Stop drilling those TBs, fix stalling without computer tuning...
Originally Posted by Hayrab
I cannot get the TPS to reset. I've got it to read 2%, and followed the steps but when I start the car after plugging the TPS back in it still reads 2%, what could I be missing?
TIA
TIA
according to another post.. after doing this mod you should make sure the TPS voltage is still less than .6V otherwise it messes up the fuel trim selection. is this point valid? after setting my TPS to 3% above stock my voltage is .67V.
Originally Posted by PewterZ28
I'm sort of having the same problem. I can get it to reset once but after I turn off the car again and restart it, it goes back to reading 3.5%. I've tried this at least 10 times and every time it only works the first time I restart the car. Then if the car dies or I have to turn it off and restart it, right back to reading 3.5%. WTF!!!
Originally Posted by PewterZ28
I'm sort of having the same problem. I can get it to reset once but after I turn off the car again and restart it, it goes back to reading 3.5%. I've tried this at least 10 times and every time it only works the first time I restart the car. Then if the car dies or I have to turn it off and restart it, right back to reading 3.5%. WTF!!!
The problem happens when you go too high on the TPS voltage, it's not because you're doing the procedure wrong. The only way to get around it is to drill the throttle blade or turn the tps clockwise by elongating the mounting holes.
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It was mentioned early on that the author was unsure if this technique would work on other PCM's. I have a large Solid Roller cam in my '96 OBDI converted Z28 and I had idle issues after the engine was fully warmed and when I pulled up to stop lights/signs. The motor would labor down to around 500 and, after a few seconds would regain the desired idle of 1,000. Using the method described, I too was able to get the perfect idle behavior. Thanks a ton for this great writeup and technical advice!
Step 8 needs to be added. You need to check to make sure you are getting 100% WOT when the pedal is to the floor after your adjustments. On my TCS equipped car I had to adjust it.
Idle tuning To see my setup go to; https://ls1tech.com/forums/generation-iv-internal-engine/790938-my-lsx-454-buildup-pics-side-tips-i-learned-along-they-way.html
I've been tinkering with the car some more. I just reinstalled the A/c into it, and that aggravated my crappy idling. Also even after the dyno tune it had some surging or bucking at low throttle or no throttle at lower Rpm's. I have been fighting the throttle body for weeks now. If I screw the throttle open far enough to bring the Iac counts down to a reasonable level, the tps reads 2-4% open even though there is no throttle.
I was reading the post; Stop Drilling those Throttlebodys
https://ls1tech.com/forums/showthread.php?t=177230
So To fix my problem I had to drill the Throttle body. I ended up with a 3/8" Hole in the blade. This brought the Iac steps down to a reasonable level, I show about 5-10 Iac steps at hot idle no a/c, and about 100 Iac steps with the A/c on. And WOW did that make a incredible difference in the driveability and stability of the car!! Day and night difference, It has no bucking or surging anymore!!!!
So with that big of a engine and cam, and a small throttle body it needs a hole. No amount of resetting the tps will fix it if the blade is open so far that the tps dose not go back to zero.
Also I did try to elongate the tps holes and that helped some but not enough.
__________________
I've been tinkering with the car some more. I just reinstalled the A/c into it, and that aggravated my crappy idling. Also even after the dyno tune it had some surging or bucking at low throttle or no throttle at lower Rpm's. I have been fighting the throttle body for weeks now. If I screw the throttle open far enough to bring the Iac counts down to a reasonable level, the tps reads 2-4% open even though there is no throttle.
I was reading the post; Stop Drilling those Throttlebodys
https://ls1tech.com/forums/showthread.php?t=177230
So To fix my problem I had to drill the Throttle body. I ended up with a 3/8" Hole in the blade. This brought the Iac steps down to a reasonable level, I show about 5-10 Iac steps at hot idle no a/c, and about 100 Iac steps with the A/c on. And WOW did that make a incredible difference in the driveability and stability of the car!! Day and night difference, It has no bucking or surging anymore!!!!
So with that big of a engine and cam, and a small throttle body it needs a hole. No amount of resetting the tps will fix it if the blade is open so far that the tps dose not go back to zero.
Also I did try to elongate the tps holes and that helped some but not enough.
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Last edited by 1Hotbird; Jul 21, 2008 at 09:10 PM.
Great post. This worked well for me also. I pulled the screw out of the throttle body and turned it around so it was easier to get at. I like this method. I am around 30-32 counts on IAC position.
My throttle body blade had a hole drilled in it when I got the car. I am also running the vacuum system that is stock on my 70 which has ten miles of vacuum hose and probably has a few leaks.
My throttle body blade had a hole drilled in it when I got the car. I am also running the vacuum system that is stock on my 70 which has ten miles of vacuum hose and probably has a few leaks.
Last edited by Eddie 70; Oct 2, 2008 at 07:39 PM.
I showed this procedure to a fellow tuner last night and it worked great on an LSX with a nasty cam. Down to 35 IAC count and 900 rpm's
1) You will want to monitor your IAC, Idle Speed, throttle position voltage and your throttle position %.
2) With the key in the ON position, adjust your tb set screw until your throttle position is 2%.
3) Turn your key to the OFF position.
4) Unplug your Throttle Position Sensor (TPS).
5) Turn your key to the ON position for a few
seconds, and then OFF again.
6) Plug in the TPS and then turn your key to the ON position and restart logging. Your throttle position will now be reset to 0 degrees and about .45-.55 volts. Any higher can put you into the wrong fueling cell.
7) Start your engine, if you are not at your desired IAC position redo the above procedures in smaller increments.
1) You will want to monitor your IAC, Idle Speed, throttle position voltage and your throttle position %.
2) With the key in the ON position, adjust your tb set screw until your throttle position is 2%.
3) Turn your key to the OFF position.
4) Unplug your Throttle Position Sensor (TPS).
5) Turn your key to the ON position for a few
seconds, and then OFF again.
6) Plug in the TPS and then turn your key to the ON position and restart logging. Your throttle position will now be reset to 0 degrees and about .45-.55 volts. Any higher can put you into the wrong fueling cell.
7) Start your engine, if you are not at your desired IAC position redo the above procedures in smaller increments.
I dont think it is needed to unplug the tps sensor between your steps. The learning will happen on its own as long as the key is cycled. There are perameters you need to change like TPS for base spark tables and others need to be moved up a little to make sure there are no other issues. But this method definatly works as i use it and tell others to use it often...
We tried to do it without unplugging but it wouldn't zero out (with EFI live it said 20% throttle). By unplugging it the PCM threw a code and when we plugged it back in to reset itself because the fault was gone. Either, yes it works great and is very easy.
I have my counts down to 32 at around 900 RPM. The voltage is at .67. I understand this needs to be come down about .25mV. Will loosening the screws on the TPS and moving it get this voltage where it needs to be? I am guessing that the relearn will have to be redone again since the TPS has been moved.
If this does not get the voltage where it needs to be, where do I go next?
If this does not get the voltage where it needs to be, where do I go next?
You can try to loosen and it and adjust it but there is a small tab you may have to remove to get it to move and/or slot the screw hole out a like bit. But yes, this should work to lower the voltage.
I adjusted the TPS to around .49 volts. I can go a little lower to around .41 but thought that the middle would be good enough. I wound up pulling the TPS and filing the tab off and elongating the holes. So far so good. Lets see what happens.
Is it normal for the car to smoke a little while doing this procedure? I'm not getting blue smoke just a faint white smoke. I've got my IAC's to 40 on idle and almost 100 while the a/c is on and it's hitting my desired idle.