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how do you adjust TPS (Page 1/1)

traceymac

DEC 06, 04:08 PM

87 gt v6 how do you adjust TPS ?

Dennis LaGrua

DEC 06, 04:18 PM

I believe that no TPS adjustment is called for. Its like that on many vehicles

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Patrick

DEC 06, 05:05 PM

Some people will describe bending the lever to get the correct voltage. I like this alternative method better. Go to 2:50 on the timeline.

Dennis LaGrua

DEC 12, 05:18 PM

If setting the throttle position sensor voltage was critical on the basic Fiero ECM then why did the GM TPS units all come with fixed holes so that no adjustment is possible? Most TPS units come with oval holes that permit adjustment and thats what Patrick did here. Just trying to understand that GM's TPS design was made, as the part tolerance was good enough to provide the min and max voltages bolted in as is.

Patrick

DEC 12, 05:32 PM

quote

Originally posted by Dennis LaGrua:

Most TPS units come with oval holes that permit adjustment and thats what Patrick did here.

Dennis, I just want to clarify that the video I linked to was not made by me. However, I linked to it here as I feel the option demonstrated by this fella (rotating the TPS) is safer than the other method (bending the metal lever) which is often mentioned/used to adjust the TPS voltage.

theogre

DEC 13, 08:00 PM

TPS doesn't need adjusting.
Because ECM will "learn" true idle volts every time you start the car as long as within ~ 0.5 to 1.1 volts. (Charts etc list Max Limits that you don't want to push.)

Important Note: To 86 model year 4 cyl and other using 300 or 220 series TBI use same/sim TPS sensor and this applies to them. While 87+ w/ 700 Series TBI doesn't have the arm problem but most applies to them too.

If a Good Sensor "needs manual adjustment" by you for any reason...
TB/TBI have bent/worn parts.
Idle Stop is messed up or worn.
Has other electrical problems.
Maybe all at same time.

"Bent arm" on sensor then sensor is Bad.
Some problems... Arm could be bent, rusted or hole it goes thru has worn out.
If Sensor arm is bent then likely TB/TBI arm is bent too or someone bent it before.

Some TB/TBI problems... (Common problems w/ Carbs too.)
Bodies are soft Aluminum and shaft holes are often worn and oval shape. That damage is often hard to see or feel because of return spring(s) on the unit.
Shaft Arm that pushes the sensor arm wears and/or bends.
Idle stop screw tips can wear or dig a hole in the arm that hits it. That's w/o problems by people adjusting the stop.
Any/all can mess w/ the sensor.

Sensor ground is thru ECM. Do Not Ground a Meter to the block or anywhere else because may have ground problems. So May show 5v in above video but not to the ECM ground. Plus above shows 0.3 volts isn't good but value maybe different as ECM read it.

To test, back probe the plug. (A ECM scanner will show real value ECM sees but often need to check sensor really gets 5v w/ a meter.)
Open back door if needed and push 3 needles between wire and plug insulation to reach the pins. (Make sure Needles don't have coatings etc to mess w/ meter.)
If Weather Pack plugs, push needle between plug shell and big insulation.
Measure Power and Ground, then Wiper to Ground.

Power Should be 5v related to ECM ground path but iffy wire(s), plug(s) or ECM can have power or ground problems and wiper value doesn't matter then.

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[This message has been edited by theogre (edited 12-13-2021).]

Dennis LaGrua

DEC 13, 09:18 PM

quote

Originally posted by Patrick:

Dennis, I just want to clarify that the video I linked to was not made by me. However, I linked to it here as I feel the option demonstrated by this fella (rotating the TPS) is safer than the other method (bending the metal lever) which is often mentioned/used to adjust the TPS voltage.

I make no issue with you or that video. The elongated holes on the TPS probably allow for a finer adjustment but I've just always screwed them in place and they worked. Its certainly not a good idea to bend anything to fix an adjustment and agree that if you must adjust, the rotation method is safer.