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Hi. My name is Walter. I am a newby. I do have a decent technical aptitude but not sure about this? I have a 94 LT1 Z28 that I would like to change the stoich from 14.7 to 14.4 to slightly enrichen my engine. I am having trouble passing California smog test and wondering if the E10 we are using these days is causing my problem. I do have Eehack and 9495 and a cable. Not sure if I should try this myself or not. Where do I start! Thank you!
:welcome:
Where to start, Hmm. One thought is to data log and post the data logs here for other gearhead-efi member to look at.
Is the engine stock? Usually stock engines, with a stock PCM Flash will pass emissions. Perhaps there is mechanical problem causing the emission failures?
dave w
Thank you for the reply. I have posted to another forum here: https://www.camaroz28.com/forums/lt1...-again-887486/ The posted log is after a reset. I am fairly convinced there is nothing wrong with the car however I could very well be mistaken. This has been a huge struggle for me every 2 years. California keeps tightening the specifications. Just failing NOX. Egr system has been tested thoroughly and the cat was just replaced. O2 sensors are 2 years old. Blm in normal range. I understand that the E10 fuel does cause a slightly lean condition and wonder if possible to change the stoic from 14.7 to 14.3? Thank you!
(You probably get that O2 sensor settings don't need any adjusting.) - misspoke here
My guess is you'd multiply the open loop AFRs by .95, since GM programmed those AFRs prior to E10, and stoichiometric for E10 is 14.09.
Does the test distinguish WHEN or WHERE you are failing NOx?
What were your other results?
Most recent smog reports attached. Before and after new cat. Cat was 2 years old. Thank you 🙏
Can't tell if 2.73 or 3.23, or what gear you'd be in @ 15MpH or 25MpH.
Anyway, based on the improvements you made from the 1st test to the 2nd, you have room to go a bit richer.
If you're still in open loop, multiply the relevant cells by 0.95 (depends on coolant temp sensor & MAP sensor).
If you're in closed loop, you could try raising the 1st 2nd & 3rd O2 swingpoints [away from 350mV] toward 500mV. (Leaving it like this after the test might waste MpG a bit.)
There are other shortcuts, like moving your BLM Cell RpM and MAP Boundaries and then driving around a lot to get better resolution at those speeds.
2.73 in drive. Car in closed loop. Where do I learn a crash coarse in doing this? Sorry to be su new. I do have eehack and a cable. Thank you. Walter
You have $EEhack and a cable. Do you have TunerPro, or C.A.T.S., so you can actually make changes to the .bin file?
With $EEhack but without TunerPro, you'd be making the adjustments in realtime, in front of the tester.
Assuming TunerPro, and steveo's $EEx, adjust
Air Fuel Metering - Block Learn Mode - BLM Cell RpM Boundaries
Air Fuel Metering - Block Learn Mode - BLM Cell MAP Boundaries
Closed Loop Configuration - O2 Swing Voltage
Transient Fueling - Open Loop AFR Target
Have trouble thinking of anything else that would help, apart from adjusting the Main Spark Advance & Extended Spark Advance tables [under Spark Timing], but even with $EEhack, this would require more a bit more road testing to optimise than the above measures.
Mechanically, you may have too much carbon buildup. Consider trying SeaFoam, Marvel Mystery Oil, Chevron Techron Fuel System Cleaner, or something along those lines.
Some Google Information:
What causes CO to be high in emissions?
A rich air/fuel mixture can be caused by a number of issues such as leaky injectors or excessive fuel pressure. This will cause high carbon monoxide levels as well as high carbon dioxide emissions. Malfunction in the air injection system. This system reduces the emissions of hydrocarbons and carbon monoxide.
What causes CO emissions failure?
Some common causes are spark plugs, spark plug wires, misadjusted timing or vacuum leaks. When you fail because your CO or carbon monoxide is too high, that means the fuel and air ratio is way off and there is evidence of incomplete combustion or burning of the air/fuel mixture.
What Causes High Hydrocarbon (HC)?
Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible for high Hydrocarbon emissions.
1. Improper Ignition Timing
2. Defective Ignition Components
3. Lean Fuel Mixture
4. Defective Catalytic Converter
5. Defective Air Injection Components
6. Low Cylinder Compression
dave w
On his 1st test, he was failed by HC & NO.
Then he replaced his catalytic converter.
On his 2nd test, he was failed by NO.
He was never failed by CO.
(It'd be cost-prohibitive and unjust for Wbacall to upgrade to 96-97 exhaust. Also, the EGR doesn't come into play til 4th gear, and the AIRpump is a useless piece of garbage on LT1s.)
Check your base timing and coolant temp.
Cooling system is in excellent condition. Radiator is fairly new ac delco. Distributor is not adjustable. Thanks ��
More Google information: ( https://www.discountconverter.com/te...rter-&News=216 )
NOx can be formed by many component failures and system malfunctions - anything that allows the combustion chamber temperature to exceed 2300 degrees Fahrenheit. For example, if the cooling system is utilizing pure water, it will absorb combustion heat and obtain its boiling point rapidly, leaving an air pocket around the combustion chamber. The air pocket will become a hot spot allowing for the combustion chamber temperature to rise. Equally bad is 100% antifreeze, which forms a blanket around the combustion chamber, keeping heat in and allowing the combustion chamber temperature to rise.
dave w
Not mechanically, of course not.Quote:
Originally Posted by Wbacall
Nonetheless you may need to make adjustments to the Main Spark Advance & Extended Spark Advance Tables under Spark Timing. Try the other stuff 1st, though.
I'm curious, when or possibly have the injectors ever been serviced?
dave w