Another 102mm Throttlebody
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
Another 102mm Throttlebody I have a 98 T/A ls1 automatic. I put a 102mm intake and throttle body on. I had Dyno tuned but still running just a tad Rich. Not enough for the check engine light but codes stay in pending on my scanner. I have done a reset/relearn on tps and iac. I sometimes (depending on how long it just sitting at idle) will pull a IAC code for more revolutions then expected. I know that the throttle body blade and stuff is all set. checked for intake leaks, I know I have read and read and read a lot of forums on here and done a lot of the solutions ive seen and read here and have gotten it as good as its gonna get. seems real strong and ok but when it is at cold start up it does not wanna stay running till I hold gas pedal down for a minute then it chugs till warm then idles at a nice 900rpm. I did buy an eBay 102mm throttle body. I noticed that the port for the iac motor does not have a path of air flow like the stock throttle body does for the iac motor to even function properly. Is this on purpose or was it not machined right? can I drill a small path for it to work right? why is it not idling at 1100 - 12200 rpm at start up then come down when it gets warm like it should? maybe rich from a bad injector?
ya.... def an iac problem. The iac port is too small and wont allow the engine to idle when cold. You can open the blade a tad to see if it helps but then you run the risk of maxxing out the iac closed when warm. You need to either drill the iac passage or get a different tb (not a fast). After you get that sorted i bet a lot of the issues will go away but you will still need to fine tune it.
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
Thanks. scared as all hell im gonna try the drilling a passage with a small bit at first and see what happens. I got some jb weld to block it back up if that doesn't do it. if seems a little better then I will go one more size drill bit up and then go from there. should the iac motor plunger be able to just twist in and out or not?
This is a good tip and Russ certainly knows his stuff. If you have the counts in range then that's a good starting point however it still doesn't mean the iac is large enough.
Recently on my own car i had 50 counts hot but it would still die when starting cold even with the iac maxed out
Recently on my own car i had 50 counts hot but it would still die when starting cold even with the iac maxed out
Trending Topics
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
I don't know how to check the counts. I only have this Actron meter to tell me whats up. hope this helps.
MILL STATUS - OFF
ABSLT TPS - (%) 0.4
ENG SPEED - 977
CALC LOAD (%) 5.5
MAF (LB/F) 2.09
MAP ("HG) 9.4
COOLANT (F) 167
IAT (F) 57
IGN ADV 20.0
SECOND AIR ATMOS
ST FTRM1 (%) -34.4
LT FTRM1 (%) -1.6
ST FTRM2 (%) -35.9
LT FTRM2 (%) -1.6
VEH SPEED 00
FUEL SYSTEM1 CLOSED
FUEL SYSTEM2 CLOSED
O2S11(V) 0.790
ST FTRM11 (%) -37.5
O2S12(V) 0.450
O2S21(V) 0.805
ST FTRM21 (%) -39.1
O2S22(V) 0.450
OBD2 STAT CA
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
I noticed the factory 87mm throttle body has this passage for the IAC Motor to do what it should. There is no passage for the IAC on this 102mm throttle body. how is the IAC supposed to do its job without that passage?
The dyno shop, (PCMFORLESS) or Big Shots in Hudson, Oh said the car shows 10.0 on the computer which means it is running rich. IDK? But I seen it at 10.0 and as the car went faster and more throttle it would go to 14.0
The dyno shop, (PCMFORLESS) or Big Shots in Hudson, Oh said the car shows 10.0 on the computer which means it is running rich. IDK? But I seen it at 10.0 and as the car went faster and more throttle it would go to 14.0
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
Oh yeah and where should the Throttle Blade be at when I reset/relearn the TPS and IAC Motor? And when the throttle set screw is all the way out, should the blade be fully shut as in NO AIR can get threw?
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
This is a good tip and Russ certainly knows his stuff. If you have the counts in range then that's a good starting point however it still doesn't mean the iac is large enough.
Recently on my own car i had 50 counts hot but it would still die when starting cold even with the iac maxed out
Recently on my own car i had 50 counts hot but it would still die when starting cold even with the iac maxed out
IAC large enough? What do you mean? Is there another IAC motor to buy that will fit and work better? Orrrrrrrrrrr?
