*Update*

I have not done what scsexy has recommended yet.

However I just got done looking over my car and decided to check all the sensor connections for any frayed wires. Sure enough some of the wires on the TPS connector fell right off upon inspection. Luckily I have a spare harness that I will be replacing the wires with. I am hoping this will resolve my problems. I have played with the TPS so much and taken the plug on and off repeatedly that it must have made it worse each time also it does not help that my harness is 27yrs old haha.

I will report back soon.

 

good find, have had to replace tps and iacv connectors, all the high use connectors like the coilpacks suffer from that problem.
pretty bad at getting the coolant sensor connector off personally, rest of them have gotten better at over the years.

 

*Update*

Unfortunately I am still chasing down this issue. I have cleaned up somethings that may have been causing issues but have not fixed my overall issue with the poor cold start.

I tested the map with the key in the on position and the sensor is putting out 2.6v and from what I have read that is accurate. Could the MAP still be bad? Is there a better way of testing it?

I have swapped on a different stock FPR and no change.

I have removed the BCD and no change.

I have noticed that the only time I get a good cold start is when I reset the ECU. Could this mean the ECU is bad? Cant figure out why it would only have a perfect cold start after resetting the ECU.

I did just purchase a new fuel rail, AFPR and new fuel lines that I will be installing not sure if that will fix the problem but it cant hurt to upgrade.

Thanks

 

Yeah i mean try double keying it up unless u have your pump flowing full force once u key up. I saw u said you would let the system prime but for how long? I usually wait like 3-5 seconds tune the radio to whatever i want then do it. It can't hurt cuz its an easy test.

crank sensor and wiring is all good? Your ecu could be bad if it always works on reset but it could also mean you have a bad sensor reading and on reset it goes off default settings

 

Yeah I got the the pump setup on the 12volt mod so its full power as soon as I key on. But I have tried waiting a few seconds and even tried double keying and no change.

Any idea what sensors default after reset?

Only sensors that I have not tried replacing are IACV, Distributor, MAP, Coil packs.

I feel like it's not the coil packs due to the fact that the car does start. I feel like if it was the MAP it would do it all the time and the car has good AFR's in boost and out of boost with an occasional lean AFR on a hot start.

I'm thinking maybe the IACV could be bad. However it resets every time the car is shut off.

I have checked the distributor and wiring is all good there but it's possible could be going bad internally.

 

Keep us posted because mine has the same issues but it always starts up second attempt when i leave the key on for a couple seconds before trying to start it.

 

Will do. Waiting for a MAP sensor to show up and see if that helps at all if not I'll just keep working my way down the list of sensors.

I started thinking it could also be related to the iat sensor but 1 at a time.

 

*Update*

Ok, after throwing more money at the problem unfortunately it still has not been resolved.

Good news is I no longer have a tachometer issue and no longer have a starting issue.

Bad news is I still have a weak cold start idle. The car will start perfectly fine and the RPM will jump to about 2k real quick then bounce off of it and drop down to about 1050-1100RPM.

The things I have changed recently to help remedy the problem are below.

Map Sensor
Distributor
IACV
Radium Fuel Rail
Radium FPR
fuel lines

I am currently waiting on some new Yaris coils so I can have a true COP setup and to eliminate the ignitor all together. Not sure if this will solve the problem or not.

But at this point I really don't know what it could be. The odd thing is I can get the car to do a perfect cold start if I reset the ECU. But once it relearns everything it goes right back to low idle at cold start.

Any suggestions are appreciated and I will continue to update this thread as I try to resolve this issue.

