94 Mustang gt 5.0 running with tps unplugged

[HISSIN50]

In a pinch, a thin/small safety pin or dental pick suffice for probing.

IIRC 553 is an AIR (smog) code, which is different than the EGR system.

 

[MarshallPhil3]

I tested the TPS and i it started at 0.006v and went to 0.042v and from what i read that isnt what its supposed to be. any help would be appreciated.

 

[HISSIN50]

How did you test it? Did you ground the meter lead to the chassis or use the TPS ground?

 

[Canary94GT]

I just tested mine, it should be 0.5v to 1v with the throttle completely relaxed (key on engine off), by back-probing the top two wires on the connector.

With the key on engine off still, pull the throttle cable fully to WOT and the voltage should increase to 4.5-5 volts.

You need to also insert a probe into the bottom wire and check the voltage between it and the battery negative terminal. It should be *approximately* 5v with the key on engine off. If it's not, there's a problem with your PCM or the harness.

If it is getting the 5v from the PCM but the other voltages are wrong, then you need a new TPS.

 

[toyman]

This message is for MarshallPhil3. You come to the forum seeking help but you consistently refuse to follow the advise given and jump to other matters such as fuel pressure, MAF or whatever. You've been told that a computerized system needs the input from the sensors for the car to run properly and yet I don't see where you've taken steps to address the sources for the problems. Maybe I've missed something in the multiple threads you've started but I think not. You have to either get "with the program" or peeps will dial you off. I don't mean this to be dismissive but you need to deal with these matters in a logical and sequential manner if you truly want meaning results.

 

[MarshallPhil3]

Okay thanks im going to try it again maybe the ground wasnt good enough. And this is to Toyman: Yeah i understand and i appreciated the help i just dont have alot of time to check everything else my thinking was find out why it stopped running good so i can get back on the road, and the tps has been disconnected so i figured it couldnt be that. But i realize now that its probably the reason it stopped working right. i'ma start doing what ya'll advise cause ya'll seem to know more about this car. thanks

 

[MarshallPhil3]

Turns out there is a "deadspot" when reading the TPS. Im replacing it now ill see if that the problem. Do i need to do anything like disconnect the battery to clear the KAM while im putting the new TPS on or not?

 

[HISSIN50]

You should not need to. It'll RATCH upon turning the key on for the first time.

 

[toyman]

It's always good practice to remove the negative terminal before replacing electronic/electrical parts. This way you are assured that a short doesn't feed back to the PCM or just blow a fuse thus creating another unnecessary issue.

 

[MarshallPhil3]

Okay i replaced the TPS and the check engine light went off. But it still is not running right, like it sounds like its getting to much gas and not enough air or vice versa. Im leaning more towards not enough air cause at a steady 2000rpm just fine, but if i try to give it more it just cuts out. Plus if it was fuel delivery i wouldnt think it would hold a steady 2000rpm rev with sputtering or cuting out. Oh and if i try to punch it from idle i barely get anything and a loud popping?? If ya'll can help would greatly appreciate it. thanks

 

[HISSIN50]

What codes have changed now that the TPS issue should be resolved?

 

[MarshallPhil3]

I dont know yet i havent tested them again. Is that what i should do next?

 

[Canary94GT]

Codes from your other thread:

121 Throttle Position (TP) sensor out of range -
116 Engine Coolant (ECT) sensor out of range
157 Mass Air Flow signal is/was low or grounded
172 Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S
173 Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S
136 Oxygen sensor not switching/system lean Left or Front HO2S
137 Oxygen sensor not switching/system rich Left or Front HO2S
536 Brake On Off open or shorted to ground
632 E4OD - Transmission Control Switch (TCS) should be cycled once between engine ID and Goose test
158 MAF sensor is/was high or short to power
312 AIR not diverting
581 Cooling fan current was excessive
564 Fan Control (FC) circuit failure


Next step: Buy a Haynes manual and test all of these sensors/components for correct voltages and such.

Looks like you have a problem with your MAF system, cooling fan, and o2 sensors so they need to be tested.

The MAF sensor and o2 sensors could cause running problems like you're having. Also, is your cooling fan going on/off (particularly when you turn on the A/C it should go on)

 

[MarshallPhil3]

Okay ill do that. Im not sure, my a/c needs to be charged so i dont use it. So you think i should check the MAF and O2 sensors first? i have to have it running be tuesday so i need all the help i can get.

 

[Canary94GT]

the haynes manual will tell you how to backprobe the maf sensor for the correct voltage

or you might be able to find that info on the internet, but i wouldn't count on it

once you figure out if the maf sensor is working correctly or not, next step would be to check the o2 sensors.

Also, I'm just asking if your radiator cooling fan is coming on at all. You can check if it comes on by just turning on the A/C or getting the car to a warm operating temperature

 

[toyman]

Shouldn't the fan cycle on low and high when you start to pull codes? It's been so long since I had the stock PCM I can't remember for sure.

 

[Canary94GT]

Ah yes it does. With the door open, you should be able to hear the fan cycle on/off right after turning the key on (engine off) while doing the tests.

 

[BIGDATOWN]

Sounds like a dirty maf sensor to me or a loose connection on the maf sensor harness. I would check that first

 

[MarshallPhil3]

Okay thanks ill check it out tomorrow.

 

[MarshallPhil3]

How do i check the MAF voltage? And whats the best way to clean the MAF? thanks