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04 CTS-V with codes!!!!!!!!!!!!

8K views 39 replies 6 participants last post by  av8erdunn 
#1 ·
I just bought a 04 CTS-v under the impression the motor needed to be replaced. The engine was running rough and would die if you let it idle; I got it home run a scan and came up with codes P0101 MAF and P0300 Random / multiple misfire. I drove the car home and it would run decent as long as I kept the RPM's above around 2800 RPM. If it dropped below that it seemed like it would start misfiring worse but I guess its only more noticeable with a low RPM vs high RPM.Is that a reasonable assumption? Any ideas on what could be the cause? I am thinking about changing the MAF and see what happens but I would rather not spend the money if there is a way to clean it or if there may be another issue causing both codes.


Forgot to mention that if am making the engine stay around 1200-1500 RPM I smell a very rich (unburned fuel) exhaust smell if I am just sitting in the driveway.
 
#5 ·
The computer codes generally point to the problem. I would follow the trouble shooting charts for the codes you have before checking things at random. I have attached DTC P0106 because it is listed in the DTC P0101 chart. The P0300 code you have is a general misfire/vibration code that can be caused by anything from a failing rod to a bent wheel, so I would chase the P0101 first.
 
#6 ·
Ok. I bought the car from my best friends wife when he passed away in a flying accident. He was a gm service manager and recieved world class status from ase certification so the guy knew his stuff. Me on the other hand, I design aircraft engines for a living and have built many aircraft, motorcycle, boat, jet ski etc. engines but never an auto engine. That being said, I am no dummy but when it comes to diagnosing a possible electrical / sensor issue I am eager to learn. She didn't want to sell the car but doesn't have the money to fix it. It was sitting idle while she was getting her tires serviced with air and it started idling really rough and finally died. The engine has developed a slight tick from the right side but not a knock so to speak only a slight tick. I cleaned the maf with electrode cleaner but it didn't help. I have since run it again and it had a few other codes pop up as well. We were going out of town and the wife made me leave before I was finished checking all codes. I will let y'all know as soon as I get back in town. I hope I can salvage the motor but worst case I have a ls3 waiting to be put in. The car has been run hard but still ran good until this point. The reason I was going to check plugs due to the fact he had the headers off at the time he passed and his other friend put them back on and I wondered if he may have damaged one during installation. Could that cause the mentioned codes? I will be completely honest with you, the first PDF you sent with p0101 diagnostics I pretty dang confusing. What program do I need to buy in order to perform the testing from that document? Like to monitor throttle position etc. ? Thanks for taking the time to help.
 
#7 ·
The trouble shooting charts do assume that you have a GM Tech II scanner, which allows you check certain parameters as well as turn various circuits on and off on the fly. These are expensive, but many non-dealer shops have them.

If the headers were off the car it is likely the entire intake, including the MAF were also off the car. It is also possible the MAP tube at the back of the intake manifold (passenger side) was off. So you may be looking for an uninstalled / mis-installed tube or wire anywhere around the engine. And spark plugs are often broken during header installations.
 
#8 ·
The maf or any other parts really were not off the engine as he was only replacing the motor mounts. The engine has a very noticeable miss and smokes/ smells of fuel when revved up. It really smells rich when idling. Would a broken spark plug cause a maf code? I don't see how they would be related. But like I said I am here to learn. Thanks
 
#9 ·
Ok reading your post reminds me of when I was messing with some Bolt ons and tuning on my 04 Burban. I know it isn't the same car but very similar motors with very similar codes. Mine usually was a fueling/tuning issue. I was running to much fuel or to little after messing with things. It could be something like checking all plugs and wires and maybe getting some tune flashed on it and go from there. If he had those other parts on there and some things could have changed the tune might not be right for what is on there now. Just a thought but you never know. Like you said you have other options if you can't figure out what is going on with what you got now so why not reflash and start fresh just to see? Just my .02.

BDV
 
#12 ·
Thank you!!! I am really not disappointed if this motor is toast as I will build the car to what he eventually wanted to do. That's why he had an ls3 ready to go in and also had a 7.2 stroker him and his 13yo son was putting into a vw karmenn ghia. That's right I said 7.2 in a vw ghia. He loved building things. He once rebuilt an airplane in the garage of his house. He would test run it tied to a tree in the back yard of a nice residential neighborhood. Dang I miss that guy.
 
#13 ·
Well I got home today and connected the battery and started the engine. It ran real rough and I had to keep my foot on it to keep it from dying. As long as I keep the rpms up to 1200 or so it will stay running. If I let off it dies. It finally threw another code but this time it was only the p0101 MAF code . Would a bad MAF cause this problem? I have a feeling if I would have kept it running, it would have eventually thrown the p0300 misfire code but I can't say for sure. I also pulled a couple plugs and tested them and they had good spark. I will pull the others tomorrow to make sure they are good.
 
