I recently installed a set of Bosch III 32lb injectors in my LT1. The new tune that I have been working on looks pretty good, except for startup. On a cold start it will stumble a little then start. On a warm startup it will really struggle unless I put the throttle to the floor. It seems the initial injector pulse is too much, smells very rich. Is there a TunerCat table where I can correct this situation?

 

If your injector size is input correcly into the tune and your fuel pressure/injector size combo is correct for what you entered into the tune then you should not need to modify the settings listed below. Mine was fine even with 42lb Ford Green top injectors, when i switched to 83lb injectors I believe it was still somewhat ok but when I started reducing the injector size in the tune to compensate for lean tip in is when my crank/startup problems popped up.



I posted this in another thread but some info should apply to you:
https://www.camaroz28.com/forums/sho...d.php?t=560089 POST #240

My warm start delay annoyance problem is all fixed!! Starts right up warm like it did when stock FINALLY!

To fix it I had to actually LEAN out WARM CRANK FUEL by doing this:
1) Prime Pulse Width Vs. Coolant Temp
2) Crank AFR Vs. Distrib. Refer. Pulse Vs. Cool. Temp

Initially I thought it was too lean so I was adding fuel and this only made warm start worse, so I went back to stock then removed about 1/2 the values from stock and sure enough when warm starts right up cleanly everytime! No more tapping the throttle to get it to start. Bout time

Cold start also seemed to "jump to life" fiercly so I leaned out a little fuel there too now cold start seems normal as well. Makes sense since I had to pull about 1/2 fuel out of all the other fuel tables at some point.

 

Thank you, that's exactly what I was looking for!!

When I first installed the injectors I had the constant set at ~32 and the fuel pressure at 43psi. It was dangerously lean across the board at these setting. So, I gradually decreased the constant, and even increased the fuel pressure to get the idle and part-throttle values in line. Each time I would lower the constant or up the fuel pressure the starts would get worse.

I'm running Bosch III 32lb injectors. They seem much more sensitive than the stock Multecs.

 

I reduced the values by 25% in those two tables, and the car started much better today. I may try another 5-10% just to see what happens.

Thanks again for your help.
-Mike

 

Great to hear, when it fixed things for me I was fired up as well.