Car has no power, doesn't rev well and jumpy. Spark issue?

[Yellow302]

Finally got the explorer engine in.

Timing is set but the car does not want to rev, idle is pretty crappy, driving around some times it falls flat on its face, then surge up to normal power for a second then flat... car overall has 0 power, stumbles and doesn't want to move.

Its a junkyard explorer that I rebuilt.
Engine grounds are good and clean tested.

My gut is telling me the spark plugs I got were damaged or gaped wrong...
I also made custom length spark plug wires...

the rest of the ignition system worked fine before the swap these are the only 2 things that changed.

I need plugs for gt40p's under boost. (recommendations)
What should i gap them at? i'm thinking .035ish

 

[earleys94gt]

Sounds like you already answered your question...start with the spark plugs.

 

[Yellow302]

mpg is a joke, maybe 7 mpg compared to about 15 i would get. im guessing its not burning the fuel and blowing it out in liquid form? if the spark isn't happening?

 

[juiced_94gt]

Is it bad if there isnt spark sometimes?? will it damage an engine or will it just run rich??

 

[KamiKaziDK]

Check you MAF, sounds like what was wrong with my car and it sat for over a year because

 

[HISSIN50]

Did you pull codes and run a cylinder balance test?

 

[Yellow302]

no codes
maf is clean
tune is fine, i do it myself

picking up spark plugs today

how do i do a balance test?

 

[hotcobra03]

I like to follow this.engine is a 5.0 ,5.0ho, 4.6?

 

[Yellow302]

well i got plugs for a 2000 for explorer 5.0 one range colder... autolight 103's

when i pulled out what i had bought before the thread is half the size...

the new ones have about 1/2 inch thread.

the old ones have 1/4inch thread...

 

[Yellow302]

XP103... i bet i bought the normal head spark plugs... so the spark wasn't going in far enough into the cylinders...

autozone.com is showing the xp104 (one range colder was 103's) with the extra thread...

Hope this is the problem

 

[divit250r]

XP103... i bet i bought the normal head spark plugs... so the spark wasn't going in far enough into the cylinders...

autozone.com is showing the xp104 (one range colder was 103's) with the extra thread...

Hope this is the problem

For what it's worth, I did something similar with my TW heads... wrong plug that didn't get down into the cylinder. It was this way for over a year, and after swapping in the correct plugs, no difference. Not sure that you'll see any change from that, but good luck!

Scott

 

[hotcobra03]

Sometimes spark?what i get from that is you checked cyl1 for spark than checked cyl 2 spark was good than next was 3 or 5 .than thats when you noticed spark problem? If yes i go with firing order

 

[Yellow302]

i checked my firing order, is it different on an explorer? 5.0 than our cars?

 

[Yellow302]

i checked my firing order, is it different on an explorer? 5.0 than our cars?

same engine same firing order, im good

 

[hotcobra03]

Im no expert but difference between them is cam and firing order. You said u did the rebuild .spark sometimes is what gets my attention.how bad would it run if its off because of oversight on cam .i can pull 4 wires and still run .we all make dumb mistakes. Because of just that the 4cyls not firing but the stroke is you dont get back fire as if 1 is just out of order

 

[Yellow302]

how the hell do i change spark plug #6 w/o taking off the LT....

im thinking cut a big slice into the spark plug socket and slip it over?

 

[hotcobra03]

Hissin am i right with that thought? And cant he just move wires on cap. Timing is timed to cyl 1 which should be able to be set.

 

[Yellow302]

i put in the new plugs and it runs smoother, gaped all at .035, the ones i had in there were for the stock heads not gt40p's and they were gaped at .025

but now when i tune the car, because its running lean, it refuses to use more fuel when i tell it too...

checked the tps, set at .98 volt and no dead spots.

 

[hotcobra03]

Mobile format bites. Slap me if im wrong 15426378 5.0 . HO13726548

 

[Yellow302]

5.0 Engine Tech And Specifications

im looking at the firing order... number 3 is above ... mine is number 1... ill try moving them

using HO spec.