milesz Posted December 20, 2012 Share Posted December 20, 2012 I have a 73 240z with a 5.3 w/ls6 cam and intake. When I start the car and put it into gear, I can take my foot of the gas pedal and sometime it will surge. When it surge, the RPM goes up and I have to ride the brakes to slow it down. What is this all about? I replaced the idle air control value and there were no difference. Anyone else had this problem? Thanks Quote Link to comment Share on other sites More sharing options...
Domzs Posted December 20, 2012 Share Posted December 20, 2012 Check for vac leak , cracked vac line(s) . Any DTC ? Quote Link to comment Share on other sites More sharing options...
milesz Posted December 20, 2012 Author Share Posted December 20, 2012 Check for vac leak , cracked vac line(s) . Any DTC ? Will do but what is DTC? Quote Link to comment Share on other sites More sharing options...
wfritts911 Posted December 20, 2012 Share Posted December 20, 2012 If you are moving along at possibly any speed, the LSx motors have some BS that makes them try and keep the revs up above ~1000 so shifting is more "friendly", also seems to make it rev down slower in between shifts. If the motor is at really low RPM's it will surge because it gets bogged down. Your post is not very descriptive of when it is actually happening. Does it happen at all RPM? Or just really low? What gear are you in? How fast are you going when it happens? Could also be in your tune since you have a cam. -Will Quote Link to comment Share on other sites More sharing options...
spotmy4 Posted December 21, 2012 Share Posted December 21, 2012 This might sound dumb but make sure your throttle body blade is completely closing. I had the same issue when i let off slowly it would stick slightly open and i was fighting to slow it down. Mine turned out that the spring for the throttle blade wasn't completely winded so it was sticking open. Quote Link to comment Share on other sites More sharing options...
ktm Posted December 21, 2012 Share Posted December 21, 2012 Will do but what is DTC? A DTC is an error code that will normally throw a CEL or check engine light. If you have HP Tuners you can scan the PCM for the codes. If not, then you'll have to find someone who can scan the codes for you. If you have a smart phone, there is an application that uses a blue tooth ODBII module that you can buy for scanning codes as well. It sounds like it is happening when you are idling. I don't know how much more aggessive an LS6 cam is over that which came in the 5.3L, but if it is enough then your tune will be off. Idle tune is the hardest part of tuning a car, especially one with a cam. I would also search LS1tech.com for an answer. Quote Link to comment Share on other sites More sharing options...
milesz Posted December 21, 2012 Author Share Posted December 21, 2012 A DTC is an error code that will normally throw a CEL or check engine light. If you have HP Tuners you can scan the PCM for the codes. If not, then you'll have to find someone who can scan the codes for you. If you have a smart phone, there is an application that uses a blue tooth ODBII module that you can buy for scanning codes as well. It sounds like it is happening when you are idling. I don't know how much more aggessive an LS6 cam is over that which came in the 5.3L, but if it is enough then your tune will be off. Idle tune is the hardest part of tuning a car, especially one with a cam. I would also search LS1tech.com for an answer. Thanks Quote Link to comment Share on other sites More sharing options...
milesz Posted December 21, 2012 Author Share Posted December 21, 2012 If you are moving along at possibly any speed, the LSx motors have some BS that makes them try and keep the revs up above ~1000 so shifting is more "friendly", also seems to make it rev down slower in between shifts. If the motor is at really low RPM's it will surge because it gets bogged down. Your post is not very descriptive of when it is actually happening. Does it happen at all RPM? Or just really low? What gear are you in? How fast are you going when it happens? Could also be in your tune since you have a cam. -Will Will, Thanks for your reply. It basically happens when I turn the car on. If I let it warms up it ilde at 5.6 rpm. When I put it in gear it goes up to 1+ rpm. Sometime if I have it in gear and stay on the brakes it will idle back down to 5.6. Also, sometime, when I am on the freeway doing 50, 60 or 70 at act like it on cruise. I can literally take foot of the gas pedal and it will keep that speed. This does not happen all the time but I know that is not right. Quote Link to comment Share on other sites More sharing options...
milesz Posted December 21, 2012 Author Share Posted December 21, 2012 A DTC is an error code that will normally throw a CEL or check engine light. If you have HP Tuners you can scan the PCM for the codes. If not, then you'll have to find someone who can scan the codes for you. If you have a smart phone, there is an application that uses a blue tooth ODBII module that you can buy for scanning codes as well. It sounds like it is happening when you are idling. I don't know how much more aggessive an LS6 cam is over that which came in the 5.3L, but if it is enough then your tune will be off. Idle tune is the hardest part of tuning a car, especially one with a cam. I would also search LS1tech.com for an answer. Thanks Quote Link to comment Share on other sites More sharing options...
milesz Posted December 21, 2012 Author Share Posted December 21, 2012 Check for vac leak , cracked vac line(s) . Any DTC ? I checked the intake bolts and they all were loose. So I retighten them and it seem to do better at idle. Have not test driven it yet because of the wheather; but thanks for the advise. Miles Quote Link to comment Share on other sites More sharing options...
