Replacing the TPS (Throttle Angle/Position Sensor) - can it be done? - The Acura Legend & Acura RL Forum
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Old 04-19-05, 03:42 AM   #1 (permalink)
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Replacing the TPS (Throttle Angle/Position Sensor) - can it be done?

I'm researching a potential TPS sensor replacement for my 88 Legend sedan. This is a sensor that is attached to the side of the throttle body. Called Acura and they said that no, you cannot buy the sensor separately- it's attached to the throttle body with "rivets" and that I would need to order the entire throttle body (at $450) if I wanted to replace this sensor.

Looking at the sensor itself, it DOES have some sort of "not-easily-removable-and-if-I managed-to-do-so-couldnt-get-them-back-on" bolts.

Has anyone actually replaced the TPS and if so, how did you do it and where did you get the sensor?
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Old 04-19-05, 04:14 AM   #2 (permalink)
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This is a precision calibrated sensor onto the throttle body and don't mess with the positioning. Some people have fluked out and replaced it with another used one, Like the TDC it appears a high level of precision is required for reassembly.

I HAVEN'T checked but I would not be surprised if all PGM-FI systems, Accords, Preludes etc carried the same sensor but the reassenbky is still an issue.
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Old 04-19-05, 04:19 AM   #3 (permalink)
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Quote:
Originally Posted by GREYLEGEND
This is a precision calibrated sensor onto the throttle body and don't mess with the positioning. Some people have fluked out and replaced it with another used one, Like the TDC it appears a high level of precision is required for reassembly.

I HAVEN'T checked but I would not be surprised if all PGM-FI systems, Accords, Preludes etc carried the same sensor but the reassenbky is still an issue.
So, then, per Acura, replacing the TPS sensor really means replacing the entire throttle body, correct?
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Old 04-19-05, 04:23 AM   #4 (permalink)
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If you confirm that THAT is 100% the problem then trying a swapout with another sensor is OK since you have nothing to lose but your time and a used sensor. But swapping it out just to see if that is the problem is a NONO. if it isn't you might just wreck a good one up. Get a used Throttle Body, what about the one from your old motor?

By the book Acura is right. But they also never said you can resolder the main relay either.
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Old 04-19-05, 05:40 AM   #5 (permalink)
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Quote:
Originally Posted by GREYLEGEND
If you confirm that THAT is 100% the problem then trying a swapout with another sensor is OK since you have nothing to lose but your time and a used sensor. But swapping it out just to see if that is the problem is a NONO. if it isn't you might just wreck a good one up. Get a used Throttle Body, what about the one from your old motor?

By the book Acura is right. But they also never said you can resolder the main relay either.
I tried disconnecting the TPS connector and measuring the resistance. The reading went from around .5 at idle up to 4.1 at full throttle.

I don't have the old engine - the guy who swapped the JDM engine in has/had it - just seems unnecessary to take such a big, heavy, dirty and basically smoking object home at the time. If I knew what (little) I know now, I would have somehow shlepped it home..

That said, I located and ordered a throttle body off car-part.com for $50 shipped. The guy said that 95% of the throttle bodies he sells are for TPS replacement purposes - 5% for folks actually needing another throttle body.

THAT said, is there a HOW-TO to replace a throttle body available? As you know, this is all new to me and I'm willing to try, but then again, I don't want to catch fire either.
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Old 04-19-05, 06:20 AM   #6 (permalink)
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Looks like the reading you got is fine.
If the readings progressed smoothly then your TPS is OK. So you might have to scratch that one off and look elsewhere.
So to recap, the bogging is ONLY when it is warmed up right?
Wait .....You disconnected to get resistance but the readings were at .5V to 4.1 volt????????? Surely you had them connected to get reading.
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Old 04-19-05, 06:35 AM   #7 (permalink)
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Quote:
Originally Posted by GREYLEGEND
Looks like the reading you got is fine.
If the readings progressed smoothly then your TPS is OK. So you might have to scratch that one off and look elsewhere.
So to recap, the bogging is ONLY when it is warmed up right?
Wait .....You disconnected to get resistance but the readings were at .5V to 4.1 volt????????? Surely you had them connected to get reading.
That was K-ohms, not volts.

I road-tested just now and there is no bogging evident. The engine was hot so the bogging is apparently no longer tied to a warm engine. I was wondering.. when the car was in the JDM swap shop, it sat outside for at least a month not used. If the kick-down cable is rusted up inside it's enclosure, and it "sticks" occasionally, could this manifest itself with intermittent bogging or stumbling or logging or pinging (I don't know what to call it now).??
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Old 04-19-05, 07:02 AM   #8 (permalink)
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I suspect you have some sort of intermittent contact somewhere. Either in the harness or connectors somewhere. That's a frustrating situation as you can't "catch" it easily. The only thing to do is to first eliminate the connector question. Go to an electronics shop and get some contact cleaner. Go through all your connectors you can find especially the ones with sensors. Inspect and clean them, that way you know it's definitely not the connectors if still get bogging. While doing so, carefully inspect the harnesses at the same time for any signs of cracks or crimping damage during the install. Also double check your ground connection points and clean them too.
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Old 04-19-05, 08:54 AM   #9 (permalink)
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Quote:
Originally Posted by GREYLEGEND
I suspect you have some sort of intermittent contact somewhere. Either in the harness or connectors somewhere. That's a frustrating situation as you can't "catch" it easily. The only thing to do is to first eliminate the connector question. Go to an electronics shop and get some contact cleaner. Go through all your connectors you can find especially the ones with sensors. Inspect and clean them, that way you know it's definitely not the connectors if still get bogging. While doing so, carefully inspect the harnesses at the same time for any signs of cracks or crimping damage during the install. Also double check your ground connection points and clean them too.
Did another road-test and was able to getting the "bogging". Here's what I noticed: I'm driving without problem, then suddenly hear something in the engine that sounds like an upshift. At that point the RPMs are at about 2000. If I press the accelerator, the engine does NOT rev higher and the tranny doesn't downshift, which is what it would normally do. If I press harder on the throttle, suddenly the engine rev much higher (4000rpm) and the tranny downshifts. Letting go of the throttle causes the trans to downshift and engine to go below 2000. Then slowly pressing throttle, it stops at 2000rpm and if I slowly press more throttle, I hear backfiring (pinging?) from the engine. If I press harder, again the engine will suddenly rev higher (over 4000rpm) and trans downshift. It's like the engine gets "stuck" at 2000rpm.

