I puchased a clean looking OBD2 B18C (Sir-G) swap from JDM Engine Depot last summer and finally got a chance to install it in my 2001 GSR a few weeks ago. The car was running a Type R block and GSR head with some minor work done including a Skunk2 intake manifold (and no I do not have the OEM GSR manifold), but all of that was removed and sold so I can't go back at this time. Anyway, everything with the JDM B18C swap went fine and the car started up the evening that I finished it. I knew it would need a few things buttoned up before I ran it, so I put it aside for a week until I could get back to it. After I finished everything and started the car I noticed that it idled at 2 to 3k until I reached my hand down and pushed the throttle back manually on the TB, and then it idled fine. I adjusted the throttle cable thinking that was holding it open just enough to idle high to no avail. Then I took the TB off and clean it until it was perfect inside and the same idle problem remained. I have also switched throttle bodies, and it still does exactly the same thing. I am running the JDM OBD2A ecu with a jumper harness, mostly because I thought it would be easier as the JDM ecu wouldn't be looking for a few sensors that my JDM engine didn't have. I don't feel that this is an ecu problem because if so pushing the throttle back with my finger wouldn't fix it. Obviously this makes it hard to drive the car as when you let off the gas pedal, it stays revving at 2 to 3k. The only other issue at this time is that the tach falls on its face when I hit VTEC, but I am assuming that the two problems are unrelated. Any help would be greatly appreciated as I have the car sold as long as it does not have any issues. If you have a question, please ask, but don't be a jerk about it. I have done more than 50 swaps including H and K swaps so I know this stuff pretty good, but I am running out of options at this point. Thanks!

 

maybe as simple AICV or Vacuum leak in the IM? Maybe leaky head gasket?
I'm surprised you have run into this problem with so much knowledge about swaps.

Anyway. Here's a link that I think will help a lot.
http://www.imperialclub.com/Repair/F...auge/index.htm

 

Same thing started happening with my gsr after an attempt to clean the IACV.
Haven't had a chance to buy a replacement and see if that would help.

 

Well I haven't located any vacuum leaks, so I have sort of ruled that out. I will look closer though. As far as number of swaps, I really put that in there so people wouldn't say things like, did you use the right throttle cable or something silly. I just need to get to the bottom of this asap. thanks for the input!

Also I was thinking last night that the IACV could have an issue, so I way try cleaning mine tonight.

 

The tach could be a ground issue. Is the engine properly grounded?

Regarding the idle, did you confirm that the TB physically closes with the return spring?

 

As far as being grounded, everything looks grounded where it should be although the car has one of those braided grounds from the valve cover to the radiator support instead of the oem one. Could that ground be causing the tach issue?

The throttle body does physically close by itself if off of the car, but it doesn't seem to return when it is hooked up. Are you aware of a vacuum port that actually helps close the TB when you let off of the gas pedal?

 

That is strange that it will not do it while on the car. Is this a stock TB? The return should be only with the spring.

 

Stock throttle body that came on the JDM GSR intake manifold.

 

Problem solved...The spring was installed incorrectly on the throttle body which made it so that it would not snap back properly. As for the tach issue, I still need to figure that out. Mod, please delete this thread. Thanks!