2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Jumping Idle

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Old Feb 11, 2002 | 12:02 PM
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From: sandiego, ca
Jumping Idle

Ok.. Common post but I adjusted the tps with two pretty blue radio shack lights. I turned the screw just until one light turned off. All my poping went away and my idle came back down and smoothed out. But...

When cold like 1minute after its been on , the revs jump from 1000-1500 and bounce.... Now I adjusted my tps and was doing this before the misadjustment. What can be causing this... I dont think its a stuck back because I dont have AC.PS. Also when I decelerate off the gas I hear a missing sound one every second evenly. I replaced the plugs and wires and still does it.

Can dirty fuel injectors cause the ECU to do this??? The engine was rebuilt 10,k ago and purred since before I started F-IN with it.
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Old Feb 11, 2002 | 12:28 PM
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My TII had a similar prob. Crappy idle and the warm up bounce. I just outright bought a new TPS, installed and used a voltmeter to adjust to 1.00v. Crappy idle and cold bounce went away after that.

Hope that helps,

Joe
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Old Feb 11, 2002 | 12:42 PM
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Damm. So I guess this is another tps question ansewer. All well. My tps is only 40k old but I guess I will have it looked at. THNX.. and anyone else????
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Old Feb 11, 2002 | 12:44 PM
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Buy it used or new? If it's not used, then you might want to look for other problems. But never rule out anything.
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Old Feb 11, 2002 | 04:25 PM
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Josepi, did your car drive ok with the bad TPS? I have adjusted to 1 ohm, then checked weeks later and it was at .5 ! It was completely warmed up when adjusted. I readjusted it to 1 ohm again, but it still idles rough cold and hot. The motor runs fine if not idling. I 'm planning to check it again this weekend. If it reads different than 1 ohm again I guess it is my problem, but I assumed a bad TPS would affect it accelerating. They aren't cheap are they?
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Old Feb 11, 2002 | 04:33 PM
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No, my car drove like ****. Ask Erik, he rode in it (medium bucking). The idle was shitty, if I hit the brakes about 50 times really quick it would stall, felt like I had a bad secondary, or the turbo was going bad. Any time I got on a particular part of the throttle, it would just drive like ****, bucking around (like it wanted to idle while going at 3K-surging a lot)

Decelerating was horrible, after 2k and falling it would buck...

It can make itself noticable during accel or decel. 1 ohm? Do a search for Hailers method of setting it to 1.00v using a multimeter. The resistance (ohm) will only tell you if it is working correctly, not tell you the voltage that it (the TPS) is sending back to the ECU. When the car is fully warmed and the key is in with all the idiot lights on (initial set grounded) it should read @1.00v.

Mine started out with a lil bad accel. Then a twitchy idle. Then it was shitty on decel, and even worse on both accel and idle. Had the idle jump while warming up too.

Swapped for a new one from mazdatrix, set it using the voltmeter, and it's been perfect since.

S4 NA or TII is around 160
S5 TII is 260
I forget what the S5 NA runs...

Joe
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Old Feb 11, 2002 | 06:16 PM
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From: sandiego, ca
Oh.. But when cold my car spits out gas too. I can tell when I look under the muffler like someone put gas in a squirt gun and sprayed it...Dont think the tps would do that.
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Old Feb 12, 2002 | 07:38 AM
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Josepi, thanks for your reply. I wasn't having a great day yesterday, I meant to say 1 volt , not 1 ohm. Sounds like my problem isn't TPS as I thought, the motor runs fine except idling is rough. I am going to check TPS setting again though since it did seem to change.
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Old Feb 12, 2002 | 08:31 AM
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What about BAC valve? That causes that kind of idle problem. It fixed my GTU.
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Old Feb 12, 2002 | 09:38 AM
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I have replaced the BAC once in 183K miles, not to say it couldn't be bad again except isn't the BAC on only when using AC and power steering? I replaced it years ago when it would die coming to a stop with AC on.
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