Bad ground question

[gn_steve]

I restored my hole engine bay and built a new motor! Powder coated every braket possible! Now i whent to start the motor and its hard to start and when it dors start number 6 and 3 are missfiring

I changed the folowing:
Coil
Injectors
Intake gasket
Battery
Injector harness
Positive wire
Chip
Ecm
Grounds every where
Set cam sensor a million times with tool and a volt tester
Reajusted the valves
Fixed all the bad wires(grounds)
Adjusted tps
Checked compresion was all at 150

And car is still runing like shit and missfiring!

My question is i niticed that my turbo j-braket was powder coated and forgot to scratch it off can that be the problem if so how can the engine start and run and all accesories work if ground is bad??


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[Lil Truck]

Does the starter crank over fine without sounding weak? Are the battery cables getting hot?
Those are signs of the a bad connection to the starter circuit, like powder coat on the bracket.
Have you checked the crank sensor and it clearance ?

 

[626gn]

Don't rule out the ignition module.

 

[Lil Truck]

Don't rule out the ignition module.

Yes, I have experienced that with new units from parts houses. Had to get on from highway stars.

What MAF are you running? Is the screen in place? The original MAF will give you fits if the screen pops out from to much clamp pressure.

 

[No disintegrations]

Double check how you wired the coil inside.

 

[gn_steve]

I changed the crank senso
I cganged the ignition module
Maf is stock unit but runs fine cause i tried it on my other gn and works perfect

Sometimes the starter cranks like if there where no spark plugs in the hole its realy weird??



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[No disintegrations]

3 and 6 share the same part of the coil pack. Can you confirm that the yellow,green and blue wires are set right under the coil pack?

 

[gn_steve]

3 and 6 share the same part of the coil pack. Can you confirm that the yellow,green and blue wires are set right under the coil pack?

I took the coil pack and ignition module off my other gn and same thing!


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[No disintegrations]

then i'd move injectors 3 and 6 and see if the problem follows them. Or plug wires bad on those cyl? try swapping them from other cylinders. Also have you tried starting engine then unplug cam sensor? If it runs better unplugged then cam sensor is bad or set wrong.

 

[gn_steve]

then i'd move injectors 3 and 6 and see if the problem follows them. Or plug wires bad on those cyl? try swapping them from other cylinders. Also have you tried starting engine then unplug cam sensor? If it runs better unplugged then cam sensor is bad or set wrong.

I bought new injectors still same problem
Changed the wire bought new
Cam sensor changed for new
Still same problem!


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[Lil Truck]

I am not sure about this possibility you might try asking TurboBob, Bob Bailey.
It's possible that a pin on you control module connector has a bad or broken connection that will affect the firing of those 2 cylinders. ???

 

[No disintegrations]

I bought new injectors still same problem
Changed the wire bought new
Cam sensor changed for new
Still same problem!


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As Litruck said check that all the pins are tight fitting into the module/coil pack. Other than that I've seen worn cam lobes run poorly but can past a compression test. Roller cam or flat tappet?

Fuel, air, spark. You seemed to have ruled out everything fuel or spark. The only thing left is leading to cam or valves. (The air part of picture)

 

[hotairgnx548]

I restored my hole engine bay and built a new motor! Powder coated every braket possible! Now i whent to start the motor and its hard to start and when it dors start number 6 and 3 are missfiring

I changed the folowing:
Coil
Injectors
Intake gasket
Battery
Injector harness
Positive wire
Chip
Ecm
Grounds every where
Set cam sensor a million times with tool and a volt tester
Reajusted the valves
Fixed all the bad wires(grounds)
Adjusted tps
Checked compresion was all at 150

And car is still runing like shit and missfiring!

My question is i niticed that my turbo j-braket was powder coated and forgot to scratch it off can that be the problem if so how can the engine start and run and all accesories work if ground is bad??
I am not saying this is your problem but to get a good ground you need the powder coat off I also use star washers on the grounds. John

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[hotairgnx548]

I'm not saying this is your problem but you need a good ground and the powder coating needs to be off. I also use star washer on ground wires to cut into the painted surfaces. John

 

[Lil Truck]

I am not sure about this possibility you might try asking TurboBob, Bob Bailey.
It's possible that a pin on you control module connector has a bad or broken connection that will affect the firing of those 2 cylinders. ???

Also check the wiring harness to ECM connectors, moisture and corrosion will cause all kinds of problems there!
T top cars are the worst !

 

[mikestertwo]

How are you determining that cylinders 3 and 6 are misfiring? Is your ignition module properly grounded? The ignition module is grounded through the mounting brackets. If the mounting brackets are all powder coated then you may have a bad ground through the brackets. Just a thought.

 

[TRICKSIXPA]

Yep just what I was thinking I powder coat everything and always have to take the Coil mount brackets and grind the powder coat off so there is a nice metal to metal connection for the ICU to ground to. Also your main grounds should be bolted to the rear of the passengerside head. If not you need to use a ground stretcher kit. I don't recommend grounding at the intake either!


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[Boost231]

Yep just what I was thinking I powder coat everything and always have to take the Coil mount brackets and grind the powder coat off so there is a nice metal to metal connection for the ICU to ground to. Also your main grounds should be bolted to the rear of the passengerside head. If not you need to use a ground stretcher kit. I don't recommend grounding at the intake either!


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Y not?

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[TRICKSIXPA]

The main reason is the quality of the bolts on the connection. The ground bolts were specifically used for the back of the heads. I've seen a small handful of cars where the intake is used for a ground with using only one bolt! Will it work most likely but I know I never have to wonder that when the ground are where they are suppose to. Even when I do Wide band hook ups the ground is directly on the head. So I don't know if piece of mind is an excuse but I'm good with it!!


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[Emiliano Lago]

Don't rule out the ignition module.

x2