possible tps problems

[ke5moh]

my 85 crown vic has been running rough. it starts with difficulty when it does start it idles fine but with any touch of the throttle it dies. I have recently changed the plugs, cap, roter, and wires and the fuel filter. i suspect the tps because the sensor looks burnt and if i unplug it the car runs much better.

how would i test it to find out if im right and if it is how do i change it

its a 302 with cfi

[Pirate]

my 85 crown vic has been running rough. it starts with difficulty when it does start it idles fine but with any touch of the throttle it dies. I have recently changed the plugs, cap, roter, and wires and the fuel filter. i suspect the tps because the sensor looks burnt and if i unplug it the car runs much better.

how would i test it to find out if im right and if it is how do i change it

its a 302 with cfi

You have to be REALLY careful here, because if you touch the purple/pink/black wire in the wrong way, the car will become an instant firebomb, vaporizing your upper torso if you don't get out of the way fast enough.

Testing it requires you to have a voltmeter that can go below 1 volt....a 'test light' doesn't cut it. However, if it is visibly compromised....it might be a good idea to go ahead and replace it.

So far as replacing it is concerned....the CFI unit actually has a choke of sorts hooked up to it, and that has to be removed first before you can pull the TPS off. So far as adjusting it goes....there's not really too much room to monkey with it, because if you install both retaining screws, one of the screw holes is oblong instead of round, extremely limiting the 'adjustability'. I've drilled the hole out to allow for adjustment; do not, at ANY time, screw around with the throttle-adjusting screw, because, once again, like the purple/pink/black wire, if you even touch that screw, the car will become an instant fireball, but in this case, it's your lower extremities that will be instantly incinerated. NO TOUCHY!.

You could also simply pull the TPS off, and put the new one in, and not have to worry about checking it....

[87_crown_vic]

does the CFI have IAC that could be gunked up. i know on SEFI those are big problems with the plungers in them getting sticky and not operating right causing issue...

as far as what Pirate said... leave the screw alone that adjusts the throttle arm... it is unnecessary to touch that unless you are looking at having bigger issues happen. i have known people that messed with that screw thinking they were helping the car... the car actually went up in flames a few weeks later on them. that is no joke.

[gadget73]

No IAC on a CFI car. They're basically a carb but with injectors instead of venturi. They have an idle stop screw and all that. there is the little plunger dealie for AC and high idle use, but if its not working, all that happens is the motor doesn't idle up when its supposed to.


If the TPS looks damaged, replace it. I'd also unhook the battery and allow the ecm to reset when you replace the sensor. They don't really need adjustment, the ECM is OK with values somewhere between 0.7v and like 1.2v. The actual setting at idle is not crucial, so long as it falls in that range. Most of the time the tps is designed so you can't really move it around anyway.

[85crownHPP]

the pics in the thread should help you get the choke levers back on after you change the TPS...

CFI choke