LNF - Something Contacted Sparkplug - What?

[nota4re]

Embarassingly, I think we've encountered a pretty expensive lesson as a consequence of poor tuning.... We've had great success tuning our 2009 Solstice Coupe and have now tracked it several times with very good results (and good datalogs to validate the tune.) We applied our limited tuning experience/knowledge to our recently acquired, low mileage (14K), adult-owned Cobalt SS and expected to have similar results. My daughter drove the Cobalt 4 hours from SoCal to Pahrump (near Las Vegas) and all was fine. However, she noted that there were a couple of situations where the car pinged and fell flat - but quickly recovered when she lifted off of it and no CEL was ever triggered. After a quick stop in Pahrump, the car headed off to Vegas. While climbing a modest grade, the car allegedly started pinging under load and the driver - not recognizing the ping, tried to drive through it. The car bucked and sputtered and immediately set a CEL and went into what felt like Limp mode. After resetting the ECU - assuming it was simply limp mode, the car still would barely idle. Here's the really bad part.... We removed the sparkplugs and determined that the plug in cylinder 3 has had the ground electrode pounded into the center electrode. Ouch. We replaced this plug with a new plug and the car still doesn't run right.... so the assumption is that there is sill a significant mechanical problem with this cylinder. Upon removing the new plug, it was fine - so whatever contacted the first one appears to no longer be present.

We made arrangements to have the car trasnported back to our shop on Wednesday so we do not have the opportunity to do any further diagnosis until then..... and the suspense is killing me.

Any educated guesses from the experienced people here as to what happened? Just how costly of repairs are likely to be needed? (I know you'll be guess, but your input - especially if you've seen something similar, is appreciated.)

[cobaltssoverbooster]

Can you post the tune for which this occurred? I have pounded these in the same manner when tuning timing. Overheating the cyl causes the electrode to either droop or close after it droops far enough to contact the piston. I'm currious

[nota4re]

CobaltCustom1.hpt

I would really welcome ANY input, suggestions you may have!!!!

[T-Man]

Does the car have 3 bar MAP sensors? If not, I would change the MAP sensor data back to stock as this could greatly affect things.

[Iam Broke]

Detonation killed a plug on #2 on my old lnf. Sadly it's time for a compression and leakdown test. Might have had a chunk of ringland crack off and blow through.

[nota4re]

Guys, ALL input appreciated! Yes, the car DOES have the 3 bar MAP sensors in it (we installed them before starting the tuning).

We have too many cars and I bought this one to be my reliable track dog. I figure that I need 200 or more hours of track time to try to improve my own skill set and thats what I wanted to do with this car. What I thought would be a great initiation weekend on the road course turned out to be a DNS! We installed the KW V2's on it and also some Enkei PF01 with a square set-up of 235/40-18 RS3's. I'm really bummed about what happened and hope that we can get it corrected without a lot of effort/expense. We can do a compression and leakdown tests as soon as we get the car here. We also have a borescope which might shed some light on the situation.

[cobaltssoverbooster]

you turned the boost way up on the dals to a level that usually isnt required on a factory turbo setup. if you want to race track this car you cant boost more than 22psi or you will overheat a few laps in.
also you haven't tuned the maf at all so everything up top is going to run really lean when you boost. if it turns out you didnt crack a ring land and pass it on, then if the compression checks out i would recommend setting the maf to tune mode and dialing the final boost value in.

sometimes a big change of wgdc without adjusting the maf causes a problem. the problem is once you do finalize the maf if the boost change was a lot like over 6 psi change without fuel adjustment the engine will experience boost creep when you dial the fuel in properly. i have seen it a few times so just make like a few boost adjustments then set the maf in roughly until you get the boost you want this way the fuel isnt off a lot.

[nota4re]

cobaltssoverbooster - Everything you said makes a lot of sense and we will follow your advice. Absolutely agree on boost limits on the road course - especially in a hot areas like Pahrump, NV (Spring Mountain Motorsports). We are targetting 20-22psi of boost for track use and also running 100 octane fuel. In the Solstice, this is pretty much what we have accomplished and when datalogging the knock table it is pretty much all zeros. I think we were a little premature to get te Cobalt out on the track where we should have spent more time on the tuning and validation. Lesson learned. Thanks again for your insight and recommendations.

[cobaltssoverbooster]

i will be moving to the Reno NV area in december or january 2013-2014
i think its like 7 hrs to pahrump though. long a$$ drive.

how you like the track in pahrump?

