Another LFP SBTB issue

[davidbcasey]

I got the KB installed...not too bad of a job but a couple things turned out to be PITAs...like the blower to intake bolt right under the plenum...never did get that thing tight enough. The vacuum lines as well. I should have put the vacuum line into the boost bypass before putting the blower on as it was not fun finagling that hose into that opening.
Another issue is the car doesnt idle correctly. I bought a new LFP SBTB and it looks like a nice piece but the blade wont close completely...or I have TPS issues. When I open the throttle and just let it close on its own it will not idle back down to 850...it stays around 1200-1500. I can manually push the blade closed and it will then idle correctly. Is there a way to tighten the spring on the TB? Or is this a TPS issue? I tried to datalog the TPS voltage using only the xcal3 but I am not sure if what I was doing was correct. The idle TPS voltage read 203v...I unscrewed the TPS and turned it clockwise as far as it would go. The datalog reading only changed to 195v. Any ideas? Thanks.

I tried doing the method Doug at BF suggested but it didnt work...


1. Warm up car
2. Turn engine off and REMOVE THE KEY
3. Disconnect negative lead from battery and turn head lights on( this removes the capacitive charge in the system)
4. Connect negative lead to battery
5. Back off the stop screw on the throttle body
6. Start car
7.While grasping the throttle lever with your hand, give it a small amount of throttle and let off SLOWLY.
8. Adjust the stop screw to just meet the lever and give it another 1/8-1/4 turn and, then lock it down.
9. Turn ignition off.
10. Turn key to "ON" position and check TPS voltage.
11. Turn key off.
12. Repeat steps 1-4 to reset ECU.
13.Drive car as you normally would so that the ECU can relearn again.

So the only change I made was adjusting the set screw to where it touches the blade stop. It still reads 203v on the TPS and the idle is still around 1000. It threw 2 codes due to this as well...p0511 and p0507. I cleared them but they will return if I dont get this fixed. I guess I could put the set screw back where it was and put a second spring on there...

 

[cobracide]

You need to set the base idle along with the tps voltage (.98v). It will take the car a while to learn the new TB setup and the idle will come down (well it did on my Dragon). The blade needs to be adjusted just BEFORE it hits and catches while closing. Search on "setting base idle". Good luck.

 

[davidbcasey]

Thanks for the info..I will do the search, but how do I set the base idle and get the TPS voltage down from 203v to 0.98v?

I adjusted the blade set screw to the point where the blade stop just hits it. When I first installed it, the blade wouldnt hit the screw with engine running or not.

 

[cobracide]

Thanks for the info..I will do the search, but how do I set the base idle and get the TPS voltage down from 203v to 0.98v?

I adjusted the blade set screw to the point where the blade stop just hits it. When I first installed it, the blade wouldnt hit the screw with engine running or not.

I know you are not saying that the tps voltage is now 203v. What is it?

 

[davidbcasey]

Well, that is what the xcal3 and livelink say the voltage is...tp_absolute or something. That not the TPS voltage?

 

[cobracide]

Well, that is what the xcal3 and livelink say the voltage is...tp_absolute or something. That not the TPS voltage?

You need to use livelink and I think 205 counts is 1V, so you want

205/1 = x/.98

205 = x/.98

(205) (.98) = x

x = 200.9

So you need 201 counts. Please verify with SCT on the counts to volts.

 

[cobracide]

BTW - I used an Aeroforce gauge and checked the TPS voltage key on engine off. Not sure you can do that with the livelink.

 

[davidbcasey]

Makes more sense...with KOEO the number is around 197. Running it is 203ish. When I back the set screw to where the blade stop wont touch it and manually push the blade closed, the reading is around 191. I put the screw back to where it just touches the blade stop with the engine not running. With the car running, I can blip the throttle and the blade will not go back to the stop.

 

[cobracide]

Makes more sense...with KOEO the number is around 197. Running it is 203ish. When I back the set screw to where the blade stop wont touch it and manually push the blade closed, the reading is around 191. I put the screw back to where it just touches the blade stop with the engine not running. With the car running, I can blip the throttle and the blade will not go back to the stop.

