13 replies to this topic

[BloodyCar]

So I am going to start a topic on this and try explaining what is happening.
Only had the car for 3 weeks.
Right from the beginning something wasn't right. It was going when I didn't give gas.
P1125 and later P1120 pointed to the TPS (Throttle position sensor Intermittent or out of range)
After changed the TPS, it was ok for 2 days. Maybe 50km. This is the only time I felt the car was under my control, ever.
How much gas? If you press the gas in neutral up to 4000 rpm.
How do I know? When I notice it's doing it, I push the shifter neutral, that is how high it goes. It doesn't jump up, it take linearly increases in 2 or so seconds.
To get it down, all I have to do is stop the vehicle. Actually when it slows down a slow roll, that is enough.
From this you know that idle is fine, in fact it's a problem because hard to diagnose while moving. Haven't find a mechanic I can strap to the open hood yet :)
Starting up is about the same. Sometimes it will start rolling just fine but as soon as I step on the gas a bit, something else is giving it more gas.
Which is why I don't think it's a mechanical problem. It can get stuck, but how does it increase?
Like it's favorite spot is at 60km. I just notice I can take my foot off the gas and it keeps going. But in a minute or so I notice it inch up 200rpm, and then 200 more.
In fact I am most of the time just driving it lightly on the gas and see how it goes. Mayne next I step on the break, maybe need to keep my foot on the gas.
After changing the TPS I though maybe another faulty TPS or the wires get some noise, loses some voltage, but it's not really random, there is a theme to it. I have been trying to figure out what.
Something that can give gas, while moving. It doesn't think it has enough, so it keep giving it. To a point.
In fact can someone tell what is that other cable next to gas cable to the throttle?
I don't want to go back to mechanic just yet, so we can start the lets change a fuel pump, lets change the computer etc.
I do have that MaxTrip scanner, so I know there are no other codes in there.
The scanner also gives me a TPS number, but I did not find it useful. I don't even know what it means. It loves 18.4 but sometimes it will shows that in a runaway moment, other times at idle.
I did measure the resistance on the 2 TPSs , but didn't expect them to be the same. It is a pot after all.

I don't know what else to add, so add your input.
thanks

[emdagosta]

BloodyCar, on 31 August 2010 - 10:01 PM, said:

So I am going to start a topic on this and try explaining what is happening.
Only had the car for 3 weeks.
Right from the beginning something wasn't right. It was going when I didn't give gas.
P1125 and later P1120 pointed to the TPS (Throttle position sensor Intermittent or out of range)
After changed the TPS, it was ok for 2 days. Maybe 50km. This is the only time I felt the car was under my control, ever.
How much gas? If you press the gas in neutral up to 4000 rpm.
How do I know? When I notice it's doing it, I push the shifter neutral, that is how high it goes. It doesn't jump up, it take linearly increases in 2 or so seconds.
To get it down, all I have to do is stop the vehicle. Actually when it slows down a slow roll, that is enough.
From this you know that idle is fine, in fact it's a problem because hard to diagnose while moving. Haven't find a mechanic I can strap to the open hood yet :)
Starting up is about the same. Sometimes it will start rolling just fine but as soon as I step on the gas a bit, something else is giving it more gas.
Which is why I don't think it's a mechanical problem. It can get stuck, but how does it increase?
Like it's favorite spot is at 60km. I just notice I can take my foot off the gas and it keeps going. But in a minute or so I notice it inch up 200rpm, and then 200 more.
In fact I am most of the time just driving it lightly on the gas and see how it goes. Mayne next I step on the break, maybe need to keep my foot on the gas.
After changing the TPS I though maybe another faulty TPS or the wires get some noise, loses some voltage, but it's not really random, there is a theme to it. I have been trying to figure out what.
Something that can give gas, while moving. It doesn't think it has enough, so it keep giving it. To a point.
In fact can someone tell what is that other cable next to gas cable to the throttle?
I don't want to go back to mechanic just yet, so we can start the lets change a fuel pump, lets change the computer etc.
I do have that MaxTrip scanner, so I know there are no other codes in there.
The scanner also gives me a TPS number, but I did not find it useful. I don't even know what it means. It loves 18.4 but sometimes it will shows that in a runaway moment, other times at idle.
I did measure the resistance on the 2 TPSs , but didn't expect them to be the same. It is a pot after all.

