Hello! Lt1 issues, rich but lean.

**92rslt1** · 06-15-2014

Hello, I finally got my car on the road and its running good but I have a few issues.
My brand new CAT is glowing cherry red and smells bad. I think its burning pig rich at idle, it was so bad before I put the cat on it was burning my eyes.
Also, I started data logging about 100 miles ago and today I got a code that says right bank O2 lean which really doesn't make sense. Also it has maxed my BLM all the way to 160 making it even worse.

I have tried to attach my bin file, trying to find out if its something in my tuning or maybe my injectors are going bad. How can I log the entire rpm range so I can see if its a fuel delivery problem or tuning issues? If I could log the O2 data I could pin point the air leak or injector issue.

**steveo** · 06-15-2014

blms at 160 mean its dumping a TON of fuel because it thinks its lean, but that glowing exhaust means its probably not actually lean.

initial diagnosis? exhaust leak before o2 sensor, o2s are bad, or both.

other stuff such as a spark missing from a cylinder can do that, that cylinder is just pumping air, so it thinks its lean, then dumps fuel, which reacts in the exhaust even worse from all that extra air being pumped in there.

**92rslt1** · 06-15-2014

Originally Posted by steveo

blms at 160 mean its dumping a TON of fuel because it thinks its lean, but that glowing exhaust means its probably not actually lean.

initial diagnosis? exhaust leak before o2 sensor, o2s are bad, or both.

other stuff such as a spark missing from a cylinder can do that, that cylinder is just pumping air, so it thinks its lean, then dumps fuel, which reacts in the exhaust even worse from all that extra air being pumped in there.

So the O2 are both new, and I dont hear a leak at the header surface. I think that maybe its the injectors, one or more. The car sat for a long time, about 5 years. I'm thinking maybe I need to replace the injectors with 30lb.

Is that as easy as installing the 30lb injectors, then setting the computer injector size to 30lb injectors? right now it has 24lb stock injectors, but its set to 24.57

**steveo** · 06-15-2014

Is that as easy as installing the 30lb injectors, then setting the computer injector size to 30lb injectors? right now it has 24lb stock injectors, but its set to 24.57

assuming the new injectors are flow rated at 43.5psi, then yeah, that'll get you in the ballpark.

there's also the difference between n-heptane or gasoline flow ratings, which is a small difference, but it does make a difference.

depending on the level of ethanol in your fuel, you may have to account for that in your injector flow constant as well, since the stoich afr variable (if it exists) in EE is unknown.

then there's your offset table.

you should make sure before you buy injectors that a proper datasheet including a proper offset table is available.

30lb injectors are a bit big for a stock-ish engine, but will give you some growing room.

why dont you confirm this is the issue by doing a homemade flow bench? disable the ignition coil for safety then, hang the rails and put a container under each injector.

keep fire extinguisher handy

first just run the fuel pump to check for leakage. then just crank the thing until you get a good sampling. if you have one injector flowing more than the rest, you'll see it real quick in the jar.

you should also check fuel pressure and the other basics while you're in there

**92rslt1** · 06-15-2014

Originally Posted by steveo

assuming the new injectors are flow rated at 43.5psi, then yeah, that'll get you in the ballpark.

there's also the difference between n-heptane or gasoline flow ratings, which is a small difference, but it does make a difference.

depending on the level of ethanol in your fuel, you may have to account for that in your injector flow constant as well, since the stoich afr variable (if it exists) in EE is unknown.

then there's your offset table.

you should make sure before you buy injectors that a proper datasheet including a proper offset table is available.

30lb injectors are a bit big for a stock-ish engine, but will give you some growing room.

why dont you confirm this is the issue by doing a homemade flow bench? disable the ignition coil for safety then, hang the rails and put a container under each injector.

keep fire extinguisher handy

first just run the fuel pump to check for leakage. then just crank the thing until you get a good sampling. if you have one injector flowing more than the rest, you'll see it real quick in the jar.

you should also check fuel pressure and the other basics while you're in there

Sorry, I should have specified more, its a cc306 cam, mild ported heads, 36mm TB, aftermarket ignition, hooker headers and 3 inch cat back. Tuned by a very reputable tuner who no longer offers lt1 services so I'm trying to learn on my own. It ran amazing before being parked, it had stock fuel pump in it then too. When I started it up after its 5 year slumber it ran terrible, was missing several cylinders. I took the injectors out and soaked them over night in carb spray and blew air through them and when I reinstalled them it ran good. It now has a walbro 225 with stock regulator still. It actually still runs really good, but is too rich and lopes a bit more then it should at times. I'm leaning toward the injectors being suspect. I will try to get them to flow like you said and see what happens. My friend has a snap on scanner that will fire injectors, so I will try to rig up a pump and clear glass tank to spray test.