CUTLASS Replace TPS or Carb?

[blk7gxn]

 

[Eddie Cutlass]

Code 21 is "open TPS circuit or misadjusted." It could mean the TPS is worn out, they are a bit flimsy inside. But to me it sounds more like a wiring problem. Anyway, I'd definitely want to check it with a voltmeter first. How are you with a voltmeter?

It’s been a while, but I can follow some directions if it’s not too crazy. Thank you for the knowledge! If it was a wiring issue, that would be ideal.

 

[Eddie Cutlass]

Your carburetor number for an 85 VIN Y 307 V8 should be 17085282.

If you need a new TPS, buy a GM/ACDelco one p/n 17078448. It's what came in it, and the one you have is probably original. If it is, 35 years in action isn't what I'd classify as flimsy IMO. I strongly advise on two parts for your G-body Olds you should never deviate from always using ACDelco brand if possible and that's the TPS and the O2 sensors. (O2 sensor--> AFS-16P, AFS-20). Bosch may make good stuff for other cars and such, but not sensors for an Olds G-body.

The only other brand of TPS I might trust is Borg Warner, aka BWD, and that's under p/n EC1014. I have reason to suspect those guys made the part for GM. But nobody I know of that's used a BWD sensor has said they've had an issue with it. However, I still would be standing pat on the Delco O2 sensors.

And, if you are running a genuine GM TPS in your carb, I will disagree that it is flimsy. It's probably the most robust brand of TPS you can find. A lot of them are still running on the factory part.

If you are not mechanically and/or electrically handy, then it's best to get the carb rebuilt correctly. I would stay away from remanufactured garbage sold in the box stores. You're going to pay a lot and get some generic chunk of aluminum that probably isn't adjusted at all close to what you have right at the moment.

For that kind of money, and if you don't have to have the car for a bit, I'd remove it, drain it of all gas and contact Everyday Performance and let them know what you got and what you need done and follow their instructions for shipping the carb to them. They can go through the carb and make it good as new again, and best of all, it's SPECIFICALLY for YOUR CAR! It's pretty much a bolt it on and go after he gets done with it. Plus, ensure to ask about upgrading to alcohol resistant rubber bits for inside the carb if you run ethanol infused gasoline.

Thanks for the thorough advice! It’s not my daily driver (yet), so sending the carb out sounds like it might be the plan after I check all the wiring first.
I already bought a Bosch O2 sensor (PN 12014). You recommend I return it and get a AC Delco instead?

 

[Eddie Cutlass]

Code 21 is "open TPS circuit or misadjusted." It could mean the TPS is worn out, they are a bit flimsy inside. But to me it sounds more like a wiring problem. Anyway, I'd definitely want to check it with a voltmeter first. How are you with a voltmeter?

Thanks for the info! Any links or steps on going about checking the wiring other than the obvious frayed wires? Thanks again!

 

[69hurstolds]

Thanks for the thorough advice! It’s not my daily driver (yet), so sending the carb out sounds like it might be the plan after I check all the wiring first.
I already bought a Bosch O2 sensor (PN 12014). You recommend I return it and get a AC Delco instead?

I won't tell you to return it. Only you can if you want to. Not saying it won't work for you. Just saying that for those two sensors, I use nothing but ACDelco and have never had a problem. Can't say that with Bosch.

FWIW, I'm not the only one who's bought Bosch O2 sensor and been unhappy with them. NEVER had seen any complaints of using the Delco replacement. Not saying there isn't any, but just going on personal experiences.

$17.85 plus any applicable sales tax and you can get a brand new genuine Delco AFS-20 (which is the AFS-16P replacement) delivered to your door. You probably paid more than that for that Bosch unit.
https://rover.ebay.com/rover/1/711-...0001&campid=5335822911&icep_item=373049415969


The latest and greatest I've found is the AFS-21. It'll work too.

 

[jiho]

I forgot. After you install a new carb, you also need to adjust the T.V. (throttle valve) cable, that runs to the transmission, when you hook it back up to the throttle bracket on the carb. If you don't the car will run like crap on the road, after all your work fine-tuning the carb.

EDIT: Actually you need to adjust the T.V. cable any time you hook it back up after unhooking it, not just installing a new carb.

The factory shop manual for your car would really help you, if you have to get into very much.

Gimme a bit to figure out the best way to explain how to check the wiring. I've checked my TPS adjustment and all, but I've never had a Code 21.

 

[jiho]

Ok, I remember now.

The b***h with testing is the terminals. You really need to make up a set of jumper wires -- 3 for the TPS -- using 20, 18 or 16 AWG wire and pairs of male-female Weather-Pack terminals (aka Weather-Pak). You plug the male ends into the socket on the carb, and the female ends into the plug on the wiring harness. They line up this way:

top
A +5V DC (approximate, rarely exact)
B TPS return signal
C ground

The TPS connector is located on the front driver-side corner of the carb body.

