Hey all, just wanted to leave a data point for NTK TPS's for the 82 Crossfire. A little while back, I did a full tune up and changed out the old TPS for a brand new NTK TPS. theyre a relatively decent brand so i figured itd be ok. Mine failed in a few thousand miles so if youre chasing some odd idle/throttle issues and it seems ALMOST fuel related, check the TPS. its also easy to check resistance as you roll through the sensor. setting requires .525 volts but it seems like its a simple potentiometer that takes voltage input and has a different voltage output.

I know the TPS was working fine when installed so im wondering if the internal pot just can't handle the current passing through it. I changed it with an SMP sensor - will see if this one survives.

symptoms were: odd idle drop on decel (it liked when i was on-throttle, hated idle position), really badly rich coughs during idle drop. While rolling into throttle, the TPS was operating fine and the car would run up through the rev range OK. seems like the potentiometer range where the TPS was parked often (idle/off throttle) failed.

 

As someone who's battled aftermarket parts, I highly recommend getting the OEM TPS sensor. I got it off RockAuto for about $75 (not including taxes/shipping). The part number is 213-902. In my experience the Crossfire system is very sensitive to the parts used and if it's not within certain specs it seems to not like it and starts to run terribly.

 

Hi Ahrmike,

Thanks for the info on tps brands.

I am fighting an issue with my 82 crossfire and was just wondering if any of your bad tps symptoms included what I will call bad performance when rolling in the throttle through low to mid exceleration? How about a popping / backfire sound that seems to come from the throttle body units ?

Last question.. Where you able to adjust both of those tps’s to the .525 volt output on the signal wire ?

Thank you for any thoughts..
Jon

 

It had really bad performance on throttle roll but i didn't have backfires or popping. I believe mine was reading too low though so it was likely just running lean. From your symptoms, its possible its the TPS if its reading high and thinks youre on the accelerator?

I was able to adjust the badTPS to .525V BEFORE it went bad. Noting I had a LOT of movement in both directions. I didn't check afterward since I did a simple resistance check and realized there was a dead spot where it would spike to near infinite resistance. I would recommend checking your TPS with a simple resistance check as you rotate the sensor. I am thinking it may have been damaged when I initially installed since i let the sensor "flick" back to zero a few times too rapidly when i was first installing.

You should check the voltage at the TPS harness as well as the resistance to ground through the ground wire on the harness. Maybe you have a bad ground or bad ECM voltage supply?

HIGHLY recommend the ALDL cable too. relatively easy to use once installed and it gives "live" information from TPS to temps, etc. From your symptoms, you likely have a bad ecm or bad sensor somewhere so the ALDL cable would narrow that down significantly.

 

Thank you for your clear and detailed reply!

So both my original TPS and the new one cannot be adjusted to the .525 setting. They both run out of physical room for adjustment I move the sensor to the highest position and still can only .480 or something right around there. As you pointed out I did verify that the ground going to the TPS connector, seems good and my measurements didn't change when I put the meter on another solid ground. Also the input voltage to the tps is 5 volts.

I was always thinking mine was a lean pop. I think you are saying that your tps was reading low and you did have a lean condition. I think with my base tps setting at .480 then the computer would always be supplying less fuel and behind the throttle plate and air supply position. Does that sound right and possible to you?

I am going to try opening up the tps slot to allow me to get that base setting correct, even if its just a test to verify this theory.

Thanks, I'll look into that cable. I suppose you need a computer and some specific software to complete that function?

Thanks again, much appreciated!
Jon

 

That's very strange re: sensor position and voltage if BOTH are roughly the same. If they both output about the same i'd lean towards your car being the issue, not the sensor. Can you check and clean your harness connection? I wonder if the connection is bad enough that it increases resistance, lowering voltage output? Can you also check power to TPS + ground with the TPS already installed? I wonder if its possible you have a bad sensor power supply from the ECU OR a bad wire or a bad ground somewhere. Im not sure about the C3 ECM, but I've had instances on other cars (C5, notably) where various other "bad" sensors pull down the voltage to a good sensor because they were powered off of the same supply. Are all your other sensors working ok or do you have any failed ones? When the car is running, is the alternator output stable?

ALDL cable requires the cable and a free software + windows laptop. Pretty simple to set up but it does take a little research into what to connect/where.

 

Thanks again for your thoughts!

I was doing the TPS voltage tests by back probing the wires with the connector attached.. But you have a good point. If the wire from the TPS output is compromised back to the ECM the ECM could be receiving and acting on an incorrect reading. I will try to identify this wire and check it..

Will soon replace the Coolant temp sender and the MAP sensor. But not sure that they are bad just replacing to rule them out.

