Help Me Figure Out What I Broke at the Track Today

Yup, it finally happened. 500+ passes on my car with no incidents. It had to happen sooner or later.

So here's what happened. On the 1-2 shift, I had a little bit of detonation, exactly during the shift. While I know it's not good, I've had that happen dozens of times. It literally only happens for a small fraction of a second. Anyway, this time, when it shifted to 2nd, it was still detonating. I immediately let out of it. I got back on the throttle just enough to get to the end of the track (<1/4 throttle), and I noticed a BAD vibration. Like shake the mirror off type of vibration. Not good.

Well, the car quit running and I coasted to the end of the track. Shortly after I quit kicking the front tire and telling it what a slow piece of **** it is, I popped to hood and started looking around. I found absolutely NOTHING out of place. No smoke; all plugs and connectors where they were supposed to be; no oil leaking; everything LOOKED good. So I proceed to crank it back up. It took a little while, and it was VERY noisy/shakey. BUT, it cranked back up, and with a little persuasion, made it back down the return road to my parking spot. A little more persuasion and it got back to running a lot better. I took it real easy getting back from the track, and I thought for sure it was completely done for, but it made it. Thank God.

It now just has a pretty bad miss/vibration. It's also down on power a good bit. BUT, it's running. And other than the miss, it's running relatively well. As I said, no smoke at all, no leaks, all plugs/connectors are good.

What do my friends on Stangnet think could be the problem?


My thoughts (in no particular order):

1. Pistons/rods/rings. This was my very first thought. BUT, since it is not smoking AT ALL, and since it has been driven over 100 miles in it's current state, I wouldn't think this would be the cause.

2. Bent valve. This was also a first thought. But after a little more consideration, I doubt this as well. I don't know for sure, but I would think it would be smoking if there was a bent valve, but I could be wrong. PLUS, both valves would be closed in the event of detonation, so I'm not really sure how it could bend a valve.

3. Spark plugs. I have read once or twice about a spark plug tip breaking off. I don't know, kinda grasping at straws here, but I don't really know of anything else.

What do you guys think?

bhuff30 said:

First thing I would do is pull the plugs. If you are getting oil or coolant through the cylinders, it will show up on the plugs and they will look fouled (and obviously cause a miss). Other possibility is that the detonation damaged the porcelain or ground strap, which could cause a miss. Either way, looking at the plugs often reveals important clues about what is going on. If nothing shows up, then do a compression check and some searching for an ignition/coil issue causing the miss.

It is pretty common to hear detonation between shifts. Sometimes, a faster shift will help the problem. During the shift, the engine experiences very high load because the rpms are being dragged down. Some ECU codes even add timing for quick changes in rpm, because it assumes you are accelerating quickly in first. I would be concerned about he health of the transmission if takes long enough to shift that you hear detonation between shifts. You may eventually need a rebuild, but higher line pressure and shifts kits can help make the shift a bit quicker. My GT used to ping on power shifts when my clutch was getting soft and not grabbing well.

Click to expand...

I plan on pulling the plugs first thing tomorrow. It is still a little warm right now, and I didn't want to pull them with the heads still hot. One problem at a time, haha.

That makes sense about the shifts. I have done the J-mod, and have a transmission cooler. It doesn't shift super super fast, but I heard it bark the drag radials on the 1-2 shift a couple of times today. I do, however, want them to be faster/harder. I told my tuner that last week, but I don't think he changed anything. If he did, it was negated by how much faster the RPM are climbing at redline.

d98gt said:

Lets start with the easy items and pull some plugs out and see what we are looking like as far as detoniation goes. Then check the obvious fluids such as oil/coolant to see if anything seems out of place.

No CEL?

Click to expand...

Pulling the plugs was/is my first line of attack. I wanted to see if there were any other obvious things that I may be missing.

Coolant and oil both visibly look fine. No signs of coolant in the oil.

No CEL. I thought about that earlier, and it is a bit odd that there isn't one considering how rough it ran for a while, and how badly it's missing now.

d98gt said:

What plugs are you running and which gap? I think you went lean and lost some plugs

Click to expand...

NGK TR6s gapped at .036.

I did leave out a little bit of info. I HAVE already messed with the plugs a little bit, or at least the plug wires. I pulled each one of them off (one at a time) and drove it around the parking lot. Some of them OBVIOUSLY resulted in a big loss in power, whereas I was unsure with some of the other ones. Not sure what that means.

