CUTLASS Replace TPS or Carb?

Eddie Cutlass

Eddie Cutlass

Apprentice
May 3, 2020
74
18
San Diego
Just curious...is the exhaust leak a 'tap-tap-tap' sound? If you engine has them, it could be a cracked air injection reaction (AIR) tube on the manifold. It will be more pronounced under acceleration.
Yes, more of a ‘tap’ than a “spit”. I’ll check the AIR tube. Thank you!

y’all been a lot of help! Appreciate your time.
 
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69hurstolds

69hurstolds

Comic Book Super Hero
Supporting Member
Jan 2, 2006
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Sounds to me like you should at minimum go through some of the hoses and vacuum lines to replace bad and cracked ones. Those being bad can cause death by 1,000 vacuum leaks. Meaning you may not pass smog. I have no idea what you have to go through in San Diego to get it done, but that pretty much needs to be done anyway it seems. Do a little at a time. You can usually get the vacuum lines by the foot at the local auto parts stores. Check your plastic tubes for melt through spots. They can cause headaches, too.

Also, the wiring in general should be checked over. If you cleared your 21 code because of the TPS wiring, and now it's back WITH a code 34....hmmmm....
 
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Eddie Cutlass

Eddie Cutlass

Apprentice
May 3, 2020
74
18
San Diego
Sounds to me like you should at minimum go through some of the hoses and vacuum lines to replace bad and cracked ones. Those being bad can cause death by 1,000 vacuum leaks. Meaning you may not pass smog. I have no idea what you have to go through in San Diego to get it done, but that pretty much needs to be done anyway it seems. Do a little at a time. You can usually get the vacuum lines by the foot at the local auto parts stores. Check your plastic tubes for melt through spots. They can cause headaches, too.

Also, the wiring in general should be checked over. If you cleared your 21 code because of the TPS wiring, and now it's back WITH a code 34....hmmmm....
Thanks! Ordered vacuum line.
As far as codes, 21 is back along with 34.
 
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Eddie Cutlass

Eddie Cutlass

Apprentice
May 3, 2020
74
18
San Diego
UPDATE: Hey guys, so I was able to get rid of code 34 (MAP sensor) with plugging in vacuum lines that were old or unplugged. Plus, car is idling a lot better!

Also found the exhaust leak. Rotted out AIR tube. (See photo).

So after fixing vacuum lines, Still getting code 21 for the TPS. Took it to a local shop, old man checked for voltage, but nothing. He recommended to replace the ECM computer. Your guys’ thoughts?
 

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69hurstolds

69hurstolds

Comic Book Super Hero
Supporting Member
Jan 2, 2006
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The other side AIR tube will likely need replacing at some point as well, so when you buy the one, get the passenger side one too. Change the one, and either change the other or put the new one up for when you do have to change it out, then you'll have it. Check the check valves to make sure the check flap isn't burnt up. You'll be taking them off anyway to change the tubes, or you could buy new ones (recommended).

Believe me, fixing an exhaust leak due to AIR tubes is a lot better than fudging around with the exhaust pipes and rusted fasteners.

Cars cost money just to maintain stock. Sucks but it's what it is.

The old guy is jumping the gun. No voltage should give you a code 22. Code 21 is a TPS high voltage condition. Did he check the ECM terminal pinout # 21 for ~5 volt reference signal (gray wire- top position, terminal A)? Probably not. Dark blue wire is ECM pinout #2, middle position, terminal B, and the black bottom wire is ECM pinout #22, terminal C. It's your ground.

If you jumper the terminals B and C, your voltage should drop below 2.5V. If it doesn't, you may have a broken dark blue wire somewhere. And of course, a potential issue with the ECM as there's a couple of resistors in that gray wire source voltage that COULD go bad (inside the ECM), but that's last on the list and unlikely.
 
Eddie Cutlass

Eddie Cutlass

Apprentice
May 3, 2020
74
18
San Diego
The other side AIR tube will likely need replacing at some point as well, so when you buy the one, get the passenger side one too. Change the one, and either change the other or put the new one up for when you do have to change it out, then you'll have it. Check the check valves to make sure the check flap isn't burnt up. You'll be taking them off anyway to change the tubes, or you could buy new ones (recommended).

