LSJ throttle body swap, idle issues
10-21-2013, 03:50 PM
#1
LSJ throttle body swap, idle issues
First, let me start by saying that I cant stand buying from ZZP, nothing about their products is exceptional in any way. It sucks that I was forced to buy from them yet again for a product no one else makes.
That being said, I installed my LE5>>LSJ tb adapter plate today, kinda overkill price wise for what you get, just a metal plate with some screws and a gasket. The plate is bored slightly larger on the TB side and tapered to match the intake manifold, which kind of defeats the purpose of using the larger TB, but that remains to be seen on the dyno. I thought this would have been a 5 minute job, i zipped off the old throttle body, went to install the plate, when I realized there was no mounting hardware to mount the throttle body to the plate. Not only are the existing LE5 bolts too large (m8 vs m6 required) they are too short to reach through the throttle body to the plate itself. So i had to reassemble the car, and swing on over to ace and pick up some M6x45 cap screws with lock washers and some loctite blue.
Installed the tb when I got back, cut down my silicone elbow a little further to match the height difference as best as I could, although its running out of room here to say the least, you can see it is getting stretched on one end, again defeating the purpose of the larger TB in terms of flow.
At this point all is well, heres some installed pictures....
So i start the car up, and immediately notice a problem...high idle. About 1200 rpms and holding. So as im sitting there, the car drops in idle back down to 700rpms, about 3-5 minutes of idle time into it. So i rev the car, it stutters slightly, but revs up very fast throughout the rpm range, much faster then before, i would hope this signifys an increase in air velocity through the intake. As it begins to idle back down, once again it stops at 1200, and it holds this 1200 rpm until you either shift into reverse or drive, or restart the car. So i figured it might need some changes in HPtuners in terms of throttle area size, so I make all the appropriate changes, making the throttle area size changes as necessary to match the LSJ tb. Program the car, start it back up, same issue, it likes to hold this high idle when you rev it up, otherwise the car is completely fine and havent noticed any significant issues. Has anyone had this issue with the LSJ tb conversion? Should I be looking to see if ZZP wired the conversion harness wrong?
That being said, I installed my LE5>>LSJ tb adapter plate today, kinda overkill price wise for what you get, just a metal plate with some screws and a gasket. The plate is bored slightly larger on the TB side and tapered to match the intake manifold, which kind of defeats the purpose of using the larger TB, but that remains to be seen on the dyno. I thought this would have been a 5 minute job, i zipped off the old throttle body, went to install the plate, when I realized there was no mounting hardware to mount the throttle body to the plate. Not only are the existing LE5 bolts too large (m8 vs m6 required) they are too short to reach through the throttle body to the plate itself. So i had to reassemble the car, and swing on over to ace and pick up some M6x45 cap screws with lock washers and some loctite blue.
Installed the tb when I got back, cut down my silicone elbow a little further to match the height difference as best as I could, although its running out of room here to say the least, you can see it is getting stretched on one end, again defeating the purpose of the larger TB in terms of flow.
At this point all is well, heres some installed pictures....
So i start the car up, and immediately notice a problem...high idle. About 1200 rpms and holding. So as im sitting there, the car drops in idle back down to 700rpms, about 3-5 minutes of idle time into it. So i rev the car, it stutters slightly, but revs up very fast throughout the rpm range, much faster then before, i would hope this signifys an increase in air velocity through the intake. As it begins to idle back down, once again it stops at 1200, and it holds this 1200 rpm until you either shift into reverse or drive, or restart the car. So i figured it might need some changes in HPtuners in terms of throttle area size, so I make all the appropriate changes, making the throttle area size changes as necessary to match the LSJ tb. Program the car, start it back up, same issue, it likes to hold this high idle when you rev it up, otherwise the car is completely fine and havent noticed any significant issues. Has anyone had this issue with the LSJ tb conversion? Should I be looking to see if ZZP wired the conversion harness wrong?
10-21-2013, 06:44 PM
#4
Yes all of that was adjusted to match the LSJ settings, i compared the two hptuners files side by side.
Last edited by Spawne32; 10-21-2013 at 06:44 PM. Reason: Automerged Doublepost
10-23-2013, 06:18 PM
#8
wasnt happy with the way the car felt with it, put it up for sale if anyone is interested
https://www.cobaltss.net/forums/part...%2Anew-303626/
https://www.cobaltss.net/forums/part...%2Anew-303626/
10-23-2013, 06:42 PM
#10
I felt like it gained more top end but lost alot on the low end, it probably needs a better tune to match but I dont have the time nor money to invest in that right now, better off just leaving it stock then fighting tuning issues for 4-6hp.
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