2008silverado 4.3v6 has miss when you ecellrate changed plugs doing it again engine light back on

Hi there, P0506 IS usally a dirty throttle body. In order to clean properly, with the battery disconnected, they need to be taken off and cleaned front and back til' they are shiny. Sticking a rag soaked with solvent in there while it's still attached isn't going to cut it, i've seen many mechanics do it this way. When they do this, they very often DO NOT unhook the battery which you NEED to do for about an hour while cleaning.. Otherwise, the computer won't relearn the clean throttle body, and you'll have your light on again. It's very easy and cheap to do it yourself. Let me know if you'd like instructions on how to do it.

Here's what you do. Remove the air plenum/duct from the throttle body. Pull the mass air flow(MAF) sensor from that. Use brake clean and spray the MAF from both sides(do not use a brush or fingers to clean it, sensitive). Use the brake clean and a toothbrush to clean the throttle body, clean especially around where the throttle plate rests and the back of the plate, plus as far as you can in the throttle body. Start the engine (it will take a second or two to start because of the brake clean), then rev it up and spray brake clean in the throttle. Throttle it, as it will want to die. Do this for a few seconds or so. Turn it off and reassemble the plenum. Check engine light will go off as soon as you reconnect the MAF. If you still have a slight stumble, Then remove the hard plastic tube from the plenum by the throttle body. Start the engie, after it is warmed up, pour water down that hole while revving up the engine, as it will want to die. This will clean all the carbon build up off the pistons and valves. Again do this for a few seconds. If you still have the stumble, then you have bad valve seats.Where the vavle sits on the head. To fix this is $800+

the crank sensor is favorite they are unreliable that explaines why the trans not getting engine speed signal unless its a manual box and that code will allways be logged advise start by checking for water ingress in engine control module located lower rh a post then change crankshaft position sensor or better still try and borrow one from a good running car

check out your throttle position sensor voltages w a scan tool , engine off key on, compare to specs given in auto repair manual for your car. Voltages should change smoothly in the specified range, if voltage takes a sudden jump or experiences a zero reading anywhere then the problem is the tps. When is the last time your fuel filter was changed ? Some of these are not replaceable without removing the fuel pump in the tank. When you put in the plugs did you also replace the wires? P.S an intermittent tps won't always leave a trouble code in the computer. Also clean out the throttle body and idle air control unit with an approved spray cleaner and a rag with engine off and key off. Have someone hold the throttle pedal to the floor to make this job easier. After cleaning hold gas pedal to the floor and start up then when engine starts, rev engine half way a couple of times to remove any excess carbon from the system then let engine idle. This should be done once every 6 months whether having idling problems or not, just to avoid having them. If the throttle body is dirty it can and will cause a stumble comparable to a miss.

What did the spark plug look like?Did it have oil or gas on it?

You need to determine if the ETC Failsafe is from a
bad throttle body motor (TACM) or coil misfires that are
putting it into failsafe.

The TPS Sensor you replaced,wasn't likely the issue.

Put in new spark plugs
The champion 1 piece ones 7989-- from Napa CHA 7989

You will need the Lisle 65600 Broken Spark Plug Remover Tool
as you will get a couple OEM 2 piece glued together ones break.

Remove PCM from fire wall to get to #4 Plug on pass side

Change the front O2 Sensors at 100,000 miles & clean the MAF
Sensor & Clean the Throttle Plate again.

do a compression check on the engine, and replace the bad sensor, i take the throttle body off to clean it and some sensors are touchy about cleaner, i fear maybe something got on the egr valve pintle

change the trottle position sensor and reset your code reader after and read again, Your question about resetting is yes , do it.

Is there any check engine lights on?The throttle position switch could be a problem,but so can fuel pressure.Fuel pressure is what I would check.Battery voltage and charging voltage needs to be checked,Battery voltage of course should be 12 volts.The charging voltage should be 13.65 to 14.25,and the battery cables cleaned real good and shiny.Does the vehicle start good,or drag when starting?See if auto zone will read the codes for you,and tell you what they are,but don`t purchase any parts until you come back to this site to see what the codes can actually mean.If the o2 sensor showed lean,then it is possible that the fuel pressure is low,fuel pump replacement will be a must. I hope this was helpful,but need information,so do these things and return to the site.thank you.

Have they replaced the coil on #5?? There are no plug wires on this motor. They have ignition coils mounted atop the sparkplugs called COPs. If a misfire is still detected, possible coil malf or cam or crank sensor malf. Hopefully this helps