...I was having a problem with it giving me a code 33, but the only real time it ever ran bad, was like when I'm having to cruise through a parking lot real slow or something to keep from hitting anybody /forums/images/icons/wink.gif it would stall and also would stall sometimes in 4x4

    I ordered a new MAP sensor from Autozone (I tried to get the AC Delco w/ 1year warrenty (nearly $30 cheaper than form the dealer), but even though their website said they had one, they didn't and I had to a Wells brand w/ 3 month warrenty)

    Anyway, it worked fine for 2-3 weeks...no rough idle or stalls and no code.
    Then it started doing just like it had been

    I just got another Wells MAP sensor in, but I don't want to put it in unless I can figure out why they keep going bad...I don't mind spending $75 for an AC/ Delco, but I don't really want to if it's just going to go bad on me all of a sudden

    I did replace that little tube that runs from the back of the TBI to the valve cover will that help any??
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,975
    Likes Received:
    189
    Location:
    Roy WA
    Get a scanner and a service manual. Look whats going on with the system. Either that or head over to thirdgen.org and look/ask around. Two Delco MAP sensors will buy you one scanner.
     
  3. BrianDamage

    BrianDamage 1/2 ton status

    Joined:
    May 14, 2001
    Posts:
    753
    Likes Received:
    0
    Location:
    Alabama
    so those scanners are worth having huh? I've seen up there at Autozone, but wasn't really sure if I needed one or not..is any one brand better than the others?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,975
    Likes Received:
    189
    Location:
    Roy WA
    You are going to want to get a "live" data scanner, one that allows you to both capture data from the ECM/sensors, and one that allows you to see the info as its happening.

    I've got an auto x-ray 240 I bought off of Ebay for about $140, used, but had all 3 cables to do dodge, ford and GM. Will do up to about '91 on GM stuff, I *believe* the scanner hookup port (ALDL on ours) changed with the coming of OBD2, which the 240 won't work with. Apparently some of the later scanners work with OBD 1 AND 2, so if you have some later vehicles, a newer one that does both might be handy.

    Of course, with a laptop, you can run the free software online (winALDL.com for one I think) you just need the right cable.
     
  5. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Check for any vacuum leaks. Broken or cracked vacuum lines, a loose intake, loose throttle body, etc. Any leaks will cause the MAP sensor to "see" the incorrect engine vacuum.
     
  6. 87GMCJimmy

    87GMCJimmy 1/2 ton status

    Joined:
    Nov 21, 2001
    Posts:
    582
    Likes Received:
    0
    Location:
    Phoenix, AZ
    If you can't afford the scanner the map sensor is very easy to test. It reads from 0-5v depending on the vacuum. You could temporarily wiring a voltmeter in to see what values it has, if I remember correctly lower voltage means higher vacuum. Or even take is off the truck hook up the voltmeter and find something/someone to apply a vacuum on the port of the map sensor. Probably not a good idea to ask the wife/GF for this service /forums/images/icons/smile.gif Also check vacuum lines for leaks. Try to figure out what is wrong before replacing parts, the map sensor is a simple device and doesn't usually go out.

    Hope this Helps,
    Mike
     

Share This Page