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dzrtrat1111

How does this happen

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Took my car to Ocotillo last Monday for another attempt at a first shake down run. (Those who have read my other threads know it’s been one problem after another). 

Anyways, The car was running great when I got out there. No trans or clutch problems and everything else was working well. Made several short trips around the area close to where I parked and a couple of high speed runs up and down San Felipe wash. Hit 90+ MPH a few times and everything felt good. 

At the end of my last short run, as I headed back to the trailer the engine felt down on power and sounded like a cylinder was missing or not firing. 

After checking all the electrical connections I pulled the plugs and found a spark plug with a burned up electrode. The burned plug was not loose in the cylinder head but took little effort to break it loose.  Stuck a borescope down the cylinder and didn’t find any damage. All the other plugs looked good. 

What could cause this in one cylinder?

29C401BA-2F2C-4547-9A17-68A0A5FDAC94.jpeg

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that's no bueno, what is the motor application, turbo? intercoolers, gas type, who tuned it, fans on intercooler, boost etc

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Burned/melted electrodes means too hot. Lean?

Fuel  pressure ok?

When were fuel filters changed last?

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Brand new car and new N/A Ls3 Gm crate engine with Mefi 4 tunes by CBM. Fuel system including cell and filters are new. Pressure is steady at 59 psi.  Burned plug is on cyl #7  

Engine also did not have a thermostat at the time and struggled to get over 160 deg. Tstat is now installed. 

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Cbm tune🤷🏻‍♂️

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fuel delivery is first thing to come to mind.  Fuel injection pumps are pushers not suckers.  I have lots of issues with cars that are sucking from the top of a fuel cell--this is an issue. I don't care if the customer tells me it has been that way for years, it is not right.  FI fuel pumps should always be gravity fed, and the pump should be mounted at or near the bottom of the fuel tank.

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Show a plug that is not damaged.

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6 minutes ago, Air450 said:

Show a plug that is not damaged.

 

image.jpg

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4 minutes ago, dzrtrat1111 said:

 

image.jpg

That thing looks great! The one that's bad, I don't know. Broke or melted is the issue. Melted may be a possible injector issue? Broke? Defective and put a new one in and hopefully it won't do it again.

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58 minutes ago, John@Outfront Mtrsprts said:

fuel delivery is first thing to come to mind.  Fuel injection pumps are pushers not suckers.  I have lots of issues with cars that are sucking from the top of a fuel cell--this is an issue. I don't care if the customer tells me it has been that way for years, it is not right.  FI fuel pumps should always be gravity fed, and the pump should be mounted at or near the bottom of the fuel tank.

John, I get what you are saying about the pump sucking from the top of a fuel cell which is what mine is doing. The pump is mounted under the cell and there is still 3 to 4 feet of fuel line before the pump. Is the solution a secondary pump?

Why would this this cause a problem on just one cylinder?

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Posted (edited)
5 minutes ago, Air450 said:

That thing looks great! The one that's bad, I don't know. Broke or melted is the issue. Melted may be a possible injector issue? Broke? Defective and put a new one in and hopefully it won't do it again.

Just installed new plugs and tried to fire it up. This thing never starts well when it is cold but was hard to get started without some throttle now. Once it started it was still missing so I shut it off. Air I think you are right and it might be an injector issue or possibly some blockage in that section of fuel rail. 

Is there a DIY injector test or do I have to send it out?

Edited by dzrtrat1111

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Take them out.  Call around and get it done locally or take them over to CBM. Maybe keep the bad one marked to know for sure. I'm pretty sure its inexpensive.

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And youtube has some guys showing how and what to do. Hopefully its as simple as a clogged injector.

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And since this is a new build you might have got something in one of the new fuel lines after the filters.

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12 minutes ago, dzrtrat1111 said:

John, I get what you are saying about the pump sucking from the top of a fuel cell which is what mine is doing. The pump is mounted under the cell and there is still 3 to 4 feet of fuel line before the pump. Is the solution a secondary pump?

