aklim

Make sure you have the lever in the right position with the other lever on the TB. Ask me how I know

TheBlaster9001

The MAF cars still did take a 0% value to account for small variation in the reference voltage - I had started my car back when it was MAF with my foot barely on the gas, and it ran terribly. Key off, key on, and back to normal. Plus, the shop manual gives a range of voltages that is 'acceptable' for a 0% value, and shifts where the WOT is based on that initial value.

And I agree, OP should check the reference voltage. If the reference voltage was at 2.3, then 2.3 is all he will get from the TPS. In addition, his '0' mark would be off if the reference was half of what it should be.

JasBass

The lever arm coming from the TPS sits nicely against the lever arm from the TB. I don't see any other way it could be possibly oriented?? I can check tonight to see if I manually move the tps lever if I can get to 5v.


Yessir, confirmed it is getting 5v. Everything is leading to the TPS being bad. Seems to account for why I had crummy mid range throttle response (3-4500)

JasBass

2.8 was all I could get out of it. And that was depressing the TPS lever, not just tb lever. Picking up a new TPS tomorrow and we'll see how it turns out. Tune should be here tomorrow as well.

aklim

If you have 5V reference and 2.8V by depression of the TPS lever, we are done with the the TPS. Ebay special Slightly used

LWesthaver

Maybe this will help: TPS diagnostics

JasBass

So, picked up a new BWD TPS and installed it last night. Odd thing here is, still only getting 2.2V at WOT. Getting 5V at at bottom battery input. I cleaned the connector terminals, no corrosion was present. At this point, I'm stumped

JasBass

TheBlaster9001

That's no good. You get 5 volts measured bottom wire to ground wire? How about bottom wire to a ground anywhere else (frame, header bolt, etc). I'm thinking that someone or something has gone all 'amateur electrician' on your wiring harness.

When I had accidentally hooked my MAP sensor up backwards, the TPS input would not pick up until about half throttle, and wouldn't get above 2 volts. I used the same ground for TPS and MAP. So power went into the ground on MAP, then from the power on map, to the same ground wire as TPS.

Nothing got broke, but sensor input for both sensors was garbage. I don't know the way your car is wired, but I imagine you have several sensors sharing the same ground coming back in to the ECM - my car did. I wonder if there is a short/bad conection somewhere in the harness, or if a sensor that is also on that ground is acting up.

Try this, if you can - get a wiring diagram for your ECM, and ideally, a 5 volt power supply of some kind. I suppose you could jumper from another sensor, but a run from an external supply would be ideal.

First, start off by disconnecting the other sensors that share a ground with the TPS, one by one, and then all at the same time. All different combos of disconnected sensors that are on that same ground. Check TPS signal voltage each time.

If a certain sensor appears to be at fault, it may be bad. If that test ends up being inconclusive, then we know the power/ground wiring to the TPS is not shorted by another sensor.

Next, I'd try hooking a 5 volt supply up to the TPS, attaching the signal wire, and measuring signal voltage again, just to check.

I'd then repeat this at the ECM, only you will need to take the pins for TPS voltage and ground out, and hook them to the supply. What's the signal voltage do then?

TheBlaster9001

That's quite possible, it could be a bad connection in the wiring harness, or at the ECM

JasBass

JasBass

Did a quick check of the TPS connector. Top wire ground will complete the 5v circuit coming from the bottom supply. The culprit seems to be the ECM reference wire. Once again, it only reads .40 at rest and WOT 2.2V. So, thinking maybe a connector issue? Loose at the point of the connector. Visually, the wire is intact until it enters the harness firewall passthrough. And the part I can see entering the ECM visually passes the test. I'd hate to think it's a bad ECM, but between the connector, the ECM reference wire, and the ECM, these seem to be the culprits.

TheBlaster9001

I don't think the ECM would be to blame, unless it was shorted out and putting a voltage out on the TPS sensor input pin

TheBlaster9001

Try this for me - can you de-pin the middle wire, then hook the TPS up to the connector? I just wonder what it'll do with the middle wire absent.

JasBass

I'll hit it either later tonight or in the morning! Is there a way to check resistance of the ECM reference wire?

TheBlaster9001

You could measure resistance of the wire itself by taking a multimeter and going from the TPS to the ECM connector. Make sure you don't test resistance there with the ECM plugged in, that could hurt it.

JasBass

TheBlaster9001

I feel ya, sounds good.
While you've got the ECM pin pulled, you could reconnect the ECM minus that pin, and then measure the voltage with the wire off of the ECM - that way you can find out if the issue is the ECM or not

JasBass

Damn, I wish I had checked this before I did that. I ohm'd the ECM reference wire from connector to c13 as per FSM and got 0.00. I used the tables in the web link one of the members here posted for the Ohms of the TPS, confirmed all the specs within 0.5-1. Hooked power back up and probed power input and top ground and got 5v.

The facts as the lay now:
TPS is receiving 5v.
TPS top ground wire holds 5v and has no resistance to ground.
ECM reference wire itself has 0.00 ohm resistance.
When power supplied, TPS connected, probed and checked, ECM reference wire at rest is 0.30v now and WOT is 2.12.

At this point, the finger is pointing to the ECM... Frustrating if this is the only thing wrong with the ECM, but really, it's kinda a big thing lol.

TheBlaster9001

Does the pin have 2.2 volts at WoT? Check it with just the pin, if it is 5volts on the pin with the pin not connected to the ECM, then the ECM is at fault.