LS missing - tried almost everything to fix

[Barrrf]

Hey all, I completed an LS swap awhile ago and have been chasing gremlins ever since. First, background - its a 6.0 block to .030 with stock crank and caps. Using LT4 rods and -5cc DSS Pistons. Heads are 61cc 243s that have been ported. Cam is Elgin .585/.585 228/232 112LSA. Truck intake. 12613412 felx fuel injectors, 92mm TB. D585 coils. MSD wires (theyre bendable so I can clear the headers better). Plugs have socks on them. 3200 TSI Converter. 4l80e. 3.73 rear.

I was running FAST wires with boot protectors. I was getting a miss so I pulled the boot protectors and noticed some burned marks on the boots. I replaced the wires and the boot protectors and took it out immediately and I still have a miss. The only thing that ISNT brand new are the coils. I hesitate to buy new coils at this point because I understand these are rarely the cause of failure.

I have the battery post grounded to the fender and to the block. And the block ground to the frame all using 2 gauge (except the fender ground). I double checked the harness ground behind the head.

Has anyone else had a similar experience here? Or thoughts as to what I may be having as an issue?

[csouth]

What engine controller are you running? If its stock, have you scanned for codes? Also, I have know the MAF to cause surge in idle issues.

[rchaskin]

Spray water on each header tube up near the head to find the cylinder not firing. It will be much cooler than the rest.

Switch coilpack from the missing cylinder to a firing cylinder and see if the miss follows the coil.

????Just a suggestion.

[Barrrf]

Stock controller. Maf less SD tune. No codes for misfire and maf codes are tuned out.

I'll give the water thing a try.

[Barrrf]

Well that actually worked much better than I thought it would. Number 4 is dead. So I swapped the coil over to number 2 and 4 is still dead. I'll check the plug next but I need to wait for it to cool off.

[csouth]

Stock controller. Maf less SD tune. No codes for misfire and maf codes are tuned out.

I'll give the water thing a try.

Gotcha... When I first installed my Holley EFI, I was having some issues with it running funky. Holley is also SD, It was asked "How short is you air intake tube?" Mine was very short at the time. I lengthened it and the problem went away.

While checking with water you could also try removing and reattaching spark plug wires one at a time. Typically this would cause a change in idle if its firing correctly. When you find the one where the idle doesn't change, that could be the culprit.

[rchaskin]

LOL....

The water trick works!!!

[csouth]

Well that actually worked much better than I thought it would. Number 4 is dead. So I swapped the coil over to number 2 and 4 is still dead. I'll check the plug next but I need to wait for it to cool off.

Good deal!

[Barrrf]

I decided while it was still hot to check the injectors. Tried the old screw driver on the injector trick. Injector is working. That leaves only the plug. Now I wait for it to cool.

Brand new plug. Maybe I dinged it while putting it in?

[mklinger]

Put an ohm meter on the plug. I just chased down a similar problem. Plug would fire when grounded but not under compression. Ohm meter didn’t show infinite from tip to body. Replaced plug, all good. Plugs were AC Delcos

[badazz81z28]

You haven’t tried everything if you haven’t swapped the coil. I would suspect a coil before a plug or a wire. They go bad all the time.

I would also move that coil to another spot and see if the problem follows.

[rallystyle]

did you pull the plug to see if its sparking at all? check power and ground at the coil plug also.

[Barrrf]

I appreciate everyones help here.

Turns out that even though everything was brand new, there were still bad parts. The water trick showed me which hole was bad. So I went from injector to coil to plug wire then down to the plug. The porcelain was cracked. This whole time it was just a plug.

So I changed the plug and went for a drive. WEEEEEEE!
Note: I have a GPS Speedo


https://youtu.be/P96zI_p5Kv0

[rchaskin]

Awesome!!!

Glad you got it fixed.