I'll be brief.. I just got my TBSS or NNBS intake manifold swap done, along with a 92MM throttle body, and I'm having problems getting it to idle correctly. Specifically, after doing the Russ K idle config, the #'s that I'm getting from that log, when put into the tune, the engine will no longer run. So, I have to INFLATE the #'s that the log gives me in order to drive the truck. Also my Dynamic air is DOUBLE what my Idle Desired Airflow is.. From research that I've been doing I *think* it means I have to adjust my IAC Steps vs Effective Area but wanted to be absolutely sure before I go down a rabbit hole. Also, if you look at the log my TPS voltage at idle is .14V... I have had to close the throttle blade as much as possible to get the idle speed down and to actually have the IAC active. Otherwise, if I open the throttle blade up to get TPS voltage up, the IAC always shows ZERO counts at idle even on a cold start. It occurs to me that the engine is getting air from some other source than the IAC.. If anyone can review the log and tune and let me know why the disparity between Idle Desired and Dynamic, I would appreciate it. The log I did this morning was the FIRST time the engine actually idled on it's own all the way from start up to operating temp.

If I need to log additional channels, please advise and I'll make it happen immediately. Thanks for any/all help and suggestions.

 

Is this one of the budget 92mm throttle body’s?

 

Yes. It's a FI Tech 92MM throttle body. It looks to be the same China trash as the $67 92MM units I see all over Amazon and ebay. I bought it on amazon for $180.

 

I had a Holley and my tuner couldn't get it to idle right. Swapped to a Nick Williams and idles fine.

 

https://ls1tech.com/forums/generatio...azon-ebay.html

This is another post I made in the Gen 3 external engine forum.

 

I used a past idle log where I was doing the RUSS K idle config and after setting up an IAC steps position graph in the scanner, when I play that log I see that my IAC steps vs effective area table is off about 60% across the board. The factory #'s are 60% HIGHER. I've gone in to the tune, updated the changes, and after breakfast I will go out, and load the tune up to see if this has a positive effect.

 

Looks like I'm going to have to go beast mode on this throttle body as nothing I have done has achieved a stable idle. At some moments it will idle just fine, then at the next red light it will surge and stall repeatedly and then the next red light it will idle perfectly, and the next light it will idle 2-300 rpm higher... No consistency at all. I've done the following;
Ve table tuning with Wideband O2
MAF tuning with wideband O2
BRAF tuning doing the Russ K idle config-I should note here that EVERY day it spits out different #'s.. sometimes as much as 2-3 grams per second DIFFERENT than the day before under same/similar conditions. NONE of the #'s it spits out are ever high enough to achieve ANY idle at all and I have to increase them 10-20% in order to get it to idle at all.
IAC Steps vs Effective Area
Idle spark tuning (Park & In gear)
Idle overspeed and underspeed tables
Cranking VE table
Cracker tables to bring it back to idle nice and smooth and the log shows it decaying nicely. Once you come to a complete stop and it enters the idle routine-it's at that immediate point that the idle goes to poop. It won't enter the idle routine until you are completely stopped and then a split second later you can hear the note of the engine change, and it then begins surging/stalling/coughing trying to catch itself.

Reading on-line on other peoples experiences it seems the idle issues are common with this specific 92MM throttle body. Some people are saying it's because the machined bores for the butterfly shaft are poorly machined and that there is a leak between shaft and TB bore allowing unmetered air into the engine that then creates the problems. One poster said that as the temperature of the TB changed, his problems got worse and worse. I hope to fix the leaky shaft scenario and see if it really fixes the issue.

This is a FI Tech 92MM throttle body that is creating all of this drama. I recommend that you guys avoid this TB and just move on to a higher quality part to begin with.. I'm pulling the throttle body off today and disassembling it. I will get the butterfly out, and then the shaft out of the body, and then will mill the shaft bore in the throttle body to then insert turned brass bushings. I'm also milling the throttle body so that I can install seals into the body that will mate with the shaft where it exits the TB. If this does not fix it.. I will then consider it unsolvable and will either buy the Nick Williams 92MM, or get the adapter and put my 78MM factory truck TB back on. You guys DO NOT want this drama.. Trust me... It's not worth it. Leave the china trash on Amazon and Ebay-the only place it belongs.

I will post back after my machining expedition. It will take HOURS to fixture and set up, and minutes to do the actual milling.

