Super high idle at start-up with new tb

Cobra912

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Jun 25, 2005

#1

• Jun 25, 2005

• #1

Ok, I just replaced the stock tb for a frrp 65mm unit with matching egr spacer on my 86. Everything's back together but now everytime I fire it up , it'll rev up to 2300 rpm for 15-20 seconds before it drops to a 1000 rpm. probably not a problem for most but this car is LOUD and at 5:00 am it's sure to get the neighbors and my family a little upset. I've heard the TPS sensor has a lot to do with idle speed but will adjusting this help. I essentially just screwed it into the new one. How do I check this and at what voltage should I have it at? I know a new tb doesn't give you maybe more than a couple extra horses depending on your combo but she really pulls hard now and I can squawk the tires going into third gear. HHHHEEEEEHHHHHAAAAAWWWWW!

 

Vipersix

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Jun 25, 2005

#2

• Jun 25, 2005

• #2

The voltage should be as close to 1.0 as you can without actually hitting 1.0 (i.e. .999). It very well could solve your problem.

 

HISSIN50

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Jun 25, 2005

#3

• Jun 25, 2005

• #3

I agree. I think your IAC and TPS perhaps are now out of whack. What is the IAC situation now. Was any work done to it?

Here is a write up which might help you to start from scratch and go though the idle adjustment.

ALso ensure you dont have any vac leaks. Good luck.

 

Cobra912

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Jun 25, 2005

#4

• Jun 25, 2005

• #4

I had no problems with idle before. No vacuum leaks that I can detect. Put in all new gaskets. Tried to set tps voltage but stuck volt meter on it and had no idea how to take proper reading. Adjusted screws but it didn't seem to help.

 

Cobra912

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Jun 25, 2005

#5

• Jun 25, 2005

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hissin50 i tried your link thanks. I cleaned the IAC motor with throttle body/carb cleaner to no avail. Is this normal to have it rev that high at start-up? Due to it being an 86 speed density?

 

W

wildstang87

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Jun 9, 2005

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Jun 25, 2005

#6

• Jun 25, 2005

• #6

you will probably have to reset the computer and let it relearn to the new parts, adjust the idle screw, then the tps, then you might have to adjust the idle again after a quick drive.

 

HISSIN50

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Jun 25, 2005

#7

• Jun 25, 2005

• #7

That is not a normal cold start up idle. It should be ~1200 rpm if you have a ~700 RPM warm idle.

Resetting the KAM is important after cleaning the IAC if it was dirty. Otherwise, the puter has stored adaptive controls about how much duty cycle it needs to have it idle where it wants. With a clean valve, the idle will be even higher than it was before.

FWIW a stockish motor should have 15-20" hg of vac at warm idle. Even with mods you should have a vacuum signal similar since you are SD. If not, I would look for a leak, which can raise the idle.

Good luck.

 

Cobra912

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Jun 25, 2005

#8

• Jun 25, 2005

• #8

Holy smokes! have I really messed the car up? I thought put a smallish 65mm on would be no big deal. I need to reset the computer? How do I go about that?

 

Cobra912

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Jun 25, 2005

#9

• Jun 25, 2005

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Im positive I have no vacuum leaks. Will the TPS adjustment make this much of a difference? What do you mean by reseting the KAM?

 

HISSIN50

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Jun 25, 2005

#10

• Jun 25, 2005

• #10

Disconnecting the battery deletes all the stored adaptive measures the computer has taken (starts you off with a clean slate).

TPS should have been checked. If it is ~0.97 volts or slightly under, you should be fine.

 

Cobra912

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Jun 26, 2005

#11

• Jun 26, 2005

• #11

Well I adjusted the tps today to about .983 and all seems good. Start up is still 1900-2000 rpm for 10-20 seconds, then it eventually drops to a thousand. I talked to a couple of different mechanics with 15 or more years of experience each and they all seem to think that the idle is good. Go figure.

 

Cobra912

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Jun 29, 2005

#12

• Jun 29, 2005

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Hhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeelllllllllllllllppppppppppppp

 

Cobra912

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Jun 29, 2005

#13

• Jun 29, 2005

• #13

It's now worse. starts up around 2300. disconnected battery. still doin it.

 

Cobra912

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Jun 29, 2005

#14

• Jun 29, 2005

• #14

the car only started doin this after the tb and spacer. Is it just because it's bigger and sucking in more air?

 

Cobra912

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Jun 29, 2005

#15

• Jun 29, 2005

• #15

tps setting good, was told not to screw with idle control screw and haven't, and IAC is the same and untouched as it was when I took it off except for new gasket :damnit:

 

HISSIN50

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Jun 29, 2005

#16

• Jun 29, 2005

• #16

Does the TB have a hole in the butterfly plate?

What does it idle at when you have the high cold idle? If you lower the warm idle, does the high idle go down?

Good luck.