I don't know what else to add, so add your input.
thanks

i had a ford probe which thru these codes and we ended up taking it to ford they told us we needed a tps and a new MAss air flow meter.. we took the car home and replaced the tps for 80.00 adn cleaned the mass air flow meter out and the car ran fine until my son drove it into a telephone pole .. dont sleep while driving..also try reseting the ECU.. by unplugging the fuse and leaving it out a few minutes put back in and let idle for 10 to 20 minutes to relearn.. these are all I can suggest at the moment others may be able to help..
Dont forget to post back and let us know what resolved the problem it may help others in the future

[emdagosta]

emdagosta, on 01 September 2010 - 03:59 AM, said:

i had a ford probe which thru these codes and we ended up taking it to ford they told us we needed a tps and a new MAss air flow meter.. we took the car home and replaced the tps for 80.00 adn cleaned the mass air flow meter out and the car ran fine until my son drove it into a telephone pole .. dont sleep while driving..also try reseting the ECU.. by unplugging the fuse and leaving it out a few minutes put back in and let idle for 10 to 20 minutes to relearn.. these are all I can suggest at the moment others may be able to help..
Dont forget to post back and let us know what resolved the problem it may help others in the future

to add to this the MAF is responsible for the mixture and if it is clogged up it will not read what is going thru correctly causing the computer confussion.. cleaning the MAF is most likely all you would need to do it is generally simple and not time consuming... Ford wanted us tp replace at a cost of 400 for that part and they wanted 300 something for the tps. I knew we could find the tps for less and that the MAF could be cleaned out and that would most likely be all that would be needed.. we were right.. car ran fine after that.. if that doesnt work I would look into oxygen sensors possibly be the issue.. let us know.. it always helps when people post the fix on these threads..

[BloodyCar]

Update:

Thanks for all that, I never got to it. Yesterday morning it was really bad, revving high all the way to work and would not come down, so on the way back I had to stop by a mechanic.
After some thinking and discussion, he disconnected the IAC Idle Air Contol. Since it was still running at 500rpm, I left to see if it worked better. It did. At least after starting it up, the car was under my control again.
So I am looking into cleaning it but now I also read about an Idle Increase Solenoid. Well... one thing at the time :)

[BloodyCar]

So far I have sprayed it with air-intake/throttle cleaner a few times, no help. Measured the resistance, seem to be ok.

[BloodyCar]

BloodyCar, on 07 September 2010 - 08:02 PM, said:

So far I have sprayed it with air-intake/throttle cleaner a few times, no help. Measured the resistance, seem to be ok.

I also checked to see if it switches. It does. It seemed for a while spraying was helping, but now I don't know. Haven't got it off yet.

[BloodyCar]

In the mean time I have been driving it with the IAC disconnected and I have noticed that the reported TPS number doesn't make sense. I have one of these maxiTrip readers with the gauges. I don't know what the number means and since it probably depends on the pot it may not be the same as yours. However, if someone could give me some readings, I would appreciate it.
I have around 18.4 during idle. The problem is sometimes this number drops to below 10. So is it misreported? Read correctly and the replacement TPS is gone again?
By the way, it used to be 18.4 when it was stuck and revving at 3000rpm too.

[Terry Haines]

..Points to note on fitting a TPS.

*I have seen many of these fitted incorrectly.First be sure you have the correct TPS for the throttle body. Throttle shaft direction of rotation is not the same is all models.Note the direction of rotation from close to open of the throttle shaft.When you unscrew the old TPS you should note that the light spring within the TPS will turn the whole sensor BACK against the direction of rotation of the t/shaft. Be sure you engage the new TPS into the t/shaft 'tang' in a position that needs the TPS to be turned a little IN the direction of rotation of the t/shaft to align the screw holes. This starts to move the TPS off of its 'stop position' a little..which is correct.You can feel a slight spring resistance on the TPS as you move it to line up the screw holes in the direction of rotation of the t/shaft.
The TPS range is not from the hard stop on the TPS but just off it....This is the correct way to feel and fit the TPS and all readings should show as per the specs...easy eh!!!

[BloodyCar]

Terry Haines, on 14 September 2010 - 08:55 AM, said:

..Points to note on fitting a TPS.

