Got a question on an 84 T/A 5.0 H.O. and I can't seem to find much in my Haynes (hmmmmmmm) or online after four hours of trying. I'm trying to set the TPS on a new, OEM carb and I can't find the procedure. I know you use a voltmeter, but I'm not sure what the voltage should be or what wires to take a reading off of. I assume the engine should be warm when doing this, but not sure if it needs to be running or just key on. Any help will be appreciated. Thanks in advance.

 

The engine does not necessarily need to be warm, but you need to be certain the high idle cam is fully retracted so the throttle plates are in the curb idle position. You also need to be certain that the curb idle RPM is correctly set, so performing this with a fully warmed engine is easiest.

• Insert the probes of a digital voltmeter in terminals ‘B’ and ‘C’ on the TPS connector (center and bottom terminals). You may have to insert a paper clip or similar object into the rear of the connector to make contact.
• Turn on the ignition but do not start the engine. Read the voltage of the TPS.
• If the voltage is not within the desired specification, remove the top plug (19) and adjust the TPS screw (18) to
  obtain a reading of 0.48VDC across the terminals.

NOTE - If your meter probes are reversed, the reading will be -0.48VDC. The important factor is the number.

OTHER NOTE - Adjustment of the TPS plunger travel screw requires a 2.5mm hex with a very thin outer wall. In addition, adjustment of the mixture control solenoid lean and rich stops requireds a 2mm and 8mm and double "D" tool. All these sizes are available as OTC 7667 or through other sources, such as Lisle, Skyway, Snap-On (Lisle again) or others.

• Replace the hole plug in the adjustment screw hole when the position is set.
• Recheck the curb idle RPM and adjust as necessary, then adjust the TPS again as necessary until both are correct.

NEXT NOTE - Adjustment of the mixture control solenoid will likely be necessary after these adjustments.



You can get a little more detail on that by downloading this guide: E4ME Adjustment.pdf

 

Wow, thanks for the quick reply This answers two questions, the TPS and the idle bleed adjustment. I've got the two double d's for the M/C adjustment, but just not sure where to use the 8mm one. Guess I'll be studying tonight and looking at the car in the morning.

On a side note, I'm doing this to try to correct an excessively rich condition at all engine speeds (no black smoke, just burns your eyes and makes clothing reek when near the back of the car). The motor has 3500 miles on it, and I did a high $ rebuild, holding back nothing. The carb was bought new from GM. I'll let ya know what happens after I get the TPS checked/adjusted.

BTW, I saw that small plug for the TPS adjustment this afternoon. Should I drill it and put in a small sheet metal screw followed by pulling with a pliers to get it out? There is no provision to just pry the thing out. Thanks.

Bill

 

I've had some work with a sheet metal screw, and on some older carbs I've had to drill out the plug completely. With a new carb, you should be able to pull it relatively easily.

The small "D-D" is for the upper (rich) and lower (lean) travel stops adjustment screws for the MC solenoid on most DualJets and Quadrajets, and the larger (10mm) "D/D" is for the MC solenoid rich adjustment on some E2SEs. The set I have also has the 7mm "D-D" for removing the main jets.

An excessively rich condition? Checked the wet float level? Inlet needle and seat for damage? Main metering well plugs (on the underside) for leakage? Those are teh common ones.

And for the system to work correctly at all, you need a reliable O² sensor in the loop. If the duty cycle of the MC solenoid can't be controlled by the MC adjustments, you might need to tweak the idle mixture screws before adjusting the MC.

 

Thanks for the feedback. So far I've found that the TPS setting was off; voltage was at .64 volts and has been corrected to .48 volts. No change in exhaust smell. I've finally found a dwell meter and will be setting the idle air bleed today. My fingers are crossed and I'm hoping there are no surprises.

I took a chance and assumed that the float is set properly, there is no damage to the needle valve/seat, and that there is no leakage on the well plugs. I've been bit before on new parts not always being good, but there is no blatent evidence of flooding. I may soon find that I'll have to revisit these things. I also don't know what the float setting should be

The O2 sensor was new when I put the motor in (3500 miles on the motor) and there are no codes stored in the ECM. For now, and in absence of anything better, I've set the rod controlling the rich setting for the M/C at 3/32". I'm unsure how to properly set these, other than to cure a flat spot. But that won't cure the excessive HC condition. Do you have the proceedure for setting the M/C solenoid? Thanks in advance.

BTW, I was able to adjust the TPS by using a piece of 1/8" copper tube with the I.D. drilled out to 7/64". I have a pic of the setting being made with this tool and can email it if you'd like it for future use. Actually, I plan to take pics of any significant steps and would be happy to make them available.