Tps
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Joined: Jan 2008
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From: wilmington de
Tps
do i need different tuning when i put a bigger throttle body on .. cause a guy at my speed shop said the bigger throttle body the tps isnt reading accurately..because between 1500-2300rpms it stumbles and hesitates and bogs down then takes off like a rocket.. he said the computer is getting bad signals.. is this true??? if so could i just unplug the tps and run it and see if it changes
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Joined: May 2008
Posts: 58
If you unplug the tps sensor, your engine probably would run but if you touched the gas, the motor would fall on its face because you are adding more air into the motor and the computer is not telling the injectors to add more fuel to keep the air-fuel ratio right. I never knew that you could adjust the tps so i'm learning a new thing today too.
What does the motor do when you give it a quick rev? Does it stall and then the rpms climb or does it rev quick?
What does the motor do when you give it a quick rev? Does it stall and then the rpms climb or does it rev quick?
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Joined: Apr 2005
Posts: 1,960
From: San Diego, CA
How much bigger are we talking? I'm running a 54mm tb and have never adjusted it and I don't seem to have any issues. I was later tuned for it, but I'm not sure if that adjusts the tps. I think I'll do this anyhow, I suggest you do also:
http://www.golenengineservice.com/html/tps.html
So just to make sure that I understand all that......after oblonging the bolt holes, I'm moving the position of the tps around any any direction while tightened slightly until I get the right readings, or is the set screw touched at all to get the voltage?
http://www.golenengineservice.com/html/tps.html
So just to make sure that I understand all that......after oblonging the bolt holes, I'm moving the position of the tps around any any direction while tightened slightly until I get the right readings, or is the set screw touched at all to get the voltage?
Last edited by MarcR94v6; Jun 17, 2009 at 02:14 AM.
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Joined: Aug 2007
Posts: 746
From: Bennett N.C.
read this also
http://members.***.net/chipsbyal/page/idle/index.html
Drilling the IAC bleed is simply copying a factory setup. Look at your stock TB, it has a bleed. Not doing anything wild. The L99 and LT1 actually had different sized bleed holes even, the L99 being smaller displacement they gave it a smaller bleed.
By cracking the blades open with the throttle stop screw you partially defeat the IAC circuit.
When I bought my BBK 58mm used the blades were cracked open a hair. I noticed this TB hurt idle quality so I went looking for a cause and found this. A little trial and error drilling out the bleed and closing the throttle blades improved idle quality with the tiny ZZ4 cam I had at that time.
Drilling the IAC bleed is simply copying a factory setup. Look at your stock TB, it has a bleed. Not doing anything wild. The L99 and LT1 actually had different sized bleed holes even, the L99 being smaller displacement they gave it a smaller bleed.
By cracking the blades open with the throttle stop screw you partially defeat the IAC circuit.
When I bought my BBK 58mm used the blades were cracked open a hair. I noticed this TB hurt idle quality so I went looking for a cause and found this. A little trial and error drilling out the bleed and closing the throttle blades improved idle quality with the tiny ZZ4 cam I had at that time.
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Joined: Jan 2008
Posts: 224
From: wilmington de
Yeah mine is a 52mm.. it just falls on its face between 1500 -2300 rpms i almost gotta floor it to get it over.. i think i might just let a professional mess with it.. anyone know someone good with lt1s in delaware or around it
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From: Hell was full so they sent me to NJ
Changing to a 52mm throttle body should not require 'tuning'. Its VERY easy to check the TPS voltage. All you need is a volt meter. Why not start there? I don't think that's the problem, but since someone at the shop said they thought TPS voltage was a problem, why not check it and put your mind at ease?
Is the engine idling at spec? Should be 550rpm in gear, 650rpm in neutral (allow for the fact the typical tach reads 100-200rpm higher than actual engine rpm), with the A4 tranny. Did the problem with the stumble/bog at 1500rpm exist before you swapped in the 52mm TB? In a speed-density system, like your 93 has, the most likely suspects are the IAT sensor and the MAP sensor.
Is the engine idling at spec? Should be 550rpm in gear, 650rpm in neutral (allow for the fact the typical tach reads 100-200rpm higher than actual engine rpm), with the A4 tranny. Did the problem with the stumble/bog at 1500rpm exist before you swapped in the 52mm TB? In a speed-density system, like your 93 has, the most likely suspects are the IAT sensor and the MAP sensor.
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Joined: Jan 2008
Posts: 224
From: wilmington de
i bought the car with the bigger throttle body and the issue has always been there .. i just never got around to having the money to play with now i do so i am trying to get the car running 100% like it should be . i replaced the tps awhile back so i dont think that it is the issue.. i heard alot of people say the map sensors will cause that. and yes the engine idles right around 550 thats what the tach says when i first start it , it will be at like 850 then will drop down to about 550
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