 

I hope the TB overhaul works, as it would give some hope to those saddled with poorly made TB's.

 

Just one of the reasons we've stopped tuning nearly all Gen3 setups, failing IAC motors and other old sensors and no more "OG" ones out there available to grab, add in the proliferation of cheap chinese junk throttle bodies with things that leak and cause the IAC plunger to stick and you have a recipe for something that just won't idle correctly. Just get a Nick Williams and eliminate at least some of the variables but we've even seen some problems with those over the years, but it's your best shot.

 

pull the iac motor and look down in the bore it goes and make sure all that is correct, the iac should have a inner bore to seat on. i had one a long time ago i had to modify. i dont remember details.
if the blade isnt seating you could try loosening the bolts that hold it on just enough to let it move and open and close it a few times carefully to let it self center then tighten the bolts back. it should be pretty easy to tell if light is passing through or not.
a tb is a simple thing, i never really got the point in spending so much for a NW, though i appreciate how nice they are, i had one on my c6z.
good luck.

 

Here's the update... I removed the TB from my engine and brought it to the bench. Removed IAC, TPS, and the return spring and throttle cable lever from the end. I then realized that if I held it up in the air and shook it it was rattling.. I then grabbed the butter fly blade with my fingers and could move it back and forth in the bore much more than I should be able to. I picked up my factory 78MM throttle body and tried the same test-it has very minimal movement. I then put the FI-crap in my vise and set it up such that I could measure shaft movement/butterfly movement in the bore. With my dial indicator zeroed I measured .032" movement of the blade back and forth in the bore.
I then squirted some oil down into where the shaft exits/enters the TB housing on either side of the blade and with a little air pressure blast directed toward the outside I was rewarded with oil easily getting past the bearings on both sides. Yes, it has bearings-BUT NO SEALS-on the shaft. I went ahead and removed the blade and removed the shaft. On the TPS side there is a closed faced caged needle bearing and no seal. That side relies upon the O-ring on the TPS to be the vacuum seal for that end of the shaft. On the side that the cable hooks up to (passenger side?), there is an open faced needle bearing, and again no seal. As I was removing the shaft from the bearings I gave it the side to side wiggle test.. LOTS of slop there.. I mean a TON of slop. There is no way the shaft is going to seal on those bearings and having no other type of seal on the cable side is probably the vacuum leak. At this point I inspected the TB housing and there just is not enough meat there between the bearing, and the inside bore of the TB to machine anything. I then thought-I'll just chuck the shaft into my lathe and cut an O-ring groove on the shaft such that the O-ring will seal against that small amount of TB bore that is still there. The shaft is hardened and apparently ground well... I was turning it and my groove cutting tool was having a very difficult time cutting the groove. I stopped and sharpened the groove cutter and went back to cutting. It seemed like it was going well until it wasn't... I was taking a very slow cut, like letting it barely bite and keeping it lubed, and the next thing you know the blade flew out of the holder and the shaft went all wonky. Game over for the shaft. It's now almost "L" shaped at the end.. But has the beginning of a NICE O-ring groove in it!

If anyone has an idea where I can get another shaft, I will continue with this mission. If someone has a 92MM throttle body they took off their project and would like to donate it, or sell it to me-I'm in. Obviously I'll cover shipping. I think if I had not flubbed up the machining operation, This could have worked. Otherwise... I can machine another shaft from bar stock but that will take more time than I'm willing to invest.

The other thing I noticed as I compared the FI-CRAP to my factory TB is that the ports for IDLE AIR are significantly smaller on the FI-CRAP. The ports on the factory unit are massive on BOTH sides. The inlet side of the port on the FI-CRAP seems like it is a decent size.. But then you look at the vacuum side, or exit side into the intake manifold and it is much smaller than the inlet side.. I have a feeling that it would take significant porting on the air exit side to get the volume needed for a fast adjustment of the IAC to catch the engine before it stalls. The FI-CRAP just does not have a big enough hole for the IAC to work with on that side.

Anyways.. Failed attempt but only because I destroyed the shaft. I just purchased the Nick Williams unit from BTR.. But I still want to MAKE the China crap do it's job..

 

You probably had a sniper from holley and not a real holley tb. We use holley tb all the time and they are super easy to make idle. There is a HUGE difference in a holley and a sniper. Sniper is a Chinese tb sold by holley, the holley tb is high quality.

 

Yep, Sniper. Not the billet one.