tuning for cold engine

[vortecfiero]

I have a rough spot around 3000 rpm when the engine is dead cold... probably in open loop
the engine goes flat.. and a little rough

To test F28's overall effect I set the values to .092 and have noticed an improvement
im sure its the wrong way to do it.. but i cant seem to find where to adjust open loop
cold fueling
i have set...
0x06CDKEGRTEM1EGR - Temperature Level For EGR Enable151.2Deg. C

craig

 

[leroy]

Re: tuning for cold engine

Have you tried the f56 table? Cold engine tuning is difficult because the engine warms up, and you have to wait until the next morning (or until it cools off) to test your changes.

Jim

 

[vortecfiero]

Re: tuning for cold engine

Have you tried the f56 table? Cold engine tuning is difficult because the engine warms up, and you have to wait until the next morning (or until it cools off) to test your changes.

Jim

yes i looked there but it seemed that it was a closed loop table since it is setting
AF ratios (with the oxy sens ?). I could be wrong of course lol

 

[JSM]

Re: tuning for cold engine

Yes, it is an AFR, but not really based on O2 in cold. As you make the AFR lower it will put more fuel in during those temps.

Nothing really there to change just one rpm range though, it will affect the whole thing.

 

[turbodig]

Re: tuning for cold engine

yes i looked there but it seemed that it was a closed loop table since it is setting
AF ratios (with the oxy sens ?). I could be wrong of course lol

Doesn't work that way... the AFR term in the fuel equation is pretty much an arbitrary fuel value... lower it, and you get more fuel, raise it, and you get less.

The reason it might seem RPM sensitive is that it multiplies with the VE and other tables... which may make it much worse at some RPM ranges vs others.

Like Jim said, it's tough to tune because you only get a short window of time. Below zero weather helps - takes less time to cool down. Best to have your wide-band warmed up and ready, then start the engine. Read the data, change the cold fuel table, repeat.

3-4 cool-down sessions later, you'll be a lot closer.

If it makes you feel better, the factory cal was no great shakes in this aspect. They had federal and Cali emissions to meet, and needed to be lean.

Many years ago, I had to add a bunch of fuel to a Ty owners cold fuel table to get it to run decent -bone stock. Turns out the intake had a hairline fracture, and had a vacuum leak.
This leaned it out enough when cold to make it run poorly, but would work ok once the ECM hit closed loop and would start correcting.


Later,

Dig