Help with a couple check engine codes?

[Gearheadvr4]

P0113 - Powertrain, intake air temperature circuit high input

P0014 - Powertrain, "B" camshaft postion timing over advanced or system performance (bank 1)

P300 - Random misfire



170k miles. Also have a rough idle. Here is what I've done so far. Cleaned throttle body, changed spark plugs, cleaned CPAS, oil change with mobile 1 syth.

May have two seperate issues here? How do I check each coil to see if I really am getting a spark? How do I do a compression test on these engines? Is there a test for the CPAS to verify it's working?

 

[The_Roadie]

You could even have three or four issues.

1) How many miles, any other maintenance history, and please fill out your profile so we don't have to guess what year and drivetrain.

2) If an I6, did you use Delco 41-103 iridiums? If not - change them to the right plugs first.

3) Compression test involves getting a compression gauge and removing each plug to screw it in.

4) Depending on the mileage, you may simply need a new CPAS, not a cleaning. A high end scan tool or a GM Tech II can command the timing advance through its range of motion and see if it's moving as commanded. Nothing the typical DIYer can do. Although an OBDII bluetooth dongle an the Android Torque app can give you a readout of timing angle.

5) Pull the connector to each coil in turn to see if the engine behavior changes. If you pull the connector, and the roughness doesn't change, that's a bad one. Or else you slightly tilted the coil when you reinstalled after the plug change and it's not seated properly.

5) Also, a decent scan tool (not a super high-end one) can tell you what your IAT data looks like. Do you have one?

6) Can you describe the roughness more precisely, and how it started (all of a sudden or progressed slowly over time)? Is it different if you're in PARK or DRIVE with the brakes on?

 

[Gearheadvr4]

Updated the profile info.

Just purchased the vehicle so no ideas on the history. I used AC delco plugs. For the compression test would I pull an ignition fuse and just turn over the starter? What is a good compression number for these engines? Any way to know if the CPAS is bad without an expensive scan tool? I only have the bluetooth ODBII tool/Torque app and not sure what I would be looking for with the timing angle.

The roughness only happens at idle. This issue was there when we got it. It will be smooth and running fine then feels like it will miss and you can feel a slight jump. Feels the same in park or drive.

 

[The_Roadie]

Ahhhh, I see. How many miles? If over 100K, you need to do every fluid right away. Especially the transfer case fluid that's a surprisingly short 50K interval.

Motor mount failures have a very specific behavior - a rotational 10 Hz vibration you can see physically on the intake manifold especially, that's worse in DRIVE with your foot on the brake, and less bad in PARK. The idle RPM never goes up and down as it does for other causes.

Replacing the CPAS is cheaper than an hour of diagnostic time with a high end scan tool.

You can pull all the plugs and coils and spin the starter on each cylinder in turn. I haven't done a compression test, but others who have will be along soon.
For now, check out this video by our own MAY03LT:

https://www.youtube.com/watch?v=DjL_Wefla0s

and maybe this sort of generic one on another vehicle: (Youtube is LITTERED with this sort of tutorial!)

https://www.youtube.com/watch?v=ThN67v9oKFQ

 

[khill]

Compression tests are pretty easy, far easier with two people. You can buy (or maybe even borrow) a compression test kit from your local auto parts shop (autozone, NAPA, etc) for anywhere between 20-$$$$. The cheap ones have served me well for the past few years.

-You want to pull the fuel pump fuse and run the car til it quits.
-Remove the coils and plugs
-Hook the compression tester up to a cylinder and hit the starter for 4-5 revolutions. (This is where a helper comes in handy, you read the gauge and move it around, they drink your beer and hit the starter)
-Read the pressure on the dial.
-Rinse and repeat 5 more times

Mine has consistent ~200 lbs compression in all 6 cylinders. Yours could vary by model year so just look for conformity. If any is drastically different from the others, you have a problem.


Probably also want to throw some new O2 sensors in there and run a bottle (or 3) of your favorite fuel system cleaner. Techron, Redline, and BG44k are all good choices, Seafoam is not. Use the max amount of cleaner for the minimum amount of fuel recommended. eg: "One bottle treats between 10-20 gallons" either stick two bottles in a full tank or one in a half.


Though to be honest here, I and several others also have the "slight misfire at idle" issue. I have tried many things and am almost just resigned to live with it. How soon does the misfire show up if you just let it idle?

 

[BlazingTrails]

I have noticed the same thing with my truck. You can hear it miss if you listen to the exhaust but you can't feel it in the truck at all. No cel and runs great. I just figured the compression a slightly un-even? It doesn't bother me.

 

[Gearheadvr4]

It's my wifes daily driver and a check engine light glaring at her definatly is a bother. She cannot stop bugging me about it... Thanks for the tips. I'll get back on it this weekend and try the compression tester and a new CPAS. Then swap coil packs one by one.

 

[KNBlazer]

It's my wifes daily driver and a check engine light glaring at her definatly is a bother. She cannot stop bugging me about it... Thanks for the tips. I'll get back on it this weekend and try the compression tester and a new CPAS. Then swap coil packs one by one.

Highly recommend using a GM CPAS, it's hit or miss with aftermarket sensors and our trucks...

 

[The_Roadie]

It's my wifes daily driver and a check engine light glaring at her definatly is a bother. She cannot stop bugging me about it...

Normally that's Sheldon's job

[video]https://www.youtube.com/watch?feature=player_embedded&v=KMhp2ShPVQw[/video]

 

[Gearheadvr4]

Swapped out the CPAS. No check engine light yet and it's a bit smoother but can still feel a slight miss about every 4-5 seconds.

On to swapping coil packs and compression test. I figure with 170 K swapping the CPAS was a good idea anyways. No telling if it was ever changed before.