3.3TT How Do These Pistons Look?

[Metalmania82]

Got new Denso plugs in over the weekend, gapped to 22, same issue this morning driving to work. Back to square one!

 

[cncBilly]

I'll try that as well.

You guys know this car needs to be warmed up good before stomping on it right?

 

[Metalmania82]

Of course

 

[springspeed]

On picture number 2 the edge of the piston doesn't look good. Excessive heat. The pistons are really clean, that's not really good. With your tuner can you add fuel? A lean condition creates lots of heat on the pistons. I hate to say this but I have seen pistons that look like that and the ring lands are usually cracked. What's oil consumption like?

 

[Spaceme17]

Pistons look fine.

Everyone "seeing" things on the pistons, the pictures are too grainy to see any fine detail. And if you are seeing anything, it is most likely some carbon deposits. Only way to really inspect the pistons would be the pull the heads.

Most likely if there is a hiccup at cold start, the likely cause is build up on intake valves.

I would take the time to pull the intake manifold and check out the valve build up and do some cleaning if there is any deposits.

 

[Metalmania82]

On picture number 2 the edge of the piston doesn't look good. Excessive heat. The pistons are really clean, that's not really good. With your tuner can you add fuel? A lean condition creates lots of heat on the pistons. I hate to say this but I have seen pistons that look like that and the ring lands are usually cracked. What's oil consumption like?

No consumption at all. As far as adding fuel, not sure if the JB4 can do that but I'll look into it, thanks.

 

[Metalmania82]

Pistons look fine.

Everyone "seeing" things on the pistons, the pictures are too grainy to see any fine detail. And if you are seeing anything, it is most likely some carbon deposits. Only way to really inspect the pistons would be the pull the heads.

Most likely if there is a hiccup at cold start, the likely cause is build up on intake valves.

I would take the time to pull the intake manifold and check out the valve build up and do some cleaning if there is any deposits.

Any point, in your opinion, to run a GDI specific cleaner through the intake, like the kit that CRC sells?

 

[Vermillion]

Yeah, new sparkies were never going to fix it.. I took the manifold off and cleaned it with some Wynns, different car like (Alfa 159 2.4 diesel) but the basic premise is the same. I'd also seriously recommend at some point getting it on a diagnostics machine to see if its sucked deposits into the fuel system, my Piezo's had suffered to due to the fact. It's easy to read, your injector spray correlation values will be within a 0+ / - value, if any of them look off (like unusually high or low you have injector issues).

It's one of the other major causes of poor idles, starting issues, fuel economy problems and weird power problems. Also I don't know about US spec cars but over here we require PPF's (petrol particulate filters) or DPF's (diesel) and EGR's, when an EGR gets clogged guess what happens? Poor idles etc. etc. I've cleaned that out on several cars including petrols.

Finally it could be a sensor issue but if you find any clogging (buildup) then you know it isn't a sensor. It's a right job when I did it, had to drop the subframe just to get to it.. If you're not thoroughly confident with engines I'd probably leave it to someone else, also any information stated here is discussion only. Essentially if you mess something up it's on you .!

 

[Metalmania82]

Yeah, new sparkies were never going to fix it.. I took the manifold off and cleaned it with some Wynns, different car like (Alfa 159 2.4 diesel) but the basic premise is the same. I'd also seriously recommend at some point getting it on a diagnostics machine to see if its sucked deposits into the fuel system, my Piezo's had suffered to due to the fact. It's easy to read, your injector spray correlation values will be within a 0+ / - value, if any of them look off (like unusually high or low you have injector issues).

It's one of the other major causes of poor idles, starting issues, fuel economy problems and weird power problems. Also I don't know about US spec cars but over here we require PPF's (petrol particulate filters) or DPF's (diesel) and EGR's, when an EGR gets clogged guess what happens? Poor idles etc. etc. I've cleaned that out on several cars including petrols.

Finally it could be a sensor issue but if you find any clogging (buildup) then you know it isn't a sensor. It's a right job when I did it, had to drop the subframe just to get to it.. If you're not thoroughly confident with engines I'd probably leave it to someone else, also any information stated here is discussion only. Essentially if you mess something up it's on you .!

Thank you for that insight and information. I'll add this to the list of possibilities and things to look into.

 

[Spaceme17]

Any point, in your opinion, to run a GDI specific cleaner through the intake, like the kit that CRC sells?