Why would this this cause a problem on just one cylinder?

because one has to go first, just which one?   lots of people always ask why it was "that one" and not all simultaneously, how come one rod bearing goes bad and not "all" rods at one time.  perhaps that cylinder runs hotter than the rest, maybe that injector is a few % less flow then the rest. perhaps that cylinder had better compression then the rest and was making more power (more heat)

yes a lift pump, perhaps a sump between tank and main pump is in order.  4 feet is not good, fuel when sucked on has a lower boiling point (vapor lock) or even pump cavitation and the fuel is aerated (micro bubbles) .  no one can tune for a deviating fuel system.    And im going to guess that you were not looking at the fuel pressure gauge at 90mph.  regardless even air can be pumped up to 58psi so you could have fuel and air, not just fuel and your gauge would read the same.

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I also should mention that after just changing the plugs and firing it up for just a few seconds. The header pipe going to the cylinder where the bad plug was, is significantly hotter than the others which would lead me to believe that this cylinder is very lean. 

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You have a lean condition.

Whether it is an injector, tune or fuel delivery.

I would have the injectors flow tested.

Replace all filters.

Did CBM do a dyno tune?

If you bought the whole package from them, take it back to them.

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maybe trying to put the injector in another hole and record where you put it.  significantly hotter while idling isn't anything but working well.  I don't think you could hurt a motor being too lean at idle.  That test you did says nothing to me.  Lean under power is the issue.  lean at part throttle not going to hurt the motor either--just run poorly

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it looks like it did not melt off, it looks like the end broke and then was melted, 

if the injector is lean that can happen, also if you spend the time to pull the header,  on that cylinder if it is a lean problem, then the ex valve will be almost all white and the other will be a dark black, 

what injectors are you running, I am now crazy about what injectors I run and only run one brank only, 

I am not a big fan of that plug also, some like a iridium plug but for me the cars get very little use and the iridium has a small contact point, I like a NGK TR-5 or TR-6, 

I have seen a issue with detonation, the Mefi is a very simple system so I am not sure on the fuel you run, but if it was tuned on fresh fuel then it need that same freshness, 

the ex valve will tell you allot 

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Mefi batch fires the injectors so you would have more that looked lean if it was a tune or ecu problem, I would be looking at the injector either defective or plugged.

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I was running a 40 micron stainless filter after my pump instead of a 10. Thinking I needed that due to the flex fuel and ethanol. Anyway it let crap through and partially plugged all of my injectors. Sonic cleaned and flow tested the 6 of them. After a fair amount of miles one of the injectors stuck wide open at the dunes just getting back from a 40 mile ride. That much fuel hosing into the cylinder made it knock and sound like a broken motor.  Just sharing this seasons experience with my injectors. Pulled that one at the dunes and beat it on a piece of wood. (Pulled the little injector screen also)  Ran perfect and put 200 more miles on the car that trip. 

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Posted (edited)

sometimes a plug just breaks,    I know it is some work but the exhaust valve is easier to read on a sand car than a spark plug, if the exhaust valve looks good, I might give some piece of mind 

to clean the injector, I have took a 9V battery with a momentary button,  used a hose with a tie strap around one end of the injector and the other on the nozzle of the injector cleaner spray can, and sprayed it tell the pattern looked perfect,  this is a easy quick way to clean the injector, 

 

also just to consider for everyone, these are run like performance motors, I have not tried them myself but wanted to, gapless plug this is a article on them 

 

also 

NGK-5777_ml.jpg

NGK-5626_ml.jpg

https://www.enginebuildermag.com/2017/03/fire-hole-racing-spark-plugs/

Electrode Configurations

A traditional J-gap plug is still the most common design for most stock and racing applications. On standard plugs for stock engine applications, the side electrode usually extends over the center electrode. This design shrouds the spark somewhat but also provides more surface to extend the life of the ground electrode.

An old racer’s trick that still works today on most standard J-gap plugs (not long life plugs) is to file back the tip of the side ground electrode until it is half way over the center electrode. This will open up the spark a bit for better flame propagation and reduce the firing voltage slightly by providing a sharp edge directly over the center electrode.

