PontiacBonnevilleClub.com

So I am back after testing it all.

And this what I understood very well: A is aground, C is a feed that ECM gives 5V, then B is a return that TPS sends to the computer or other hell device.

You were right Black wire A ground, B - Blue output from TPS, Grey is C for 5V feed from ECM.

So I have measured A and C on the connection socket and yes right on between 4.75 to 4.95 so rounded well 5V is fed.

When the socket was connected into TPS I have measured A and B, but instead of 0.5 to 1VDC at closed position I have 0.05V and when I open the throttle to the max it reads 0.31V. Is it possible on my bonnie is such low setting for TPS or just TPS is dying out? TPS still works but not enough probably that is why there is hard start and no check engine or no DTC showing on scanner.


For the vacuum problem:
Now as the car was in the cold engine not on yet I have hooked scanner and it showed this:
LT FTRN1 (%) = -3.1
As engine running then
LT FTRN1 (%) = 4.6
then it went to LT FTRN1 (%) = 10.2
Does it look erroneous or it is kind of weird setting?

Now here was a question if I have tried to run with MAF disconnected, and I start but then engine right away dies. MAF was replaced a year ago.

So how does it look on TPS side, is verdict that it needs to be replaced? If yes where could I find the most cost efficient replacement and what would be the cost?

And what about the vacuum problem is it there or not really?

Thanks,
Larry

According to my old Chilton's, the TPS should be reading 5 volts with the throttle wide open. It appears that you need a new one.

I want to make sure that you are testing that voltage with the connector attached to the TPS. As Curt mentioned, you may need to pierce the wires with needles that touch the conductors to provide a contact for the voltmeter with the connector attached and the ignition on.

You wrote "I want to make sure that you are testing that voltage with the connector attached to the TPS. As Curt mentioned, you may need to pierce the wires with needles that touch the conductors to provide a contact for the voltmeter with the connector attached and the ignition on." - I did exactly that.

Suggestions on where to find best deal for TPS?

Thanks,
Larry

I buy a lot of stuff locally from O'Reilly's. When I have time to wait I order from http://www.rockauto.com

I found four offers of TPS there, made by: Delphi, ACDelco, Airtex, and Standard Motor Products, which would be good to chose from?

Thanks,

Larry

I am sorry, just had a thought, since TPS is adjustable, could I adjust it somehow so it could give me more voltage when throttle is open? I have cleaned intake throttle body 1 yr ago, and is it possible that I placed it in wrong?

Thanks,
Larry

92 was the last year for the adjustable TPS. Your's isn't, at least not in the traditional sense.

There is a tang on the throttle shaft that must engage the TPS when it is installed on the throttle body. It is possible to assemble it so the tang does not engage and the TPS, then, does not work. If that had been the case, however, the PCM (engine control computer) should have stored a code and illuminated the Check Engine Light (CEL). Remove the TPS from your car. Look at the TPS where it links to the throttle shaft, then look at the end of the throttle shaft as you open the throttle. It should be obvious how it must be assembled to work properly.

Thanks for reply.

I appreciate that.

As it goes regarding the correct assembly of TPS on TB, I am very sure that I have done it right, normally I do it even better then manufacturer does. So that was just a thought. Going to look for TPS now, see it in the states for 50$ while here in Canada 90$, gotta plan trip to south.

Moreover there was mentioning that my vacuum data from scanner was king of strange. Please advise if at the same time I could look into whatever additional problems and to fix them.

When talking vacuum, do you refer to the little tubes and rubber connections that run around the engine? Should I consider replacing any of them (rubbers i mean, I have done few in the past, replaced by similar size small diameter rubber hose ends, of course with elbows and tees that is more complicated, so these are original)?

Also I do have very important for me inquiry: under the right front fender, maybe even at the bumper there is a little black reservoir (tank) and there used to connect the hose, the plastic connector has rotten away and the the hose is not connected to that thing any more. Do you know what the hell is that thing and what it does and how important that is. Actually there lots of kind of vacuum sound that comes from there. Any advise?

Thanks,
Larry

It sounds like you might be referring to the vacuum line that goes to the charcoal cannister for the EVAP (evaporative emission) system. Plug the line for now. You'll have to replace the broken part. Pictures are a great way to make sure we're talking about the same part. That could be the cause of the high LTFT (long term fuel trim) & could also be contributing to the hard starting when cold.

Doesn't your scanner display the TPS voltage? We hate to see good parts get replaced.

