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.

Emissions question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 87Blazerlady, Oct 11, 2002.

  1. 87Blazerlady

    87Blazerlady 1/2 ton status

    Joined:
    Oct 2, 2002
    Posts:
    749
    Likes Received:
    0
    Location:
    Southeast PA
    Our new engine was failing emissions even though we put on a new O2sensor. The mechanic lowered the idle until it was almost going to stall and he got it passed. He also said that the new engine during its break-in period would also effect the emissions. According to our book, idle is not to be touched. Is there more than one way to slow the idle down and do you agree with what this mechanic said and did? 87Blazer 305 TBI --Failed CO
     
  2. imiceman44

    imiceman44 1 ton status

    Joined:
    Aug 5, 2002
    Posts:
    15,160
    Likes Received:
    1
    Location:
    Sacramento, CA
    When you say new engine, is it rebuilt, crate, just used and transplated recently?
    If it's failing CO, I would say check your air intake, timing might also do it but I would assume he checked that, another possibility is the injectors, if they are worn out and dumping extra fuel, or if you have a low temp thermostat, that will trick the ECM into dumping more fuel to warm up the engine.
    If you didn't understand anything I said here, let me know so I can put it in another form /forums/images/graemlins/smile.gif
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    It was certified at a given idle speed, it will pass emissions at that idle speed IF everything is working right.

    Could be a lot of things. Throwing codes ever? Plugs, wires, cap and rotor all in good shape? (not necessarily new, that means nothing) As has been suggested, timing, thermostat temp, etc? You can check the coolant temp for certain with a scanner if you can get your hands on one.

    http://www.fuelinjection.com/autoxray.html the 240 will get the job done, I got mine off of Ebay for around $140 with the three cables. By the time I get the TPI in my truck, I'll probably be using winALDL or equivalent instead of the XP240, but when you are troubleshooting without vehicle or drivetrain swaps, and know what values you are looking for (service manual is a huge help) the XP240 is perfect.
     
  4. 87Blazerlady

    87Blazerlady 1/2 ton status

    Joined:
    Oct 2, 2002
    Posts:
    749
    Likes Received:
    0
    Location:
    Southeast PA
    Here goes--This is from my backyard mechanic----crate--- thermastat 195----air intake and timing was checked----plug and wires new-----cap and rotor were corroded, cleaned them up, however, tonight on my way home from work truck was idling rough, so with all the rain we've been getting, it may be wet. Probably need new---not burning rich because the tail pipe isn't black---Coolant temporature sensor- will do resistance test with ohmeter since no scanner---will check for codes in the morning---thanks---Leo

    I ordered the Chilton's guide to Fuel Injection through the library and will pick that up tomorrow--lots of copying. Also have the Haynes manual for this truck, too. That book loses me alot. Too general. thanks /forums/images/graemlins/smile.gif

    ~~Judy~~
     
  5. 87Blazerlady

    87Blazerlady 1/2 ton status

    Joined:
    Oct 2, 2002
    Posts:
    749
    Likes Received:
    0
    Location:
    Southeast PA
    Hi------Leo here. I checked for ecm throwing codes and there were none. Disconnected the code reader. Started the engine and lots of smoke. Left the tailpipe black. Ran a couple minutes, shut the engine off, then put the code reader back on and got 12...15...12...15...12...15 etc. With the code reader still on I started the engine and the check engine light came on and then started blinking fast. After about a minute, I revved the engine then got a slower blink for about 30 seconds and then fast blink again. Revved once more and it would blink fast then slow then stay on, blink fast then slow then stay on etc. The Chilton's guide to Fuel Injection and Electronic Engine Control states this tells whether the system is in Open or Closed Loop operation. Shut the engine off, disconnected the code reader and cleared the codes by disconnecting the battery.
    The 15 indicates the coolant temperature sensor. But not sure why the 12, or should that be ignored? The repair manual says 12...no reference pulses from the distributor are reaching the ecm. Not sure of when to read code 12 as a trouble code.
    Did a resistance test on the coolant temperature sensor=no reading--dead short
    Did a voltage reading on the line coming to it=5
    So coolant temperature sensor must be bad. Going to replace. Thanks for pointing me in the right direction guys.
    Also the temperature gauge only gives a reading after the engine is turned off. This has always been happening. It reads somewhere between 180-190.

    Question:
    1. Is the system, for some reason, going back and forth from open and closed loop?
    2. How do I know when to read code 12 as a trouble code?
    3. Can you tell me what's up with the temperature gauge?

    Really appreciate the help. Leo
     
  6. Burbinator

    Burbinator 1/2 ton status

    Joined:
    Sep 14, 2001
    Posts:
    898
    Likes Received:
    0
    Location:
    Tempe, Arizona
    Code 12: Handshake code and/or no distributor reference pulses.

    Seeing how a code 12 is thrown when the engine is not running, that would make sense. The code 15 (CTS, low temp) is your trouble code.

    Sounds like you are on the right track.

    /forums/images/graemlins/burb.gif
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    Yeah with the engine in open loop, it will be running extra rich. Your mileage should be sucking too. (at least compared to what it can be)

    If the sensor is known bad, I'd definitely replace it. No brainer if the part tests bad : ) Of course there are many other factors for open loop operation, but if the sensor is showing up as bad, and tests as bad, go with it. I'm assuming the engine (or radiator) is physically hot when its been run? I had an Olds motor with no t-stat, and that thing ran ICE cold. I thought the gauge was bad, but in actuality, it was the PO's removal of the t-stat that was causing the problem, but it was obvious when I noticed no pressure in the cooling system.

    FWIW, I believe even the later trucks used TWO coolant sensors, one for the ECM, and one for your gauge. If there is one on the drivers side head, with one wire, (green on mine) it will be gauge, and another (in the intake?) with two wires will be ECM.

    Great news if you ask me, thats what these computers are there for! (both the one I'm typing on, and the one in your truck : )
     
  8. imiceman44

    imiceman44 1 ton status

    Joined:
    Aug 5, 2002
    Posts:
    15,160
    Likes Received:
    1
    Location:
    Sacramento, CA
    Glad we were of help /forums/images/graemlins/smile.gif
    I haven't dealt with computer controled much but I have read enough to know some things.
    I can see that Dorian has more in that area, although I am getting there. But basically I think you got it narrowed down, the temp is not reaching normal so the ECM is sending more fuel and that brings up the CO.
    /forums/images/graemlins/thumb.gif
     
  9. 87Blazerlady

    87Blazerlady 1/2 ton status

    Joined:
    Oct 2, 2002
    Posts:
    749
    Likes Received:
    0
    Location:
    Southeast PA
    I did forget to mention there was a strong fuel smell as well, just for a short time. That was after starting the engine and the smoking.

    Thanks everyone. /forums/images/graemlins/smile.gif
     

Share This Page