throttle position sensor replacement (Page 2/3)
Bruce DEC 03, 06:06 PM
Runs a little better, but still stutters at the beginning of each shift and at cruising speed, although not too bad at the latter.
The TPS went on without any problems, so that's a plus for my temperment.
bb
phonedawgz DEC 03, 09:07 PM
Motor Mounts. They aren't expensive. Not a huge job but more than a TPS to replace. Replace all three.

Bruce DEC 03, 09:24 PM
How would motor mounts affect acceleration?
Incidentally, all motor mounts were replaced about 15,000 miles ago. They shouldn't fail that quickly, should they?
Thanks!
bb
phonedawgz DEC 03, 09:45 PM
Well if they were just replaced, and if what you are having is a studder, not a shudder, the I will retract my 'engine mounts' statement

No SES light?

The SES light does work right?

Any access to either a fuel pressure gauge or an ECM scanner?
Bruce DEC 03, 10:45 PM
PD,
I'm going to take it into a diagnostic expert nearby, since I've done everything that is within my reach. I don't want to go in uncharted territory and really screw something else.
I wrote another entry entitled "what else can I possibly do," or something to that effect, in which I document everything I've tried / replaced to date (idle air control valve, mass air flow, mass air temperature sensor, ) O2 sensor, fuel injectors, fuel pump (though I'm beginning to doubt the quality of the replacement), s sensor,spark plugs and wires, cap and rotor, Cardone remanufactured distributor; cleaned throttle body; throttle position sensor, air temp sensor, coolant temperture sensor, and ignition control module. My neighbor checked the ignition coil, and I'm taking his word that it tested ok
The catalytic converter is only 15,000 miles old and was a stainless steel product I purchased from Summit, The muffler is a Flowmaster from WCF. Hopefully these two items live up to their hype.
I'm thinking it must be some kind of fuel flow problem, since the stuttering occurs to greater and lesser degrees at every part of shifting and acceleration. Or it may be a vacuum leak, but I don't want to blow myself to eternity to find one (vacuum leak, that is).
It's been very educational in my quest to find the problem, particularly since I am not much of a mechanic. I'll leave the intricate stuff to the very well regarded mechanic with whom I've made an appointment.
Thanks, though, for all your help. You have always responded quickly and with great advice to my previous questions.

Best regards,
Bruce
34blazer660 DEC 03, 11:28 PM
if you replaced the TPS, the voltage must be checked and adjusted within tolerance. the ECM calibrates at KEY ON and uses the base reference voltage as 0% TPS, unless the voltage at idle is over, iirc ~.530V. a voltmeter or scanner will help verify TPS voltage, if voltage is over ~.530V the engine will have trouble starting and part throttle hesistation, do to the ecm thinking theres an OFF IDLE condition

------------------
'97 Ram SS/T
'87 Mustang GT- 7730 w/S_AUJP V4
'86 Fiero SE- 7730 swap in progress
'85 S10 Blazer- ARI 3.4; GT3582R

Bruce JAN 17, 09:37 PM
It's been a while since I posted this, but I installed the TPS without doing any of the calibration. The car runs great (especially after I replaced 2 AC Delco spark plugs that had cracked ceramic insulators). Should I still have the TPS calibrated to be on the safe side, or should I leave it as it is.
Thanks, and Happy New Year!
bb
mcguiver3 JAN 18, 07:22 PM
If it's starting and running OK you could leave it but it would be nice to know what the value actually is.
.5 volts at idle is the place to be.
Bruce JAN 18, 08:36 PM
I'm taking in on Wednesday to have the harmonic balancer replaced, so I'll have the TPS voltage checked then.
Thanks for responding!
bb
notaguru DEC 22, 11:59 PM
If the TPS is just a potentiometer, calibration may not need a scanner or an OBD-1 connection. We should be able to measure voltages with pins and a common Digital VoltMeter (DVM) - like the perpetual freebie from Harbor Freight. Depending upon the wiring, you may have to trim away some insulation to access the wires. Stick a pin into the center (where the internal copper is) in each of the three wires. There should be a stable voltage (5? 12?) between two of them, then 0.5V between ground and the one that's connected to the potentiometer's wiper. You can't go wrong, because the voltage to the other connection will be many times greater.


GROUND --->VVVVVVVVVVVVVVVVVVVVV<--- +V
----------- ^
0.5V


As commented, if the torx screws pass through slotted holes, adjusting should be a snap - just slight rotation. I looked at one photo of a Fiero TPS and saw only round holes, so perhaps there's zero or little adjustment room.

Will that work?

If you're a bit paranoid, almost any glue or sealant will restore the wire's insulation.

[This message has been edited by notaguru (edited 12-24-2013).]