I don't see anything to indicate the alternator out put is off but I'll check it next time I'm able.

Thank you for the ALDL cable info. Any idea of what the software is called or where it might be available?

Thank you again and have a very Happy 4Th of July !!

 

Happy fourth! hope you get this figured out soon. I was out driving my '82 today and it was great.

I bought the ALDL cable from:
https://aldlcables.com/collections/aldl-obd1-cables

For the '82, we need the 12 pin ALDL cable.

The software is here:
https://winaldl.joby.se/

you should donate to the guy if you get it working - I made sure to send some his way as a thanks for getting this program working. His site has a lot of instructions on how to get things to work properly.

The stock 82 ECM number is: 1225550, which you need to select on the winALDL software during startup.

If you order it and need more help, let me know - i can walk you through it step by step.

I'd recomend doing the MAP anyway since its so easy to get to - if it changes nothing, keep the old MAP as a spare. If it improves it, toss the old MAP and buy another one as a spare. The coolant temp sender may help but just realize youre gonna bleed a little coolant. While doing the MAP sensor swap, I'd recommend changing out the vaccum line too since the old lines usually have invisible pin-holes and leak. Mine definitely was leaking.

In my car, I have a spare MAP, ICM, rotor, cap, longest plug wire, extra plug, TPS, fuel filter, and the tools to swap them. nearly all of them will take less than 30 minutes to change and its pretty easy to guess which one is going bad. I don't have a spare coolant sensor since i figure if it goes bad, itll run like crap but still run til i get home.

 

If you can get your hands on a decent scan tool, you'll be able to read live data that the ECM sees, and any outputs that the ECM enables without probing any wires. The hard part is to understand what all the data means relative to the other values. If you don't have that experience, it might be cheaper in the long run to have someone with experience take a look. Honestly, I wouldn't replace any parts unless you can confirm if they are bad. The only sensor that's considered a service part is the oxyfen sensor.

 

Again great info! Thanks..
I had researched the cable and software but as you said there were a lot of choices. Thanks to your specific info I think I'm all set. Very wise to keep those spares. Even though it's said they don't go bad they are so accessible I'd say it's a reasonable troubleshooting step. I'll update as soon as I have those sensors swapped.
Take care,
Jon

 

Thanks for your thoughts. And you could be 100% correct. But in my case with somewhat limited test equipment. All sensors cost less than 1 hour of labor for someone to take over the trouble shooting at this point. Don't get me wrong if and when the time comes I will be happy to pay an expert for them to work on it. The trouble then is finding that expert!

Thanks again for your help..

 

Just curious.....have you checked fuel pressure? Whenever I check a fuel injected car with a drivability concern, that's my first step. The ECM always makes decisions based on the assumption that the fuel and ignition system are operating properly because it has no way to monitor them.

 

Yes thanks. Made a fuel pressure gauge test rig for between the 2 throttle bodies and the fuel pressure is within the factory specs. Thanks again…

 

Just curious, what is the pressure since you said it is in GM spec?

 

I'd also be curious as to which wires you're probing/testing on the TPS as well. The correct wires should be the bottom two of the three. I did a test on mine to see if I could replicate your issue and the only way I could was by connecting the multimeter to the top two wires.

 

You should have gotten a - value as well when done wrong.

 

Depending on which voltage range is selected the multi-meter is on, sure. For example, I just had mine set to 20 and if I connect the to the top two it reads 4.68v and if I connect to the bottom two it reads 0.53v (of course this is closest to the correct reading based on the voltage setting of the multi-meter). Basically just saying that it's possible that the wires were crossed and/or the incorrect setting was used.

 

I had another idea to check as far as the TPS sensor issue goes. Earlier today I was swapping throttle bodies and when it came to the TPS and getting it set correctly, I too was struggling and it wouldn't get up to the .525 and barely registered no matter how far up and down I moved it. What it turned out to be for my issue was that the tang/lever that connects to the throttle shaft was a different shape and potentially not seated correctly. I took the lever off the throttle body that was registering the correct TPS voltage and installed it (and ensured it is seated correctly). At that point the TPS was showing the correct voltage. I also had to make sure that the rear bolt hole (closest to the rear of the engine) was pushed down far enough.

So if you're able to sweep it while its not installed and you can register the .525v (and higher), then its likely not seated properly when installed.

 

Yes - that could definitely cause big issues. the lever has to be moving when you depress the throttle pedal. an easy way to test is to have the dmm hooked up and either compress the cruise control bellows, or pul the lever between the two throttle bodies. if the lever is on the other side and the voltage does not change your car essentially thinks you are not depressing the throttle at all, and will run lean and spit and pop.