myLEXsc400

I'm very happy to hear this. I just can't figure out what went wrong with my car. Maybe my ECU is going bad, idk....

ashtray

iTrader: (12)

I wouldn't say going but IS bad...try another ecu

BuffNStuff

I just spent hours opon hours trying to fine tune the tps with the idle screw, and gapping the plugs down to .024, setting timing, making sure wiring is correct, and replacing ALL vacuum lines. I got to know my car pretty well and I could tell right away if an adjustment I made left it running better or worse. I think that is the key. Having a shop do it makes it difficult to be "in tune" with what is going on.

187

Any advice on the screw and tps? I've spent hours on it with the same end result.

BuffNStuff

I have my car idling around 1000rpm

187

It doesn't try and idle down from there? No matter what my ecu tries to bring it down.

Ali SC3

iTrader: (10)

if you crack the throttle body enough via the screw the ecu will try and idle it down via the IACV, but it will max out and not be able to lower it anymore. you just haven't gone far enough so it can still compensate by closing the iacv up more, it reaches a point where it wont go lower.

issue is that if you go much past that, then the tps wont adjust to the right position cause the slots in the tps are only so large, but there is a small sweet spot where you can set it to 8-1000 rpm's and everything still work on the stock throttle body.
If you have a q45 throttle body (think ffim) with the tps adapter you can set it to any position you like and turn back the tps as there is no slot problem then.

187

My tps is maxed just to keep it in the range where the motor is happy. I've had the idle at 1000 yesterday but it just forced it back down and to its death pretty much. I set the idle back to normal and smooth, so i was going to look into the dashpot because apparently that's a thing we have and seems to be what controls the mechanical action i was describing about revving down

Ali SC3

iTrader: (10)

yeah dashpot uses vacuum to hold the throttle open some on rapid deceleration. its not needed but it helps with emissions and keeping down backfires, especially on manual trans cars.

187

My guess was just that it wasn't calibrated to deal with the flow of air and vacuum now traveling through the stock intake and just not compensating. I don't know where it is yet but if i can adjust it that would be amazing

Ali SC3

iTrader: (10)

generally the dashpot does not affect the idle. it only cracks it open while decelerating, then it doesn't do much.
its the thing with a vacuum line coming off if it right next to the tps. its got a plunger looking thing that extends out on deceleration to keep the throttle from closing all the way. when you hit idle vacuum it retracts and then the arm will rest on the idle screw.

187

I was under the impression what you described was the "throttle opener" according to the manual I have. Not really sure what that does but it doesn't seem to be adjustable?

Here is what i'm taking about, idk if it exists but its for a 2jzge from a supra

Ali SC3

iTrader: (10)

the thing in the picture above is what I described as the "dash pot". I am not sure what you mean by a different throttle opener sometimes its called both of those names.
when they say extend it with the screw driver and set it at that rpm, what happens is when you decelerate rapidly, the plunger is extended out to hold it open by the vacuum line (with the screw driver you are simulating this), but when the rpm's come down enough the vacuum changes again and the plunger retracts and does not affect the idle anymore. most of the time its just for a split second most people will never see it move much.

it should not be extended so much that in the open position it is affecting the idle, as in the plunger is pushing on the metal arm. there should be a gap unless you are decelerating. generally you do not need to ever readjust this from factory. I had actually ripped it off the ls400 throttle body I was using for quite a while. you get the occasional pop on deceleration from unburnt fuel but it never bothered me.

eblick99

iTrader: (1)

are you sure your tps is at 650 when you ohms check it with the throttle fully closed\tps unplugged? im using ffim/q45 TB, no iacv or "dash pot" etc, it idles 850-1000rpm and runs fine. the ONLY adjustment i can make is the throttle screw, i even cut all the extra stuff off the q45 ( im also obd1?). im trying to think of what could cause your problems but im not good at trouble shooting.

187

I was assuming that the dashpot and throttle opener were independent of each other. The throttle opener is supposed to be that weird thing in the front near the tps as where the dashpot is under the throttle cable stuff? The car will essentially do anything to idle at 650, so its either play with these two things or force the thing to not be able to go under like 1000 at the cable.

I can't even see it because its dark when i get out of work now but i didn't want to stumble around with these weird things in there. And i can't find much except that i can test both but only adjust one