Thanks, yes you are very right, that is a charcoal canister exactly.

The head to which the hose plugs in is broken. Not sure how to attach it.

Maybe need to look into screwing a metal tube on and attaching the hose to it?

As for the scanner showing TPS voltage, unfortunately it does not, I have tried many ways. But Voltmeter I think did good job, and I pierced the wires through to get readings. Will use silicone to cover it when this repair is done.

Will check the new TPS when I get it installed so I see exactly the needed voltage ok.

As I have noticed junk yards just sell TB in one piece and not just TPS.

Thanks,
Larry

I'd just get a cannister from the junkyard & while there remove the TPS & take it up to the counter. This is assuming you haven't already been told by this junkyard that they just sell it with the throttle body. You might also be able to epoxy the fitting back onto the cannister.

laimisl wrote:When the socket was connected into TPS I have measured A and B, but instead of 0.5 to 1VDC at closed position I have 0.05V and when I open the throttle to the max it reads 0.31V. Is it possible on my bonnie is such low setting for TPS or just TPS is dying out? TPS still works but not enough probably that is why there is hard start and no check engine or no DTC showing on scanner.

Just to be sure you are not getting your wires crossed; C is Ground Ref. (black wire), so that is where your black test lead should be connected. A is the +5volt ref. (Gray wire). So when you are monitoring the changing voltage from idle to WOT at B (blue), you SHOULD be connected between C and B. From your statement above, you are doing the wrong pins (A & B).
TIP: I verify that C is at ground by reading from the engine block to C. Should be 0 volts. Once that is established, it is just as accurate AND much easier to put the black meter lead on engine ground and only use the red meter lead on the various pins, in this case C. Just make sure you have a good engine ground.
Here is a diagram of the circuit that may help and not confuse.

Thank you RedSled for you input,

I just came back as I have rechecked the wires colors and voltages.

In my car:
A - Black - ground
B - Blue - Return signal from TPS
C - Grey - ECM feed.

So I checked ground from pin A (that is the same as the engine block) with B and at IDLE reading is 0.05V, while at WOT reading is 0.05V.

I very much liked your suggestion to find exactly which is the ground pin by using engine block and I have verified that in my car engine block to A black wire reads 0V, and engine block to C Grey wire reads 5V.

So once again the TPS is faulty here, verdict TPS will be replaced.

Now for the vacuum leak from LTFT (long term fuel trim) referring to the vacuum line that goes to the charcoal canister for the EVAP (evaporative emission) system I was lucking for the line and when I touched it just broke into pieces as it was plastic line, made from crap, well I will have to find whatever is left from it and plug it.
Do you know if there is a need or part availability for such line together with the canister?

Thanks.
Larry.

Just a thought, since I have broken rotten vacuum line that fed into the black canister (under the fender and bumper in front right corner), can I find the same line under the hood (in the engine compartment) and plug it there?

Do you have pictures, diagrams etc?

Thanks,
Larry

If I remember correctly, there are three lines going to the cannister.
1- crosses the engine bay under the radiator & then goes back to the gas tank.
2- goes to the engine to supply vacuum to the cannister. It connects to the purge valve on the engine.
3- is just a short line that connects to the vent valve that mounts to the top of the cannister.

Thanks for that, but to tell you the truth, that makes me even more puzzled.

Is there any diagram of that or picture of some sort?

Anybody please help.

Thanks,
Larry

laimisl wrote:Is there any diagram of that or picture of some sort?

Does this look like it?

Yes this looks like that, and it looks like that intake manifold vacuum line that connects to the canister, exactly the knob is rotten off and exactly the line is rotten off and its piece of about 6 inches I broke off accidentally, it was so fragile and rotten just like dry piece of thin branch.

So Can I plug that line under the hood and where to find it as well as the line that goes from canister to fuel tank, is there any problem if the canister actually will be kind of open (as intake manifold vacuum line will not connect to it)?

Thanks,
Larry

laimisl wrote:So Can I plug that line under the hood

The one from the tree to the canister? Yes, to get your vacuum leak stopped.

laimisl wrote:where to find it as well as the line that goes from canister to ...

Confused... are you having trouble finding a vacuum line in there?

laimisl wrote:is there any problem if the canister actually will be kind of open (as intake manifold vacuum line will not connect to it)?

That line from the fuel tank bleeds any fuel vapors via the canister into the engine to be burnt and disposed. So leaving it open is an EPA issue (fuel vapors into the air). Your decision.