milesz Posted August 11, 2011 Share Posted August 11, 2011 Hey guys need some advice. I have a 2002 5.3 with a LS6 intake. The problem I am having is that when the car is in park or neutral, it idles fine but when I put it in gear Y(D or R)the RPM goes up. It's getting so bad that I can be at a stop light with the car in drive, take my foot of the brake and he car will go to 10 mph to 20 mph to 30 mph without me touching the gas pedal. What could cause this? I have already replaced the throttle sensor and the air sensor with no change. Quote Link to comment Share on other sites More sharing options...
Neverdone Posted August 11, 2011 Share Posted August 11, 2011 Is your throttle cable messed up so that it can't fully close the throttle body? Or your throttle body could also be messed up that it's not returning to idle position or it's leaking maybe. I would imagine you have a throttle body related problem though. Quote Link to comment Share on other sites More sharing options...
milesz Posted August 11, 2011 Author Share Posted August 11, 2011 Is your throttle cable messed up so that it can't fully close the throttle body? Or your throttle body could also be messed up that it's not returning to idle position or it's leaking maybe. I would imagine you have a throttle body related problem though. No the throttle cable seems fine, it only idle up when it in D or R. Park or nuetral the idle is fine. I have another throttle body, will swap it out to see if thats the problem. Thanks Quote Link to comment Share on other sites More sharing options...
Neverdone Posted August 11, 2011 Share Posted August 11, 2011 So when in neutral the revs are actually less then when in drive or reverse? Can you give some sort of range that you're experiencing? Like what revs are you at in park vs. Drive with your foot off the accelerator. Quote Link to comment Share on other sites More sharing options...
milesz Posted August 12, 2011 Author Share Posted August 12, 2011 So when in neutral the revs are actually less then when in drive or reverse? Can you give some sort of range that you're experiencing? Like what revs are you at in park vs. Drive with your foot off the accelerator. So when in neutral the revs are actually less then when in drive or reverse? Yes Can you give some sort of range that you're experiencing? Like what revs are you at in park vs. Drive with your foot off the accelerator. Idle at 5 (in P and N)when put in gear it gose to 9. Sometime if I place it in gear and wait about a min it will lower back down to normal idle. Quote Link to comment Share on other sites More sharing options...
Cable Posted August 12, 2011 Share Posted August 12, 2011 The sensor on the side of the transmission tells the PCM when the transmission is in in gear and automatically raises the RPM to compensate for the torque converter pulling down the engine, this is done to avoid the engine from running rough and/or stalling. On lighter cars like our Z's, the converter doesn't have near as much load as a Camaro or Silverado would due the increased weight. On throttle cable cars, the idle is raised with the PCM telling the idle control valve to open enough to raise the RPM. This can be changed in the PCM tune. When you install an aftermarket cam in a car with a stock converter, the idle problem gets even worse. I swapped out my stock converter for a 3200 stall until a month ago and was able to lower the idle (both in and out of gear) quite a bit since the converter pulling the motor down any longer. Hope this helps. Quote Link to comment Share on other sites More sharing options...
milesz Posted August 14, 2011 Author Share Posted August 14, 2011 The sensor on the side of the transmission tells the PCM when the transmission is in in gear and automatically raises the RPM to compensate for the torque converter pulling down the engine, this is done to avoid the engine from running rough and/or stalling. On lighter cars like our Z's, the converter doesn't have near as much load as a Camaro or Silverado would due the increased weight. On throttle cable cars, the idle is raised with the PCM telling the idle control valve to open enough to raise the RPM. This can be changed in the PCM tune. When you install an aftermarket cam in a car with a stock converter, the idle problem gets even worse. I swapped out my stock converter for a 3200 stall until a month ago and was able to lower the idle (both in and out of gear) quite a bit since the converter pulling the motor down any longer. Hope this helps. Cable, thanks for your learned reply. How hard was it to replace the converter, and, did you have to re-tune? Lastly, would this also explain why I can take my foot of the gas pedal, from a dead stop, and the car will accelerate to 10-20-30 and on? Good to hear from you ole friend Quote Link to comment Share on other sites More sharing options...
Cable Posted August 15, 2011 Share Posted August 15, 2011 Cable, thanks for your learned reply. How hard was it to replace the converter, and, did you have to re-tune? Lastly, would this also explain why I can take my foot of the gas pedal, from a dead stop, and the car will accelerate to 10-20-30 and on? Good to hear from you ole friend The converter required pulling the transmission which I didn't do myself, instead I called in a favor at my buddy's trans shop. It was done in less than a day. Some say you need to retune to avoid a code and some other issues, but I think that is with a setup that has never previously been tuned. I drove around for a month before playing with the trans settings in the PCM (I now own HP Tuners Pro) and never had any issues. If the idle is high enough, it will easily move a light car to 30 mph. Quote Link to comment Share on other sites More sharing options...
milesz Posted August 15, 2011 Author Share Posted August 15, 2011 The converter required pulling the transmission which I didn't do myself, instead I called in a favor at my buddy's trans shop. It was done in less than a day. Some say you need to retune to avoid a code and some other issues, but I think that is with a setup that has never previously been tuned. I drove around for a month before playing with the trans settings in the PCM (I now own HP Tuners Pro) and never had any issues. If the idle is high enough, it will easily move a light car to 30 mph. Good info, thanks. Quote Link to comment Share on other sites More sharing options...
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