HELP!! Car runs horribly and cant get rid of these codes,

[BlueOvalStangGT]

Car has not ran good since I started the supercharger install in spring. Part after part after part keeps dieing and I finally want to get to the bottom of this. Right now I think I have all the kinks out of it except a leaky thermostat housing and these codes. Here are the codes I get ir the engine off.

118- Coolant Temp Sensor above MAX voltage/indicates below -40 degrees
123-TPS over MAX voltage
113- IAT sensor indicates open circuit/below -40 degres
337- EGR circuit above MAX voltage
539- Air Conditioning on during self test(it wasnt)
564- Fan Control circuit failure

Someone in the 5.0 section said I have a bad ground but he wont tell me how to fix it. Ive checked all the plugs I can find and so far so good. I just replaced the coolant temp sensor cause I broke it so the sensor is not bad. My car wont idle good sometimes, its slow, trouble starting sometimes nad other random problems like that. I took the chip from Razors Edge out and the belt off my blower so im not running any boost and I am running the stock computer. What could be the problem here?

BTW I have a laptop on the way and im still looking for a tweecer r/t, maybe that will help?

 

[stang_gt_1994]

It does seem like a ground. Unhook the tps connector and use a DMM and set it on ohms and ground one lead(to battery - post) and put the other on the ground on the tpd connector. I do not recall the color of the ground wire on the tps right this moment, just look in your manual.

 

[BlueOvalStangGT]

Someone on southfloridastangs.net said I might need a new computer?

 

[Chythar]

Fixing a bad ground is easy. FINDING IT is the hard part. You're gonna need to look for a wire that's attached to the chassis by a screw. There's one right on the negative battery line (black wire) right next to the battery itself. I'm not sure where the others are offhand, perhaps someone else can pitch in?

On the issue of "but he wont tell me how to fix it", he DID tell you how to fix it. You just don't have the knowledge to understand it. I'm sorry to have to tell you this, but there is a limit on how far anyone can provide help on this forum. Your wording of your e-mail makes it sound like you want someone to hold your hand throughout the whole process. That may not be what you intended to do, but it sure sounds like it.

Let me put it another way. This forum is here to help you with Mustang-specific issues. You asked for help on the issue, and help was given. The help was fairly technical to the not-so-electrically minded, but the help was given. Your next question was not "I still need help with my Mustang", but "I need help understanding electrical terms and testing procedures" or "I need help learning how to use my voltmeter". THAT is the part that is beyond the scope of this forum.

Anyone have any URLs that will help explain how to test the electrical system? I certainly wouldn't mind the links myself.

 

[BlueOvalStangGT]

Yeah I know forums have their limits but this thing is driving me crazy and I cant get the right reading he said I would the way I am doing it. With the ignition on I get 5-6 volts in 2 of the pins for the EGR.

 

[BlueOvalStangGT]

It does seem like a ground. Unhook the tps connector and use a DMM and set it on ohms and ground one lead(to battery - post) and put the other on the ground on the tpd connector. I do not recall the color of the ground wire on the tps right this moment, just look in your manual.

Ok did that, put the pos of the DMM onto the signal wire of the TPS and the ground(DMM) onto the ground of the TPS. At first I got -.69 volts at idle(haynes manual says .5-1.0 is good) I figured I had the wires backwards so i tried on my battery and my DMM is right on, the voltage is negative from the TPS. Then I did it at WOT and got 3.0-3.3(haynes says4-5 is good). Then I tried again and it kept varying from -.7 all the way up to 4.0 volts at idle, seems like it was around 3.0-3.3 most of the time tho. That was all at idle. The voltage would differ if I grounded it to my intake or not too.

 

[BlueOvalStangGT]

It does seem like a ground. Unhook the tps connector and use a DMM and set it on ohms and ground one lead(to battery - post) and put the other on the ground on the tpd connector. I do not recall the color of the ground wire on the tps right this moment, just look in your manual.

Did this, and I cant get a good reading. The reading I get constantly fluctuates and wont stop at a certain number. Is there a certain way to backprobe a harness?

 

[BlueOvalStangGT]

My dad said that if its a bad ground I might be able to take my computer and just make a new ground to my battery or soemthing and if it helps then I know its a bad ground. Will that work?

 

[BlueOvalStangGT]

I just backprobed the TP sensor, CT senssor and the IAT sensor and put the ohnomter on it. I got a good reading(.5-.8) from the TPS to the CTS and a good reading(same) from the TPS to the IAT. I still cannot get a accurate reading from my battery ground to my TPS or my CTS. Could that be where my problem is? How do I fix it if so?>

 

[BlueOvalStangGT]

Ok on the ohmeter, I get like .3-.8 for the TPS,CTS,IAT all to each other. If I do the intake to the battery ground, its good. Battery to ground by oil pressure sender is good too. Oil pressure ground to manifold it good too. But when you put the manifold to the TPS/IAT/CTS its no good(DMM reads like ~100) Same when you do the O P GRND to any of the sensors or vice versa. What does tihs tell me?

