Throttle Position Sensor Repair ...

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Throttle Position Sensor Repair ...

Postby cwmoser » Sat Feb 05, 2011 7:37 pm

I'm getting a P0507 code indicating something to do with the idle air control.
This code is the computer stating that the RPM is too high for the settings.

Here is my Throttle Position Sensor (TPS) from my 2000 Isuzu Trooper:
Image

How would you suggest I clean it? Looks like there is a stepper motor.

Here is the cover for the TPS:

Image
I opened this cover and there are some gold springs in it.
They are on the back side of the above.
Not sure what the springs are for. Can't find an electrical connection to them.


My Throttle at rest has this much opening. I'm tempted to adjust the screws so it closes tighter.
Do you think I should do that?
Here is my Throttle at rest:
Image

Carl


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Postby Buster28 » Sun Feb 06, 2011 12:31 am

Image one is NOT the Throttle Position Sensor (TPS).

Image two IS the TPS or more precisely TPS 1 and TPS 2. There are four
electrical connections +5 VDC, +5 VDC Return, TPS 1 output and TPS 2 output.
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Postby cwmoser » Sun Feb 06, 2011 9:35 am

Thanks for the correction - I'm learning.

The TPS in photo 2:
How does it work?
I can take it apart and there are some gold springs inside.
Is there any repair or adjustment I can do to it?

How about Photo 1 with the gears? Should I clean/oil it?

In photo 1, the throttle plate is at rest. Should I adjust it to more fully closed? I'm having erratic high idle and just got the P0507 DTC.

Thanks

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Postby Buster28 » Sun Feb 06, 2011 11:24 am

Clean and lightly lubricate the Throttle Valve Motor actuator gearing with a high temp lubricant.

The 6 springs make contact with the small removable cover which electrically are two potentiometers, TPS 1 & TPS 2.
The "two fingers" attached to the rotating part are the outputs.

I posted an image of it here :
http://forum.planetisuzoo.com/viewtopic ... ht=#397711

The traces must be clean, use electrical contact cleaner.

The 4 electrical connections to the external connector are on the opposite side of the big cover.

Stick a feeler gage between the throttle valve and the bore, it should be about 0.015
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Postby cwmoser » Mon Feb 07, 2011 12:09 am

Well, I sprayed the gears with WD-40 and used electrical contact cleaner on the traces and contacts. A test drive reveals that my idle is much lower. Need to see if the idle is better the next morning and a few more days too.

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Postby cwmoser » Mon Feb 07, 2011 7:00 pm

Well it worked well this morning.
But this afternoon after sitting all day in the parking lot, idle jump to 2000 RPMs, remained at 1000 at first stop. After warming up, still idle RPMs were higher than it was this morning. In addition there was a couple of stumbles on acceleration from stop.

With the P0507 code, its probably the TPS. What do you guys think?

Probably need to fork out some bucks for a new TPS.

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Postby Buster28 » Mon Feb 07, 2011 8:10 pm

DTC P0507 is being set because the RPM is higher than expected for the ECM commanded throttle position. Since you don't have any TPS codes set then a defective TPS is highly unlikely.
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Postby cwmoser » Mon Feb 07, 2011 10:17 pm

Buster28 wrote:DTC P0507 is being set because the RPM is higher than expected for the ECM commanded throttle position. Since you don't have any TPS codes set then a defective TPS is highly unlikely.


Any ideas whats wrong? Air leak? Another sensor? Timing tensioner?

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Postby cwmoser » Mon Feb 07, 2011 10:18 pm

Buster28 wrote:DTC P0507 is being set because the RPM is higher than expected for the ECM commanded throttle position. Since you don't have any TPS codes set then a defective TPS is highly unlikely.


Any ideas whats wrong? Air leak? Another sensor? Timing tensioner?

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Postby Buster28 » Tue Feb 08, 2011 4:46 am

I would start by replacing the PCV valve. Make sure you install the correct one for your engine. The PCV is a controlled vacuum leak, if the valve sticks or is the wrong one it wont idle properly.
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Postby cwmoser » Thu Feb 17, 2011 3:01 pm

I think I solved my P0507 code with erratic high idle by removing the Throttle body and adjusting the set screw so that the resting position of the butterfly plate was more closed.

Idles much lower and smoother after a couple drive cycles.

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Postby Mediamonkey11 » Thu Feb 17, 2011 3:55 pm

Thank you for the update, hopefully she continues to do well :-)
-Tony-

viewtopic.php?t=46954

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Postby Buster28 » Fri Feb 18, 2011 12:23 am

It would a appear a previous owner adjusted the throttle stop in an attempt so solve a problem which you must have corrected, making the adjustment unnecessary.
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Postby cwmoser » Fri Feb 18, 2011 8:26 am

Buster28 wrote:It would a appear a previous owner adjusted the throttle stop in an attempt so solve a problem which you must have corrected, making the adjustment unnecessary.


Could be. My 2000 Trooper is cosmetically in great condition. I have noticed some "messing" with things such as the PO drilled holes in the Muffler.

