Throttle Position Sensor

[fatboyfat7]

Just did a diagnostic on the car hoping something might turn up to explain my high emissions. It flashed code 14 at me which is the the Throttle Position Sensor. This would hardly affect emissions though would it? And I was also wondering would the diagnostic be valid for my car as it was converted from tip to a manual? thanks

[CJ]

A faulty TPS is usually noticible in that it can mimic problems caused by a faulty stepper motor, the main difference is the car can cut out / idle badly when warm.

A faulty TPS can increase emmisions:

The TPS tells the ECU the current angle of the throttle plate, if this information is incorrect, more or less fuel (and conversely, air) will be injected into the cylinders i.e. the car will either cut out or overfuel.

You can reset the resistance of the TPS (process in the workshop manual) if you've access to a multimeter, its not difficult but can be a little tricky to get right. If the TPS has been off at some point, its likely that it wasn't properly calibrated on refitting. The ECU is either complaining about the hi/lo tolerences being out of kilter or is getting no signal from the TPS (i.e. dead sensor, bad connection).

A new TPS is stupid money for what it is (a bit of plastic and a potentiometer), see here

CJ

[fatboyfat7]

Thanks for that CJ, yeah I read a little about jayod's problems with his alternator and it mentioned that multimeter thing for the TPS... Sure I wouldnt have a notion about reading resistance etc. I've disconnected the battery anyway so I'll check it again in a day or two and hopefully it will read the same. Then maybe Ive found my problem! I just wonder though would a faulty TPS really cause my emissions to be at 3.5 in oppose to .3? Seems a big diffence. I just want to know why they're so high at this point. I presume just getting a new sensor is just a matter of replacing it then, nothing too complicated please god.

[fatboyfat7]

Hang on a second... isnt your link and this http://www.camskill.co.uk/products.php? ... b0s9p51061 the same?

[CJ]

Different part numbers, 2 different TPS units it would seem. I don't have CAPS handy so can't check. Note that if the TPS is out of tolerance, it needs to be physically moved. Have a close look at it on the TB, you'll notice that if the 2 screws are loosened its possible to rotate the TPS left or right. Theres usually a small line of paint across the TPS and the TB which you can use a guide, the paint strip would have been applied @ the factory when the setting was correct. if its out of line, line it back up.

CJ

[CJ]

The idle on the GX has been hunting ever so slightly of late, a diagnostic threw up TPS and air intake temperature sensor flags. I disconnected the battery for 10 seconds and let the car idle for 10 minutes afterwards (as per section 13A of the workshop manual). Car is now cutting out coming to a stop at junctions (I should have left it well alone!). I reckon I'll look at investing in a set of sensors to see if this cures the problem, the TPS hasn't been off at any point by the looks of things so I assume its well within tolerance.

CJ

[colm_mcm]

does GX share TPS and Air intake sensor with GPX? you're welcome to try mine in yours if they do. no point in splashing out unnecessarily.

[CJ]

does GX share TPS and Air intake sensor with GPX? .

Very likely, TCL appears to be the dictating factor in terms of which of the 2 TPS units are in place. Colm, I'm assuming you're talking about spare parts as opposed to pulling them off your own motor? If so, I'll deffo take you up on the offer.

Got stuck into the workshop manuals (13A-77)and found the following on ftoaustralia.com:

Adjusting the position of your Throttle Position Sensor

Symptoms I had when my TPS needed adjusted were erratic revs, at exactly 30 mph in third gear, just what you need when driving in town in a tip car! However adjusting you TPS is a breeze.

Tools you will need,

Screwdriver, crosshead type
Pins, sewing type
Multi-meter
0.65mm thickness gauge

For cars without Traction Control

Place the thickness gauge between the fixed SAS, the speed adjustment screw on the bulkhead side of the throttle body, and the throttle lever so the throttle is very slightly opened. Then push the pins through the two wires on the engine side of the TPS and attach to a digital OHMeter. These are wires 1 & 2 and are the actual switch of the TPS.

Loosen the TPS until it can move then turn it clockwise as far as it will go. Check that the switch is ON, ie that there is continuity between the two wires. Now turn the TPS gently anti-clockwise and find the point at where the switch opens. Ie you have no continuity of circuit. Now tighten up the TPS.

To check the TPS output voltage push your pin in to wires 1 & 3, turn on the ignition but do not start the engine, the output voltage should be between 400 – 1,000mV. If there is a deviation then check the harness and the TPS itself.

For cars with Traction Control

Do not place the thickness gauge in at the SAS.
Push the pins through wires 1 & 3 and connect to a digital voltmeter. Turn on the ignition but do not start the engine. Check that there is between 580 & 690 mV for the sensor output. If it is not within this range loosen the TPS and adjust until it is within this range then retighten.

Remember that cars with TCL also have an idle position switch and accelerator pedal position sensor so if these steps do not wok it may be this that needs adjusted.

If this procedure throws up an error code then disconnect the battery for about ten seconds and this should erase them.

Armed with a couple of sewing pins (great idea, never would have through of this) and a multlimeter, I went out and broke into the TPS circuit, the outcome is I'm not getting any continuity on the circuit on pin 1 and 2 which would lead me to deducethat the switch is banjaxed. The TPS output volage is 850mV which is in tolerance so thats throwing me off a little bit.

