Idling issues and "Engine Malfunction Service Now", Fiesta Mk7 S1600

[SwanseaS1600]

Thanks Peter,  At the moment I've decided to "live with it", including the awful limp mode that accompanies it, since the dealer's parting words were "if it happens again we'll have to look at swapping out the wiring, but the cost then is mostly labour".

Kevin

[Tdci-Peter]

2 hours ago, SwanseaS1600 said:

f it happens again we'll have to look at swapping out the wiring

I am not sure whether this information will be of assistance, tracking down connectors & wiring is not easy.

The wire from the APP (Pedal sensor) to the PCM seems to go direct, it is a YE/OG (yellow/orange I guess!) form pin 5 on the APP to C1-A2 on the pcm.

The wires from APP to IC go via connector C12: The signal wire is BU/GY (twisted with a YW/GN ground wire) from pin 2 on the APP to pin 1 on C12, to pin C1-14 on the IC.

This is from a 2008 year diagram, which I think covers up to 2010.

I don't know where C12 is, but it has at least 9 pins, & links engine stuff to body stuff. So it will be near the front bulkhead between engine compartment & cabin. On the Focus, there are a couple of connectors like that, just in front of the passenger front door, under the trim panels. Because of their location, they are subject to damage & corrosion due to water, and are known to cause a range of problems.

The only other wiring connection I can see in this loop, is the CAN bus. But errors here would usually create DTCs (error codes), relating to CAN bus errors. This CAN bus also goes through C12 between IC & PCM.

The DTC you are getting does seem very specific to this difference between the two APP signals, it is hard to see what else it could be.

Please post here if the symptoms change (may give another clue, or you get any results!

Hoping that this nasty problem can be fixed soon.

Peter.

[iantt]

c12 is fairly high up on n/s bulkhead near passenger fuse box

[SwanseaS1600]

Thanks Peter and Ian,

One thing I have noticed with the car is that there seems a slight power lag at normal speeds at the moment.  Previously going up a hill in 4th at 30 was no problem at all, now I get feedback from the car as though it's struggling.  Also when the error kicks in it's usually when driving at 30.  I'm having to keep the car in 3rd more than normal or I get the 'struggling' feeling, where you feel some hesitation in the car, it's normally when I feel that hesitation that I know to expect the problem to crop up shortly.  If I am driving at higher speed, 40+, the hesitation isn't apparent and it hasn't gone into limp since.

Recent limp issues have been:

1. Pulling out of a junction turning right, 2nd gear accelerating before going to 3rd.
2. Doing about 20/25 approaching a junction to go up a hill.
3. Approaching a roundabout, doing under 25.
4. Going up a hill in a 30 zone (with cameras) doing about 28.

I'm starting to wonder whether the lag and struggling is a symptom of the issue, rather than just a wiring issue.  I've had idling issues and stalling whilst slowing or stopping as an intermittent issue for a while (Ford diagnostics show nothing).  I know the error is Throttle/Pedal Switch/Sensor A/B, but could the issue be more throttle than pedal, since the surging and revving is something I've experienced.  On idle the car will 'rev' itself and you can see the RPM's rising and dropping as well as feel a shudder when they drop too low.

I found this on the web: https://www.yourmechanic.com/article/p2135-obd-ii-trouble-code-throttle-pedal-position-sensor-switch-a-b-voltage-correlation-by-blake-griffin

It still doesn't give me an exact "what to do next" as the Ford dealer seems to be in a "replace each bit until they fix it" mode, rather than a find the problem mode and I'm not that technical when it comes to the inner workings of the car.

Kevin

[Tdci-Peter]

3 hours ago, SwanseaS1600 said:

I know the error is Throttle/Pedal Switch/Sensor A/B, but could the issue be more throttle than pedal,

I must be blind! But then so was the garage.

I did not properly read the "/" between Throttle & Pedal, it makes a huge difference.

Throttle Body OR Throttle Pedal, Switch OR Sensor, A/B (comparison).

But how stupid is that for a code! The PCM knows full well whether the A/B fault is throttle body or pedal, but it is not letting on. Great!

It looks like Ian may have been right all along (nothing new there!), and it is one of the position sensors in the throttle body that is playing up.

I would guess that if there is a difference, the pcm takes the lowest value (safer!), so that could explain the power dips you get. And the difference may have to be fairly significant, or long term before it flags up the error code. These electronic units are designed to keep going as best they can, despite appearances.

