Rep Power: 117

I don't remember what voltage the sensor reads, I always went by the percent on my scanner and I would suggest that you do the same.

 
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ok.i will do that

 
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i searched the wire harness for damage from the IAT Sensor but i didn't found any so i didn't bother to cut any wire. I checked the TPS and it was off a little. It was off by 2 volts on the open side. it should be (4.50, same as v4.5) when close but it was 4.48. When its close it should be 0.50 same as 5v. When i recalibrate it,it was 4.5v close and 5v open. i put it back together and replaced the throttle body and it was showing 4.51 opened and 5v close.i removed it and recalibrate it again and put it back where it need to be and its go off again on the open side. I didn't bother to mess with it. So it was 4.51 open and 0.50 close. But my problem still exists mon. Still having the. Same RPM issues.i dint know what else to do.

 
Rep Power: 117

What percent is the TPS reading at idle on your scan tool? Again, if it reads too high it will think you are pressing the gas and it won't idle right. Also, when you say you checked the IAT harness for damage, I presume you mean you opened up the harness and carefully looked at both wires all the way from the sensor to where the wires go through the firewall?

 
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i forgot you told me to use the scanner to check it also. Also,its idling at 800 RPM but its just that when i press the gas pedal it doesn't come down fast as it should and when it drops it will sometimes stop at 1000 Rpm for some seconds and slowly goes to 800 Rpm. And yes, i opened up the wire harness and looked for damage but didn't see anything.
you said to connect the scanner but dont start the car,just turn the key to the on position and check on the Rpm reading.it should shows 8-9% right?

 
Rep Power: 117

Yeah just connect the scanner and turn the key on, it doesn't need to be running. The throttle position will not be under RPM, it will be under TPS. And yes, it should read 8-9% with the throttle closed. The reading at idle is much more important than the reading at full throttle, as long as it reads 8-9% at idle and somewhere around 90+% with the throttle wide open its fine.

 
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so let me get this right. The 8-9 that you mention its the RPM you are talking about and the 99+ is with the scanner showing the reading?

 
Rep Power: 117

This has nothing to do with RPM, it has to do with the throttle position percentage the scanner is showing. The number that I circled in red is the one I am referring to. TP is throttle position.

 
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ok. Wasn't trying to be difficult anyways.its just the two different numbers with 8-9% and 99+%but ok..i will let you know later.

 
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ok. Wasn't trying to be difficult anyways.its just the two different numbers with 8-9% and 99+%but ok..i will let you know later.

 
Rep Power: 117

Understood, I see where your confusion was coming from now. You thought I was talking about 2 different numbers. It's the TP that should read 8-9% at idle and 90+% wide open.

 
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yeah thats what i was confused..i will give you the information later.
i every time i tried upload a video of what i made about my RPM issue it wont let me upload it.i dont know why.

 
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so i just did check the TPS both ways and i got 9.8 throttle closed and 92 fully open .look at the picture below

 
Rep Power: 117

9.8% at idle is definitely a bit high. I do not know exactly at what percentage the ECU reads idle at, but mine didn't idle right with the TPS reading 10% at idle, my scanner doesn't show the decimal, so that could be the problem. Did this issue by any chance start around the time you changed the TPS?

 
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so you remember you told me to just turn the key to the on position but not start it and connect the scanner and it should read 8-9%? And 99+% with throttle fully open. Thats what i did. My car idle at 800 RPM.

 
Rep Power: 117

That is correct, it doesn't matter if the engine is running or not. As long as it reads 8-9 at idle and around 90% or more with the throttle fully open its fine, the percentage at idle is the critical one. Where did you get 99+% from?

 
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sorryb 90 i mean. I couldn't get 90 percent with engine running. If open the throttle plate that much with the engine running i might blew my engine because that would pass the red line by far.i open the throttle with the engine off and i got 92.2..
i might need to take it to shop for this issue because i dont know whats going on with this. And i forgot to answer your question. I dont remember if the problem start after installed the TPS though.its an aftermarket TPS.

 
Rep Power: 117

That's why I told you to do the testing with the engine off, it will read the same either way and you won't rev it to redline.

 
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yup. I dont know what else would cause this problem bro..i might have to seach through this forum for anyone with the same issue.i fond one with RPM issue but it was his IACV was dirty and his EGR valve. And my EGR valve and passage are clean. Especially my EGR passage clean it out about a month ago so thats not the problem.

 
Rep Power: 117

The EGR has nothing to do with this, it isn't used at idle. I would suggest calibrating the TPS to read correctly, that could be your whole problem. Like I said, if it reads too high the ECU will think you are pressing on the gas at idle so it won't try to bring the RPMs down.
If you still have this problem after adjusting the TPS I would see what price you could get your extra ECU flashed for, a problem with the ECU sounds pretty likely since the IAT sensor is new and you said the wiring is good and you are still getting that code. An extra ECU that is flashed to your car is a nice diagnostic tool for situations like this too since the only way to really test an ECU in a situation like this is to swap it with another one.