#16 · (Edited)
The P0101 can be caused by the following:
1. The harness to the MAF sensor is routed too close to: (a) the secondary ignition wires or coils; (b) a solenoid, (c) a relay, or (d) a motor.
2. A low minimum air rate through the sensor bore at idle or during deceleration caused by: (a) deposits on the throttle plate or in the throttle bore; (b) any vacuum leak downstream of the MAF sensor; or (c) any contamination or debris on the sensing elements of the MAF sensor.
3. Water intrusion that reaches the MAF sensor.
4. Any significant restriction in the induction system or the exhaust system.
5. A defective MAF/IAT sensor.
6. A skewed or stuck Engine Coolant Temperature (ECT) sensor.
7. High resistance of 15 ohms or more on the ignition 1 voltage circuit. (This high resistance may cause a drivability concern before this DTC sets.)
8. High resistance on the low reference circuit of the Manifold Absolute Pressure (MAP) sensor.
9. A short to voltage on the 5 volt reference circuit of the MAP sensor.
10. A restriction in the MAP intake manifold tube.
11. Any leak in the throttle body or intake manifold, including an unplugged MAP or brake vacuum tube.
12. A defective MAP.

http://www.cadillacforums.com/forum...ral/278234-check-engine-light-code-p0101.html

http://www.cadillacforums.com/forum.../240189-codes-p0300-p0101-rough-low-idle.html

Edit: Supplemental Info

Since this error code can be caused by intermittent signals from powertrain management sensors (MAP, ECT, or MAF) another potential cause is bad grounding caused by oxidation of the engine harness-related grounds. This oxidation is not readily apparent because it does not look like the corrosion that can develop on battery terminals. The fix is to pull the grounds and freshen them with some abrasive material - star washers can also help.

The critical grounds on the CTS-V include: the negative battery terminal; the ground located just beneath the hood stick mount; the ground located on the back of the passenger-side cylinder head; and the two grounds located on the back of the driver's-side cylinder head.


 
#18 ·
I got home and pulled the the valve covers and found a broken exhaust valve spring on cylinder 3. I am ordering a new set from texas speed tonight.

http://texas-speed.com/p-1383-ls6-valve-springs-good-to-550.aspx

Are they a good choice?



Now if you can enlighten me as to why the the engine would run like crap with this condition. The valve appears to still be closing all the way; I know this is the problem but I didn't think a broken exhaust valve spring would have caused such a bad running engine since the valve isn't stuck open and is still operative but slow on response.

Thanks again for all the help.
 
#19 ·
Well the good thing is that you did not drop a valve into the cylinder.

The LS6 valve springs are a direct replacement for what you have. You could look at upgraded springs, but most would bring the need to upgrade pushrods and perhaps some other hardware.

The broken spring means the exhaust valve is never actually closed.

I hope this is the only problem. Good Luck.
 
#29 ·
Thank you!!! I finished up last night at about 11:00 and she is running just fine. Thanks for everyone's help. It's really appreciated. Now that this engine is ok and doesn't need replacement, I can focus on stroking the ls3 into a 416 and not have to be in a hurry about it.

Thanks again
 
#30 ·
Update .... I ran the car for a few minutes and I can still tell it has a misfire. I should have changed the plugs while I was in there. Its giving me a po352 and a po302 code. I could see the po302 cyl 2 misfire being caused by the plug because I accidently put the plug from cyl3 with the broken spring into cyl 2 and now I get the code. Where do I start? Plug change?
 
#31 · (Edited)
See attached.

The P0352 points to an ignition-related fault on cylinder number 2 - faulty wiring, faulty ignition coil, or a fault in the PCM. After rechecking the wiring and the spark plug, I would try moving the No. 2 coil to another location to see if the misfire follows that coil - if it does the coil is the problem.
 
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#35 ·
I doubt that the valve spring event damaged the lifter because you report no damage to the top of the piston. These motors make noises that are particularly noticeable with the engine cover off. It is possible though that the lifter is damaged, or perhaps rotated such that the roller did not stay parallel with cam lobe. If there is damage of that kind there will usually be metal in the oil.

With 119k miles on the motor, if you want to make sure the motor is reliable you should consider pulling the heads and letting a machine shop do a valve job, with all new springs (assuming you have not done that already). Assuming the cam is undamaged, you could throw in a fresh set of LS7 lifters (GMs standard replacement for these motors now) and put it back together. The bottom end on these motors can last up to 250k miles and beyond.
 
#36 ·
I already replaced all of the springs so that's one less thing they would have to do. Once I pull the heads will that give me a good view of the cam to see if its OK? I will change the oil tomorrow to see if there is any metal in the oil. Thank you for all of your help, I really appreciate it.
 
#38 ·
And the saga continues......... today on the way to work I threw another code. PO113 IAT sensor 1 circuit. It also seems to have a slight miss while idling. Nothing too bad just a slight miss. Which is circuit 1? I am going to eventually get this thing code free.........at least I hope I do!!!!!!!
 
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