little LS swap help, Gen 3

Ron said:
I feel bad for the folks who are paying for this expert service.
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I feel bad for the folks who are providing it unpaid.
 
Ok coils do spark...
Noise light flashes...
But all injectors ohm out the same 12.0/12.1..still digging at it little by little
Ron said:
I feel bad for the folks who are paying for this expert service.
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They don't, I only charge maybe few hours for crsp like this. Its part of my hassle sometimes with these custom projects, I'm ok with that.
 
Chris_Keziah said:
Does it have headers on it, if so what plug wires?
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Stock everything.
So coils are firing, injector harness side checks out good with the noise light, all wires check to their corresponding place on ecu, all the injectors ohm to 12.0/12.1, but yet somehow 1/7 and 2/8 not working.
 
marty79 said:
Stock everything.
So coils are firing, injector harness side checks out good with the noise light, all wires check to their corresponding place on ecu, all the injectors ohm to 12.0/12.1, but yet somehow 1/7 and 2/8 not working.
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Swap plug wires and see if the misfire travels with them.
 
Check the spark plugs?
 
Jody Treadway said:
Swap plug wires and see if the misfire travels with them.
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Everything is new, plugs, wires, coils, but ill swap em and report back. Can't believe this issue, doesn't add up being symmetrically misfiring on each side!
 
marty79 said:
Everything is new, plugs, wires, coils, but ill swap em and report back. Can't believe this issue, doesn't add up being symmetrically misfiring on each side!
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I'm going out on a limb here and guessing you haven't had to diagnose many things. Misfires are only one of a few things, ignition related (coil, plug, or wire), fuel (ie the injector) or mechanical in nature which a compression check or even leak down will give you an indication of what's going on.

Ignition is the easy shit to check and usually the first to start with, as mentioned above swap components with a known cylinder that isn't the issue. If the misfire follows the part then you have your answer. Checking for spark should be an obvious one here as well, spark tester or a known good plug laid against a ground. Usually need an extra set of hands so you can watch it while someone turns the motor over. What the spark looks like will also tell you a little bit about coil health.

Fuel is pretty easy, noid light will let you know if the injector is getting power. Stethoscope on the injector while the motor is running can tell you if it's pulsing or not. Again the parts swap method works here as well. If it ends up being a clogged injector just swap them all, don't ever change just one injector unless it's a shit box.

If it ain't fuel or spark related just start drinking beer and know it likely won't be an easy fix, though if it is mechanical in nature you really should've figured it out before all that prior work just based off of how the motor sounds while turning over and/or running.
 
If the motor has been sitting for a long time in a humid environment you can have rust develop on the valve and seat, resulting in lost compression. Whichever valves were open at shutdown can be effected vs the ones closed won’t be.

You can tap on the valve stem with a rubber or hard plastic hammer/punch to knock the rust off and get the valve to close properly.

I always always always start with checking compression & leakdown during a misfire condition with an engine of unknown history. It gives important data that can save time and headache or rule out a mechanical issue before troubleshooting fuel air and spark.

Just bc the injectors are flashing with noid light doesn’t mean the nozzles are clear and firing fuel.

If the engine sat with ethanol fuel in the injectors, the nozzle can bc clogged with varnish. It may be worth your time/energy to have them tested and cleaned.

Not sure how far race city injector is from you? They have done several sets for me.
 
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Chris_Keziah said:
I'm going out on a limb here and guessing you haven't had to diagnose many things. Misfires are only one of a few things, ignition related (coil, plug, or wire), fuel (ie the injector) or mechanical in nature which a compression check or even leak down will give you an indication of what's going on.

Ignition is the easy shit to check and usually the first to start with, as mentioned above swap components with a known cylinder that isn't the issue. If the misfire follows the part then you have your answer. Checking for spark should be an obvious one here as well, spark tester or a known good plug laid against a ground. Usually need an extra set of hands so you can watch it while someone turns the motor over. What the spark looks like will also tell you a little bit about coil health.

Fuel is pretty easy, noid light will let you know if the injector is getting power. Stethoscope on the injector while the motor is running can tell you if it's pulsing or not. Again the parts swap method works here as well. If it ends up being a clogged injector just swap them all, don't ever change just one injector unless it's a shit box.

