check engine code help

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by 98burban89, Dec 2, 2011.

  1. 98burban89

    98burban89 New Member

    ok so my suburban has had some codes for a while now and normally i get the 32 downshift sensor code but this time i didnt here are the codes that i got

    P0302: which i believe is cylinder 2 misfire but correct me if i am wrong
    P1416: i have no idea about this one i read somewhere it was the secondary air injection??????
    P0785: which i have read is a shift timing malfunction

    any insight would be helpfull
  2. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    What type vehicle is this on and what engine, Is it your screen name?

    Secondary air injection in any car is the metal tube hooked on your exhaust manifold, that looks like a small flex pipe and usually runs down to the catalytic convertor or your air pump.
  3. 98burban89

    98burban89 New Member

    98 chevy suburban xl 4x4 5.7 vortec with the auto tranny
  4. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    Okay, Lets look at each code individually. You are correct, P0302 is the code for cylinder #2 misfire. PCM sees the crankshaft speed as being less than the expected amount and it cannot, with in the limits of the calibration, increases the fuel to #2 cylinder. If it cannot correct the problem it fires off the MIL.

    This is from my factory manual: The most likely cause for this DTC is the following:
    - mechanical Failure causing low cylinder compression.
    - a fuel leak at the high pressure fuel injection lines or injection nozzles
    - a fuel injection nozzle stuck closed.

    The troubleshooting procedure involves the use of a scan tool with the ability to manipulate PCM parameters to see the effect. Oddly enough, there is no mention of the spark plug wires being an issue. Why, because gm wires are made to go the distance. Mine are 13 years old and have 253,000 miles and no misfires. Never the less we are still going to eliminate them from the equation since you are going to have to pull #2 plug to do a compression check. Right off the bat determine if the plugs and wires are Genuine GM. Might not correct the problem but if they are not GM, your truck is not going run it's best.

    You will want to examine the plug closely. Are there any cracks in the insulator? Does the plug smell of gas and does it have the appearance of a plug that has not been firing? Inspect the wire along it's length. Any cracks in the insulation or burnt places? Remove the plug wire from the distributor cap. Oxidation arcing or other connectivity problems. Go ahead and pull the cap, chances are slim and none that you would have a bad cap causing one cylinder to misfire. But stranger things have happened. Again, look for cracks or oxidation, anything that might interfere with the spark getting to its intended spot. Look at the contact in the center of the cap and on the button. Again worn or damaged is what we are trying to avoid. Now DO NOT OVER TIGHTEN YOUR CAP SCREWS. The tabs on the distributor are plastic and will only strip out if you are lucky. Usually one breaks off. Wire ties will fix this condition a lot cheaper than replacing the distributor.

    Check compression. No smoking guy there then we look at the injectors. Look for problems with the spider or wiring. Swap the injector with one from another cylinder. If the problem moves to that cylinder, you found the problem. I cannot get real specific on the injectors. I have not had to do anything to mine yet. I do have something going on but the fuel economy is pretty much what is has been.
  5. 98burban89

    98burban89 New Member

    ok so i got the solenoid replaced today which was a pain in the a$$ but before i changed it out when the tranny got to operating temp it wouldnt shift out of 3rd and wouldnt go in overdrive, so i got that switched out and cleared the codes and took it for a test drive, i drove it for about an hour threw town and on the highway and the tranny was shifting fine and it was acting like it was supposed to so after i got home i was curious to see if there were any pending codes because the cel wasnt back on yet so i read for codes and the p1416 came back so what now?

    ---------- Post added at 07:18 PM ---------- Previous post was at 06:52 PM ----------

    also the burb has 2 cats with i believe 4 oxygen sensors and as far as i know its all stock
  6. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    Okay, this is all good. So the mis-fire thing went away by itself? Changing a tranny solenoid has suck written all over it. You are a better man than I. I would not loose sleep over the pending code. The when it happens you need to read the freeze frame data so you can see what the engine conditions were at the time that it triggered.

    In the mean time, you should check out all the components of the air system. I am sorry if my previous responses were insultingly elementary. Not intended to be. You changed a tranny solenoid; I am not worthy, I am not worthy.

    You are basically looking for anything that might obstruct the tubing or leak. Plastics - look for melting, cracks basically anything that leaks. If you need component level detail, let me know and I will pull some stuff from the manual. WHat kinda mileage are we talking?
  7. 98burban89

    98burban89 New Member

    So is that sarcasm? anyway it is actually the third solenoid i have replaced in this tranny, at first i replaced the 1 2 solenoid and then the 2 3 solenoid and when that didnt work i had to special order the downshift sensor and it took 3 days for my local shop to figure out what the hell it was and then another 2 weeks just to get it in but anyway the millage used to be awesome before the check engine light, but since it was stuck in third gear im sure that had something to do with the bad millage
  8. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    No, sarcasm. I am serious. I don't have time to tackle a job like a shift solenoid on my daily driver. I also do not have the space to do it. Sorry, by mileage I am referring to how many miles is showing on your odometer?
  9. 98burban89

    98burban89 New Member

    oh ok well they really arent all that hard all you do is unbolt the tranny pan and then all the sensors are right there the 1 2 is identicle to the 2 3 and the downshift sensor is just like the lock up controll solenoid but anyway the odometer has 214 thousand on it
  10. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    So where are we at right now? Two of the three gone with one pending?

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