lt1 has misfire after bbk header install???

[9302z28SS]

My lt1 is misfiring badly. To the point where it has a lack of power
Sputters off the line unless giving 1/4 or alittle more of gas
Has little top end (could be my kickdown adjustment)

I do know i have 2 exhaust leaks one is the slip cover
I used to connect the exhaust together for the straight pipe

The other is where the egr tube for the 94+ lt1s egr tube
Bolts to the passenger header (sounds awful)

I just used a flat peice of a 98-02 camaro headlight bracket
And some lockwashers to block it off, (bad idea)

At 40 mph it bucks like its bouncing off a wall.

When i did my header install i ripped the elbow boots
For #7 and #8 cyls trying to take them off so i tried
Replacing just the boot and ripped off the part that snaps
Onto the spark plug, so i put it back on and thought i did a
Good job.

But i also changed to a msd coil and gm icm i think
Was from a 95??

Other then that ive done nothing else to the car besides
Block off the area on the back of the intake where the egr tube
Would run from the intake to the passenger header.

The egr valve is still in place. Could that be my issue??

[ryanwarby01]

Sounds like you need to change your plug wires.

[93formulalt1]

Fix the exhaust leaks. They may be causing funky O2 readings, resulting in a lean/rich condition, which would make things worse for you overall. Also, check spark plugs for cracks in the ceramic, if you didn't replace them when you swapped the headers, do it now (will require removal of Driver's side Header). Also, new plug wires, and try swapping the old coil/ICM back in to see if they help the problem or worsen it. I had an MSD coil on my car, it didn't help performance at all, and even with new plugs/wires/Opti, it ran better with a stock coil than it did with the MSD.

[Gregs_gsxr]

maybe also a cracked plug, pull the wires and plug double check them both, also look into the exhaust leaks, like Nick said above.

[ruckusz28]

Clean up the leaks, change the plugs and wires. Don't cheap out. I ran the e3 plugs and it was well worth it over the delco junk I had originally purchased.

[9302z28SS]

Well i fixed the exhaust leak at the egr lastnight
Not sure if its leaking again or not. But i fixed the egr
With a gen 1 block fuel pump block off plate.

Paid 7 bucks for it. Drilled a 3/8s hole in it where i wanted
It. Put it on just like this gasket/carboard/blockoff.

And i switched back to the stock coil and icm.
Its not misfiring as bad. But still has a slight miss
When in gear holding the brake and giving alittle gas.

But for the problem of pulling off and it sputtering
Its almost like a new car. Touch the gas and it goes.
But now my damn serp belt is screaming when i get
On it.

Time for another one. But i did change the plugs 3 days
Before putting the car up for the header/trans install.

So theyre brand new plugs.

Im going to replace #7 and #8 spark plug wires today an
See how it works out

[9302z28SS]

o2

I just remembered i do have an o2 sensor on the
Passenger side i couldnt get screwed in all the way
Cause it was such a tight area. Its snug in there

But could that be causing the miss? Its on the y pipe
4in front the header flange.

[mcalus]

What he is saying about a cracked plug is wackkng the header on it during install.

[Gregs_gsxr]

pull all the plugs and make sure there isnt a hair line crack in the porcelain, causing it to ground out on the block therefore not even making it into the cylinder, in return giving you a miss fire.

[9302z28SS]

Changed #7 and #8 plug wires. Went back to stock
Icm and coil. Checked all the plugs they were good.
Fixed exhaust leak at #8 cyl. Cleaned the throttle body
(that thing was filthy) checked for intake and throttle body/
Air lid leaks. Everything checks out.

Runs ALOT better. But still has a slight mis. Ill just
Throw a set of plug wires on it if it doesnt clear up after a
Few burnouts at the cruise today

[jderry]

pull all the plugs and make sure there isnt a hair line crack in the porcelain, causing it to ground out on the block therefore not even making it into the cylinder, in return giving you a miss fire.

And since you need to do this ^ Just replace them. I would get a set of Delco wires too...

[9302z28SS]

Misfires were caused by the leaking egr tube area on the passenger
Side header. So I need an egr tube from a 94+ lt1

[9302z28SS]

Ok so ive ran through everything with a fine tooth comb.
Well my passenger o2 sensor in my header is about halfway
Backed out.

Thinking thats whats causing my misfiring issues.
Pulled a couple plugs and they looked good.

Checked the rockers on the drivers side. All were ok.
I tweeked a few with a 1/4 turn to get some slop out

Ive been running this car past 7k rpm since the cruise
Yesterday so i think a few loosend up. Now its got some
Guts.

Runs smoother then it did. But still has hesitation
Off the line and alittle jolting at 40mph. Runs great at
An idle. Has a slight hardly noticeable mis.

Need some input here.

[mcalus]

Check all your plugs not just some. You could of easily cracked one. Seems like you are ruling out stuff that you didn't completely check over. Make sure all of your plug wires are where they are suppose to be. Also check at night time and see if any of your wires are arching on something. My ac delete pully took out 2 of my wires.

[meissen]

Ok so ive ran through everything with a fine tooth comb.
Well my passenger o2 sensor in my header is about halfway
Backed out.

Thinking thats whats causing my misfiring issues.
Pulled a couple plugs and they looked good.

Checked the rockers on the drivers side. All were ok.
I tweeked a few with a 1/4 turn to get some slop out

Ive been running this car past 7k rpm since the cruise
Yesterday so i think a few loosend up. Now its got some
Guts.

Runs smoother then it did. But still has hesitation
Off the line and alittle jolting at 40mph. Runs great at
An idle. Has a slight hardly noticeable mis.

Need some input here.

When you say you tightened a couple rockers 1/4th turn to get some slop out -- do you mean you tightened them AFTER hand cranking the engine so that the cam was in the proper position for tightening the rockers, or did you just walk up after the car had been sitting for awhile and feel the slop and tighten them? If it's the latter, no bueno - the lifters will bleed down a little bit after sitting and you'll feel slop even though the rockers are adjusted perfectly. My dad fell into this when he was adjusting his rockers -- he'd hand crank to the proper cam phase to adjust the rockers, then he'd tighten a few and stop and take a piss and he'd come back and feel slop again and tighten them more... turns out he was waaaay past zero lash

But yes, I'd definitely fix that O2. If the O2 isn't sealed properly, it's going to suck oxygen in and then the O2 is going to tell the PCM "Hey I'm seeing to much O2, add more fuel you're running lean!" The PCM is then going to add more fuel to that bank and you're going to be running rich. No bueno.


Lastly -- you're driving an LT1... why in the hell would you be revving it PAST 7k?! Are you wanting the optispark to go bad?