Idle adjustment screw problem

7M4EVR

7M4EVR

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So back when I didnt know what I was doing I thought it was a good idea to turn the idle adjustment screw on th throttle body counter -clockwise a bit to bring my idle speed up. Since then I have heard that it shoudl always be closed fully clockwise. Well, the problem is if I leave it fully closed, when I come to a stop my car stalls. Does my TPS need to be re-adjusted?

Thanks,
 
7M4EVR

7M4EVR

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Midwest_Mudder;1995470 said:
reset the throttle screw, then reset the TPS. clear codes and try again.
Click to expand...
Reset the TPS? you mean calibrate? I get no code 51 so in my thinking the TPS is in it's operating range, but maybe it still is snapping shut too much too fast and doesnt throw a 51? I also think I need to test the dashpot.

HVYMAN- If i back it off a couple turns (to idle around 750) it still stalls sometimes...feels like it has to be backed out about half-way to where i know it's gotta be an air leak before it doesnt stall anymore...plus, then the idle is about 1100. If I keep the idle where it should be it stalls. Something is not working properly.
 
DeMoN2318

DeMoN2318

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Calibrate the TPS, follow these steps per TSRM:
1) set throttle screw...I have always heard all the way in...
2) set throttle stop screw
3) set Dashpot
4) adjust/cal TPS
 
7M4EVR

7M4EVR

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Midwest_Mudder;1995479 said:
have you checked your IAC unit? if its not moving freely it could stall. mine was filled with carbon, pulled it apart and cleaned it and idle smoothed out nicely

and yeah, recalibrate the TPS
Click to expand...

I have not pulled apart the IAC recently. Although about 800 miles ago before I put the new motor back together it was cleaned. At least around where that black ball looking thing seals. I did not ever take it apart further than removing the whole unit from the manifold. It does click like normal like it should though...Looks like I'm just going to have to spend the time and recalibrate/check everything. I was hoping someone would say if you have no code 51 and the IAC clicks then its something simple like a vac leak or something haha
 
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super51fan

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If your throttle body is 88' or older it has a real idle adjust. Idle air bypass screw is under a rubber plug on top of throttle body. Sometime it may require a minor adjustment.

Dash pots can fail.
 
7M4EVR

7M4EVR

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I will do those things. Ive already tested dashpot. But Ill go back and do it in that order soon. Right now, I have the tb bypass about halfway out. I got the wideband on it, and my car seems like no matter what im doing with the afpr (fuel pressure), or the AFM screw I end up with 16.7 idles, 15.6 cruise and like 9.4-10.6 at WOT. My boost controller is cheap and very touchy so my car just either just feels slow as hell at 10psi, or i barely move the controller nob and it spikes to 17-18 psi and my car breaks up real bad up top (like FC but no CEL or code).

Something is causing my car to be lean under idle and cruise and very rich on wot. I need my safc hooked up and a dyno lol but need to fix the possibility of these other ssues first. Also i should mention that my VF is always at 4.96 unless I pull the EFI fuse and clear everything. When I do that it stays at 2.75 for a while until I shut the car off it seems like. I need a good tuners help. Anyway here are my main questions right now if someone could help answer these I would be very appreciative:

1.) Can u hit fuel cut without a CEL or code being thrown? Im wondering if Im hitting fuel cut or something else is going on. It doesnt buck or jerk like fuel cut it just loses power, and my exhaust sounds all poppy like its breaking up.
2.) Can an improperly adjusted tps not throw a code and still be off, and can an improperly adjusted TPS cause a loss of performance?
3.)Will the throttle bypass screw have an affect on AFR's, and what would the difference be between all the way in and all the way out? To me, all the way out is essentially a boost leak so it would match my current AFR symptoms.
4.) I have only felt my car at its potential ONE time and its extremely frustrating that i dont know what i did to make my car run like that but before that pull and after that pull it has never felt close to that good. The worst is knowing your cars potential and not being able to get it back there. Is it really that much difference in a perfect tune or is it more likely I have other issues?
 
