Engine/turbo troubleshooting 800 etec

[maxwell]

I can't figure out for the life of me why my turbo etec took down this piston. It's melted in the corner. The other piston looks fine and has great compression. If my fuel map was not correct wouldn't they both be lean? The sled ran amazing. Maybe a little too amazing I was thinking if an extra injector failed it would lean out that cylinder but then wouldn't I have runabity issues? Would the boost it box not sense an enjector fsilure and throw some sort of code?

Just trying to load pics

 

[maxwell]

 

[TROLLCAT]

needs more oil

me thinks

 

[Diamondledinc]

I'd say that, yeah. it got too hot. Leaned out. like you said perhaps an injector fault. I wouldn't think the Boost it / ecm would throw a code unless it would have been detonation. Detonation would have caused rod problems i am inclined to think. Not overheating in the cylinders. How are the plugs?

 

[Clode]

are you running an AFR gauge ? looks lean to me, and one cylinder always burns down first, its a very rare occasion to have both fail at the same time. Increase the numbers in the boost-it box (they go up by 5) say 25. I remember Neil posting something about how to trouble shoot the injectors using the XIC box on the forum a few years back. I dont think it was an injector problem, likely lean or fuel that is just borderline on octane requirement.

 

[Diamondledinc]

Yeah, agree- 11.5-12.2 i believe are the numbers at WOT we need to be seeing.

 

[maxwell]

Yah I am running an AFR gauge but burned down so fast I didn't even get one pull in to look at it. Not to mention how fawking fast this thing was it's going to be hard to look at. Guy needs a data logger . But look how different he pistons are coloured

 

[Diamondledinc]

Yah I am running an AFR gauge but burned down so fast I didn't even get one pull in to look at it. Not to mention how fawking fast this thing was it's going to be hard to look at. Guy needs a data logger . But look how different he pistons are coloured

Was it at WOT when it happened? I usually just putt around until i can find a steep deep hill to PIN it and watch the numbers / rpm.

 

[Clode]

Yah I am running an AFR gauge but burned down so fast I didn't even get one pull in to look at it. Not to mention how fawking fast this thing was it's going to be hard to look at. Guy needs a data logger . But look how different he pistons are coloured

the burned piston shows lean, lean burns the black carbon off...the XIC has a wire you can tie the AFR into and it records the value in 250rpm increments for fine tuning the fuel curve....what were you running for fuel?

 

[Lund]

View attachment 207836View attachment 207837

Your cylinder definitely leaned out, but many have different idea's of what a lean out condition is. It is not an oil issue, nor is it a spark plug issue or an overheating issue.Simply the piston got too hot because the air/fuel ratio was wrong for that cylinder at that moment. The scuffing cover's the hot side of the piston Exhaust side. Pin to pin but without melting the exhaust port portion of the piston. I doubt it would be injector related as it is my experience that generally the port side of the piston would be damaged alot more as this generally happens at or near WOT.Your damage does not show that, i would check bottom end seals and intake seals. I bet you have a seal leak...most likely at the intake.BTW, the cleaned off piston crown is normal for a lean out as the carbon get completely burnt off.

 

[oler1234]

Started boosting myself this year, built my own system and having burned 1 motor down like you I will offer what I have learned in my shot half day run

i burned mag side down, primary cause of Lean failure was a improper fuel map. Further to that one , it was a leaking crank seal as well rave valve line potentially a little loose, not opening the rave all the way. Another can be a slight in-balance in the air box, this will require individual cylinder tuning.

one thing I learned quick is a etec can burn down faster than a o2 sensor wil read generally because they run excessively lean naturally. 15-18:1 down the trail is very common.

i completed my second ride out today and tuned without boost reference. This gave me a strong idea of where fuel needed to be in reference to rpm and boost. Was it crude and choppy, yes! But a major learning curve. Next ride out I will be tuning with boost reference after this rides learning.

should mention I am boosting without secondary injectors, running completely off the stock etec ones.

