I have a TBI 350 with vortec heads, aftermarket truck cam (don't have specs), and full emissions. When rapidly opening the throttle from a stop while in gear, it has a tendency to pop back through the intake or bog down. I even made it stall once while rolling along at a low rpm and then punching it. If you roll into the throttle gradually, it comes on nice and strong. My question is , what would cause this? Is it bad tuning in the custom Jet chip ? I was wondering if it might be a transient fuel problem or maybe EGR. It feels like it is leaning out. Do you think it is something I can eliminate by tuning or is it hardware related?

Thanks!

Don

 

My guess is that it is a tuning issue.

I am having a similar problem on my '95 Z. I've been trying to fix it by running in speed density mode and manually tuning VE tables. It's a real pain, though!

I've asked about the same thing, and no one had any suggestions about what to try first (timing, AFR, etc.).

Wish I could help more, but I am pretty sure you can fix it with tuning (not a hardware prob).

 

Probably tuning!

Probably need to tweek the PE table and maybe the Acceleration Enrichment vs Delta TPS

It's pretty hard to get it right with a mailorder tune.

Steve

 

Thanks for the help. Looks like I need to find me a chip burning setup now. Anybody have some suggestions for a good setup?

Thanks!

Don

 

Well, I solved the problem. After burning several chips which disabled egr, increased the ve tables and "pump shot" that Jet made too lean, I still had a really bad pop that would occur and sometimes stall the motor. I re-adjusted the valves and it still did not fix it. As a last resort, I advanced the distributor just a couple degrees (My father's suggestion ). That was it! No more pop. I also picked up a lot of power on the low end and eliminated the hesitation. The distributor was originally set by the book with the wire unplugged under the dash and set to zero with a timing light. It apparently did not like it. I am really happy now .

 

Thanks for posting. I never would have guessed that you had a timing issue. Now that you've got you burner you may be able to tweek some of the timing tables, head to the dyno and tune your PE table to flatten out your AFR.


Steve