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T.P.S. setting on Rochester 4-bbl


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04-03-04, 06:25 AM   #1  
stumped04
T.P.S. setting on Rochester 4-bbl

I'm installing a kit on a Rochester 4-bbl carb that was on a 1984 Pontiac Parisienne w/305 Chevy engine (made in U.S., not Canada) For reference: carb # is 17084201; repair kit is from GP Sorenson, stock #96-566A. I'm stuck on setting the Throttle Position Sensor. I've been told by mechanics that it has to be "scoped" or that their machines won't cover carbs that old. I even had one Pontiac dealership (who will remain unamed, although I'm tempted!) that told me a T.P.S. is only on engines with fuel injection! Install instructions clearly show the T.P.S. and I definetely have it on my carb! Its obviously a critical setting and I dont have a clue on how to set it. Can you help? Thanks!

 
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04-03-04, 08:49 AM   #2  
TPS Setting

Straight out of my GM Computer Command Control (CCC) book:

TPS setting: 0.48 volts.

I believe the hex driver tool size is 3/32".

1. Drill a 5/64" (0.078") hole about 1/16" to 1/8" deep in the aluminum plug covering the TPS adjustment screw. Be careful not to damage the adjustment screw.

2. Start a No. 8-1/2" long self-tapping screw into the plug enough to ensure good thread engagement.

3. Pry the plug out with a wide-blade screwdriver. Discard the plug.

4. Unplug the electrical connector at the TPS, then connect jumper wires between the three terminals of the connector and TPS.

5. Connect a digital voltmeter across the center and lower terminals: terminal "B" (Dark Blue) and terminal "C" (Black).

6. Position TPS as described in carburetor charts - 17084201 is 0.48 volts.

7. With ignition switch ON, engine and AC/ OFF, turn the TPS screw with tool j-28696 or BT 7967-A (or equivalent) to obtain the voltage specified in the carburetor charts.

8. Remove jumper wires and voltmeter, and reconnect the TPS connector.

9. Install new tamper-resistant plug, until flush with boss. If not available, use silicon RTV sealant or equivalent.

HTH

Matt

 
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04-09-04, 10:29 PM   #3  
stumped04
Thanks for your info. Made it easy! Have one more question, though. Can't find any info in the owners or Haynes manual that says how to set the timing. Emission sticker on fan shroud is from a 1988 not an 84. Are they the same? If not, what is it supposed to be set at and how do I set it?

 
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04-10-04, 09:23 AM   #4  
Timing

Assuming your engine code is "H" (8th digit of the VIN):

Base timing is checked by disconnecting the 4-wire connector near the distributor. This takes the computer out of the equation.

Loosen the distributor hold down bolt just enough to rotate the distributor and set the timing.

I don't have specs here at home, but if I remember correctly it's either 6 or 8 degrees BTDC. I mark the timing indicator AND balancer with "white out" to pick up the timing light strobe. This is especially handy if your timing mark is behind the water pump where it's difficult to see.

When you get the timing set, tighten the bolt, reconnect the 4-wire and disconnect the battery negative cable for about 30 seconds to clear the check engine light.

HTH

Matt

 
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04-10-04, 02:29 PM   #5  
stumped04
Thanks Matt! And thanks to all at DIY for your advice. I know just enough to be "dangerous" and am too poor to take my heap to a shop, so you are definitely a lifesaver!

 
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04-11-04, 08:28 PM   #6  
You're Welcome!

Glad I could help.

Matt

 
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