 

[skegpro]

Started boosting myself this year, built my own system and having burned 1 motor down like you I will offer what I have learned in my shot half day run

i burned mag side down, primary cause of Lean failure was a improper fuel map. Further to that one , it was a leaking crank seal as well rave valve line potentially a little loose, not opening the rave all the way. Another can be a slight in-balance in the air box, this will require individual cylinder tuning.

one thing I learned quick is a etec can burn down faster than a o2 sensor wil read generally because they run excessively lean naturally. 15-18:1 down the trail is very common.

i completed my second ride out today and tuned without boost reference. This gave me a strong idea of where fuel needed to be in reference to rpm and boost. Was it crude and choppy, yes! But a major learning curve. Next ride out I will be tuning with boost reference after this rides learning.

should mention I am boosting without secondary injectors, running completely off the stock etec ones.

I have heard about that imbalance in the air box.

What's the solution for that? Add a snorkel?

 

[oler1234]

I have heard about that imbalance in the air box.

What's the solution for that? Add a snorkel?

an imbalance is where one cylinder is reviving more volume of air than the other, not necessarily more psi in one. Remember they are different, psi and volume. Given my example of a leaking seal and a imbalance I programmed one cylinder to be slightly richer than the other. Reading a spark plug is necessary OR you can just richin it up till that one side looks happy.


adding a snorkel just gives you a cold intake charge.

 

[skegpro]

an imbalance is where one cylinder is reviving more volume of air than the other, not necessarily more psi in one. Remember they are different, psi and volume. Given my example of a leaking seal and a imbalance I programmed one cylinder to be slightly richer than the other. Reading a spark plug is necessary OR you can just richin it up till that one side looks happy.


adding a snorkel just gives you a cold intake charge.

But what causes the air imbalance?

Design of the airbox?

 

[oler1234]

But what causes the air imbalance?

Design of the airbox?

Desin of the air box, charge tubing entering the box and bends before the box.

this is why you will see some with a very large oversized air box.

 

[maxwell]

This burnt down in literally 10 seconds or less running 100%race at 10Lbs full throttle.If both were lean I would think fuel map issue but it's just the one. Also this sled ran flawlessly as a stocker this was the first run out boosted so I would think if it was a seal it would have burnt in stock form?

 

[Merc63]

How old are the injectors? Have them flow tested to confirm they are both good or replace. If you had a seal leak, it would have ran hot or burned on the trail up under part throttle. It would need to be a huge seal leak to lean the mixture WOT.

Looks like hot out the exhaust, could the timing be off on that cylinder or they controlled together?

 

[Allseasons]

Maxwell. Did you mix any oil in your Fuel? This is a must with an etec.

Nobody has asked or mentioned so Ill state some obvious and go from there. Your stock oil pump sprays oil only the bearings and piston skirts which is why they use so little oil. So when you add a turbo and the aux injectors which drives more fuel in you need to mix your fuel at 100:1 to to oil the things your stock oil pump isn’t keeping up with, like lubricating your crankcase and top end. And again, the aux injectors and added fuel dilutes what oil the stock pump is spraying in creating a very lean scenario at wot. Sorry for the vague terms. My buddy runs a turbo etec and that is how it was explained to me when I was tuning my Cat and asked if I should oil to my fuel, no because the Zuk and etec are different, I’m non turbo but high compression with P/P.

 

[Lund]

oler1234, is on the ball.
I completely agree, an imbalance air/fuel ratio caused this. Either from an intake or crank seal, air box design or improperly programmed ecu fuel delivery.
In the old day's we use to stagger jetting for this very reason. A 2stroke is a 2stroke, the principle is the same.
Word of advise, always do plug chops, relate your finding with your EGT's or O2 wideband. Every motor is different on what is safe for it, before saying all is good to play, it time consuming but will save you alot of grieve.
Good luck

 

[maxwell]