Lean #1 cylinder, not fuel or electrical. Waht's left?!!

[John B]

#1 is much leaner than the other cylinders. I'm using NGK 6's in three cylinders and a 9 in #1.
I've replaced everything electrical from the SBEC to the injector, including SBEC, all wiring, connectors, injector (3 times), fuel lines and rail. There is no fuel or electrical item left to change. So, is there any mechanical possibility? Compression is even across the cylinders. Totaly stumped. I asked my Pastor to do an exorcism, but he thinks I'm joking.

[contraption22]

Have you tried moving injectors from cylinder to cylinder? Why are you using a different plug in one cylinder?

[wallace]

What is the vacuum reading at idle and is it steady? I see you list a ported intake was it welded and then ported? Wondering if you dont have a crack in the #1 runner as it sounds like you've proved everything else out.

[John B]

What is the vacuum reading at idle and is it steady? I see you list a ported intake was it welded and then ported? Wondering if you dont have a crack in the #1 runner as it sounds like you've proved everything else out.

It's 18 at idle, which is the best it's ever been since new.

[John B]

Have you tried moving injectors from cylinder to cylinder? Why are you using a different plug in one cylinder?

Yes, I've changed injectors around and replaced injectors. I have a cold plug in #1 because it is so lean. A 9 reads OK but a 6 is chalk white, The other cylinders are perfect with 6s.

[John B]

You guys are going to think I'm playing silly games here, but this whole thing started when #4 cylinder went lean suddenly. I pulled the injectors and sure enough #4 had high resistance. So I put a known good injector in at #4 and the problem moved to #1! I figured I had mistakenly put the bad injector back in so I put another known good injector in at #1 but there was no change. Since then I've lost count on how many times I have swapped injectors around (I threw the high resistance injector away). This is the first time I have ever been completely stumped (except with women..)

[contraption22]

Any chance of oil or coolant finding its way into the cylinder causing deposits to form on the plug?

[John B]

Any chance of oil or coolant finding its way into the cylinder causing deposits to form on the plug?

I guess at this point I have to consider it a possibility, but I'm not losing any coolant that I can tell. I have considered putting my backup head on as a last resort.

[2.216VTurbo]

C'mon Todd, you're slipping This is an easy one Ported 2 piece, big throttle body, you picked up a ton of flow right? Unfortunately, the lions share of that flow increase is going allll the way to the end of that modded intake manifold and 'crashing' down the #1 runner. I'd bet if you had that manifold flowed, #1 is gonna waaaay outflow the others. Do the easiest thing and order an larger injector for that hole. How much larger can be a matter of debate... 5PPH, 8PPH? Dunno Flame away guys on why this is a bad idea

[GLHNSLHT2]

It's a bad idea only because it sounds like it's somehow electrically based because he changed 1 injector and the leanness switched holes. Not like he changed the manifold and all of a sudden that caused that hole to run lean. I see your reasoning but don't think it applies here.

[John B]

C'mon Todd, you're slipping This is an easy one Ported 2 piece, big throttle body, you picked up a ton of flow right? Unfortunately, the lions share of that flow increase is going allll the way to the end of that modded intake manifold and 'crashing' down the #1 runner. I'd bet if you had that manifold flowed, #1 is gonna waaaay outflow the others. Do the easiest thing and order an larger injector for that hole. How much larger can be a matter of debate... 5PPH, 8PPH? Dunno Flame away guys on why this is a bad idea

The thing is, this #1 cylinder was fine before with the two-piece, and just went lean after I put a new injector in #4.

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It's a bad idea only because it sounds like it's somehow electrically based because he changed 1 injector and the leanness switched holes. Not like he changed the manifold and all of a sudden that caused that hole to run lean. I see your reasoning but don't think it applies here.

And now everything electrical has been changed out.

[wallace]

Have you verified fuel pressure under load?

[contraption22]

C'mon Todd, you're slipping This is an easy one Ported 2 piece, big throttle body, you picked up a ton of flow right? Unfortunately, the lions share of that flow increase is going allll the way to the end of that modded intake manifold and 'crashing' down the #1 runner. I'd bet if you had that manifold flowed, #1 is gonna waaaay outflow the others. Do the easiest thing and order an larger injector for that hole. How much larger can be a matter of debate... 5PPH, 8PPH? Dunno Flame away guys on why this is a bad idea

Did the lean issue on #1 coincide with changing out the intake manifold?

Are you checking the plugs only under a WOT blast?

A bunch of part throttle running could give bad info.

Could be a vacuum leak at the manifold gasket at #1 causing a part throttle lean condition localized to that cylinder. Or a bad injector O-ring. Injectors not seated correctly. Etc.

[John B]

Have you verified fuel pressure under load?

No, but the wideband read mid 10s at WOT.

[John B]

Did the lean issue on #1 coincide with changing out the intake manifold? No, the manifold has been on for a couple of years now.

Are you checking the plugs only under a WOT blast? No, but I will. thanks for reminding me.

A bunch of part throttle running could give bad info. I've been putting a hundred miles or so on the plugs, both autobahn and city, and then looking at them.

Could be a vacuum leak at the manifold gasket at #1 causing a part throttle lean condition localized to that cylinder. Or a bad injector O-ring. Injectors not seated correctly. Etc.I understand how a bad o ring would leak, but how would it create a lean condition? Anyway, I've swapped injectors around countless times now.

I'm trying to answer each point of each question so you'll have the most complete picture. Thanks for the help!

[wallace]

Have you inspected the fuel rail? Only thing I can think of is a blockage of some kind.

[contraption22]

I understand how a bad o ring would leak, but how would it create a lean condition? Anyway, I've swapped injectors around countless times now.

A vacuum leak at a particular cylinder would cause that cylinder to ingest more air than the others, especially under high vacuum conditions.

[John B]

Have you inspected the fuel rail? Only thing I can think of is a blockage of some kind.

Yes, took everything apart and blew out all passages. It's clear.

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A vacuum leak at a particular cylinder would cause that cylinder to ingest more air than the others, especially under high vacuum conditions.

How can I check for that?

[wallace]

Yes, took everything apart and blew out all passages. It's clear.

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How can I check for that?

You can use brake clean or propane and spray around the suspected area ifyou note a change in rpm you found a leak. Aren't the stock fuel rails a tube inside a tube? Could the inner tube be loose at that end?

[John B]

You can use brake clean or propane and spray around the suspected area ifyou note a change in rpm you found a leak. Aren't the stock fuel rails a tube inside a tube? Could the inner tube be loose at that end?

It's a FWDP rail.