 

honestly doesn't sound like there is much wrong? maybe I am not understanding how you are describing it.
when you say bounce off of it, does it stumble/miss and then fall immediately to the lower rpm, or is it a gradual fall?
1100 is not that off for a cold start once the ecu has learned stuff... the actual idle rpm for a cold start depends on how cold it is and is as well as learned values from the previous starts, so it is always higher before the ecu learns some values.
if you are at 1000-1100 cold start, and then down to 750-800 when warm that sounds normal, well depending on outside temp.

changing out coils isn't going to help an idle issue, it will not help what you are describing.
you could try and tweak the set stop screw and tps some, but it might just make it worse also especially if its in the right spot already.
another thing that has an affect on these cars with learned values is an intake pipe leak, it will throw the ecu off as it learns and you get issues like that.

it might just be working fine, maybe post a video of the next cold start so we can see it cause what you are describing sounds pretty normal.
the ecu is supposed to learn stuff for cold starts, it will dial it in to only the rpm you actually need as it learns more.
If I could see it happening I feel like I could point you in the right direction.

 

I have considered that it may be working perfectly fine as driving and any other aspect of the car seems to be fine. I have just always read cold start idle is usually around 1300-1500RPM for about a min or 2 then down to about 750-850RPM. I will do a boost leak test and determine if I have any leaks. I will take a video tomorrow morning it should be about 50 degrees outside.

I am also comparing this to my GS400, LS400, and Camry. When I start any of them for the 1st time of the day it will idle at about 1400RPM for a min or 2 before dropping down to its warm idle.

When I say bounce off I mean you can see the needle hit 2k and as soon as it does it immediately drops down to 1k-1100RPM. No stumble or misfire, it has a smooth idle.

On a side note something I have discussed with you before is a lean issue on a hot start. This occasionally happens and the AFR is about 17.5-18.5 when this happens it does sound like a misfire is happening and you can feel a little stumble happening. Any reason for this?

Thanks

 

It is more or less normal on the tt ecu for it to have the low idle faster with the mod, you probably don't have a leak but worth a check.
I think the gte throttle body is slightly larger so could be part of the small difference.
You could turn in the throttle stop screw ever so slightly to crack the throttle plate open a hair more, but you will have to turn your tps back to match also.
it is easy to go too far and throw it all off is why its probably not worth messing with it unless you are comfortable adjusting tps.

generally the tt ecu tends to learn fast and will correct faster than alot of the other ecu's I have played with.
I think part of it was to keep emissions down as they already had issues with that having to go to the maf on the usdm models.

The hot start issue is normal for any map sensor car and is well documented, when you shut down your car your engine and coolant temps actually rise for a while (no circulation).
The hotter combustion chamber affects the combustion as well as the ecu reading hotter temps and usually means trimming the fuel more.
It is something that the turbo cars just live with, and really only effects emissions and not performance as those misfire pops let out unburnt emissions etc. and usually clears out when you load out the engine.

on the non turbo cars, cali spec obd1 and all obd2 and vvti the 2jzge has a vsv on the fuel pressure regulator which instead of seeing idle vacuum on a hot engine start (which lowers fuel pressure), it will actually open up the fuel pressure regulator to ambient air (like when engine is off, floored in acceleration, or when crossing 0 psi into boost for turbo cars; this raises fuel pressure compared to idle vacuum), which raises the fuel pressure so you get more fuel in to help fight the hot start and thus not have misfires making emission problems (each single misfire adds a significant amount to your readings).
It will only do this temporarily controlled by the ecu when it detects hot start conditions.

The reason this is only on n/a models, is because 0 psi is the most you can ever see without a turbo/Supercharger, so there is no chance of blowing your motor by running lean on fuel pressure if you just start the car and floor it like you are at a track.
Now on a turbo car, you can get in and on the first pull hit 14+ psi, but if your fuel pressure regulator is open at 0 and doesn't see the extra 14 psi, you will run horribly lean and blow your motor, which would be bad.

So instead of making it possible to blow your motor if you get in your car and immediately redline it, they decided to live with the extra emissions it caused for whatever reasons.
They could have fixed it in the software somehow, but that is clearly not what happened... instead they just phased out the gte completely due to emissions instead of even trying to bring the vvti gte stateside.