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Sounds like it's time to adjust your TPS.  It should be 0.5 closed and 3.7v WOT.  Test signal wire of TPS while key is turned to ON (not running).  Once the TPS is calibrated then re-tune your air adjust screw and re-check timing (timing light).

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So I'll turn the key to the ON position, then hook up my voltmeter to the TPS signal wire, test closed and WOT? I'll try to get under the hood tomorrow morning and check. If it doesn't check out, how does the TPS get adjusted/calibrated?

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I would suspect that short elbow hose between the throttle body and the VAF, that you say is cracked. It is a common problem for that hose to get brittle with age. If it lets in any unmetered air, you will get a rough idle. (On these cars, even removing the oil dipstick will usually cause it to stall.) I think it's a dealer only part.

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Awesome, thanks for the quick responses. I understand that elbow, if its cracked and not replaced or repaired can cause idle issues, but I don't think that's causing my problems with the idle, because I wrapped that sucker really good. I'll be replacing that piece for sure with an aluminum piece for a short ram intake. I'll test out my TPS in the morning and post the readings I get so I can get to the next step of getting my idle back to the 600-700 range.

 

This site has been very helpful even with the littlest things, and I love getting replies from more senior members who have been here awhile. djdevon3, I've watched a bunch of your videos and I gotta say, you do awesome work and cover every detail. My other ride is a 93 Kawasaki Ninja ZX-6E model, theres a forum for it like mazda626.net here, and we have a saying on there, "ZX6E.net, My bike came with a family, what did yours come with?" and for me, that goes with my 626, it came with a family, Mazda626.net!

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It's always nice to be complimented.  Thank you.  This site is pretty special because of the people in it.  Unfortunately the people that run it stay behind the scenes sometimes and don't get the credit they deserve.  Thank the administrators.  They're the ones that make all of this possible.

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You're right djd3, the administrators make the whole site possible, keeping things in order and all that jazz. Thank you administrators.

 

I had to put off testing my TPS, because I had some errands to run this morning before work. I had another issue pop up that really took me by surprise. I was getting on the highway and just getting into the power band after 4k RPMS, and the car started jerking like I had not given it enough gas after shifting. On the way home, it progressively got worse, doing it at lower RPMS, but it would still idle fine with a little bounce in it. Once home, I popped the hood to check a couple things. I did notice when I was trying to adjust the idle this weekend, a plug on the timing belt side of the engine, if I tapped it the right way and hard enough would kill the engine. Looked it over and unplugged it and there was some coolant on it, probally from when the waterpump and timing belt were replaced. So I blew out the coolant and plugged it back in. As I leaned over the engine to look at the vaccum lines, I placed my hand on the distributor where the 1, 3, 5 wires meet it and they slid down a very slight bit. So I decided to check the three on the bottom side, and one of them was hanging on with just the tip of the boot. So I popped it into place and headed off to work. Well, I got my power band back. Hopefully have time tomorrow to get the TPS check done.

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Alright, I'll be under the hood a while because I have to change the oil, have probally 7-8k on this change. I like sticking around 4-6k. Is there a post on here running through the TPS, idle air cleaning and adjustment? Or do you got a vid on that djd3? I'm pretty good with adjusting the distributor.

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When adjusting the TPS, should I have the car running or not? I had the car close to running temp, and tried adjusting it. The engine didn't even shiver. I notice now though, that my rpms don't fall like they use to when downshifting, but its like I still have my foot on the gas when I do it. This was just a quick adjust to see where it went, this weekend I'll do really careful adjustment and I'll probally take the throttle body off the car to better clean it and take care of the IAC.

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There are 2 electrical tests to do on the TPS doesn't matter what engine or trans config one has.  It's much easier to do tests on the V6 TPS than the I4 TPS due to location differences.  The I4 is a pain to get at but on the V6 it's very easy to access.

 

TPS Resistance Tests:

You should do a resistance test with the car off and TPS plug disconnected.  You remove the TPS and take it to a bench if it makes it easier for you.  I just did it with it installed in the car but it was a bitch and I was cursing a lot behind hunched over for a while trying to probe 2 pins and adjusting it to find my min/max values.  Do yourself a favor and write them down. 

 

The WSM requires 2 resistance measurements. 

1. Closed Throttle - Adjust the TPS to get min/max closed throttle resistance values

2. Wide Open Throttle (WOT) - Again, adjust the TPS to get min/max WOT throttle resistance values

Those are your min/max values.  As long as your resistance checks are within specification then you can move on to a voltage test.

 

TPS Voltage Test:

The TPS uses a single signal wire to tell the ECU what values the throttle is at.  Find that wire and back probe it while the engine is running.  There are different expected voltages per year, engine, and trans config.  Consult the WSM to learn which values you should expect.  That will tell you which way you should adjust the TPS until you get the expected voltage during closed throttle.  You do not test for wide open throttle voltage for obvious reasons only closed throttle voltage.