So having rather thoroughly eliminated the pedal (& the demo unit should have done that!), all eyes should be on the throttle body now.

Sorry I did not spot this before. Part of wiring diagram including throttle body is attached, showing the pair of sensors.

Peter.

 

 

 

[iantt]

if it does end up being  a throttle body or connection to the throttle body, then that's another ford garage that doesn't know how to diagnose(.No surprise there then) lol

the connector pins need checking for a tight fit, connector pins can and do open up occasionaly giving poor contact.

 

[SwanseaS1600]

Thanks Peter, Ian,

I'm half tempted to take the connector off and take a look for myself, I've got a jewellers screwdriver set so could possibly tighten (carefully) the pins.

I would have thought a problem with the PCM would have had more effect than what I'm getting, I've had the uneven idling and the self revving for a while and assumed air flow sensor (MAF/MAP/TMAP or whatever Ford want to call it this week), but reading that link I posted, the problem could have been with the throttle all along.  Considering I get some of the symptoms (stalling, revs dropping and then rising, power fluctuations) without the error but then sometimes the error and limp mode engages, I would guess it's more likely the sensor and having the pedal replaced without fixing it may enforce that.

Half tempted to tell the garage to take the new pedal off and put the old one back on (since they thoughtfully gave me the old one) as their recommendation didn't fix it (and of course refund the cost of an unnecessary part).

If the problem is the sensor on the throttle body, I might have to instruct them on how to remove it without knackering the throttle body - apparently Ford Loctite the screws that hold it in place so you have to remove the throttle body and heat around the screw holes with a blowtorch to release the glue, otherwise the screw will snap and it's a new throttle body and lots of £££££.

It would be so nice to have a car that just works rather than have one with a mind of it's own!

Kevin

[Tdci-Peter]

17 minutes ago, SwanseaS1600 said:

'm half tempted to take the connector off and take a look for myself, I've got a jewellers screwdriver set so could possibly tighten (carefully) the pins.

I would!

[SwanseaS1600]

Well I disconnected both the throttle body connector and the MAP connector, they both looked fine and the connectors didn't have anything I could have tightened with a screwdriver (the throttle body was awkward to get to).

I haven't had the engine malfunction in 3 days but still getting lumpy idle, sudden drops in RPM and stalling (having to keep my foot on the throttle when on stop at times to keep the revs over 1000) when the revs suddenly drop below 500.  

I used the ODB2 tool on the car, the battery voltage is around 14V, on idle the revs are around 750 to 790, the air flow is reported as 1 to 2 bar and, the throttle pedal is 7.8% and the absolute throttle around 12.9%.  When I rev the car, the air flow increases, the revs increase to 1500 (I didn't hammer the revs), the air flow increased to 5 bar, the throttle pedal went to 14.1% and the absolute throttle also went to about 14%.

I do see variations in the revs and absolute throttle on idle, the throttle pedal stays constant until pressed and the air flow fluctuates slightly (presumably in response to the throttle).  The negative of the battery is connected to the chassis and both ends of the connector are smeared in grease, presumably to prevent water ingress affecting the connection.

I'm happy the error isn't so frequent (although not convinced it's sorted) but the lumpy idling and stalling is a pain.  Thinking about it, the car seemed happy enough in the winter, it was last summer and this summer (with the warmer air) that the problem seemed to get more pronounced.

Any advice would be appreciated.

[Tdci-Peter]

1 hour ago, SwanseaS1600 said:

the air flow increased to 5 bar, the throttle pedal went to 14.1% and the absolute throttle also went to about 14%.

I do see variations in the revs and absolute throttle on idle, the throttle pedal stays constant until pressed and the air flow fluctuates slightly

It is good to see some real data, even if, as is often the case, it seems to add to the confusion, initially.

I do not understand the pressure readings, it cannot be in Bar, is it mBar perhaps? (1 bar is about atmospheric pressure, or 14.5PSI). Even a turbo charged engine will only get up to about 2.4bar (abs), a non-turbo engine will always operate with the manifold below atmospheric pressure ("vacuum").

MAP stands for Manifold Absolute Pressure, where 0 would be a perfect vacuum, and about 1 Bar is typical atmospheric. (Look at a weather chart, Lows can be under 980mBar, Highs can be over 1030mBar). Another likely unit would be kPa, where 100 kPa = 1 Bar. Then the idle pressure of 1-2kPa (abs) would seem reasonable (10-20mBar), and 5kPa (50mBar) at 1500rpm.

