Just got a built tranny installed. On start ups it will idle in park but when I go to reverse it shuts down. Do you guys think I need some type of modifying PCM. I do have a large cam but never had issues prior to new tranny. Someone please help

 

Did you do the idle relearn after installing the tranny? Do you give the car a moment to adjust to having been put in reverse before starting to back-up?

You can try raising your idle speed by 50 - 100 rpm and see if that helps.

 

I did do the idle relearn. I also put about 60 miles on it but still had problems. I could not let it adjust because as soon as it hit reverse it would shut off. Like a light switch. I am going to get taking it in to a shop localy to see if they can do anything with ls1 edit.

Gilbert

 

id check your fuel pump. a fuel pressure gauge is a nice investment as well. easy to pinpoint that problem.

 

Just a guess,something with the neutral safety switch or the VATS system?

 

It has to be the tranny. It shifts real hard into reverse or drive from park and just shuts off. Has anyone ever heard of this problem. Could the shop that did the tranny set it wrong? Like I said earlier it will idle all day in park but as soon as I go to put in D or Reverse it Shifts hard and dies.

 

TTT anybody else have an idea what might be the problem. Not a idle problem. It feels like the tranny is shifting to hard into gear and that is causing the car to die?

 

The car is in the shop and the tranny guy is saying the converter is probably bad. I hope he is just not passing the buck. What do you guys think?

 

I had a situation that is kinda similar. My car used to slam into gear real hard from park into reverse or drive. The cause of this on my car was that I used LS1 edit to increase the line pressure. What happened was, I used the table multiply feature and just increased the line pressure by a straight 25% everywhere. Problem was, the line pressure was too hard at low engine speed, hence the slamming into gear from neutral or park. The fix for me to go back into LS1 edit and reset all the line pressure numbers to stock, and only leave the line pressure numbers higher at wide open throttle. If you have an aftermarket trans it probably has different boost valve to increase the line pressure, similar to what comes with the trans go shift kit. You may need LS1 edit and drop the line pressure way down, say up to 1200 rpm or something. That way it shouldn't shift into gear so hard. If you bring the RPM up slightly, does it slam in to gear REALLY hard but stay running, or does it stall then, too? Is there just now way to keep the car running when you shift it into gear? About the converter being bad, the only thing that I can think of is that I guess it could be frozen up inside somehow. If this was the case, the car would stall whenever you shift into gear because the input shaft on the trans has to stop turning on the trans when it's in gear.