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DeMoN2318

DeMoN2318

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7M4EVR;1995807 said:
I will do those things. Ive already tested dashpot. But Ill go back and do it in that order soon. Right now, I have the tb bypass about halfway out. I got the wideband on it, and my car seems like no matter what im doing with the afpr (fuel pressure), or the AFM screw I end up with 16.7 idles, 15.6 cruise and like 9.4-10.6 at WOT. My boost controller is cheap and very touchy so my car just either just feels slow as hell at 10psi, or i barely move the controller nob and it spikes to 17-18 psi and my car breaks up real bad up top (like FC but no CEL or code).

Something is causing my car to be lean under idle and cruise and very rich on wot. I need my safc hooked up and a dyno lol but need to fix the possibility of these other ssues first. Also i should mention that my VF is always at 4.96 unless I pull the EFI fuse and clear everything. When I do that it stays at 2.75 for a while until I shut the car off it seems like. I need a good tuners help. Anyway here are my main questions right now if someone could help answer these I would be very appreciative:

1.) Can u hit fuel cut without a CEL or code being thrown? Im wondering if Im hitting fuel cut or something else is going on. It doesnt buck or jerk like fuel cut it just loses power, and my exhaust sounds all poppy like its breaking up.

When you hit fuel cut the CEL light will come on for about 3 seconds and then go out, however, code 34 will be stored. exhaust break-up and popping would point toward ignition system

2.) Can an improperly adjusted tps not throw a code and still be off, and can an improperly adjusted TPS cause a loss of performance?

improperly adjusted TPS should throw a code 41...but the CEL will not illuminate. improperly adjusted TPS CAN (and most likely will) cause performance issues

3.)Will the throttle bypass screw have an affect on AFR's, and what would the difference be between all the way in and all the way out? To me, all the way out is essentially a boost leak so it would match my current AFR symptoms.

Not sure on this

4.) I have only felt my car at its potential ONE time and its extremely frustrating that i dont know what i did to make my car run like that but before that pull and after that pull it has never felt close to that good. The worst is knowing your cars potential and not being able to get it back there. Is it really that much difference in a perfect tune or is it more likely I have other issues?

The ECU is really pretty smart, so with any issues it will try to protect the engine which will reduce performance.
Click to expand...
 
7M4EVR

7M4EVR

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Thank you both!

Supra is sleeping and waiting for my intercooler piping and hose kit, and the new accordian hose to arrive. Then I'm going to install those, take the throttle body/ISCV off and clean everything and calibrate the TPS all at once. I did get new plugs and re-gapped them in the meantime. Hopefully all of this together solves much of my problems. Will report back as soon as I get this done. Appreciate the feedback.
 
7M4EVR

7M4EVR

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Okay, got all new coolant and vac lines ran. Pieced together the intercooler piping, set idle screw all the way in, set stop screw, checked dashpot per tsrm thats good, and calibrated TPS (actually didnt have to mess with it much, it was good). So I dumped new coolant in, and was going to do a boost leak test on the new piping before I took it for a spin....Well, I still hear the same damn leaking air sound that I did before I upgraded all the hot side piping, but I think I might have found my problem. My BOV flange (the only pipe I have yet to replace) is leaking horrendously. From where my BOV sits it always sounded like the leak was definitely coming from the hotside pipe, however a little dish soap on the BOV flange tells the story. So...just ordered a new one from DM along with some other goodies. The symptoms I was having do jive with a bad boost leak, but the breaking up in the higher RPMS I still am not sure if I have knocked that out yet. Maybe I was running so rich up top it was cutting out? I did lower the gap on my plugs a little and noticed that my #3 spark plug MIGHT not have been pushed down all the way, could that be a possibility?

Anyhow, I believe the car will run much better after i get this leak fixed. I'll know soon.
 
IndigoMKII

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Boost leak that's big can cause the break up, think about it. AFM is seeing all this air coming in, ecu tells the injectors to go nuts for the added incoming air but it's not making it to the cylinders. You're getting the same fuel but not the same air causing a really rich condition and the plugs can't burn it all.
 
7M4EVR

7M4EVR

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Thanks Indigo. That is exactly what I was thinking, but didnt know exactly what kinds of pbysical effects actually happen when all the excess fuel doesnt ignite. Im feeling much more at ease about all these symptoms now and cant wait to drive it again. I was scared thinking compression loss or something bad! From my past experiences a small part of me is still being reserved so when i fix the leaks and have the same symptoms i dont cry like a baby haha
 
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