Topic: Idle slow to get back to normal

[jfrabat]

Hey, guys, I got a question.  I put my 62mm bored out 4.0L TB and a 62mm TB Spacer in, and after some "learning", the idle is back to normal (about 900 RPM's; not exactly normal, but the same it was with the 2.5L TB).  Anyway, I just wanted to know if it is normal for the idle to be up to about 1,500 RPM's when I get off the gas (as when I am getting into the off ramp of the highway).  The computer eventually adjusts the idle back to normal, but it takes it about 20 seconds to get it all the way down (it goes drops the RPMs little by little) to the original level.

I am guessing this is the ECM using the "old" (as in 2.5L TB) fuel curves and that it will eventually "learn" the new curves as I drive in different conditions, but I am not sure...  Anyone has any experience with this?  By the way, I DO notice more power with the 4.0L TB...

Felipe

[Sidscan]

You did reset the computer right?  Disconnect the battery and ground it to the frame.  Check that there are no air leaks and all the hoses are plugged in.  When I put on the 4.0 tb I had the high idle thing.  I found that because I also put on a TB spacer  the cables where sticking a bit, due the angle change.  I added spacers to the cable bracket and it helped. 

[VA_YJ]

You should run the 2.5 liter Idle Air valve on the 4.0 liter TB.

[jfrabat]

You did reset the computer right?  Disconnect the battery and ground it to the frame.  Check that there are no air leaks and all the hoses are plugged in.  When I put on the 4.0 tb I had the high idle thing.  I found that because I also put on a TB spacer  the cables where sticking a bit, due the angle change.  I added spacers to the cable bracket and it helped. 

Yes, I did reset the ECU.  I have yet to check for air leaks, though.  I'll check that.

You should run the 2.5 liter Idle Air valve on the 4.0 liter TB.

I am running the 2.5 IAS.

Felipe