What's your idle rpm now?

 

[davidbcasey]

If I back the screw out to where it wont touch the blade I can get the idle down to 800 and the TPS voltage where it needs to be. When I set the screw to just touch the stop, there is too much airflow around the blade and it reads over 1 on the TPS voltage...and idles around 1100-1200. But how it is now, the idle hangs around 1500 unless I manually close the blade. POS TB if you ask me.

 

[cobracide]

ok, my car initially did the same thing. I pushed the TPS to about .85V just to get the idle down. Drove it for about a week or two, then after the car settled down pushed the TPS back to where it should be. .98V I had no issues doing that. You need to set the blade to just before it touches. Make sure it doesn't stick.

 

[davidbcasey]

That is where I have it...problem is, the idle will hang when I push the gas.

 

[cobracide]

Why is the idle hanging? Is the TB blade getting stuck? If so, it needs to go out further.

 

[davidbcasey]

If I adjust the screw to where it touches the stop plate then the idle is higher and the TPS voltage is higher...I presume due to too much air leaking around the blade.

 

[cobracide]

You may have a defective unit, may want to call Accufab and see if they can help.

 

[davidbcasey]

It's an LFP TB. I will probably get a new Accufab.

 

[SVT GI]

First make sure the gasket isn't flipped upside down. There should be a slot in it.

I pulled this from one of my sources:

1) Figure out where the PCM is set to idle. Often your tuner will know. If it's not tuned than 600-700 RPMS are a good bet. This will be your target idle RPM. You do not want the Idle air control (IAC) to be fighting the PCM.
2) Start it up, let it get to temp - this will take 4-5 minutes
3) Disconnect IAC. If engine stops, turn the throttle-stop screw in one full turn and start it.
4) Keep messing with this until you get an idle at the targeted RPM.
5) Shut off the car.
6) Set KEY ON/ENGINE OFF
7) Check the Throttle Position Sensor (TPS) voltage with a volt/ohm meter - it should be anywhere from .95 to .99 volts.
8) Adjust it if it's way off - anything over 1.05 v or so is not good - adjust by loosening the mounting screws, and lightly rotating TPS. If you can't get the volts in line enlarge the mounting holes with a drill.
9) The TPS wires you use are sometimes the BLACK and GREEN wire, or the GRAY/RED and GRAY/WHITE, depending the year.
10) Turn the key off.
11) Disconnect negative terminal battery cable. Hit the brake pedal a few times and turn the headlight switch on. Wait 3-5 minutes, then shut off the headlights and reconnect the battery. This clears the Keep Alive Memory where idle settings are stored.

Hope this helps.

 

[davidbcasey]

Thanks...read this already and basically did this today, except I didnt wait 3-5mins after disconnecting the battery and turning on the lights before reconnecting the battery. Regardless, unplugging the IAC had no effect on my idle. It is already too high so adjusting it up with the set screw wont work.

Gasket verified in correct orientation earlier today.

What would car do if IAC bad?

 

[SVT GI]

A bad IAC would cause stalls or intermitent stalls. Unplugging the IAC in these steps is only to make sure it isn't fighting against you when setting your TB.

In your case, you would only adjust it up IF it stalled while the IAC was unplugged.

So you have the set screw completely backed out? Can you push the blade shut anymore by hand after it is completely back out? If so, it may be sticking and sometimes this is cause by tightening the TB screws too tight and tweaking the body a little.

OR your TPS still isnt set right. I've had to really push on my TPS and tighten the screws real fast because it just wasn't happy sitting where it was. And I'm talking just a fraction, even with both screws in place you can vary your voltage quite a bit.

 

[davidbcasey]

What is the torque supposed to be on the TB bolts?

I can push the blade closed further and make the idle go down to where it should be but when I blip the throttle, it will hang around 1200-1500.

The TPS voltage measured varies with where the blade is...when I push it in by hand I can get to to the .95-.98v, but when I blip the throttle or set the set screw where it touches the blade the TPS voltage wont go below 1 no matter how far I turn it.

I will will loosen the TB bolts and try again tomorrow.

Thanks for the input.