CJ

[CJ]

FYI, cheaper alternative for TPS MD614735, I've confirmed with the supplier and they ill ship to Ireland. The same unit is £233 (versus AU$187):

http://www.cyberspaceautoparts.com.au/c ... /p230.html

CJ

[colm_mcm]

Would you not just put a second hand one on?

[CJ]

Would you not just put a second hand one on?

Assuming I can get the correct one, I'd give it a go - have you got one?

CJ

[colm_mcm]

eh.. think I have one off the GR somewhere alright. Can you post a pic of the part in question?

[colm_mcm]

Is it the part marked B?

[CJ]

Is it the part marked B?

Correct!

CJ

[colm_mcm]

Will have a look in the parts department

[Mustang]

Mustang, the diagnostic plug is mounted on a metal surround which is grounded, using this or pin 4 is a much of a muchness. It shouldn't take any more than 30 seconds (seriously) to ground pin 1, dead simple.

CJ

Actually it's a bigger job to remove the plastic panel. Simple job.
The engine light flashs constantly, and the code is delivered by the flashing of the ABS light -i take it this is normal (for cars with ABS?)

The codes it's giving me are:
13. Intake air temperature sensor. I'm not familair with this one. Where is this sensor?
14. Throttle position sensor-whicj would explain the high emissions. I know theres been some discussion on this recently -are they repairable/ serviceable?
There's two listed on camskill one at £239 and one at £145 -that's some spread. Anyone know what the diference is? which are fitted to what cars etc?

[Mustang]

CJ how did you get on with this? I'm getting a TPS error. Group buy perhaps?

[CJ]

Thread merge to keep the discussion on flow - CJ

Actually it's a bigger job to remove the plastic panel.

I hope you weren't charging by the hour Mustang! I've never had to remove the panel to get at the diagnostic plug...

The engine light flashs constantly, and the code is delivered by the flashing of the ABS light -i take it this is normal (for cars with ABS?)

Correct

The codes it's giving me are:
13. Intake air temperature sensor. I'm not familair with this one. Where is this sensor?
14. Throttle position sensor-whicj would explain the high emissions. I know theres been some discussion on this recently -are they repairable/ serviceable?

I have exactly the same issue. I changed the TPS for a second hand one (thanks Colm) and used contact cleaner on the IAT - no difference, I'm still getting the errors. I had the battery disconnected for about half an hour, may not have sufficient (although the WSM says 10mins).

I wonder is there a common factor here, more analysis needed methinks. I've the NCT nect week, will be interesting to see the result. I did mean to check that the ECU plugs were connected properly but never got around to it, wheres the torch....

Re the cost of a new TPS, http://www.panelhouse.com.au will supply and ship for AU$130.

CJ

[CJ]

Update: disconnected the negative terminal for an hour, hooked it back up, turned ignition to on, turned off AC and got the same 2 errors. I unplugged and replugged the ECU terminals while the battery was disconnected to check if there was a bad connection somewhere, no luck. Currently undertaking idle learning procedure on driveway.

Other possibilites goinging through my mind: bad earth, loss of continuity (broken wires), IAT has a dependancy on TPS, TPS is incorrectly adjusted which is throwing out the IAT.

As I understand it, the ECU will flag an error if it doesn't receive a signal from the sensor or the sensor values are out of tolerance. I wish I had a MUT-II

CJ

[Mustang]

13. Intake air temperature sensor. I'm not familair with this one. Where is this sensor?

FOUND IT

[fatboyfat7]

I got a used one from a guy breaking an FTO through ebay for £20 delivered. Emailed all of them! I know theres no guarantee it'll work but said I try it anyway. AUS$130 is very good though. Is there 2 different types of sensor depending on model? Is that why Colms didnt work for you CJ? Although id have assumed GR and GX would be the compatible ones...

[karlf]

Just seen this on ebay if anyone is interested.
http://cgi.ebay.ie/FTO-TPS-throttle-position-sensor-Fits-All-GPX-Models_W0QQitemZ180418323107QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2a01c522a3

[Mustang]

I wonder is there a common factor here, more analysis needed methinks. I've the NCT nect week, will be interesting to see the result. I did mean to check that the ECU plugs were connected properly but never got around to it, wheres the torch....


CJ

CJ I'm inclined to agree, I think it's unlikely that the TPS and IATS would fail in around the same time -on both of our cars, I was pouring over the workshop manuals at the weekend but am none the wiser really. I'd be happy enough to replace both sensors if I knew they were actually faulty, and replacing them would fix the problem -but I'm not convinced.
I was hoping to find a common fuse or relay on their repective circuits -failing that I'm inclined to think loose connection and/ or bad grounding at some point. Slightly OT but I had to fit an extra grounding strap to my stereo, when I fitted it, and It wasn't getting enough voltage to function properly without -so a gounding problem wouldn't be beyond the relms of possibility. When's your NCT -let us know how you get on. If your going to buy a TPS let me know -I might be interested in splitting the delivery with you.

[CJ]

When's your NCT -let us know how you get on. If your going to buy a TPS let me know -I might be interested in splitting the delivery with you.

NCT this Wednesday evening. Considering I tried a second hand one without result, I'm not convinced a new unit will do the job.

If I had the time I'd be:

1. Checking ground connections to both sensors
2. Checking continuity between the sensors and the respective ECU plugs (long cable and ohmeter required).
3. Checking all earth straps

Depending on the NCT outcome, I may look at leaving the car in with someone to check it out (pains me to do this but I'm flat out at the minute).

CJ

[fatboyfat7]

How did the nct go? Did she pass?