The Pascal (Pa) is the scientific & proper engineering & SI unit of pressure, and is increasingly used.

I am not sure how often the P2135 error popped up, not often I suspect, so it is early days to see if that has gone away after testing the connectors. The uneven idle remains the primary symptom.

Because it is closed loop control, one part affects the other, and vice versa. The MAP is probably used to control the valve, and the valve position affects the MAP. So it is difficult to see from the data which is the cause of the fault. Larger and longer lasting jumps in either the MAP or Valve position readings could indicate a fault in that unit. But the P2135 DTC puts the probability of error onto the Valve.

At idle, there is no link between pedal position and valve position. It is enough that the pedal reading stays constant. I doubt if there is a simple link between pedal reading and valve reading at any engine speed. It will go through mapping in the pcm. Again it is enough if the readings are stable and sensible.

I recommend monitoring it for a couple of days to see if the DTC (& limp mode) returns.

If it does not return, then possibly there is a bad connection in the Valve connector that you have improved, but not cured, and it needs further attention or testing.

If it does return, contact the garage. I believe that in these cases of changing the wrong bit, reduced charges are supposed to apply for further work on the same problem. If they refuse this, investigate taking it elsewhere, as confidence in them is being undermined.

(I would take the valve off, take up to my fairly well equipped electronics workshop, and test it thoroughly there. But that, unfortunately, is not much use for you, if you do not have that luxury(?!))

Peter.

[SwanseaS1600]

Hi Peter,

unfortunately I don't have an electronics workshop, I work in the IT sector, but not the hardware aspect of it.  Ford failed to isolate the lumpy idling and stalling problem when they first had it - stating they couldn't see a problem, despite the fact that when I picked up the car it was idling all over the place!

Presuming the sensor near the air filter is a MAP, I could pick one of those up from EuroCarParts for £32 which isn't too bad, however they also list an Air Flow Meter/Air Mass Sensor for £105 (didn't think there would be both a MAP and a MAF on the car).  There is also the throttle body for £234 with them, however I wouldn't like to try getting to the bolts for that myself as getting the sensor cable off was bad enough yesterday.

I'm loath to start replacing bits for the sake of it, I do think it's the throttle due to the lumpy idle and power/stalling.  The fact that the air pressure is rising and falling very slightly might be the throttle valve opening and closing since those values would correlate, presumably if the throttle closed too much then it would starve the engine of air and trigger a stall.

I was getting the error and limp mode once to 3 times a day on the car, but I still had the error after they changed the pedal 3 times, which is why I'm not convinced the pedal fixed anything.  

I'll give them a call next week about next steps and pricing the throttle body (since they don't sell the sensor separately).

Thanks

Kevin

[iantt]

Now you have disconnected the throttle body connector, you may need to initialize it,

1. NOTE: Make sure that the pedals remain in the rest position.
2. Turn the ignition key to position II and wait for one minute to initialize the throttle body.

3  Turn the ignition key to the OFF position.

 

[SwanseaS1600]

Hi Ian,

the S1600 has keyless start, is it just a matter of pressing the power button without the clutch in so it doesn't start, then switching off a minute later?

would it be worthwhile disconnecting the throttle body, reconnecting and then initialising?

Thanks

Kevin

[iantt]

yep.

[SwanseaS1600]

Thanks Ian, I'll give it a go tomorrow, anything has to be better than constantly watching the revs and trying to catch it before a stall.

[SwanseaS1600]

Haven't had a chance to pull the sensor cable yet but the car is behaving since the weekend. Power seems more normal too. It's a little weird. Thanks for all the advice though.

[SwanseaS1600]

Well after 5 uneventful days of no issues, last night was definitely a case of "the !Removed! is back".  Coming up to roundabouts and junctions, revs dropped and car stalled twice, the rest of the time I had to use the throttle to keep the revs up.  This morning stalling again and the Engine Malfunction service Now error.  

[Tdci-Peter]

19 minutes ago, SwanseaS1600 said:

revs dropped and car stalled twice, the rest of the time I had to use the throttle to keep the revs up.  This morning stalling again and the Engine Malfunction Service Now error.  

Intermittent problems are a beast. But having your own diagnostics aid can be a big help, you can guarantee the gremlin will go into hiding the moment it goes near a garage!

I guess it is the same error code.

It is just possible the fault was in the cable or connector that you disturbed, made it better for a while, but did not really cure it. This sort of thing is common with bad connections. Am I right in thinking the bad idle problem is much more frequent than the P2135 ... A/B correlation code? As both valve position sensors share common ground & power lines, bad connections in these lines might well cause that.