Believe me, fixing an exhaust leak due to AIR tubes is a lot better than fudging around with the exhaust pipes and rusted fasteners.

Cars cost money just to maintain stock. Sucks but it's what it is.

The old guy is jumping the gun. No voltage should give you a code 22. Code 21 is a TPS high voltage condition. Did he check the ECM terminal pinout # 21 for ~5 volt reference signal (gray wire- top position, terminal A)? Probably not. Dark blue wire is ECM pinout #2, middle position, terminal B, and the black bottom wire is ECM pinout #22, terminal C. It's your ground.

If you jumper the terminals B and C, your voltage should drop below 2.5V. If it doesn't, you may have a broken dark blue wire somewhere. And of course, a potential issue with the ECM as there's a couple of resistors in that gray wire source voltage that COULD go bad (inside the ECM), but that's last on the list and unlikely.
Thank you for the detailed info! You’re like a human shop manual thank you 🙌🏽
As for the old man, it’s hard to say if he was even checking for voltage, properly...i spent more time hearing about his ex wives and the cars he built for them, than him working on the car 🙄
I’m starting to think I might just save up for an LS swap ‘donor car/truck’ than go down a spending spiral on this Olds 307. 😕
 
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Eddie Cutlass

Eddie Cutlass

Apprentice
May 3, 2020
74
18
San Diego
Thank you for the detailed info! You’re like a human shop manual thank you 🙌🏽
As for the old man, it’s hard to say if he was even checking for voltage, properly...i spent more time hearing about his ex wives and the cars he built for them, than him working on the car 🙄
I’m starting to think I might just save up for an LS swap ‘donor car/truck’ than go down a spending spiral on this Olds 307. 😕
But in the mean time...I’m going blue wire hunting...I just bought some shrink tube for when I find frayed wires....maybe a new wiring harness 🧐??? These original wires and looms are so brittle.
 
69hurstolds

69hurstolds

Comic Book Super Hero
Supporting Member
Jan 2, 2006
3,999
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Get those service manuals and you'll be way ahead. It would take many paragraphs to detail GM's troubleshooting procedures. Basically, if you have approx. 5 volts at ECM terminal 21 at the ECM, and then you check to see if there's approx. 5 volts at terminal A on the plug going to the TPS, then you should be fine with reference voltage. Which it SOUNDS like you would, otherwise how would you get the high voltage condition from the TPS? Unless the internal resistor to the blue wire inside the ECM is hosed. Or just do a continuity check on the wires from the ECM pinouts to the TPS (ECM side plug).

If the wiring is good, I'm suspecting the TPS is glitchy, sticky, or hanging up. If the plunger's sticking down, that may be a potential cause for high voltage condition.

And if you think troubleshooting the ECM controlled 307 wiring is a PITA, wait until you start inserting that LS engine.
 
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olds307 and 403

olds307 and 403

Geezer
Oct 14, 2008
6,001
113
Melville,Saskatchewan
As said with a TPS, you need a 5V reference sitting there. You need a nice .5V or so at idle to around 4.5V at full throttle with a nice clean sweep moving the throttle. How hard is this TPS to remove?
 
69hurstolds

69hurstolds

Comic Book Super Hero
Supporting Member
Jan 2, 2006
3,999
113
As said with a TPS, you need a 5V reference sitting there. You need a nice .5V or so at idle to around 4.5V at full throttle with a nice clean sweep moving the throttle. How hard is this TPS to remove?
There's a video posted previously. It's not hard if you know your way around E-Qjets. but it could be a bit daunting if you've never done anything like this before. First time I did it about 200 years ago, I tore the air horn gasket. But I did get it changed out and adjusted. I've also adjusted them successfully OFF the car as well using a 5V input and NOT jacking with the idle screw during the process. Cut a plug off a junker and made my own test/jumper terminal. Although I seem to have lost that thing somewhere. Ain't seen it in a while.
 

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