Dans toy Posted December 21, 2012 Share Posted December 21, 2012 Did you make any tuning changes when you installed the LS6 cam? I made the same cam change in another 5.3 project and it needed a little idle tuning. If you can't get a tuner to look at it, bring your idle up to 700 rpm, that may mask the trouble. Quote Link to comment Share on other sites More sharing options...
wfritts911 Posted December 22, 2012 Share Posted December 22, 2012 Doh, didn't even think about it being an automatic. I would say vac leak or tuning issue, and it sounds like vacuum leak since your intake bolts were loose. Hope the intake bolts fixed it! -Will Quote Link to comment Share on other sites More sharing options...
milesz Posted January 17, 2013 Author Share Posted January 17, 2013 Doh, didn't even think about it being an automatic. I would say vac leak or tuning issue, and it sounds like vacuum leak since your intake bolts were loose. Hope the intake bolts fixed it! -Will No it did not fix it. I unpluged the computer overnight and cranked it the next day and it droved fine until I turned it off and recranked it. I checked for leaks and could not find any. Quote Link to comment Share on other sites More sharing options...
Domzs Posted January 17, 2013 Share Posted January 17, 2013 No it did not fix it. I unpluged the computer overnight and cranked it the next day and it droved fine until I turned it off and recranked it. I checked for leaks and could not find any. Not sure if this is related . Did you hook up park/neutral safety switch ? This signal tells ECM what gear position you are in . Quote Link to comment Share on other sites More sharing options...
milesz Posted January 18, 2013 Author Share Posted January 18, 2013 Not sure if this is related . Did you hook up park/neutral safety switch ? This signal tells ECM what gear position you are in . No, I do not have the PNS hookup. I have the 4l60e tranny, how do I go about hooking it up? Quote Link to comment Share on other sites More sharing options...
Domzs Posted January 21, 2013 Share Posted January 21, 2013 No, I do not have the PNS hookup. I have the 4l60e tranny, how do I go about hooking it up? Actually , i'm doing LS1 w/ auto . Almost finished . I'll let you know if the PNS will make difference . Will the motor surge in park or neutral ? Quote Link to comment Share on other sites More sharing options...
milesz Posted January 21, 2013 Author Share Posted January 21, 2013 This might sound dumb but make sure your throttle body blade is completely closing. I had the same issue when i let off slowly it would stick slightly open and i was fighting to slow it down. Mine turned out that the spring for the throttle blade wasn't completely winded so it was sticking open. Mines seems to be ok. Quote Link to comment Share on other sites More sharing options...
milesz Posted January 21, 2013 Author Share Posted January 21, 2013 Did you make any tuning changes when you installed the LS6 cam? I made the same cam change in another 5.3 project and it needed a little idle tuning. If you can't get a tuner to look at it, bring your idle up to 700 rpm, that may mask the trouble. I had it retuned when I changed over the cam and intake. I did not have this problem at first, but now I think about it, have been having this problem for awhile. Quote Link to comment Share on other sites More sharing options...
milesz Posted January 21, 2013 Author Share Posted January 21, 2013 Actually , i'm doing LS1 w/ auto . Almost finished . I'll let you know if the PNS will make difference . Will the motor surge in park or neutral ? No, it just idles high, but when you put it in gear, you really have to have your foot on the brakes. And sometimes with your foot on the brakes the rear tire tries to spend. Quote Link to comment Share on other sites More sharing options...
milesz Posted January 21, 2013 Author Share Posted January 21, 2013 If you are moving along at possibly any speed, the LSx motors have some BS that makes them try and keep the revs up above ~1000 so shifting is more "friendly", also seems to make it rev down slower in between shifts. If the motor is at really low RPM's it will surge because it gets bogged down. Your post is not very descriptive of when it is actually happening. Does it happen at all RPM? Or just really low? What gear are you in? How fast are you going when it happens? Could also be in your tune since you have a cam. -Will Will, thanks for your reply. It happen when it in gear. It can be idling at 5.6 rpm and put in R (initally) it will move normally and then surge to where I have to apply the brakes to slow it down. This also happen when I first take off and at highway speed it like I have a cruse control. Quote Link to comment Share on other sites More sharing options...
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