Center electrodes on both racing plugs and stock plugs may be a nickel iron alloy (standard plug), or tipped with platinum or iridium for wear resistance (long life 100K mile plugs). Multiple ground electrodes (2, 3 or 4) may also be used to reduce electrode wear for longer plug life. Spark plugs with more than one ground electrode do not generate multiple sparks because the plug only fires once per ignition cycle. The multiple electrodes merely provide multiple surfaces the spark can jump across to reduce the wear on any given electrode.

Electrode wear slowly widens the gap between the electrodes on all spark plugs, which slowly increases the voltage required to fire the plug. Eventually the point is reached when the gap becomes so wide that the spark never forms causing the plug to misfire. Plug wear is a concern in stock applications, but is generally not an issue with racing plugs because the plugs are changed frequently and don’t have to go 100,000 miles between changes.

Platinum and iridium plugs are highly wear resistant and can usually go 100,000 to 120,000 miles in most stock applications – assuming the engine isn’t burning oil due to a ring sealing or valve guide wear problem. Platinum and iridium are both very expensive metals, so they are only used on the very tip of the center electrode. Platinum may be used as a small button welded onto the end of the center electrode (and the side ground electrode in “double-platinum” plugs), or it may be used as a fine wire tip as is the case with most iridium plugs. A small diameter fine wire tip for the center electrode helps concentrate the spark and reduce misfires. Many racing plugs have fine wire iridium tips because of the spark advantages and wear resistance provided by iridium.

Another metal that is used for the tip of the center electrode in some racing plugs is silver. Silver conducts electricity three times better than iridium, and six times better than platinum. This helps to increase the current across the electrodes when the plugs fire for a more reliable spark. The drawback with silver is its low melting point and lack of wear resistance compared to iridium or platinum. Silver plugs will only last about 20,000 to 30,000 miles in a motor.

Surface gap plugs that do not use a conventional J-gap side electrode or multiple electrodes are also common in some forms of racing. The business end of a surface gap plug can be very compact, which makes it well suited for tight combustion chambers with domed pistons. There’s no side electrode that protrudes above the tip of the plug. The absence of a side electrode also means there’s no electrode to melt or break off in a high revving engine. Formula 1 and NASCAR have both used surface gap plugs for this reason.

A surface gap plug fires sideways. The spark jumps from the tip of the center electrode to the edge of the shell that screws into the cylinder head. The spark gap is much wider than a typical J-gap plug (up to 3 mm) so a surface gap plug requires much higher firing voltages and a high performance ignition system that can generate a lot of juice.

Some side gap plugs do have a small ground electrode that sticks out from the side to decrease the spark gap, while others have a series of notches cut into the end of the ground shell to create a tooth-like edge. This helps to reduce firing voltage requirements and misfires because sparks jump more easily to a sharp edge than a smooth or rounded edge.

Edited by J Alper

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53 minutes ago, J Alper said:

it looks like it did not melt off, it looks like the end broke and then was melted, 

if the injector is lean that can happen, also if you spend the time to pull the header,  on that cylinder if it is a lean problem, then the ex valve will be almost all white and the other will be a dark black, 

what injectors are you running, I am now crazy about what injectors I run and only run one brank only, 

I am not a big fan of that plug also, some like a iridium plug but for me the cars get very little use and the iridium has a small contact point, I like a NGK TR-5 or TR-6, 

I have seen a issue with detonation, the Mefi is a very simple system so I am not sure on the fuel you run, but if it was tuned on fresh fuel then it need that same freshness, 

the ex valve will tell you allot 

Jason, the engine is a GM crate engine, LS3 376/525 package. So what ever injectors came stock are what’s in it. 

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1 minute ago, dzrtrat1111 said:

Jason, the engine is a GM crate engine, LS3 376/525 package. So what ever injectors came stock are what’s in it. 

They should really be good injectors, what comes with the crate motor, 

not sure if it relates, but 2 weeks ago had a car that just keep eating fuel injectors,   and it was the filter or lack of

the car had a good filter, but it was before the pump,   and the pump itself would leave deposits of the pump into the injectors causing a issue,   not sure if you do or do not, but putting a good filter before and after the pump can make a difference, I run a SS filter 100m before and 10m-paper after,  

hopefully just a bad plug 

I would still pull the injector and spray them out with carb clean, the injectors have little filters on them and should clean out quickly,   

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