 
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wellñ i have an ECU here that i got on Ebay but it wont start,it just turning over.it might need to glash. I live in texas so where u at. Might have different price an locksmith. I might have to use the scanner to calibrate the TPS like u saud its best to use instead of multimeter.

 
Rep Power: 117

These cars have immobilizers, you will need to have the ECU flashed for it to start. I'd call around and see how much you can get the ECU flashed for and if they have a money back guarantee on their work. The locksmiths around me charge $70-100 to flash the ECU and some have a money back guarantee if it doesn't work. Prices may be different where you are though.
Using the scanner to calibrate the TPS is definitely the way to go, multimeters can be off a bit and the wiring's resistance could have a little effect too, what really matters is what the ECU sees. And recheck the reading once you tighten the sensor down, tightening the screws can have an effect on its calibration.

 
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yeah, i need to check on the price to flash the ECU. Yes, everytime i tightened the screws it throw the reading off by (one 1v) on one side. I remember you mentioned about the money back guarantee on the ECU if they cant flash it on some locksmith.. I will do a second calibration on the TPS and let u know. 9.8 fully close and 90+% fully open.

 
Rep Power: 117

I just thought of another possible cause of your idle issue. There is a little screw on the side of the throttle body to hold it open at idle. It is not supposed to hold it open a lot, it is supposed to barely hold it open a tiny bit at idle only so it doesn't get stuck closed and cause the pedal to be hard to push taking off from a stop. Does this screw appear to have been tampered with? It is painted over in yellow so you should be able to see if it was turned. If someone messed with that screw to try to turn the idle up or something and its holding the throttle open too far that will effectively create a vacuum leak.

 
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that screw you talking about is the idle adjustment screw. It was idling a little about normal so i was advised to turn it out so it would idle at the normal level which is 750-800 RPM.

 
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The reason that screw is there is to hold the throttle open a tiny bit so it doesn't get stuck closed and make the pedal hard to push when pressing it from an idle, that's it. It is not there to adjust the idle, the ECU does this automatically. Mine will actually idle fine without the screw in it at all, the pedal is just hard to push from a stop. The way the idle control system works is when the ECU sees that the engine is at idle (TPS below a certain percentage) it will adjust the IACV so it lets enough air through to keep the idle speed where it wants it. If the screw is holding the throttle plate open too far it will let too much air bypass the IACV and it will not be able to close off enough to bring the RPM back down to normal, which is a possibility since you said covering the IACV passage doesn't stall the engine. It is getting air from somewhere, likely around the throttle plate since covering the throttle body stalls it. While you have the throttle body off I would back that screw out so it is just barely pressing on the throttle the tiniest bit before you calibrate the TPS, this is how it comes from the factory. Again, you just want the screw pressing on the throttle a TINY bit, just barely enough to keep it from getting stuck. Be sure to tighten the nut around the screw so it doesn't move when you are done. The idle will not be too low, the ECU will adjust the idle with the IACV to keep it in a normal range.

 
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ok.the screw doesn't touch the throttle plate,it touches the the metal at the side of the throttle body where the cable connect to open the throttle plate.since i replaced the brake booster i feel a little difference when i cover the hole inside the throttle body.my finger is not that big to cover it all the way so there will be some space where air still can creep through.. I will find me a good shop to take it to so they can do a check on it.

 
Rep Power: 117

Correct, the screw holds the throttle open by pressing on the part the cable connects to on the side. It should only be pressing on it a tiny bit, just enough to keep it from sticking closed. If you can't cover the IACV hole all the way that explains why it kept running, I presumed you covered the hole all the way. Let us know what the shop says. I would take it to a good independent shop rather than the dealer, the dealers are often more interested in replacing parts than diagnosing and fixing the actual problem as you unfortunately found out.

 
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i really thought that screw was to adjust the idling and not to keep the throttle plate from being stuck.i really dont fancy dealer that . they couldn't even find my head gasket problem.they ran test on the car over an hour and still couldn't say that i have a blown head gasket. I talk to a guy about checking on my car but he said i would have to leave it for a week so he can look at it. Thats a long time because. I have to go to work.but i still want to have fix.
i cant cover the hole all the way because my finger isn't that big and i cant turn it sideways inside the throttle body to block it off all the way.and yeah, the screw not pushing the throttle plate too much.

 
Rep Power: 117

When I first started working on my car about 10 years ago I thought the same thing about that screw until I messed with it and caused an idle issue and did some research. I agree about the dealer, they definitely should have found that brake booster leak too. Is the idle issue consistent or intermittent?