What do you mean when you say lost some plugs? Fouled them? Or physically damaged? If the solution to all this is simply plugs, I will promise my car not to go wide open throttle for one whole week.

BurningRubber said:

If you didn't notice as drastic of a loss when you pulled certain wires vs others that is where your problem lies. Probably destroyed the plugs in a similar fashion as D98GT just posted. If that's the case, you're probably very lucky with them being the first thing to go.

Click to expand...

Yea, some of them (probably 5, give or take) had a very obvious loss of power and increase in vibration, misses, etc. And while the other 3 resulted in a loss of power as well (I think), it wasn't nearly as obvious.

Regardless, I'm planning pulling all of the plugs tomorrow. If it's that simple a fix, my tuner will be getting a call tomorrow afternoon about retuning it.

slayerripkdc said:

Sorry to hear sneaky . 500 passes????? These little 2v's are pretty stout! Well what did she run and trap before the bad news?

Click to expand...

Yea, a little over 200 on the blower. Only 6 on the new cams, though.

I can't say for sure about how it ran because only one lane had the 1/4 timing stuff working, and I didn't want to wait 1 hour+ to run one time. I did make one pass in that lane, but naturally I spun and didn't get a good time.

My best in the 1/8 was an 8.0 @ 89 mph with only a 1.94 60'. That was with no meth and a lot of timing pulled out. My previous best at this track (with a 500 feet better DA, and around 100 pounds less weight) was a 8.2 @ 86. Figure a tenth for the DA and a tenth for the weight, I figure I'm trapping a good solid 3-4 mph better in the 1/8 mile. And that's with no meth. It's definitely a noticeable improvement.

I never did get a good pass on the meth. That's what I was working on sorting out when this happened.

I think that at Rockingham (I average .25 and 2.5 mph faster there), with good weather, the car would run 12.2, maybe 12.1 at around 113-114 as it sits right now.

N8Dogg98 said:

Damn Will that sucks... make sure to take some pics of the plugs when you take 'em out.

Click to expand...

Planning on it.

Well, the car seems to be fixed. I'll post pictures soon as I finish eating lunch.

Here's what the number 1, 2, 4, 5, 6, and 7 spark plugs looked like. (i.e. normal).



Here's what the number 8 plug looked like.



And here's what the number 3 plug looked like.








Chalk it up a lesson learned. Detonation is bad stuff. Car seems to be running fine. Is it possible that the little piece of ceramic that chipped off the #3 plug damaged anything? If so, what would be the signs?

txredgt said:

Could this also have been the cause as to why you didn't get the #'s you thought you might have on the dyno?

Click to expand...

Me and my friend were talking about that earlier. I think it could have, but I don't really know for sure.

I do know this: when I took it in to get tuned, there were absolutely no misses or anything like that. I honestly couldn't believe how smoothly it idled and drove. Well, a day or so after the tune, I noticed I slight vibration when in gear at a low RPM. It wasn't a whole lot, but it was enough for me to know that it wasn't there before the tune. And if you listed closely, you could hear it miss just a little at idle. Very very slight, but you could hear a 'tick' every 5 or 6 seconds, but that was it. It was small enough that I just figured it was a quirk in the tune.

Well now, if you look at that #8 plug, you can see that the ground strap is closed up, but it's barely fouled any worse than the rest of them. That leads me to think that while it's closed way down, it was still firing at least most of the time. BUT, I can't help but think that that can't be good for the power output. How much? Who knows, but it has to be some amount. I think that that plug got damaged during the tuning session, and then the #3 plug got demolished during the detonation yesterday.

Regardless, it is running super smooth right now. No misses at idle, and no vibration at any rpm. The butt dyno is often inaccurate, but it is running VERY strong right now. I really want another chance at the track in it's current trim, but there's not another TnT at Rockingham until November.

Yea, the #3 plug was DEFINITELY not like that during the tune, haha.

But the #8 plug has virtually no fouling at all (i.e. it was still firing most of the time, even though the gap was closed virtually all the way down), which would make me think that it could have been like that for a while. And the fact that changing the plugs cleared up the slight miss from after the tune means that something involving the plugs was not right after the tune. The other 6 plugs all look perfectly fine (they are only about 6 months and 8000 miles old), which has lead me to believe at least something was wrong with the #8 plug before yesterday.