SD tune tip in lean

[98LS1]

I know this has been asked many times. I have yet seen any post that actualy tells what paramrters to change and what direction to go either by raising or lower any values to get rid of lean tip in. Have car SD tuned and runs great. Only problem is when I let off to shift gears or when running at steady speed as soon as I touch the accelerator I get a lean spike. Some times this causes a ping or knock for a spilt second that I can hear. I have tryed many things but haven't found any thing that will get rid of this problem. If I could get this fixed I will have the tune on this car complete. By the way the car is a 1998 Z-28. Any help would be appricated. Thanks Bill

[blownbluez06]

You can control how quickly PE kicks in and how soon (as far as MAP signal goes). Have you changed any of that? Post your tune.

[WS6FirebirdTA00]

Post a tune and log...

[TXZ0603]

I have this EXACT problem. Have you got it fixed yet?

[Cantalope Kid]

98ls1 - In the future you need to post a log of the issue using your scanner software, and a copy of your tune. Also a list of your mods would help too.

[Nitroused383]

Sounds like transient fueling. Fuel control > transient > fuel to wall impact factor. Look at what coolant / map readings where you are getting the lean spikes. Increasing the numbers adds more fuel. I had to almost double some values.

[TXZ0603]

^^

I notice on mine that the map readings a far below what is in the transient fueling table. IE: mine, 8.5 kpa @ 181 deg F = 18.58 AFR

The table allows for a min of 20 kpa.

[Texas_WS6]

I have the same issue. It would be nice to fix this.

[WS6FirebirdTA00]

First thing to look at is the injector flow settings, secondly is the transient fuel min mg.

[Texas_WS6]

I am running Gregg's injector data. I will try to play with the transient fuel next.

[WS6FirebirdTA00]

I posted in another thread, and IIRC the higher the value (say 0.045) the richer tip in and changes. The lower the values (0.032) the leaner. Of course this all depends on the injectors/setup. There may be other ways to make this better, but this value has worked the best for me when I did not have all the detailed injector data. This did not fool with anything but the tip in stuff and it made my commanded AFRs look like the actual. Step on the gas hard and actual took a step to the richer commanded, let off fast and it goes right back up.

[marksrig]

why do these threads just stop?

[Mcreskar]

Yea it sucks when the thread just dies off...