Engine/turbo troubleshooting 800 etec

[Merc63]

Take the Y pipe and weld two 02 bungs on each cylinder to monitor afr. Is there a sled dyno in town? I'd be going there for tuning, not the hill.

 

[Limbo]

Being the first pull there isn’t much history to go on. I would definitely start with the 2nd injector though. Heading up the trail the engine likely wasn’t loaded much and rarely saw boost for any long duration. The Etec is designed to run really lean at lower rpm, stratified combustion if I remember from my 14.

 

[ABMax24]

It's not a crank seal if this happened on boost, if the seal was leaking it would push air out richening the mixture.

I would double check wiring to the injectors just to be sure it wasn't a poor connection causing intermittent operation. But to me it's a lean condition, you need more fuel.

 

[oler1234]

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?

nope. Mine sounds the same as yours, literally 3 blips of the throttle and down she went. I boosted my ride and it has 9500km on it, ran perfect as a stocker. After the second ride I rebuilt it with a used jug, used piston and a head that definitely has damage. Fuel is key, my bet is the map is off. What size turbo are you using intake temps could be a cause as well at 10lbs.

mixing oil in the gas really is a bad way of doing it. Stop by the dealer and get the stock system cranked up, they can do this in buds. 5lbs or less go 1 value, I would suggest 1 as a minimum and maybe 2. FYI lower number add more, bigger numbers remove oil. Each sled is set differently from the factory. hat is mentioned is the etec is a dry crankcase not meant to see fuel down there. This is what cause some rods failures.

 

[fredw]

Looking at the piston picture my first guess would be detonation, poor fuel or fuelling, air box design !!

dave at redline has had many of his sleds run threw the shop, give him a call, maybe a bad air box design, he is designing me one as as well for the impulse, need a bigger design helpto get rid of bottom end bog..

He he has the ability to data log and flow test, he's swapped out a few fuelling boxes on them to his design, also did my aero and runs clean right out of the shop..

hope you you get it figured out..

 

[skegpro]

Can you bench test an injector?

How do you know the XiC is sending the right signal to the injector?

 

[Dooitorbust]

I owned a 12 xp with a tss side mount and I had the exact same failure. It ran pretty great for 1200km on boost and the only thing I could chock it up to was garbage fuel. I ran a pump/av blend at 7psi, and that was the one and only time I bought my pump fuel from a random gas station on the side of the highway. Bad decision, I know.
How old was your race fuel?Hopefully you get it figured out.

 

[b_doornenbal]

https://youtu.be/Nu3UBsSYPcg

Not sure if you found this, simple test.

 

[maxwell]

does sealed fuel in drums go bad? im sure it was over a year old.


anyways. thanks for the help guys. going to test those injectors, install an EGT guage. add some more fuel and try again. dont care how many pistons this thing eats im going to figure it out haha

 

[fredw]

I went to strait av gas four years ago and don't think I will switch anymore, it seams to be very stable, and sleds seem to like using it, impulse now with 3k on it and trouble free, have a 200liter tank under sled trailer and pick it up at airport, last fill was 1.70l, for worry and hassle free is not that bad I think and boost has been set at 10lbs for over a few years now..

 

[Catman10]

I agree with Fred W as it looks like detonation to me and very lean which is one cause for detonation. When you get your engine back together take a can of brake clean or eather and spray it around your crank seals and if your engine raises its rpm you have a leak which should be delt with before you rip on er again. Many good suggestions here about the airbox etc but a turbo is grabbing the air and forcing it into the engine so if there is a problem it would be after the turbo not the airbox. I also agree with the injector diagnosis and thats where I would start, a shortage of fuel will also make it look like a lack of oil which makes everything so complicated. If the injectors are ok then check your wiring to them and for an experiment change them around and see if the problem follows the injector, if not its time to look at the box I would think, welcome to the world of 2 stroke turbos ha ha.

 

[KatMan]

does sealed fuel in drums go bad? im sure it was over a year old.


anyways. thanks for the help guys. going to test those injectors, install an EGT guage. add some more fuel and try again. dont care how many pistons this thing eats im going to figure it out haha

https://www.youtube.com/watch?v=TAryFIuRxmQ

 

[cattechsummitrider]

A lean piston burndown starts in the middle of the piston. The ignition is to hot and starts to melt the center of the piston



A detonation piston looks like this
Detonation starts on the outside of the piston because as the fuel and air is compressed it ignites prematurely on the outside of the piston causing the outside edge to melt and the piston to expand in the bore to much scuffing the walls,, The pistons are designed to have ignition in the center and go out ( along with the heat )
Fuel in a barrel will go bad

• Perfectly stored, most race fuels will last more than a year. If you are not sure you can use the fuel up within 2 years, add a quality fuel stabilizer to the fuel as soon as you purchase it. Fuel stabilizer can only postpone fuel degradation; it can’t fix fuel that’s already bad. Sunoko fuels

 

[maxwell]

So how do you get detonation running 100% race fuel

 

[jpmez69]

So how do you get detonation running 100% race fuel

It loses it's octane value over time.