[nota4re]

how you like the track in pahrump?

We REALLY like the track at Spring Mountain.... and the staff, and the clientel, and the accomodations, etc. We (me, my 22year-old son and my 19year-old daughter) had the opportunity to drive the track as guests at least a half dozen times. It is very smooth, for the most part very safe, and the accomodations are first rate. When an opportunity came up to become a member, I jumped at it. Quite seriously, please let me know when you can attend as I would enjoy to have you as our guest anytime.

We had initially started driving the track using a 2012 and a 2013 Boss 302 Laguna Seca. My daughter still drives the 2013 Boss. I really love these cars but what became apparent to us very quickly is that weight is the enemy. Horsepower is great - and the Boss engines are absolutely first rate, but less weight would mean faster acceleration, better braking, better cornering, and less overall expense for a weekend. As an example, if driven very aggressively it is possible to go through a set of Hoosiers on the Mustang in a 2-3 day driving event. (You typically get a LOT more track time at Spring Mountain than you would at a HPDE event.) I started on a quest to buy a car which was as light as possible but which also had good track potential. Started out looking at the Solstice vert with intentions to fully cage one and then in January I stumbled across a Coupe and fell in love. As the price of the Coupes seems to have stabilized and is even trending upward, we have so far deferred caging it as this would really be something that would make it track-only. The Coupe has KW V3 on it with PF01's, the Cobalt's Brembo calipers and rotor up front and a tune (thanks largely to your instructional videos). The Coupe ALWAYS gets a lot of attention as so few people really know what it is. It is very competent on the track and my son is typically driving it.

On a lark, I drove my 2013 Focus ST on the track and it was really an eye-opener for me on how well a FWD can perform. In short, this is what led me on a quest to find the best bang-for-the-buck, lightweight, FWD vehicle I could find which is simply the Cobalt SS. I came close to buying several but eventually found an unmolested 14K mile car that is literally in showroom condition. The car was in MN and I bought it sight unseen and had it transported. Admittedly, I was lucky but the car was just as advertised. We put the KW's on it, PF01 with 235 Hankook RS3's, DOT 4 Motul fluid, and were ready to track it for the first time..... before our tuning brain fart stepped in and altered our plans. Our objective is to get the SS back to the track asap and then with my son and daughter our quest is to invest in a lot of track time to improve our driving skills. We have a a track-focused C6 Z06 that is just a monster on the track - but a clear reminder thath this car is today way outside our skill set!

[nota4re]

Here's a pic of our Sol Coupe.

SolDriveway.JPG

[cobaltssoverbooster]

I like the coupes they are so hot rod looking with the stretched roofline. Very clean car! Nice to see a people turning a track event into a family event.
Be sure to update us on the cobalt inspection.

[nota4re]

Well, we got the car back today and were able to perform a little more diagnosis. No compression at all in cylinder 3. The borescope was inconclusive. I guess we're are going to pull the entire motor as pulling the head off while in the car seems just as hard if not harder. Needless to say, pretty bummed. A very senseless mistake.

[T-Man]

Detonation for the loss

Sorry man

[Iam Broke]

Sorry to hear that, but I'm not surprised. Time for some forged pistons.

[nota4re]

Dropped the engine and trans out yesterday. We will finding the damage later today I suppose..... Ugh.

[nota4re]

Well, with the engine removed the head wasn't too bad to remove. On te bad side, a pretty big chunk of piston is missing. The good news is that the cylinder wall and the head/valves all appear fine. But, this is cylinder 3 and there is a little bit of coolant present and cylinder 4 has coolant in it as well. Anyone have a rational explanation for the coolant? The head gasket appears fine and there are no obvious "tells" where it bridged a coolant passage. Theories welcome.

Piston.JPG

[5FDP]

Looks like what a 3800 piston does after going lean with a good amount of boost and pop.

I know when 3800 heads are pulled, coolant seeps out of the head as the bolts are taken out thus filling the cylinders some.

[wyochimneysweep]

How are the turbine fins in the turbo? Coolant run in when lifting head off

[nota4re]

The turbo is fine - turbine fins on intake and exhaust side both fine (whew)! We have a brand new GM Engine arriving Wednesday. We will install that and get the car back on the road (errr, back to the track). Of course, we need to spend some time with the tune! Anyway, with the new engine in we can take our time to tear this one down and double check everything. Right now it looks like "just" a piston but maybe we'll consider a slight build rather than putting back to OEM.