*I have seen many of these fitted incorrectly.First be sure you have the correct TPS for the throttle body. Throttle shaft direction of rotation is not the same is all models.Note the direction of rotation from close to open of the throttle shaft.When you unscrew the old TPS you should note that the light spring within the TPS will turn the whole sensor BACK against the direction of rotation of the t/shaft. Be sure you engage the new TPS into the t/shaft 'tang' in a position that needs the TPS to be turned a little IN the direction of rotation of the t/shaft to align the screw holes. This starts to move the TPS off of its 'stop position' a little..which is correct.You can feel a slight spring resistance on the TPS as you move it to line up the screw holes in the direction of rotation of the t/shaft.
The TPS range is not from the hard stop on the TPS but just off it....This is the correct way to feel and fit the TPS and all readings should show as per the specs...easy eh!!!

Thanks. I figured out most of this when I changed it the first time and since I messed around with it 2 days ago I will add a few things I learned.

There is no way to put this on the wrong way. Not unless you break it if that's possible. The reason is, it will only turn one way. You can put a screwdriver in it to turn, but it is going very easy in way and I didn't push it hard the other way. The way I put it on is, I put it on (offset to the screw-hole) and tried to turn it to the hole. If it didn't go, I pulled it off and tried it the other way.
The other thing I found it is you can drive without the TPS attached, or attached but unplugged. If it is connected but not attached there is a small value fed to the computer . 6.4 on mine.
There is a bit more in the next post.

[BloodyCar]

So the first thing I did 3 days ago is got an MAF cleaner spray $11. Cleaned it and drove it a while later. For the first 15min it looked like it made a difference but then the problem came back.

Since I was still suspicious of the TPS, I decided to take it off and see if I turn it, what I get on me Trip live gauge device. I took the TPS off but it was still connected. Started the car and it was running. the gauge showed 6.4 (it would show a bit more when it's attached, because of that little turn you have to do). I guess that would be around 10, since that's the lowest I saw so far. By the way, If you turn the TPS, nothing happens. So I went for a drive like that. It was running fine. This makes me question what that thing is doing.
This is while the AIC was disconnected. So connected the AIC. Everything is still ok.
So I reattached the TPS but unconnected it. So the gauge would show zero. Still works fine. (by that I mean drive it for a while since my problem is while the car is moving not idle) So I reconnected the TPS and drive it home. So at this point everything is connected and in the last 2 days the car finally drive fine. I am very happy because other than one hard shift down as a stepped on it, the transmission seem to be working well.
However it may not last forever so the next time it is doing this I will be ready to jump and disconnect the TPS to see if that is the problem. The IAC is clearly the means to the problem but not the cause.
It either the TPS sensor, wires, or the computer.
I am not touching it as long as it is running. :)

[BloodyCar]

It started again. Haven't done anything , just noting the time.

[BloodyCar]

I sprayed the MAF sensor but that didn't help.
However I noticed on my Maxitrop that the LOD (engine load) number is changing as well as the TPS. The TPS number goes doen from idle 18.4 to like 11 and such. I know that will cause problem (shifting is one of them) and the LOD number goes up and down too. Should be around 20 when idle. It can go up to 90. (maybe about half gas) I even noticed after start, idleing around 800, with TPS at 18.4, LOD was 90!
The only problem is I don't know if TPS causing LOD increase and thus gas adjustment, or it thinks the load is high, thus uses TPS to adjust the gas.
Any suggestions? No money to swap computer or wiring harness :)

[BloodyCar]

So at the end it was an electrical problem. I didn't have time for a new harness but when we were talking about it with a friend of mine he started cut the wires open and separate them just to look at them, he found the problem. Cause later I noticed (from the numbers) that there is no problem. I put the TPS back since I was running without one for the last 2 month and it is working since. 2+ weeks now.
So the runaway car problem is solved !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sure I got P0136 and P0171 now, but at least the engine is operating more efficiently now and I still have to coat or wrap all those wires since I don't know which was the short, but I think it was a big step ahead.

Edited by BloodyCar, 06 February 2011 - 03:43 PM.

[SVTDEMON]

BloodyCar, on 06 February 2011 - 03:42 PM, said:

So at the end it was an electrical problem. I didn't have time for a new harness but when we were talking about it with a friend of mine he started cut the wires open and separate them just to look at them, he found the problem. Cause later I noticed (from the numbers) that there is no problem. I put the TPS back since I was running without one for the last 2 month and it is working since. 2+ weeks now.
So the runaway car problem is solved !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sure I got P0136 and P0171 now, but at least the engine is operating more efficiently now and I still have to coat or wrap all those wires since I don't know which was the short, but I think it was a big step ahead.

Damn Wiring Harness.LOL Glad to hear you worked it out.