 

During adjustments I removed and installed my intake components 3 times before I figured out what I was doing.  Do yourself a favor and figure out the voltage adjustment and set the TPS to that voltage and never move it.  Don't get the urge to fiddle with it.  Once you have the correct voltage set leave it alone and never touch it again.

 

Importance of Specifications:

It is important that you find the right specification for your TPS in both resistance and voltage.  You can adjust it and it doesn't have to exact either.  For example my TPS passes resistance tests but can only go up to 3.9v adjusted all the way to the right.  Expected voltage is 4.1 and that will throw off my throttle values and how the ECU compensates for A/F ratio.  I'm fine with 3.9v as it's pretty close.  Much closer than how it was set in the middle which was about half the voltage that it was expecting.  Sensor signal voltage is the most important part of the TPS and what you should shoot for when adjusting it. 

 

TPS is a tool for the ECU:

The TPS a reporting sensor only.  It provides the ECU with throttle angle information it needs to make important calculations and adjustments for the optimal efficiency of your engine.  The ECU uses TPS data in conjunction with data from the Mass Air Flow sensor, Engine Coolant Temperature sensor, Crankshaft Position sensor, Camshaft Position sensor, and O2 sensor in order to keep your idle speed and ignition timing correct.  It needs data from many different sensors to make the correct calculations for optimal efficiency.

 

TPS is not an Idle Speed Adjusting Tool:

After you correctly set your TPS, all adjustments to idle speed should be done using ONLY the air adjust screw and throttle stop screw (while in diagnostic mode).  As long as your IAC is working correctly and you have no air leaks the IAC will take care of the rest automatically like magic.  The ECU controls the IAC like JARVIS from Iron Man.  It's the one thing the ECU is really good at controlling.  You can't see the IAC plunger moving because it's encased in metal away from your eyes but trust me the ECU is telling it to open or close.  It knows what to do and will open or close air volume using the IAC stepper motor.  In order to correctly determine how much to open the IAC it must have good throttle angle data and that's why it's so important to have your TPS correctly set.  Without a good and correctly set TPS you can do idle speed adjustments all day long and might not ever get it to 650-750 RPM's. 

 

The TPS is a prerequisite to idle speed or timing adjustments, it's not an idle speed or timing adjustment in itself.

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Unless you have an idle overspeed, idle underspeed, or suspected leaking gasket there's no reason to remove the IAC.  If the ECU is unable to control the IAC it will set a check engine light DTC.

 

Next I would put the car into diagnostic mode (MECS-II for you).  Use the air adjust and throttle stop screw to adjust idle speed.  If either one of those are set incorrectly it could also produce an idle overspeed or underspeed error.  It's a fine tune adjustment that takes practice and experience to set. 

 

It's kind of like finding a radio station on an analog receiver.  Yeah you might hear it but there might also be static until you adjust the knob just right until everything sounds crisp and clean.  It's a lot like that.  After setting the TPS, the two knobs at your disposal for that adjustment are the idle air screw and throttle stop screw (while in diagnostic mode).  Hope that analogy makes more sense. :)  Oh and make sure the engine is warmed up prior to making any adjustments and putting the car into diagnostic mode.  Pre-warm the car first.

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Yes, both of those analogies make sense. So, when I have the car in diagnostic mode, no adjustment should be made with the car actually running? Just with the key in the "ON" position. May be my whole issue there. I have no CEL on, so my IAC should be good?

 

This morning, after adjusting my TPS, I was going to adjust my distributor(Have a small pop during idle) Is there more than one bolt to loosen, to adjust the dist?

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The distributor adjustment uses only 1 bolt on both the I4 and V6.  If you're having a misfire then I don't think changing the idle speed is going to correct that.  Anyway you'll want to do it with the car running so you can hear how it sounds while checking the tachometer to ensure it has a smooth steady idle at 700 RPM.  If you're having a misfire then you'll want to figure that one out first.  I don't think idle speed or timing adjustments can fix a misfire unless the engine is being starved of air.  Misfires are usually spark or fuel related not air related. 

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Ok I'll leave the dizzy alone for now. Do you think having the one wire barely hanging on the dizzy may have fouled it out? I'm unsure of how long it was like that, and can't believe the has ran as good as it did until it came off too far.

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I replaced the spark plugs this weekend with motocraft plus plugs, idle stabled out(still idling about 1000-1200)no more slight bouncing, and the misfire pop sound I had isn't as bad. I have had the car for just about a year and the two things I didn't replace air/fuel wise as routine maitinence are the air and fuel filters. The one spark plug that had the wire barely touching the dist was pretty black and the electrode was pretty much gone(Plugs I had in before replacing this time were Bosch Plat +)

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