I haven't tried the GDI cleaner that CRC sells but I am sure that it will help.

The other option is to manually clean the valves.

I haven't done it on my stinger but I have done it on an Audi with DI. The basic process was to remove the intake manifold, pour some carbon cleaning solvent into the intake track of the valves that are closed, then use wire brushes and plastic picks to physically disslodge the deposits. Then vacuum out the liquid and debri. Repeat until clean. Rotate the engine until the remaining valves are closed and clean them.

Some people have also used crushed walnut shells and a vaccum cleaner adapter to capture the walnut shells.

 

[springspeed]

Pistons look fine.

Everyone "seeing" things on the pistons, the pictures are too grainy to see any fine detail. And if you are seeing anything, it is most likely some carbon deposits. Only way to really inspect the pistons would be the pull the heads.

Most likely if there is a hiccup at cold start, the likely cause is build up on intake valves.

I would take the time to pull the intake manifold and check out the valve build up and do some cleaning if there is any deposits.

A compression check is what is needed. As for the edge of the piston, its not too grainy to see whats up.

 

[Slip_Angle]

Curious what you found out here...

 

[springspeed]

Me too.

 

[monusa]

A compression check is what is needed. As for the edge of the piston, its not too grainy to see whats up.

Before you rip things apart, one thing to use to check the state of compression on each cylinder is to get a relatively inexpensive laser thermometer(home depot or amazon) and point it at the top of each exhaust port(take off heat shield). you should get fairly even temps (do a google for approx. temps) across all cylinders if spark/compression is on the up and up........a major difference in one cylinder or several could indicate a compression problem. After plugs.....coils.....after that, an "engine guy".....

 

[springspeed]

A leak down test will tell you everything you need to know. I have used this method to diagnose many engines, head gaskets, cracked pistons, bent valves etc... If you can't do it yourself have a performance shop do it, probably around $250.

 

[Metalmania82]

Curious what you found out here...

Thought I responded to this the other day but seems like i mighta forgot to hit enter/send.

So I haven't found anything yet. Still having the same issue even with the new plugs properly gapped. Continues to happen on cold starts, both from sitting outside in the actual cold and after sitting in a warm garage. Doesn't last very long, once she's warmed up it doesn't happen again.

My next easy and cost free thing to try will be to disconnect the battery over night and see if anything changes after that.

 

[Metalmania82]

Before you rip things apart, one thing to use to check the state of compression on each cylinder is to get a relatively inexpensive laser thermometer(home depot or amazon) and point it at the top of each exhaust port(take off heat shield). you should get fairly even temps (do a google for approx. temps) across all cylinders if spark/compression is on the up and up........a major difference in one cylinder or several could indicate a compression problem. After plugs.....coils.....after that, an "engine guy".....

I assume that this should be done after the car has warmed up completely?

 

[Metalmania82]

A leak down test will tell you everything you need to know. I have used this method to diagnose many engines, head gaskets, cracked pistons, bent valves etc... If you can't do it yourself have a performance shop do it, probably around $250.

Thank you for that advice, I will definitely keep that in mind going forward. Hopefully doesn't get to that though...

 

[monusa]

I assume that this should be done after the car has warmed up completely?

Most Definitely......The "optimal" method is to "simulate" load by putting the vehicle in gear (D-with another person holding the brake or applying the parking brake for safety), then taking the temps one at a time to check for variation. Should you find a major temp difference, then something like the suggested "leak down" test could further verify your findings.....even after warmup, there may still be an issue that you don't notice but the temps won't lie.

 

[Stingah]

Started experiencing similar hiccup around 8k, only difference mine was after the car warmed up, usually under spirited acceleration, either on the highway around 2k rpm in 7th or 8th gear accelerating to pass (without manual downshift) or when speeding up to merge with traffic after a stop. Felt like a single or multiple cylinder misfire or no fire with loss of power for a split second. No codes, no trace. After some research I concluded it was either LSPI or premature carbon buildup. I found out my usual go to for gas was not a Top Tier station so immediately went through two treatments of Chevron Techron Concentrate Fuel Cleaner Plus and switched to Shell 93 Nitro+ and the problem has not returned. Sounds like you've been feeding her Top Tier gas so this may not be your issue, but might not hurt to run some cleaner anyway and see if it makes a dif.