 

[ABMax24]

So how do you get detonation running 100% race fuel

Too lean, or too much timing. But since many others run stock timing i'd suggest being too lean.

I had many of the same questions as you at one point in time, have a read of this, it's an old book but many of the principles apply.

http://www.amrca.com/tech/tuners.pdf

I found the following on page 35:

The most common, regrettable combustion irregularity is detonation, the harsh knocking you hear just before an engine seizes, or melts a piston -and the noise you would hear, when running an engine on a dynamometer, as the needle on the scale begins an ominous retreat. Unhappily, the very process by which the mixture in the combustion chamber is re-heated before its actual contact with the flamefront advancing from the spark plug, and rapid combustion thus made possible, is the process that may also lead to the sudden explosion of the combustion chamber's contents that we call detonation.

Here's how it happens: It has already been noted that as theflame-front advances, the combustion chamber's remaining unburned mixture is heated,and this heating is caused not only by direct contact with the flame, but also by radiationand the overall pressure rise within the chamber. If the temperature of this remainingmixture is raised to its ignitionpoint, all of it is consumed at the same instant in a single explosion. This explosioncreates a shock, due to a fantastically rapid pressure rise, that strikes out against all itssurroundings hard enough to make detonation’s characteristic knock - and it is a shockwith a force often sufficient to break the spark plug insulator's tip and damage both thepiston and bearings. Even so, its worst effect is to force a lot of heat out into the piston,cylinder head and the cylinder walls. These are thus brought to abnormally hightemperature, which tends to overheat the next air/fuel charge and make it detonate evenmore quickly and severely.

Should this detonation continue, it will overheat the engine's upper end to thepoint where ignition occurs before there is a spark: compression heats the mixture in anycase, and when a lot more heat is added from the piston crown, etc., the mixture will bebrought to “pre-ignite”. Detonation has a very bad effect on power output; pre-ignition(thought by some to be the same phenomena) is even worse in that regard, but will notlong continue unnoticed as it will very rapidly overload the piston - in both the thermaland mechanical sense - beyond the point of failure

 

[Modman]

Deto will erode the side / edge of the piston, similar to what you have. Typically you will see the ring locating pins come out though as well, ring turns then catches the port. Once material has been removed, the edge is thinner and therefore prone to melting faster, causing scoring. Check the ring pin to see if its loose. What is the orientation of the piston in the cylinder (to the damaged area)? Were the plugs indexed properly (I think they need to be on these motors correct?)? How does the head look? Sometimes if there is a pre-existing build up of carbon it can create a hot spot that could start pre-ignition. Is the damage to the outside of the piston (i.e. against the outside cylinder wall?)

Its important to note that detonation (or pre-ignition) can be caused by too lean of a mixture - so that's possibly how you got it running race fuel and why both theories could be correct. These engines are really lean just to meet emissions, so with boost they need lots more fuel. So some sub-par fuel and maybe slightly leaner than it should be and boom. Also, what is your ignition timing like? too far advanced will give you detonation, did it get backed down for the boost? Too hot of a range of plug also, but unlikely a cause here. Overall the other cylinder looks good from what I can see, was this PTO or MAG? Often times, due to cooling flows, one cylinder is hotter than the other, since the coolant enters the cylinders evenly from the water pump but exits only on 1 side of the head. I believe its the same on these motors. What throttle position were you in the longest just before it blew (i.e. riding along a flat area at 1/2 throttle for 1-2 mins and then punched it?). What i'm getting at is it possible you were riding in a lean spot just before you opened it up?

These engines inject the fuel directly onto the piston, so risk of oiling issues are pretty low due to the fact that the ash on the piston dome will distribute the heat and protect the dome (as its supposed to). Always worth checking but so long as 1 side was getting oil (other piston looks OK), then unlikely a pump failure but check for plugged lines, loose connections etc. anyway. Mucking around in there during the turbo install, you could have bent a line too sharp etc.

They used to correct the intake imbalance with a "boost bottle". Look up the old 440 Phazers, from mid 90's, there is a bottle between the intake boots on the motor side of the carbs. I don't see this as much of an issue since the airbox is under pressure here.

Back to deto and/or lean. Doesn't really matter at this point - run fresh race 100%, and put a bunch of fuel to it on the map, and slowly back it out. As noted, you need to do some plug readings, not just rely on A/F and / or det sensor or EGTs. Definitely need to confirm no seal leaks though, should try and give it a leak down test if you can. Just some other things to think about.

 

[cattechsummitrider]

How many km on the motor?
I have seen on boosted and non boosted motor with a little higher km on them that a 10 psi difference in compression will cause detonation on 1 side, I really see it a lot on motors where the spark plugs are hard to get at and people only check the one plug and piston for wash and color. It is a pain butt but it is the best way to set your a/f mixture.
When you rebuild check or change crank seals, at very least do a leak down test,,

ahh the fun of modding!!!

 

[neilsleder]

I always think I know a fare bit about motors till some of you guys post stuff! Then I realize I know fawk all compared to you guys lol

 

[HotShotHarry]

That's the thing about gaining knowledge....... The more you know..... the more you realize there is so much MORE to know!!