What made me want to try adjusting th butterfly plate was that I had previously cleaned a lot of greasy gunk off the throttle body and plate. Maybe the PO did a quick and dirty adjustment to compensate for a blockage.

When I got the Trooper, I also got a EGR check engine light on the way home. The EGR tube was stopped up and I cleaned it out. I assume that is why all the gunk accumulated there. But, when I adjusted the butterfly plate, I noted some oil residue on the plate - is that normal condition? It had been about a month between the time I cleaned the throttle body to the time I adjusted the butterfly plate.

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Postby Buster28 » Fri Feb 18, 2011 12:57 pm

I don't know about Trooper mufflers but a 2nd gen Rodeo muffler retains A LOT of water which causes them to rot inside and get really noisy. Back in day, mufflers came with weep holes to let the water out.

The oil on the throttle plate probably comes from the vapor hose connected to the RH valve cover.
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Postby Selahdoor » Fri Feb 18, 2011 3:25 pm

Buster28 wrote:I don't know about Trooper mufflers but a 2nd gen Rodeo muffler retains A LOT of water which causes them to rot inside and get really noisy. Back in day, mufflers came with weep holes to let the water out.


And weep holes in the muffler aren't going to have any effect on the engine.
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Postby cwmoser » Sat Feb 19, 2011 1:46 pm

After a few more drive cycles, my 2000 Trooper is running smooth, idling smooth, and the cold idle acts as it should.

This fix has made a major improvement.

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Postby SurferJoe » Sat Feb 19, 2011 3:27 pm

Give me some insight here - isn't this a TBW/FBW system and therefor the TPS cannot by itself pop a code?

I'd bet that WD40 in the TBW gears is not a good idea either.

WD40 is just a water dispersant and not really a lubricant worth all the hype it has. The 'WD' part of the product name = 'Water Dispersant' in it's original aerospace design, and not a lubricant at all.
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Postby Buster28 » Sat Feb 19, 2011 5:12 pm

There are unique DTCs for the TPS on Electronic Throttle Control (ETC) Isuzu engines. For example, P1221 TPS1 – TPS2 correlation error.
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Postby SurferJoe » Sat Feb 19, 2011 5:51 pm

Buster28 wrote:There are unique DTCs for the TPS on Electronic Throttle Control (ETC) Isuzu engines. For example, P1221 TPS1 – TPS2 correlation error.


Understood - correlations are obvious - but as far as wiper resistance failures, not so much.

The parser doesn't think it's a big deal if the human has Parkinson's or a palsy f'rinstance - so it won't pop a code and I'm pretty sure if it can hit WOT and idle voltages, then almost everything else in the middle is OK.

Right? Since the TPS isn't feedback, I don't understand how it would know something's wrong other than a couple of values that have to be cyclically resolved or if not - a code pops.

Is there a corollary with the MAF or MAP? Of course there is - but if the human element or a bad resistance value is seen somewhere in between, then I don't see how it can tell a default value has been exceeded.

In other words: the only baseline preset values are idle, tip-off and WOT - all else is acceptable - right?

I saw this problem and it was a real hair-puller on Saturns and their oddball values and what would and would not trip a CEL for TPS, ISC and ECT values all over the board.

Corollaries weren't considered and only live stream values inside a factory-set parameter were watched - all else was gibberish to the ECU and it didn't care.

Still interested in this situation.
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Postby Buster28 » Sat Feb 19, 2011 10:12 pm

These are ETC related DTCs if you would like to evaluate them:
P1120 TPS 1 Circuit Fault
P1220 TPS 2 Circuit Fault
P1221 TPS 1 – TPS 2 correlation Error
P1271 APS 1– 2 Correlation Error
P1272 APS 2 – 3 Correlation Error
P1273 APS 1 – 3 Correlation Error
P1275 APS 1 Circuit Fault
P1280 APS 2 Circuit Fault
P1285 APS 3 Circuit Fault
P1290 ETC Forced Idle Mode
P1295 Power Management Mode
P1299 ETC Forced Engine Shutdown Mode
P1635 TPS Reference Voltage # 1 Circuit Fault
P1514 - TPS-MAF Correlation Error
P1516 - Command - Actual TPS Correlation Error
P1523 Actuator Control Return Performance
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Postby SurferJoe » Sun Feb 20, 2011 1:36 am

I don't see the answer in that list.

There's no ref to excessive throttle motion by the driver.

Correlations don't figure in this - actually they don't in either a machanical or TBW system either.

I'd like to know the gate and threshold for that sort of action.
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Postby cwmoser » Sun Feb 20, 2011 10:00 am

Hey guys, I can tell from the posts that you guys know the software in the computer. I am a software programmer and find this very interesting. Like to have access to the algorithm or a detailed software description for the Isuzu computer.

In any case, my 2000 Trooper is still running and idling properly. Do you think that the problem was that the butterfly plate at rest position simply allowed too much air for a minimum RPM condition? One thing I did notice before adjusting the butterfly plate was that occasionally coming to a stop that the engine would die and I would have to restart. I'm guessing that the software in the computer only works properly if this plate is adjusted properly.

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