[Danspeed1]

Hello,

I have a 09 CTS-v that is bone stock and prior to my ownership was dealer serviced. A few weeks ago I decided I wanted to tune the car with HPT. Before I made any changes I decided to make a log of the stock file to compare later on. Its about 30 degrees here and I noticed the car was commanding 24 degrees of timing, and than timing was being pulled in and out throughout my WOT pull due to knock retard. Kind of unusual on a stock car. I got my fuel trims cleaned up nicely and removed timing (down to 18 degrees), but I kept getting random knock. Life got in the way for a week or two and I flashed the stock file back in, to continue dialing it in a at a later date.

Unrelated, I thought the idle was a little rough for a stock car so I decided... might as well pull a plug or two and take a look and see what's up. Here is what I found:

These are the stock Iridium plugs, 70,000 miles on them. Cylinders 1, 2, and 3 ironically are the worst of the plugs pictured above. It became clear the plugs needed to be changed. What's surprising to me is how inconsistent every cylinder was. Cylinder 7 was the best of all the plugs. You could clearly see the iridium tip, while again the worst plug had no tip, and a gap of almost .10 .


I replaced the plugs with BR7EF plugs gapped at .033 . To my disappointment, the low idle misfire is more pronounced. I have not had an opportunity to do any pulls with it to log data, but hopefully will do so tomorrow.

Thoughts on what might be going on here? I would like to get it running well before I modify it.

Dan

 

[ctsvken]

If your car lived a hard (lots of WOT pulls) 70,000 miles, the plug wear may be normal. I do not see any specks on the porcelain, so no detonation.
As far as the new misfire, I would look at the plug wires. Maybe one was damaged when you replaced the plugs. I doubt if there is an issue with the coils because you would have noticed that before you changed the plugs.

 

[JAustin]

Put in copper core plugs and change every few oil changes. I don't like irridium plugs for boost. Copper moves heat much better and is less likely to cause detonation. Like stated above, check the wires and make sure they are on all the way and not dammaged.

 

[jcs003]

Brick in good condition? Might be burning a lil coolant

 

[ctsvken]

The tan color on the plugs looks like normal combustion. The plug would be white if it was exposed to anti-freeze. However, the op could check the heat exchanger reservoir to see if it is low on coolant and watch periodically.

 

[07GTS]

could just be burst knock/torque management removing timing if u can log some different types of knock, timing retard, burst retard, total knock, spark retard type, all different pids to see whats happening if its a known reaction to an event to stop knock before it happens or actual knock, even log each individual cylinders knock to see where its coming from may help

 

[Sbchris]

If your car lived a hard (lots of WOT pulls) 70,000 miles, the plug wear may be normal. I do not see any specks on the porcelain, so no detonation.
As far as the new misfire, I would look at the plug wires. Maybe one was damaged when you replaced the plugs. I doubt if there is an issue with the coils because you would have noticed that before you changed the plugs.

This, grab a meter and check the ohms.


Sent from my iPhone using Tapatalk

 

[CTSV Drew]

At 70,000 those plugs are long overdue to be changed, wires too. Once the are replaced then you can check the coils and have the injectors cleaned and filters replaced. That should bring you back stock.
Being dealer serviced means nothing in this case. Don’t put regular plugs in. That is caveman technology. If your plugs are the proper heat range, iridium will make more power than any other kind.
Looking at the photos of the plugs and their colour, they are not too hot. Just worn. What’s your oil pressure like at idle. Has the oil pump O ring and timing chain tensioner been checked?

 

[Blown376]

Well, that's going to be a bit of work to get there. Might as well swap out the cam and refresh the valvetrain, bigger pulleys, etc.

 

[SoCalDave]

My 2011 was bone stock when I changed the plugs at 97k and they looked perfect. Replaced them with stock and Delco wires as well. Still runs strong after rolling over 100k last week.
Those plugs don't look good for 70k.
Thats all I got...good luck.

 

[Danspeed1]

This took a couple of days to post so I began trouble shooting. Pulled out my laptop and setup HPT with a misfire counter. At first it looked like cylinder 4 so I swapped l it with coil 3. As the car warmed up to full operating temperature the misfire got worse and my counter is showing every cylinder misfiring. I replaced the wires with a set of MSDs. Figured I could call it a "performance upgrade" even though its really not... I checked the ground on the back of the heads; nice and tight. I don't think its the coils. I usually run TR6 plugs in forced induction cars. They have historically been my "go to." Otherwise I run AC Delco Coppers in all my cars. My GTO has Delco coppers and I run E85. It runs perfect. I really feel like this car dislikes the combination of my plug gap, copper plugs or both. What are my other options for around 13lbs of boost that are iridium I guess?

 

[aluminum360]

How hot are the cats getting? I've chased some pretty odd misfire issues that have led me to plugged cats and upstream o2 sensor issues. Would like to think cats would last longer than 70k on a stock car but that doesn't take into account cheapskates that run crap fuel.

 

[ctsvken]

Maybe the BR7 plug is too cold. You could try a BR6 or the stock ACDelco plug to see if the misfire goes away. It is odd this all started with a plug change, even though the old plugs were in bad shape.