snksknr94

I can't seem to get the hydrocarbons down enough to get the car through. In fact they have gone up in every test, no matter what I do. I tried the guaranteed to pass stuff, it didn't work, I tried unplugging an injector, that didn't work, then this last time a friend of mine used LT1 edit it the car to lean it out, and they still went up. I don't know what else to do. I need to be at a .8, the first test I was at a .92, now after LT1 edit I'm at a 1.81. What else can I try to get the hydrocarbon count to drop? I know it is unburned fuel but we leaned the car out a considerable amount and it got worse. If anybody has any info. that would be great.

PGR

Is it failing the idle measurement, the high rpm, or both?

Cold be an ignition miss, a fouled CAT.

A fresh oil change with synthetic oil will lower HC levels some, might allow it to squeek by this time.

snksknr94

It's failing at highway speeds. There is no miss and the cats are brand new. Oil is at about half life.

snksknr94

ttt

Injuneer

Any misfires? Sure way to increase unburned HC's. Unburned air goes out the pipe.... the O2 sensor sees it and says "lean - add more fuel", and the PCM adds fuel to the entire bank of 4 cylinders, pouring even more HC's out the exhaust.

Pulling an injector wire will accomplish just about the same thing.... cylinder pulls in air, no fuel. Air goes into exhaust, O2 sensor sees all that O2 and richens things up for the 3 cyl's that still have injectors..... way too much fuel... lots of unburned HC's.

How is your CO? I would expect the excess air from pulling an injector wire would have reduced CO, but increased HC's.

Do you have access to a scanner? That will tell you if you have a "false lean" condition because of misfires, an exhaust leak or faulty O2 sensors.

When you say you "used LT1_Edit to lean it out".... exactly what did you do? Most emissions tests are run at low throttle postions, that keep the system in closed loop. The closed loop A/F ratio is hard coded into the PCM, not something that you can change (at least based on my limited knowledge of Lt1_Edit). What did he change to "lean it out"?

snksknr94

Unplugging an injector actually made the CO's go up. The bruchure the emissions gives when you fail lists injector problems as a reason for the CO's to fail. The other 3 times I tested they were fine, just the HC's that are high.

I'm not real sure what was done to lean it out, as I'm new to the whole LT1 edit thing, he told me was making the injectors bigger to lean it out. The car is running much leaner now. My block learn went up all across the board according to the Scanmaster. I talked to a tech at work he told me to pull some timing out, try to lean it out a bit more, and maybe change my plugs and wires, which I was getting ready to do anyway. Basically I just need to get the HC's down without raising anything else.

Injuneer

What you don't seem to understand is that making the engine think the injectors are larger doesn't actually lean it out for more than a few seconds. After the first few seconds of closed operation, while the injectors flow less fuel, the PCM saw the lean condition and added the fuel back in using the BLM"s.... that's why your BLM's went up..... NOT because it IS running lean, but to prevent it from running lean. Its still running at 14.7:1. OR maybe it isn't if you've got the "false lean" condition.