Idle issue

Clown9

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So with this post I will either be heralded as the guy who eats glue or as the guy with the continuing issue. Also apologize for the vertical filming as my phone only seems to be able to save in vert mode :facepalm:
I started the car so it could get to operating temperature before I did any tests and I noticed something underneath the car.
I will let you all be the judge of what you see as I am ashamed to even type it out.


Only that one side showed anything substantial.
Now after that fiasco, which may or may not render the rest of my post useless, I will continue.


I do not know if I did this right or not since to get to the post on the alternator I have to remove the intake manifold which I do not want to do since I'm a lazy ass.
There is a cable coming straight from the alternator post (added image). I disconnected it from the battery and tested from there.
Like I said I think I did it wrong but let me know so I can stop being lazy and actually take the manifold off and rig something up to the alternator.
Towards the end I did put the positive lead like a foot away from the alternator on the cable. Also I will add that in another video I changed the negative lead to the engine block and there was no difference in voltage.



Next up, I disconnected the pedal and there next to no change in idle.
I reconnected the pedal and disconnected the TPS and restarted the car and this is the result:


20180419_172537.jpg
 

07gts197

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That leak loots too far away from the o2 sensor to cause problems and is reflected in the logs. The ecu would be pulling fuel from bank 1 but it seems minimal.

It seems to idle better with the tps unplugged. I wouldnt go out and buy a new one yet. With the key on engine off log the resting pedal position for 10 seconds then slowly push down on the pedal all the way and slowly release the pedal. The transition should be smooth and should start around a volt and wide open throttle is around 5 volts. Im not sure exactly which pid it is as Ive never logged tps voltage on my 07 gt but it shouldnt be hard to find. If necessary back probe the harness with your volt meter then record it with your phone while you push the pedal in the car. You could also hold the throttle at varying positions for say 10 seconds each time and watch the voltage for movement. And remember usually tps’s will get flat spots and they tend to be where the throttle spends most of its time, i.e. cruising.
 

Clown9

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Just to clarify that is right behind the passenger's side O2 sensor and converter.

In forscan and in the Revx tuner there is no such thing as TPS voltage. Only thing it'll show is the TP1 and TP2 voltage.
Had to get creative with my the multimeter.
Now from what I recorded it seems right around 4.1->3.9 volts either my multimeter is cutting out or the TPS is. Also from doing the same thing from ~1.31-1.29 volts.
Towards the end of the video I do it more and more. You can here like a loud click when it cuts out.

 

redfirepearlgt

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YIP! You did the voltage check correctly. It's been 5 years since I had my 2005. I was thinking that the cable connections were all crimped to the battery terminal lug at one spot and unable to be separated as you were able to do. GOOD JOB! Now you see the AC ripple is less than 200 millivolts AC. My old mind is slipping. They say memory is the second thing to go.........I can't remember what the first is. LOL!

So at say 14vdc idle with a liberal 200mvac your AC ripple percentage is 1.42% AS long as the DC voltage is regulating properly and that blasted one way clutch inside the alternator isn't slipping (except at WOT as it is designed and supposing you have not upgraded the alternator to the later model that eliminated that stupid idea) you should be fine IMHO electrically. Now you can continue to move on to other things with confidence.

On you meter reading for the TPS, take it out of auto measure mode (if possible) and measure in a manual range mode that won't be jumping from scale to scale. If you have already done this then you may wish to get another meter to verify. I keep an old Simpson P260 analog meter around for such things. Digital displays for checks like this as good as they are may create false indications. I have one on my workbench at work for such checks.
 
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07gts197

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Hmm it looks like you may have found your problem. Did you notice around 4:30 voltage dropped below 1 volt for a split second? I kind of skipped through but did you hold the pedal steady or let off entirely at all?
 

Clown9

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On you meter reading for the TPS, take it out of auto measure mode (if possible) and measure in a manual range mode that won't be jumping from scale to scale. If you have already done this then you may wish to get another meter to verify. I keep an old Simpson P260 analog meter around for such things. Digital displays for checks like this as good as they are may create false indications. I have one on my workbench at work for such checks.

I'll retest with manual mode, thanks for suggestion 8)


Hmm it looks like you may have found your problem. Did you notice around 4:30 voltage dropped below 1 volt for a split second? I kind of skipped through but did you hold the pedal steady or let off entirely at all?

Held the pedal steady the entire time.
Like I said towards the end I showed those blips more often and it was slightly past closed throttle.
You think a dip close to WOT would cause idling problems??
 

07gts197

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I doubt one close to wot would cause idle issues but one around closed throttle would.

So you were holding the throttle open? Id say you have a big problem lol.
 

Clown9

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I doubt one close to wot would cause idle issues but one around closed throttle would.

So you were holding the throttle open? Id say you have a big problem lol.

I now realize I articulated my words in a not so efficient manner.
I very slowly pushed the pedal down to WOT and then sloooowly released it. Kept it at CT and WOT for a few seconds then slowy pushed and released.
 

Clown9

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So I tested the TPS voltage with the meter turned to manual mode and once the pedal goes about 75% of the way it shows 0 Volts (Which I'm guessing is because it is moving from one sensor to the next).
Still clicks and goes down to about .7 volts when releasing the pedal tho.
I turned meter back to auto and it does the same thing as in the video previously posted.

I still have the old throttle body. Would it make any sense or would it be feasible to swap the sensors?
The old TPS is 6L2E-9E928-AA
The new TPS is AG1E-9E928-BA
 
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Marble

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How's your antifreeze level? I've never seen an exhaust leak like that when there wasn't a leak somewhere up steam..seems rather odd.
 

Clown9

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How's your antifreeze level? I've never seen an exhaust leak like that when there wasn't a leak somewhere up steam..seems rather odd.

Coolant levels have stayed the same for the entirety of me owning the car

Edit:
Forgot to add that this was in like 30º degree weather.
 

07gts197

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I now realize I articulated my words in a not so efficient manner.
I very slowly pushed the pedal down to WOT and then sloooowly released it. Kept it at CT and WOT for a few seconds then slowy pushed and released.

So I tested the TPS voltage with the meter turned to manual mode and once the pedal goes about 75% of the way it shows 0 Volts (Which I'm guessing is because it is moving from one sensor to the next).
Still clicks and goes down to about .7 volts when releasing the pedal tho.
I turned meter back to auto and it does the same thing as in the video previously posted.

I still have the old throttle body. Would it make any sense or would it be feasible to swap the sensors?
The old TPS is 6L2E-9E928-AA
The new TPS is AG1E-9E928-BA

I would reinstall the old tb before swapping parts.
 

redfirepearlgt

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^^ MEGA DITTOS! I agree. Just not sure for troubleshooting purposes how the tune will react to the smaller TB especially at idle which is the most difficult part of any tune.
 

07gts197

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I ran a gt500 tb with a tune for the stock tb and all was well. I could tell the ecu needed some time to relearn because the idle would slighly hunt before settling. Im sure it would be the same the other way around.
 

Clown9

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Car starting with stock TB is a negative.
Engine turns over, runs for a second, then acts like I switched the key off lmao
 

Moostang313

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I know this is an old thread but did u ever figure it out? I’m having the same idling issue.
 

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