Then you can just turn the ignition key to "on" (engine OFF, do NOT start), and conveniently check anything you like by clipping meter leads onto the exposed parts of the terminals on your jumper wires (being careful not to short any of them together, of course). Aside from live voltage across A-C, you can check the signal voltage across B-C and watch it change as you move the throttle.

If you can figure out how to connect a voltmeter to the connector terminals without jumper wires, you can do a couple of sanity checks. First, sample the voltage across A-C on the harness plug, ignition "on". BEWARE of shorting or overloading!!! (The signal wire on B is harder the check, because there you want to check continuity, and to do that you have to figure out how to connect to both ends of the wire -- TPS end and ECM end -- at the same time to sample the resistance. You're on your own there.)

On the TPS socket, check resistance across both A-B and B-C with ignition "off". This is much safer. Across A-B the resistance should start out high (say over 13K Ohms) and fall as you open the throttle (to say over 5K Ohms wide open). Across B-C the resistance should start out low (say about 2K Ohms) and rise as you open the throttle (to say about 11K Ohms wide open). (These are not specs, just examples after pulling the throttle to close the choke.) This test won't tell you how well the TPS is adjusted, but does a sanity check on the TPS as an electrical circuit. There always seems to be a dead spot on the B-C test, even on a brand new genuine AC Delco TPS fresh out of the box, so just expect that and try to sleep at night.

As some annoying twit says somewhere on the 'Net just about once every second, "Hope this helps."

 

[Eddie Cutlass]

Ok, I remember now.

The b***h with testing is the terminals. You really need to make up a set of jumper wires -- 3 for the TPS -- using 20, 18 or 16 AWG wire and pairs of male-female Weather-Pack terminals (aka Weather-Pak). You plug the male ends into the socket on the carb, and the female ends into the plug on the wiring harness. They line up this way:

top
A +5V DC (approximate, rarely exact)
B TPS return signal
C ground

The TPS connector is located on the front driver-side corner of the carb body.

Then you can just turn the ignition key to "on" (engine OFF, do NOT start), and conveniently check anything you like by clipping meter leads onto the exposed parts of the terminals on your jumper wires (being careful not to short any of them together, of course). Aside from live voltage across A-C, you can check the signal voltage across B-C and watch it change as you move the throttle.

If you can figure out how to connect a voltmeter to the connector terminals without jumper wires, you can do a couple of sanity checks. First, sample the voltage across A-C on the harness plug, ignition "on". BEWARE of shorting or overloading!!! (The signal wire on B is harder the check, because there you want to check continuity, and to do that you have to figure out how to connect to both ends of the wire -- TPS end and ECM end -- at the same time to sample the resistance. You're on your own there.)

On the TPS socket, check resistance across both A-B and B-C with ignition "off". This is much safer. Across A-B the resistance should start out high (say over 13K Ohms) and fall as you open the throttle (to say over 5K Ohms wide open). Across B-C the resistance should start out low (say about 2K Ohms) and rise as you open the throttle (to say about 11K Ohms wide open). (These are not specs, just examples after pulling the throttle to close the choke.) This test won't tell you how well the TPS is adjusted, but does a sanity check on the TPS as an electrical circuit. There always seems to be a dead spot on the B-C test, even on a brand new genuine AC Delco TPS fresh out of the box, so just expect that and try to sleep at night.

As some annoying twit says somewhere on the 'Net just about once every second, "Hope this helps."

Wow! All this info from a twit?! 😂 thanks again for your time and knowledge! I’m going to order the factory shop manual so I have specs on hand.

 

[Clone TIE Pilot]

Stay away from reman carbs, remanufacturers tend to cut corners that can cause oddball problems.

All carbs will need final adjusting on the engine. This includes the TPS as it must be adjusted anytime the curb idle speed is adjusted.

 

[Eddie Cutlass]

Update: so I went ahead and started looking at the wiring harness from the TPS sensor back...at the ‘cross roads’ of wires right past the carb, I noticed 2 red/pinkish wires were stripped and touching each other (Insert dirty joke here). I taped them up for now. Also noticed a vacuum line was unplugged from carburetor so plugged that in. I reset the ECM, car started right up and no check engine light. Idled just a little wavy at first, but after driving for 20 minutes or so, idle is smooth after each start. Drive it another 25 miles afterwards and still smooth idle and runs better than the day I drove it home a couple weeks ago.( 459 miles to be exact). No more Check engine light. (For now). Hopefully I can make it to smog before anything else comes up.
Like Ice Cube said, “today was a good day...”
thank you everyone for your advice and knowledge. I’ve saved all your detailed procedures for future use. 💪🏽💪🏽 Thanksagain!
Now to figure out this exhaust leak.