oldred95

Allow me to nut shell the situation. Long story short I am running in speed density after many failed attempts with the MAF (still some bugs to work out) and the only thing that has changed from before my truck was out of comission until now is the 02 sensor. I have the truck pretty well dialed in for closed loop operation but startup is giving me hell still. For whatever reason it insists on flooding itself to death until it hits closed loop. I've brought the Choke AFR and Crank to run transition AFR down to just a few points and it still floods pretty bad. Not sure what I'm doing wrong. I was thinking someone said one table actually subtracts AFR in points and the other one adds. Anyway here is a screen shot of the two tables, the first shot being the BIN I was running (with perfect cold start characteristics) and what I'm running now that still wants to flood to death. And I started out after the 02 sensor change with the exact same tables as in the first shot and have worked my way down to what it is in the second shot. Cold start characteristics have only slightly improved in doing so. Any help would greatly be appreciated.

Before:


After:

gofast51

Choke AFR is subtracted from open loop AFR. If you want to lean it out,lower the values in that table. Made a big difference in mine, only had to lower it one point.I would put the crank to run transition AFR back to where you started and try Choke AFR first, it will probably do the trick. Good luck. I would also look at your crank pulsewidth table, if you have raised your fuel pressure this could need tending to.

91chevz71

wish I knew...I'm running EBL where's Fast?

oldred95

At what points are the choke and crank to run tables taking effect? What I'm seeing with tunerpro is a commanded ratio of around 11:1 at startup and as I rev the engine to keep it running it starts going up towards 13.8 or so and starts smoothing out. To me crank to run would be the initial pump shot of gas to get the engine to start, and the choke would be the extra fuel being added until closed loop to keep it running. Is that correct? If so do both the crank to run and choke tables subtract from the open loop AFR table which essentially richens the mixture? Seems like they both would but the crank to run table would only do so at startup, and after running the choke table would take over and keep a commanded richened AFR to keep the engine going. If thats the case it seems like I could set the tables to the same and to command a 12 or 12.5:1 ratio and let it work its way up from there, or is my thinking way off?

gofast51

Crank to run is only in effect between cranking and 400 rpm which is what the ECM assumes to be a running engine then choke kicks in. If I reduced the crank to run it took many more cranks to start the motor which will kill a starter.What I did is to just key on when cold to find the temps that I typically start the engine from in the summer then reduced everything below that by a 2 percent until I was satisfied.(choke afr) After all that stuff yes your thinking is correct.

dimented24x7

iTrader: (2)

You might try looking at the base crank PW. Keep in mind that if you have too much crank PW, the motor will flood as soon as it catches. Thats why the crank to run transition exists in the first place. A lot of the fuel thats injected while cranking remains on the floor and walls of the intake, especially when its cold. Once the engine catches, the fuel in the manifold gets pulled right into the cylinders as well as flashes over to a vapor and causes a rich condition. If theres too much fuel, itll flood no matter what. This was a big issue with the old ECMs as they had little control of the crank fueling. Try reducing the crank PW at the temperatures where it floods, enough to the point that it starts ok. If it dips momentarily when it catches, then you use the crank to run transition to cut the injector PW to allow the engine to burn off the residual fuel in the manifold after it catches.

dimented24x7

iTrader: (2)

Oh, BTW. Do a compare of your cranking PW as well as the cold start multiplier vs. # of DRPs and make sure theyre the same. Id be willing to bet theyre different. Also, if youve changed your injector flow, the crank PW table will need to be scaled to maintain the correct crank fueling.