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So Scooter, it works now? Congrats on the screw hole fixes.

Curious, what's a "$1,000 diagnostic reader"? Since an HT4100 doesn't have any standard OBD ports etc. I had thought any modern tools were useless with regard to the ISC/TPS calibration.
 

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Discussion Starter #22
So Scooter, it works now? Congrats the screw hole fixes.

Curious, what's a "$1,000 diagnostic reader"? Since an HT4100 doesn't have any standard OBD ports etc. I had thought any modern tools were useless with regard to the ISC/TPS calibration.
He has a 9X12 screen "reader" he used on my truck and Eldo with some alligator clip wiring that he previously hooked up to Christine to check/set the timing, adjust the idle speed and diagnose an electrical short I had. He says he can use it to set the TPS/ISC for me, it might be that he will use it to read the electrical values for the two units as noted in the FSM and then proceed to manually adjust them according to specification. Reading the electrical values of the TPS/ISC connectors (to me) seems to be crucial to determine what manual adjustments have to be made.The onboard integral diagnostics only tell you if there is a problem by setting a code which tells you where to look, not how to fix or adjust. As I understand the FSM, electrical values on the TPS/ISC wiring determine the manual adjustments to be made. I hope I understand him correctly but I trust his judgement implicitly, he is very good. If my understanding is incorrect as to whether he can use it in this case, I have the FSM to back it up. Either way I think his expertise will augment my feeble attempts to position those units correctly and will complete the installation. Personally, I think the OBD diagnostics are valuable in indicating a problem which is great, but other equipment is them needed to fix/repair the offending unit, thus the expensive evaluation tools,
 

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That sounds right, though I haven't ever done it or looked at that section of the FSM in a long while, thank god.
So the TPS/ISC hasn't been dialed in yet? I can tell you that the pro mechanic who did mine said basically, "I don't need to follow all the steps in the manual. This handy modern tool I have makes it much easier." And then he screwed it up and I had to take it back.
 

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$1000 9x12 . . .

The TPS is a potentiometer - a variable resistor. As the throttle moves, the resistance changes, lowering/voltage.

Old school had you use a piercing connector to read the voltage while adjusting the position.

Ideally, you disconnect the tps, hookup a proper voltage signal and ground to the pigtail and use simple meter to read the return voltage. This eliminates any problems with wiring harness, ecu, etc. After setting, hook everything up and repeat at the e cu end of the harness to confirm no voltage loss/short. Then use on board diagnostics, scanner to show what the ecu thinks the tps is at. If it is different from original setting, then you have ecu/wiring problem.

Old school again, here's my 9x12. > 30 years old, still using it for tach and friends dwell. What more do you need? Tech, dwell, voltage. . . .
 

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Discussion Starter #25
$1000 9x12 . . .

The TPS is a potentiometer - a variable resistor. As the throttle moves, the resistance changes, lowering/voltage.

Old school had you use a piercing connector to read the voltage while adjusting the position.

Ideally, you disconnect the tps, hookup a proper voltage signal and ground to the pigtail and use simple meter to read the return voltage. This eliminates any problems with wiring harness, ecu, etc. After setting, hook everything up and repeat at the e cu end of the harness to confirm no voltage loss/short. Then use on board diagnostics, scanner to show what the ecu thinks the tps is at. If it is different from original setting, then you have ecu/wiring problem.

Old school again, here's my 9x12. > 30 years old, still using it for tach and friends dwell. What more do you need? Tech, dwell, voltage. . . .
sefiro.... Right on! I also have an old tach/dwell meter collecting dust in the garage corner. Haven't used in many, many years since there are no longer 40's and 50s' cars around, Just kept it because I can't throw anything away. I'm going to take it with me when my buddy sets things up for me, I might just find that I can use it in the future to do some tracing and might even be able to learn some new tricks. Appreciate the post!
 
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