 

[BlueOvalStangGT]

bump

 

[grrrrrrr]

I'm not really sure where you're at on this, or if I'm going to help at all, but I would like to point out a few things. You first asked a question as to how you back probe a harnes. The easiest way is to sneak into moms sewing kit, steal a small stancion pin (little pin with the head on it, not one you thread with) and push that up into the harness from the back. Ohm your pin out with the metal connector on the other side to make sure you have continuity (0 ohms) and then you're ready to measure (simply put, you stick one multimeter lead on the pin you stole from mom and one on the metal pin in the harnes; should read 0 - .1 ohms, doesn't mean you have a ground, just means you have continuity). Second, for your application it's not really important whether you use the black or the red wire for chassis ground. By Chassis ground I mean when you measure your tps voltage (or whatever you're trying to check) against the engine block. Don't use your battery, use a solid screw or the cast iron of the block for your ground. Check all your connections against haynes to verify good voltage. If you think you have a ground on something then it should be fairly easy to identify. For instance, if there were a ground on the reference lead coming from your TPS (the wire with the changing voltage) then it would read close to 0 volts (0-.2 volts I think could be considered a ground if thats all the range you get out of it) From this position you would disconnect the harness (after turning the car off) and check to make sure you have a ground on the wire. You can ohm this fairly simply by putting one lead on the block and one lead on the harness wire (should be 0 ohms with ground fault; make sure you're not trying to read voltage with the ohms selection and vice versa, it's easy to get ahead of yourself and forget to switch the meter). If the problem goes away and you don't have a ground on the reference voltage wire then reconnect your TPS. If the symptoms repeat then replace your TPS. The same should hold true for just about all the other sensors you have in your car. A little word to the wise. 99.9% of the time when a circuit dies, or breaks, it developes an open, not a ground. So if you're positive you have a ground on a wiring harness in your car, it's most likely because something moving has worn or stripped away the insulation somewhere. This most likely causes an intermittent problem, and not a constant one. Keep this in mind. You'll do fine. Just a few guidelines when troubleshooting. All your sensors have a ground wire, don't let this throw you, it's how they work. All of them also have a power wire, usually 12 volts. If you turn the car on and one wire is ground, one wire is 12volts (polarity doesn't really matter, your car isn't going to switch from +12 volts to -12 volts because something broke) and the other reads a changing (or reference) voltage then you don't have a bad ground. You might have a bad sensor, but not a ground. Check this changing (reference) voltage against haynes. Now Haynes should tell you which wires to look at, and some of your sensors will have more than 3 wires, but if you have a low voltage coming out of a sensor, and haynes says you should have x.x then I would start with that sensor.

 

[mo_dingo]

Because you have so many sensors indicating a too much voltage, or not enough, I would think that you have a bad ground as well.

There are several grounds on your car. Each one has its own purpose. Any screw that goes into the body/frame of the car will be grounded. So you need to focus on the main grounds.

If the wire that connects the body to the battery is bad, it will make all of the grounds on the vehicle bad. You need to inspect & clean this cable and all of its connections. Make sure you have no resistance between from both ends of the wire.

Next, you should have a main ground that goes from the engine block to the frame/body. This grounds things like spark plugs, etc etc......Find, examine & clean this cable.

Next, if any of these don't solve the problem, you need to find out what is common with all of these sensors. This is the likely cause IMO. What I mean is, if all of these sensors are working, then their connections are bad. This means you need to trace each and every wire that hooks up to these sensors, and trace them back to the main wiring harness. Then, trace them all the way to the ccrm & finally the computer.

Check the cables for voltage bleed-over, or excess resistance & lack of continuity.

Your TPS voltage at idle should be around .8V to 1.1V, and 4.5-4.75V at WOT. If you are seeing .3V at idle & under 4V at WOT, the TPS is working just fine. You have a problem with the wiring to it. It's varying voltage like it should.

There has to be some common link. Hopefully the link is not the ccrm or the computer. That would be very sad, but very possible.

Good luck.
Scott

 

[grrrrrrr]

Check the ground lead out of the TPS, the IAT, coolant sensor and the EGR sensor and test them to ground. Make sure you get 0 or near 0 ohms. I would say you should test them all for a few reason's. If they're not all tied to the same common ground then you could have more than one broken wire.

Second you might have a cascading fault, meaning one sensor is making your computer run batty (garbage in, garbage out, makes your engine run like crap)
Third checking all of them will allow you to visually identify the harness, and determine if it's common between these sensors.
If you don't get 0 or near 0 ohms that's prolly your problem and you should get your self an allagator clip lead and disconnect the EGR. Someone help me out here but I think out of all the sensors, your car will idle and run the best without this one (lessor of the 4 evils so to speak) Ground the errant ground wire. Turn your car over and see if it runs better, then get the codes pulled again. Hopefully everything works out. Doing this proves beyond the shadow of a doubt that you need a ground on those wires to make these sensors work and that you don't have it. Then it's just a matter of hand-over-hand and finding the broken wire, or where it's not screwed in or whatever it's not doing what it's supposed to be. Good luck.

 

[BlueOvalStangGT]

From pin 46 to the ground on my battery= 20 ohms
From pin 46 to grey/red wire on tps= .04

 

[BlueOvalStangGT]

Did what you said,
I took the need that I used for backprobing, taped a wire to it and grounded it to my battery and voila! No CE light or bad idle. I let it idle in my garage for a lil and still good. Ok so now how do I find the bad wite so I dont have to have that ghetto wire running across my engine?

 

[BlueOvalStangGT]

Great, drove the car around for a lil and its a lil better. Still stalls when you push the clutch in and let off the gas sometimes nad it threw a CE light but its like on for a few secondes and then its off. Pulled the codes and got 564(is this whatthe recall was for) which was there before, and then these 2 new codes: 157 and 332. I lost my haynes manual so if anyone knows what they are let me know.