Another 454 Vortec Build Thread - Documenting, Q&A, Help

[Suburban7148]

I have seen the fueling do that in multiple instances. Every one was a dead cylinder on the bank with the maxed out fuel trims. Bank 1 is at maximum fuel adapt richer. Look for a cylinder that is not firing. Cracked or fouled plug, burned spark plug wire, bad distributor cap, or an injector that is not functioning. I would be looking for a dead hole on the LH side of the engine. Cylinders 1, 3, 5 or 7.

If you have a full exhaust now and you are still reading +25% on your fuel trim, you can rule out the exhaust throwing off the o2 readings. I think @L31MaxExpress is sending you in the right direction here^. With your fuel trims on that bank maxed out, it sounds like there could be a dead cylinder. If you don't have a scanner that can read misfires, a good/easy starting point may be to take out the spark plugs from Cylinders 1, 3, 5, and 7 and check for one with a sharp contrast from the others (very clean, very dirty, etc.) If one stands out, you can focus on the components related to that cylinder (plug, wire, distributor cap contact, injector, etc.)

 

[L31MaxExpress]

If you have a full exhaust now and you are still reading +25% on your fuel trim, you can rule out the exhaust throwing off the o2 readings. I think @L31MaxExpress is sending you in the right direction here^. With your fuel trims on that bank maxed out, it sounds like there could be a dead cylinder. If you don't have a scanner that can read misfires, a good/easy starting point may be to take out the spark plugs from Cylinders 1, 3, 5, and 7 and check for one with a sharp contrast from the others (very clean, very dirty, etc.) If one stands out, you can focus on the components related to that cylinder (plug, wire, distributor cap contact, injector, etc.)

He can also take a spray bottle, fill it with water. Start the engine, let it run 60-90 seconds then spray each exhaust tube. The dead cylinder will not boil the water off. Works on manifolds too provided the engine is not fully up to temp. That is old school misfire detection. I still use that method on engines that have an obvious misfire. Quicker than pulling out the scanner and accessing the misfire data.

I ran the injector disable cylinder balance test on the 383 in the van the other day. Every time I disabled an injector, the 02s and fuel trims did exactly what his are doing in his video. The trims would go from perfectly even to dead lean on the bank with the killed injector and the opposite bank would richen up because of the MAP sensors slight loss of vacuum and the MAFs increased flow reading from the IAC increasing to compensate for the dead hole.

 

[Supercharged111]

He can also take a spray bottle, fill it with water. Start the engine, let it run 60-90 seconds then spray each exhaust tube. The dead cylinder will not boil the water off. Works on manifolds too provided the engine is not fully up to temp. That is old school misfire detection. I still use that method on engines that have an obvious misfire. Quicker than pulling out the scanner and accessing the misfire data.

Or point a temperature gun at all 8 and see if there's a cold one. On snowmobiles we throw snow on the pipes to find out which hole fouled a plug.

 

[L31MaxExpress]

Or point a temperature gun at all 8 and see if there's a cold one. On snowmobiles we throw snow on the pipes to find out which hole fouled a plug.

IR gun would work too. The spray bottle trick is just cheap and most people already have the stuff to do it on hand. In a pinch few sprays of windex or glass cleaner will work. Just stinks and can burn if it gets too hot. I have had to do it on a road trip with spray glass cleaner when I was running either a carb or TBI years ago just what I happened to have that would boil when sprayed on the header tubes. It was either a cracked plug or burned wire in my case.

 

[Bachert24]

That's guys I'll try this over the weekend

 

[Bachert24]

Looks like misfires in cylinders 1 and 7. Considering the new plugs, wires, coil, cap, rotor, fuel injectors, fpr, and fuel pump wjere would you guys go with this information, looks like under the drivers cylinder head it's wet. Would intake gaskets cause this? I can't see how it would but I'm all ears!

 

[Bachert24]

Also of note no codes for misfires, just the counter on torque pro going up

 

[L31MaxExpress]

Looks like misfires in cylinders 1 and 7. Considering the new plugs, wires, coil, cap, rotor, fuel injectors, fpr, and fuel pump wjere would you guys go with this information, looks like under the drivers cylinder head it's wet. Would intake gaskets cause this? I can't see how it would but I'm all ears!

Intake gaskets are a possible source. I have been fighting a misfire for a while. Thought I got it beat with new plugs and a PCV catch can. Started misfiring on #3 again. I think it is actually the cam and lifters in my case as it has a lot of lifter noise on a cold start that subsides but it misfires cold to the the point I think it is fouling the plugs on the cylinders that have the lifter issues. Once the plugs have fuel fouling and deposits it just no longer runs right. I can make mine misfire to the point the thing is vibrating and shuddering holding it 1,750 rpm with no load on it. Same RPM with an actual load on it, smooth as silk. It is a bizare issue for me.

I am about to shotgun mine though, different cam and lifters, different intake manifold and 24x coil near plug swap. Hopefully resolves my issues for good. Mine ran great for about 3 days and 350 miles or so then went back to what it was doing before except it had a cylinder 4 misfire as well before. Now it just has a pending cylinder 3 or multiple random that is not setting an actual code. It shifts back and forth between P0300 and P0303 pending and so far has not actually set either code. When it stops raining here, going to pull the #3 plug and inspect it.

 

[Bachert24]

Intake gaskets are a possible source. I have been fighting a misfire for a while. Thought I got it beat with new plugs and a PCV catch can. Started misfiring on #3 again. I think it is actually the cam and lifters in my case as it has a lot of lifter noise on a cold start that subsides but it misfires cold to the the point I think it is fouling the plugs on the cylinders that have the lifter issues. Once the plugs have fuel fouling and deposits it just no longer runs right. I can make mine misfire to the point the thing is vibrating and shuddering holding it 1,750 rpm with no load on it. Same RPM with an actual load on it, smooth as silk. It is a bizare issue for me.

I am about to shotgun mine though, different cam and lifters, different intake manifold and 24x coil near plug swap. Hopefully resolves my issues for good. Mine ran great for about 3 days and 350 miles or so then went back to what it was doing before except it had a cylinder 4 misfire as well before. Now it just has a pending cylinder 3 or multiple random that is not setting an actual code. It shifts back and forth between P0300 and P0303 pending and so far has not actually set either code. When it stops raining here, going to pull the #3 plug and inspect it.

What intake you going with? Aftermarket?

 

[L31MaxExpress]

What intake you going with? Aftermarket?

Holley Projection MPFI.