????
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Old 04-19-05, 10:13 AM   #10 (permalink)
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What you have described seems to be the norm for an automatic. I think you worded improperly that when you release the accelerator it Upshifts and the revs drop. I wonder if you have been doing the dog circles now?
The only thing a little extraneous might be that since you have a JDM, you have a slightly higher compression and may need premium fuel. I believe what you are hearing is a little knocking and pinging when you step on the gas and it "bogs" down and makes some funny sounds.
Try dropping some premium in and see if it helps.

When your engine sees the accelerator depressed, it thinks you want to accelerate. Depending on how deep you press the accelerator, the vacuum will increase, advance the timing, enrichen the mixture and then downshift. When you release the accelerator, it detects that you no longer need acceleration, will retard the timing, lean out the mixture, and then upshift so that the engine runs at a lower rpm.
The throttle valve cable ( NOT THE THROTTLE CABLE by the Throttle body) might need some adjustment and lubrication a bit but other than the pinging/knocking/bogging it sounds like it is operating normal to me.

Last question, did anyone monkey around within the black box to do some timing mods???
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Old 04-19-05, 11:05 AM   #11 (permalink)
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Quote:
Originally Posted by GREYLEGEND
What you have described seems to be the norm for an automatic. I think you worded improperly that when you release the accelerator it Upshifts and the revs drop. I wonder if you have been doing the dog circles now?
The only thing a little extraneous might be that since you have a JDM, you have a slightly higher compression and may need premium fuel. I believe what you are hearing is a little knocking and pinging when you step on the gas and it "bogs" down and makes some funny sounds.
Try dropping some premium in and see if it helps.

When your engine sees the accelerator depressed, it thinks you want to accelerate. Depending on how deep you press the accelerator, the vacuum will increase, advance the timing, enrichen the mixture and then downshift. When you release the accelerator, it detects that you no longer need acceleration, will retard the timing, lean out the mixture, and then upshift so that the engine runs at a lower rpm.
The throttle valve cable ( NOT THE THROTTLE CABLE by the Throttle body) might need some adjustment and lubrication a bit but other than the pinging/knocking/bogging it sounds like it is operating normal to me.

Last question, did anyone monkey around within the black box to do some timing mods???
Then I'm not describing it correctly... When I say upshift, I mean 1->2, 2->3, etc.. I don't think that premium fuel will matter, because as I said, I am able to drive for 20 minutes at a stretch with absolutely no pinging or bogging. This is both driving slow or fast. Then, there are those times when the car will drop into this "bogging" mode from the "good" mode. It's a distinct shift. I will driving fine for a while both highway and local, then boom, the bogging ensues and the car has low power, I hear the occasional backfire; this continues from point on whether I go slow or head out onto the highway- the car won't go over 40 mph no matter how much the accelerator is pressed.

To your point, when the car is in this "bogging" mode, depressing the accelerator does not cause a downshift AT ALL. It causes more bogging and backfiring UNLESS I floor it. THEN, the revs shoot up and the trans downshift. BUT, this is NOT the normal downshifting that occurs when you press the accelerator (which is what happens prior to bogging mode). This, in contrast, is dramatic. The car feels like its choking- like something is holding it back from downshifting normally.
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Old 04-19-05, 11:19 AM   #12 (permalink)
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Try this, when the bogging starts, carefully turn off on the side. Turn off the car. Then depress and release the accelerator pedal a few times fully to exercise the sensor. Turn the car back on and see if the bogging is gone.
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Old 04-19-05, 11:59 AM   #13 (permalink)
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Could I suggest that the valves are out of adjustment, or the timing is out of adjustment. I had a similar problem with my 1958 Standard 10, I got the car from a person cheap and it was not running right. It would backfire sometimes and lose power when it warmed up. As it turns out the valves needed adjustment, they were way out. The timing was also out. If these are ok then I think you should go and replace your kickdown cable. Have you replaced your ignition leads? They can cause 'bogging' I had to replce them on my Legend when it started boggin then it went away. Also could your problem be coming from a faulty fuel injector? The injector could be intermittent, so it will work sometimes but then other times you lose power and the car starts running rough?

Just a few thoughts. Let us know if anything works.

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Steve

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Old 04-19-05, 12:13 PM   #14 (permalink)
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89HondaLegend;
Just curious, do you have to use "premium" fuel in your Legend? Your essentially driving a JDM vehicle, and as GREY has suggested to stoporder, the use of premium fuel might be needed.
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Old 04-19-05, 12:16 PM   #15 (permalink)
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stoporder;
Is the JDM engine installed with its distributor or the one from your old engine? Are ECUs also changed when these swaps are made? Just curious...
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