"Christine" does not like me

1719 Views 24 Replies 6 Participants Last post by scooter111, Sep 19, 2019

scooter111

Discussion Starter · Aug 29, 2019

1983 Seville, 4.1
I posted last month about an issue with her almost stalling and having to "bounce" on the gas pedal to keep her running while waiting for a construction crew to clear the road on my way back from a battery purchase. (Details in previous post) After checking codes, fuel pressure etc. I decided to replace the TPS and ISC motor as a precautionary measure. Well, let the fun begin! First of all, the idiot who installed the TPS over torqued one of the attachment screws and it broke flush with the base housing. So he glued it in! Everything has to come off the intake to remove the base so it can be drilled out and retapped. After 36 years the bolts for the attached parts are gaulded to the intake as are the various pipes etc attached to the fuel intake base. And trying to get to the mounting bolts and connecting tubing requires removing other sensors, also gaulded, along with the distributor. A real nightmare, I don't look forward to removing the intake manifold to drill out all of the twisted off bolts so in a flash of possibly unsophisticated thought, I am thinking to just fugetaboutit and remove the TPS and ISC motor completely. After all I can adjust the idle up or down with the throttle screw. Don't think it would be a big deal to do that, might set a code or two, but so what? The TPS and ISC are only idle control functions and seem, at least to me, to be add-on electronic gizmos that add nothing to the run-ability of the engine, just being idle control.

I am probably missing something in my reasoning, (trying to save a lot of additional work and aggravation) and would appreciate any input from anyone who has been faced with a similar situation. And,as an addendum, NO, the base cannot be drilled out while still in position on the car.

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scottelderado

· #21 · Sep 16, 2019 (Edited)

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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scooter111

Discussion Starter · #22 · Sep 16, 2019

scottelderado said:
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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scottelderado

· #23 · Sep 16, 2019

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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sefiro

· #24 · Sep 18, 2019

$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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scooter111

Discussion Starter · #25 · Sep 19, 2019

sefiro said:
$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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