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Installed Big Bore Throttle Body - Rough Idle?

Joined
15 July 2003
Messages
1,941
Location
Redondo Beach, CA
Installed the SOS Big Bore Throttle Body today. Pretty straight forward DIY project. After the install I noticed that engine revs a lot quicker than before . The engine seems more rev happy.

The problem I'm having now is the rough idle. If I rev the engine to 3-4k, the RPMwill drop down to to 300 - 500rpm for a second then goes up 1200k then fluctuates to 800-900rpm again. It will keep doing the same sequence over and over again. I did double check the hoses after the install - maybe I'll check again tomorrow.

Anybody have an idea what's wrong? Perhaps air in coolant hoses? bad 02 sensors? Reset ECU to learn new throttle body?

Thanks for the help guys! :frown:
 
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I'm no expert at all, but I would assume one of the first things you might want to do is reset the ecu to adjust to the new airflow, as you mentioned...
 
You can do that by using a propane torch (obviously without a flame). Move the open flowing torch tip around the vacuum lines and connections. If there is a leak, you will hear the motor rev up when the propane enters the the engine through the leaky line.
 
You can do that by using a propane torch (obviously without a flame). Move the open flowing torch tip around the vacuum lines and connections. If there is a leak, you will hear the motor rev up when the propane enters the the engine through the leaky line.


WOW that sounds dangerous :eek:
 
Thanks for all the help guys. I did reset the ECU (disconnect battery cable) and the idle is now steady at 800rpm. Problem solved! :biggrin:

Thanks again!
 
Do you have an intake along with the TB? I'd like to know how the 2 would do. Seems to me that both of them would work better together.
 
You can do that by using a propane torch (obviously without a flame). Move the open flowing torch tip around the vacuum lines and connections. If there is a leak, you will hear the motor rev up when the propane enters the the engine through the leaky line.
I've done this before, never blown up yet.:rolleyes: FWIW you can use WD40 as well.
 
So Henry, what prompted you to get a BBTB? Are you going FI in the future?

Wouldn't that get pretty messy pretty quick even holding the can upside down?

I think the preferred product to use for checking vacuum lines is a can of Quick Start and not WD40. I used to buy that for my Jetski to get it to start after long term storage.
 
So Henry, what prompted you to get a BBTB? Are you going FI in the future?

Hey Dennis,

I just thought I'll upgrade the throttle body since the car is a 91. I can feel the difference - the car seems to redline at ease. I have the prospeed tuned chip so maybe Brian can fine tune it once I install the headers and hi flow cats.Hope to get some dyno numbers soon. :tongue:
If I have the extra $$$ I'm definitely going FI..:biggrin:
 
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Thanks for all the help guys. I did reset the ECU (disconnect battery cable) and the idle is now steady at 800rpm. Problem solved! :biggrin:

Thanks again!

In the future, all you need to do is remove the "Clock" fuse. This is the same fuse to the ECU. It's located under the front hood in the fuse box there.
 
do yu still have your original throttle body? I need an air control valve and the dealer wants to sell me the entire throttle body for $1600. My nsx is a 1998. I would be interested if your will fit, alex
 
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