You might want to go back and check your Haynes. The numbers you are giving - 1.20-1.60V at idle, and 4.5-5.0V at WOT - are for the MAP sensor (based on my knowledge.... and you can check all the values out in my online scanner document, that is pretty much used as a standard reference by a lot of people who post here and on the several other boards I post on).

http://members.aol.com/InjuneerZZ/ScanMast.htm

The specs on the TPS are the ones I gave you. Its really not open to question. If you have more than 1V at idle, it screws things up, because the ECM assumes you are opening the throttle on purpose. There are things like idle speed that will be thrown off, since the ECM elevates the idle speed when it thinks the throttle is open for a purpose.

 

What are you tlaking about?

My scanner writeup is based on reading the sensor directly from the PCM. If you chose to measure it with a volt meter, you probe between the gray and the black wire for reference voltage, and between the blue and the black wire for output signal voltage.

I don't know what you are talking about with "drilling out theholes in the sensor".... I don't mention that at all in my scanner writeup. Appears you may be looking at someone else's page - probably Shoebox's.

Measure it between pairs of wires, as I mentioned. Not between a sensor wire and an engine ground. The ECM connects to the pairs of wires, and that's where it gets its signal from. It doesn't matter if you probe the wires at the sensor, or 6" from the sensor, but you need to probe the pairs of sensor wires, or read it with a scanner.

 

Hmm... Check page 6-14, #51 on the haynes manual, it describes the procedure and voltage numbers from idle to WOT, 1.2-1.6 to 4.5-5.0.. This must be a typo though, cuz if you look at picture 4.50a it shows a voltameter hooked up to the tps and is described as a picture for the test at idle but on the picture itself, the voltameter reads "0.67", so you have to be right about the numbers.

 

sorry I misread your writeup and thought you were doing your test by drilling out the holes in the TPS

TPS (Throttle Position Sensor):
The Throttle Position Sensor (TPS) is the reading out of the rotary motion sensor on the throttle blade shaft. The sensor is located on the throttle body, on the end of the pivot shaft, on the passenger side. When you turn your car "on", the PCM sees the closed throttle voltage reading, and sets this as "0%", or closed throttle. The factory spec for this seems to be as low as 0.40V, and as high as 0.70V. But, I have seen reports of systems that work fine with TPS closed voltages in the range of 0.20 to 0.90V. SOME PEOPLE DRILL OUT THE HOLES IN THE TPS SENSOR AND TRY AND GET THE CLOSED POSITION VOLTAGE AS CLOSE AS POSSIBLE TO SOME VALUE LIKE 0.50V, BUT THIS DOESN’T APPEAR TO BE NECESSARY. Mine always read 0.64V closed.


I will recheck the it using the black wire for ground with a voltmeter, I didn't know that you have to use the black wire for ground.

 

thanks for the link... thats a pretty good deal, $45 shipped for the cable and then you can just use free software, I was under the impression that software would've been pricey for this.. This should be a pretty simple way to diagnose the problem, once I get the cable, cuz I can prolly just send the scan to Ion and he should be able to figure out if the problem is in his tune, or somewhere else.

 

I want to say that I really appreciate Injuneer's time and knowledge. Lots of great info in this thread. Last time this subject came up, I accidentally helped confuse the thread, so this time I'm just reading.

But I have to say "Thanks" to Injuneer.

 

OK, I tested retested the TPS sensor using the dark blue wire and the black ground wire. When I did the reference check, I got 5.08, which is normal. Then with the dark blue and black wires I got 1.01 at idle and 4.33 at WOT which is still high on the idle side. But the voltage does smoothly increase as you open the throttle. Is it possible that the throttle body stop screw/bolt is just set too far (the bolt that prevents that stops that lever from coming back any further than were the bolt is, possibly used as an idle adjustment bolt? I noticed that there is a bronze plug on the stock throttle body preventing you from adjusting this, but on the BBK throttle body there isn't a plug there.) I bought the BBK 58mm throttle body used and I don't believe this bolt/screw was ever messed with once I got it, so it might have been set too far up preventing the throttle body from closing all the way? Besides that I dunno, maybe its a bad TPS... But would the extra .11 volts cause the car to run rediculusly rich at all throttle positions when the car is running?

