EGR deleted - Misfiring

[Bossman429]

No idea if the two are related but heres what i did -

My headers had a nasty crack, so I replaced them with some JBA shorties (which by the way are great), exhaust is now tighter than a witchs c*nt.

I asked my tuner if for a dedicated race car I should leave the EGR on or take it off. He said for a dedicated race car take it off... so off it came.

I blocked off the bung on the header, and made a plate and blocked off the opening on the upper plenum the egr valve bolts to. I removed the egr solenoid, and blocked off the vacuum lines with screws. (there were two from the EGR solenoid and one from the EGR valve itself. Also put the screws in the manifold where the EGR solenoid bracket used to be.

Start it up and its missing

It is difficult for me to figure out which cylinders exactly (downside of a v8). pull one coil pack connector at a time, and some make a noticable difference, but some do not. Maybe I have multiple missing is what I'm thinking now. It idles but rough, and you can hear the miss for sure under some throttle. I think its 3 cylinders on the drivers side that are missing, but am shocked that it can still idle decently and not sound all that horrible with 3 cylinders out. I believe its cylinders 1, 3, and 4 based on this diagram for the 4.6L :

Codes pulled are P0354, P0355, P0356, P0358


Its not the COP b/c I pulled one from a cylinder that i know was working and swapped it with one of the ones i beleive is not firing and the same cylinders are missing.

Anyone have any input?

 

[Wicked One]

Need a tune for egr delete, your guy should have known that. There is no monitoring of the exhaust air and the solenoids are not functioning.

Good luck.

 

[Bossman429]

I know i need the tune. But does that explain the misfire?

 

[Wicked One]

Yes it does.

EGR serves one purpose and one purpose only. That purpose is to

reduce Oxides of Nitrogen (NOx). Under normal combustion, Nitrogen(N2)

Oxygen (O2) in the air and Hydrocarbons (HC) in the fuel combind into water

(H2O) Carbon dioxide (CO2) and the Nitrogen remains unchanged. Under very hot

combustion temperatures, the Nitrogen reacts with the other two byproducts and

forms Nitrogen oxide (NO). After being released into the atmosphere, it picks up

another Oxygen and becomes Nitrogen dioxide (NO2). In the presence of sunlight,

it combines with other compounds like Hydrocarbons and forms Smog. Since

exhaust gas is inert (very stable) it doesn’t burn again. So by being introduced into

the combustion chamber, it will lower combustion chamber temps enough so that

the Nitrogen doesn’t react with the other compounds and is passed unchanged out

the tailpipe thus not contributing to smog. Now, since exhaust gas doesn’t burn, it

doesn’t exactly help with combustion. At higher RPM’s, this really isn’t noticable,

but at idle, the reintroduction of exhaust gas will cause a very rough idle and can

cause stalling if to much is introduced into the combustion chamber.

 

[Bossman429]

Mm. I understand how it works and why. I just don't see why it would effect certain cylinders and not others. Also why it would cause a consistent misfire. I could understand running like crap but not a complete misfire. Either way I'll get the tune and see what happens. Thanks