I was wondering a good starting point for my AFR on a cold start in OL??? 11's? 12s? 13? Just dont want to wash down the oil with fuel.

 

Guess not that many of u guys are using WBO2s

 

Depends on "how cold", and your individual engine set-up. They are all a little different.
Very generally speaking at around 30 - 40*F I initially shoot for the mid 11's AFR. Start on the rich side and try leaning a bit more each day until you get some rough running.
Naturally, at colder temps, the AFR would need to be richer.

Depending on the characteristics of your engine, the rate at which you decay the enrichment will need to be different. A LOT of things factor into this, including idle speed, sparkplug heat-range, and cylinder head material.

Very generally speaking, aluminum heads with a large cam and headers will need a slower decay rate.

Basically, the quicker you can heat up the sparkplugs, the sooner you can lean down the AFR. Loading down the engine by driving is the quickest way to put heat in the plugs & chambers.

 

On a cold start at 50dF garage temp I see 13.0 but after cold start for about 60 secs it actually enrichens to 12.0. I have a very cold manifold so i believe atomization is compromised with some fuel falling out of suspension for first 30 secs or so. Engine never dies and the exhaust is clean after first 10 secs or so. Car drives nicely in Ol in city under 160d.

ps I use the stock L03 Fbody crank, choke, Ol tables.

 

Thanks guys, I've been tuning my OL tune with the startup enrichment vs coolant and the OL AFR % vs coolant tables... Think those are the only two I can use?

 

My only concern is if I see a lot of idle time without driving my plugs get wet from fuel. Once I drive the car it clears the plugs up right away. I run a cool plug due to my compression ratio on 11:1. ngk7e, when I spoke to the NGK plug tech guys they said that was common when a car like mine sees a lot of idle time.

 

startup enrich is cranking only I believe. choke is coolant based and times out in maybe
.10 to 15 secs?

OL/coolant temp would be the one after choke times out.

 

Might want to reduce the VE values at idle and surround cells. To lean out excess rich idle. If you have a VE table?

 

VE Table? I'm using Tuner pro 5 for 7165 ecm 6E.

 

Would my OL tune be effected by the "Power Enrichment vs.Temp" Table at idle??? I see in that table I have a value of "0" at 133*,176*,and 219*.... In cold temps it is set to 10.94@46*...21.09@08*....26.17@03*....and 32.03@ -40*....I have pretty steady values in my startup vs Coolant table as well as my OL AFR%Change vs Coolant... The AFR seems to be hard for me to lock down steady when I get into colder weather, like 40's
So would that "PE vs Temp" table come into play in OL idle???? If it does have an effect at idle i'll 0 it out to match the warmer areas of that table and just use the Startup vs Coolant and OL AFR% Change vs Coolant tables to dial in Open Loop. hanks for any help in advance.

 

Coolant temp multiplier for OL-AFR is where I would expect to find solution.

PE at idle is too much for me to comprehend PE is a high load/low vacuum fuel adder logic.
PE modifiers are irrelevant unless PE is active, there is no reason for PE at idle, so ya lost me.

I crank up dead cold 32* @ 3.5:1, hot @ 10:1.

Choke adder, from 1 point hot to 4 points @ 32*

My whole OL table is 13.8 - 12:1.

 

???????

 

I think I made those crank & choke tables before the EBL had Crank-Prime PW, so they are likely richer than need to be.

 

PE is involked only when the TPS%(70?) is hit based on a delta of movement/time.

 

Yep, you're exactly right. I also run cold plugs. That's why I mentioned leaning it out a little more each day until you find the lean limit, and you time-out your enrichment as soon as possible. I also run extra SA for cold after-start, and idle.
Bottom line is that 14.6:1 AFR is still too much fuel for idling with cold plugs. Idle doesn't build any heat in the chamber/plug and combustion is slow. You run as much SA as you can, and as lean as you can at idle to keep the plugs cleaner.
For winter driving (non-performance) a WAI - warm air intake helps a lot with warm-up, idle, keeping the cold plugs happy, and fuel economy - both open and closed-loop.

Even taking those measures, I still have to pull & clean my cold plugs periodically. It just comes with the territory, and I consider it worth the trouble. The cold plugs are designed to be happy & safe at WOT loads, so naturally they will not be able to self-clean when 95% of your driving is part throttle.

 

Hopefully someone else will come along and confirm or deny this, but I'm thinking that your OL-AFR vs temp only has effect if its value creates a richer condition than that from the MAF table. In other words the OL-AFR vs temp sets a "lean limit" to the open-loop fueling. Between the MAF table and the OL-AFR table, the ECM uses the richer of the two ? At least that's what I'm thinking.
I wish I could be more confident on this, but I avoid MAFs, and so have neglected that part of fueling logic.


Don't expect the AFR as seen on your WBO2 to always match what the commanded AFR is.
Generally, starting the spark sooner (more advance) will result in a leaner reading on your WBO2, even though the same amount of fuel is being delivered.

So, if you increase your spark advance at idle, then expect your WBO2 reading to be leaner.
The opposite is also true. A late spark will often show richer on your WBO2.

The speed of combustion in your chambers does have an effect on what your WBO2 sees.

A dead-cold engine needs a LOT of initial fuel for cranking and the first few revolutions, - much of which does not get burned, even in the exhaust pipe. This initially shows as lean on your WBO2.

As the temp starts to climb ( just seconds after cranking ) in the chamber, the speed of combustion increases, and more of the fuel gets burned, even though much is burning in the exhaust port or pipe. This will show as richer on your WBO2.

As the temp in the chamber climbs even further, most of the fuel will burn in the chamber, - given enough/proper spark advance for conditions.
Your WBO2 reading will then more accurately represent what is going on inside your combustion chambers. It will also show a leaner reading, naturally as your enrichment is timing-out.

You will want to run as much spark advance as you can reasonably get away with, AND ride the lean edge on your warm-up cycle in order to keep your chambers & plugs cleaner. It takes some time to figure out the steps in the algorithm for the warm-up cycle and the time-out timers.

If it's any consolation, the OL warm-up cycle is by far the most difficult and time-consuming part of tuning an engine. That is if you are a perfectionist and want it exactly right. As you can imagine, most people leave a lot of fudge-factor and just run hotter plugs.

hope this helps

 

The old time TPI tuners would have contests, on whose engine would settle to a dead smooth idle the fastest, at 0df after setting over night. Now that takes time.

The more you understand about what is really happening at the sensors and in the engine the easier it is to tune.

I enjoyed reading your post. It shows much understanding of the real world.

 

Thanks 305 for pointing out the affect timing has on post choke OL A/F. I have always had a richer A/F(155-195dF) in OL idle(locked) than my OL main tables show(14.3/1) . It may be that my idle SA(locked) is at 18 deg currently rather than a higher #. I too run 2 steps colder plugs(N20). I will add more timing at idle.

 

I have had good luck at around 25 deg.
Oem tunes run rich and late at startup to heatup the cat.