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Discussion Starter · #1 ·
Guys I need your input please. I have a 97 TT six speed (motor is totally stock) and intermittently the idle drops down to 200-500rpms @ idle. This sometimes happens when I get off the free way and the rpms will drop so low that the car dies. I have cleaned the throttle body and it seemed to help. The problem came back so I thought it was the air idle control valve. I have replaced the valve and the problem still has not gone away. I am fresh out of ideas.
Please help.
 

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it could be wiring - bad ground.
 

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You might try adjusting your TPS sensor (Throttle possition sensor) That is located on your throttle body. Did you remove this sensor during cleaning? You have two, one for trac butter fly and one for main. You want to adjust the one on the drivers side or the trottle body by losening the two screws and rotating it. You have to reset the ECU for the learning to take effect. I would also recommend driving it around. If the ecu doesn't like it, it will throw a code for you to "open the trottle possition circuit" Totally safe attempt. If you want to get more agressive you can do the idle valve mod between your power steering pump vacuum lines.

P.S. if you want to clean your vacuum system try some Seafoam.
 

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Discussion Starter · #7 ·
Hands On said:
You might try adjusting your TPS sensor (Throttle possition sensor) That is located on your throttle body. Did you remove this sensor during cleaning? You have two, one for trac butter fly and one for main. You want to adjust the one on the drivers side or the trottle body by losening the two screws and rotating it. You have to reset the ECU for the learning to take effect. I would also recommend driving it around. If the ecu doesn't like it, it will throw a code for you to "open the trottle possition circuit" Totally safe attempt. If you want to get more agressive you can do the idle valve mod between your power steering pump vacuum lines.

P.S. if you want to clean your vacuum system try some Seafoam.
Thanks for the tip.
Question: Would you still suggest adjusting the TPS sensor if 60% of the time the idle is correct and 40% the idle is low or stalling. I am afraid that it I idle up the car; when its running correctly it will be idling too high.

Also, after the car dies and I restart the car the idle normally goes to the correct RPM.

Also,Also when I was driving the car home from work today I got an check engine light w/ the ODB code P0500 (Speed Sensor Malfunction). Is this @ all related.

THX!
 

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Same problem here, although it idles below normal all the time, yet not enough to turn off the engin, pretty close though. Tonight I'm going to try to adjusting the tps sensor and see how it goes.
 

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Discussion Starter · #9 ·
IntheSearch said:
Same problem here, although it idles below normal all the time, yet not enough to turn off the engin, pretty close though. Tonight I'm going to try to adjusting the tps sensor and see how it goes.
Great. Let me know how it goes.

Also, carendt242 post made me think that it could be a bad ground on my Turbo Timer. I am going to check into this over the weekend 2.
 

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Don't screw with the tps unless your going to adjust it according to the factory manual. It's impossible to set without following toyota's instructions. The ecu does not autolearn the tps after an ecu reset. If that was the case there would never be a need to adjust it in the first place.
 
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OBD code: P0500 (speed sensor malf) huh? that might have a lot to do with ur problem. its interesting u said how it dies out after gettin off the freeway; it might have something to do with ur air sensor (MAP or MAF) or possibly a vacuum leak. either case, the amount of air going into the engine is not read accurately, meaning the amount of fuel being dumped into the engine can be too much or too low. u wouldnt happen to have put a K&N ait filter in ur ride would u? cuz according to a lot of ppl, the oil used in the filter can clog up the hot wire in ur intake, causing the intake air reading to be inaccurate. if u can post more info about the condition, im talking about detailed and accurate, when where and how...hear from u soon.

Eric
 

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In the thread I linked above it has links to pages that explain how to adjust the tps correctly, after reading those pages, I’m not too sure about doing this by hand. What do you guys think?
 

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You need a feeler gauge set and a multimeter to do this. It's a pain trying to stick the leads of the multimeter in the tps with the way it points down when setting. I got some short pieces of wire, 6 inches or so, and put some small female terminals on the ends that would fit on the prongs of the tps. Connect the wires to the prongs of the tps you need to check, then connect the leads of the multimeter to the other end of the wires. Now your hands are freed up to rotate the tps and lock it down instead trying to hold the two mulitmeter probes to the terminals you can't see while rotating the tps:(. I'd check the other adjustments on the throttle body while you're at it. Follow the sequence in the manual. Not to hard of a job. Just time consuming.
 

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Discussion Starter · #17 ·
DigSupras said:
OBD code: P0500 (speed sensor malf) huh? that might have a lot to do with ur problem. its interesting u said how it dies out after gettin off the freeway; it might have something to do with ur air sensor (MAP or MAF) or possibly a vacuum leak. either case, the amount of air going into the engine is not read accurately, meaning the amount of fuel being dumped into the engine can be too much or too low. u wouldnt happen to have put a K&N ait filter in ur ride would u? cuz according to a lot of ppl, the oil used in the filter can clog up the hot wire in ur intake, causing the intake air reading to be inaccurate. if u can post more info about the condition, im talking about detailed and accurate, when where and how...hear from u soon.

Eric
Sounds good. I ordered a boost gauge and I 'll install it this weekend and post up more details when I get them.

Thanks!
 
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