 

When you change the throttle body, you need to check the settings of the IAC motor and the TPS. Generally, they have the stop screw out too far. You back off SLOWLY on the stop screw, watching the idle speed and the IAC "counts" with a scanner. When you reach the correct RPM your IAC counts should be in the range of 20-40. The leaves the IAC motor enough "play" to either increase or decrease air flow to maintain the programmed idle speed. Last step is to check the TPS voltage to make sure it is within the specified range.

The purpose of drilling out the holes in the TPS sensor is not so you can measure the voltage.... its so you can rotate the body of the sensor on the TB, to alter the voltage reading.

I really doubt that the numbers you are getting would cause it to run rich. However, your 5.08V WOT reading should be tripping an SES light and a DTC code for "high TPS voltage". Anything over 4.90V should set a code.

 

Yeah, none of that definetly wasn't done, the throttle body was just tossed on there and originally the IAC wasn't even gonna be connected cuz its a 94-97 throttle body and the IAC that came with it wouldn't work (different connector) but then when I realized the IAC off the stock throttle body bolts right up, I just put that on. The guys who built my motor didn't even have a GM OBD I scanner, so I am sure they did not play with any of that. That actually probably explains why my car won't idle, I will definetly play with that after I get a datalogging cable.

The WOT reading was actually 4.33. The 5.08 was the reference reading which was off the gray wire. I don't know, guess I will just have to wait until I get a datalogging cable, to figure out what is wrong, cuz the problem doesn't appear to be in any of the sensors, now that I have checked/replaced them all (I replaced the ECT and IAT and just tested the mating connectors, also tested the MAP and TPS with a voltameter, all appear to be fine). Also seems that valves remaining open due to improper adjustment is the problem based on the compression test, only things left now that could be causing it too run excessively rich that I can think of are tuning, improper cam/crank timing or improper distributor install. I suppose it would make more sense to do the datalogging scan before going through the trouble of rechecking the distributor and cam timing.

 

O.k. I did a search and found this
Im having the same problem you are with my car and it's a 93 also.
What did you find to be your problem??

 

I haven't seen anyone question the tuning in a while.

The 93's are particular hard to tune. That is the reason why me and Bryan have broke up the platforms we do. I specilize in speeddensity LT1 tuning and he does MAF LT1.

I don't know who either of you two got tunes from but if you got them for me stop guessing for causes to your problems and send me a datalog so I can set you straight and let you know if its a tuning issue or if its a faulty sensor.

All of this checking TPS/MAP/etc is just a big guess.

 

I wish I knew what it was, my car has just been sitting in my garage useless for over half a year now and I have no idea what is wrong, I have looked everywhere (besides the tuning part, which I know nothing about, its hard to beleive that the tuning could be off by this much, it was tuned for 42# SVO injectors and I am now running the stock 22#'s) and have have found nothing wrong thus far.

To make matters worse and aggrevate me further, I bought a ALDL cable and belkin USB to 9 pin converter to datalog the car but for some reason this crap doesn't even work. Its weird cuz the cable working perfectly on datamaster DA with the key in the "ON" position and it will record perfectly.. if I hit the throttle the TPS % and volts change perfectly. BUT soon as I start the engine up within a second or two it goes right to "Lost ALDL connection" and then if I let the engine just stall out and leave the key where it is it will start recording again (It is the correct definition file for my car and "f-car A/T" is selected) . I posted about this as well a while ago and messed with everything on datamaster trying to get it to work right (handshaking, dash refresh, pcm delay, etc, etc.) and it still wont record while the engine is running, so I have no idea what the deal there is either. If it was a bad cord, why would it work perfectly before the engine starts? But I haven't been able to find any other scanning software that works with Windows XP professional except Datamaster DA..

 

I did my own motor and so I decided to go back and check my cam.
It should be installed at 104 but it's at 112 so I messed up some ware?
Now I will have to redegree my cam in the car
Alvin, I have a different tune but my problem now is getting my cam right before I mess with any programing isues but I'm sure it's a simple matter to fix and when I get things set I will contact that person.
No it's not you and I don't want to say who it is till I get my end right

My other problem is that I blow up my starter when I try to restart the car but that is due to my cam isue, I'm sure.

 

what kind of a brand cam are you running?... i'm just trying to figure out the likelihood that my cam was degree'd wrong also?