If it ain't fuel or spark related just start drinking beer and know it likely won't be an easy fix, though if it is mechanical in nature you really should've figured it out before all that prior work just based off of how the motor sounds while turning over and/or running.
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I've done quite a bit of diagnosing but this kinda issue I guess immediately makes me think wiring issue/crosswires/missing wires just because of how it's missing. If it was a "normal" misfire, I wouldn't have hesitated to do the basics but 1 being a v8 swap I'm naturally gonna suspect wiring issue, 2 having an unknown harness and unknown computer made me more suspect of the "swap" components being an issue not engine related...then the final is how the miss is...front and back on both sides just makes you think wires are crossed or something cause that is a weird way to have a mis.
Pulling fuel rail this morning to start there...
 
Mac5005 said:
Just bc the injectors are flashing with noid light doesn’t mean the nozzles are clear and firing fuel.

If the engine sat with ethanol fuel in the injectors, the nozzle can bc clogged with varnish. It may be worth your time/energy to have them tested and cleaned.
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I'm starting with this first thing today
 
jeepinmatt said:
I feel bad for the folks who are providing it unpaid.
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They are entering into the arrangement knowingly and willingly.
Somewhere there are non “car guys” who think they are paying a professional SME for a service . That SME is going on a free forum and saying “hey guys fix this for me” - now he clouds the request with a “I have done this many many times and never a problem - just this one time is different”….he always does this. Every ‘just this one time’ is different.

Sorry maybe I woke up wrong side of bed - but I have more respect for a man with a gun and a mask robbing a store. At least that theif is honest and transparent with his actions. This thief is stealing all the same - he just hasn’t admitted even to himself he’s a thief.
 
marty79 said:
I've done quite a bit of diagnosing but this kinda issue I guess immediately makes me think wiring issue/crosswires/missing wires just because of how it's missing. If it was a "normal" misfire, I wouldn't have hesitated to do the basics but 1 being a v8 swap I'm naturally gonna suspect wiring issue, 2 having an unknown harness and unknown computer made me more suspect of the "swap" components being an issue not engine related...then the final is how the miss is...front and back on both sides just makes you think wires are crossed or something cause that is a weird way to have a mis.
Pulling fuel rail this morning to start there...
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so instead of pulling the whole harness apart and wasting time. why wouldn't you check compression (easy to do), Check spark (you said you did), if spark change coils around (just because spark doesn't mean it will fire), pull injectors and see if they are working correctly. THEN try to see if there is a wiring issue.

Im no mechanic but you start pulling apart a cut up harness your gonna cluster up more than your gonna fix.
 
Jody Treadway said:
Can you actuate each coil or injector driver independently and verify what you think is #7 is actually #7? For example.
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In Hp Tuners you can turn off injectors and I'm pretty sure coils as well. Actually quite a few diagnostic tools in the VCM Scanner program, not to mention the 8000 bits of data.
 
Jody Treadway said:
Can you actuate each coil or injector driver independently and verify what you think is #7 is actually #7? For example.
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Just did, confirmed its the dam injectors lol. Once again lesson learned, start simple. Should've pulled out my noid light from get-go and done this crap.
In my defense though, every LS swap (5now) I've had some swort of wiring issue, yes even with the top brand components but we won't go there so I assumed this was another one of those haha. My fault for assuming, thanks
 
Ron said:
Sorry maybe I woke up wrong side of bed - but I have more respect for a man with a gun and a mask robbing a store. At least that theif is honest and transparent with his actions. This thief is stealing all the same - he just hasn’t admitted even to himself he’s a thief.
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And your whats wrong with America you asshat
 
marty79 said:
And your whats wrong with America you asshat
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No, you are providing a service and from what it seems not a great one. Then you come on here asking questions on how to fix an issue and by doing so receiving free advice/work from people who normally get paid for this. I am sorry for being an asshole but as a tech of 20yrs it blows my mind that they had to walk you (the business owner and tech) through a simple diagnosis of a misfire.
 
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