2005 lt-z400 no spark. Lots of modifications. How to diagnose problem

the car needs service.
takes tools to diagnose no starts. lots
all fuses good.?
will it start with 5%(at tad) right foot depressed? on throttle.
IMMO lamp glowing on the dash and ignored? immoblizer. lamp in the cluster. per the users guide (lost)>?
there are up to 50 causes.
check for spark?

all non boxer 4 cylinder
engine are 1,3,4,2<<< bingo
boxer is pancake engine like 65 VW bug or old subaru

or read the service manual
I guess doing cam timing,.
or pulled off all spark HV wires? oops/

lots of causes.
spark bad is first (or last fuel flooding misfire)
no year told or country of VIN that gets all.
1983 to 2006 world wide (and not USA)
or 2000 to 2006 with petrol
1.8 L Z18XE I4<<< this engine?
there were 4 engines 1.8L and I can not guess em'/
the VIN tells what is there, if we decode it.
learn what engine is there first, before doing any DIY engine work.

lots of reasons. 2.2L or 3.0L V6? no engine told and is and engine question , no VIN and if told we tell you what's under that hood.
Driving to KEY West FL. huh, LOL !!!!!
not told is does it CRANK ok fast or starter is dead.?
or cranks fast but will not start,. hot. << guess yes.
so in 18 years no tuneups done??? spark, filters ,belts ,fluids?

all spark parts bad, they hate humidity when bad, for 100years.
2.2L has 4 cops spark coils in large single unit. it may be bad
or just those old old spark plugs under it. and 4 boots bad too.
V6. uses same funny unified coil pack, but 2x3 and same exact answer packs , boots and spark plugs bad.
that is about it, but no starts have 50 causes and lots of tests to find
but a tune up is always good to do , (ignored a long time)

take it to a radiator specialist shop as it indicates that there is an air lock in the cooling system that needs to be removed so that full coolant flow can be achieved

There is an insurance liability issue of you make this modification, and have an accident. You might want to consider having a shop make this modification. Your insurance may be void with this modification.

Thanks for choosing FixYa and welcome to the site. In order to change your spark plugs, you will need a spark plug socket with an extension. You need the extension because the plugs are deep. Thanks for using FixYa. If you have any questions, feel free to ask.

Your oil filter is located on the right side underneet the power steering oil. Its a black cap with a square notch on it to remove it.

Hope helps (remember to rate and comment this).

check the wheel wells for a loose liner that will rub when making turns and will come and go as it shifts sometimes also