This is the IAC hole every ls tb unless its electric should have one.Without this the iac will do nothing and idle routines will be useless. There should be 2 holes in the tb one for iac and the other for pcv.
The issue is that on many tb's this hole is too small to allow the iac to do its job effectively. The stock passage is huge compared to aftermarket tb's. Your scanner doesnt seem to show iac "counts" which is a translation of how open the iac is to moderate airflow. You're looking for it to have around 20-50 counts on a cammed car.
The issue is that on many tb's this hole is too small to allow the iac to do its job effectively. The stock passage is huge compared to aftermarket tb's. Your scanner doesnt seem to show iac "counts" which is a translation of how open the iac is to moderate airflow. You're looking for it to have around 20-50 counts on a cammed car.
I don't know how to check the counts. I only have this Actron meter to tell me whats up. hope this helps.
MILL STATUS - OFF
ABSLT TPS - (%) 0.4
ENG SPEED - 977
CALC LOAD (%) 5.5
MAF (LB/F) 2.09
MAP ("HG) 9.4
COOLANT (F) 167
IAT (F) 57
IGN ADV 20.0
SECOND AIR ATMOS
ST FTRM1 (%) -34.4
LT FTRM1 (%) -1.6
ST FTRM2 (%) -35.9
LT FTRM2 (%) -1.6
VEH SPEED 00
FUEL SYSTEM1 CLOSED
FUEL SYSTEM2 CLOSED
O2S11(V) 0.790
ST FTRM11 (%) -37.5
O2S12(V) 0.450
O2S21(V) 0.805
ST FTRM21 (%) -39.1
O2S22(V) 0.450
OBD2 STAT CA
MILL STATUS - OFF
ABSLT TPS - (%) 0.4
ENG SPEED - 977
CALC LOAD (%) 5.5
MAF (LB/F) 2.09
MAP ("HG) 9.4
COOLANT (F) 167
IAT (F) 57
IGN ADV 20.0
SECOND AIR ATMOS
ST FTRM1 (%) -34.4
LT FTRM1 (%) -1.6
ST FTRM2 (%) -35.9
LT FTRM2 (%) -1.6
VEH SPEED 00
FUEL SYSTEM1 CLOSED
FUEL SYSTEM2 CLOSED
O2S11(V) 0.790
ST FTRM11 (%) -37.5
O2S12(V) 0.450
O2S21(V) 0.805
ST FTRM21 (%) -39.1
O2S22(V) 0.450
OBD2 STAT CA
Russ Kemp
Thread Starter
Registered User
Joined: Nov 2014
Posts: 8
Likes: 0
From: Cleveland Ohio
something I may not have mentioned
Not cammed
completely stock other then the intake, throttle body and air induction. pics of car on my profile.
I have the hole in the front of throttle body but no passage out the back of throttle body to go into intake.
I have a friend who will help me out this weekend with a pro scan tool that does do the iac counts and help me out.
if all else fails and cant get it done the I am getting from other local dyno shops that I am using too big of a throttle body for stock motor. They are saying I should go down to a 92mm and sell my 102mm.
Also 2 dyno shops told me that if this guy did a basic mail order tune then its probably wrong for my set up and he should go threw it the right way and tune it properly. I know he only spent a about 2 hours on it and I felt he just gave up on it. I just want my car to be right
Not cammed
completely stock other then the intake, throttle body and air induction. pics of car on my profile.
I have the hole in the front of throttle body but no passage out the back of throttle body to go into intake.
I have a friend who will help me out this weekend with a pro scan tool that does do the iac counts and help me out.
if all else fails and cant get it done the I am getting from other local dyno shops that I am using too big of a throttle body for stock motor. They are saying I should go down to a 92mm and sell my 102mm.
Also 2 dyno shops told me that if this guy did a basic mail order tune then its probably wrong for my set up and he should go threw it the right way and tune it properly. I know he only spent a about 2 hours on it and I felt he just gave up on it. I just want my car to be right