If it is P2135 & not the wiring, then looks like the valve will have to come off for cleaning / repair / replacement. But as that is expensive, some time & effort in testing the connector / wiring is worth while. A decent local garage or auto-electrician may be able to do this, & the bit of wiring diagram I posted above might help (those diagrams may not be available to small garages unless they subscribe to the Ford ETIS site.)

[SwanseaS1600]

Hi Peter,

since finishing work I had 3 of the engine malfunction errors coupled with poor idling. The same P2135 code.

Letting the engine cool and then going to remove the sensor cable, re-seat it and do the initialisation cycle Ian suggested.

Going to phone Fords tomorrow and mention that they were concentrating on the pedal before and then the route they were going to take was replacing wiring looms and PCM but that the error equally applies to the throttle sensor on the throttle body. 

Thanks

Kevin

[Tdci-Peter]

On 21/07/2016 at 5:27 PM, SwanseaS1600 said:

Going to phone Fords tomorrow and mention that they were concentrating on the pedal before

Any new or progress?

Peter.

[SwanseaS1600]

Hi Peter,

following my re-seating of the connector on the throttle body sensor/motor I have had a week without error codes or stalling.  There has been some erratic idling at times and occasional "kangaroo" jumps accelerating from starting initially after the car has been left for a while but nothing else (famous last words there).

I has to be either the connector on the cabling or the actual throttle body itself.  I will be contacting Ford and telling them that their initial fault resolution didn't fix the issue and was likely unwarranted, however I'm then expecting them to go down the expensive "it must be the wiring loom" and several hours of labour.  I don't seem to have a local garage who would do anything except replace bits and pieces and am concerned about the money pit aspect.

If re-seating the connector does alleviate the issue then that's something, it's now back to basically how it was before the error code started (when they couldn't find anything wrong last year).

Kevin

[Tdci-Peter]

10 minutes ago, SwanseaS1600 said:

I will be contacting Ford and telling them that their initial fault resolution didn't fix the issue

There is no harm, and hopefully some benefit in doing this. I would read out, or show them, the first para of the reference you gave above, which was:

"P2135 code definition

Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation

What the P2135 code means

This particular trouble code indicates that the Power Control Module (PCM) has detected an erroneous reading regarding the voltages transmitted by throttle position sensor A or B, the accelerator pedal position sensor and or the actual throttle plate. The PCM expects both throttle position sensor outputs to stay within a logical and fairly close range of one another. The PCM will regularly compare the sensor readings as a way to test their efficiency and punctuality. Each throttle position sensor will send the PCM a voltage signal in correlation to the position of the throttle plate. The PCM interprets this signal as how far the throttle plate is open. If one throttle position sensor is reading at half throttle and the other is reading at full throttle, the PCM will set a code P2135 because the voltage readings will be so remote that it is impossible for the data to be accurate."

This mentions the throttle plate (in the throttle body) several times. This will no doubt annoy them no end, but they will have to answer or deal with it.

As far as I can tell, changing the throttle body is a straightforward mechanical job well within the capabilities of a local garage, who should be able to do the job at your specific request, without additional costs/tests. Of course, in that case you would have no come back if the fault was in the wiring or in the PCM. So the Ford dealer route might be the lesser of two evils. 

Peter.

 

[SwanseaS1600]

Hi Peter,

I was thinking the same thing so going down the route of "If I unplug and re-plug the cable onto the throttle body then the problem goes away for a bit", plus the "If you decide to change the wiring loom and charge me £300 I 4 hours labour @ £85 an hour and it doesn't fix the problem then I would expect a full refund".  My big concern is that they could charge me £640 in total for changing the wiring loom, then they discover the problem is still there and change the throttle body, so charge me £640 and absorb the £300 or so for a throttle body but still charging me £340 more than I would have otherwise spent (on top of the £150 I spent for a pedal which didn't fix it).

They could even go down the route of doing the wiring loom and then saying it's the PCM, charging me even more again.  

Surely they should be able to test the connection from the throttle body to isolate the cable (by probing the voltages on the lines) or testing the throttle body itself?

The error popped up once yesterday after over a week without it happening, all by unplugging a connector - so I don't think it's the PCM and as I didn't tug or twist the cables, I don't think there is a break or split in the cable run which is the fault (as I didn't exert any pressure on the cables to change the state of the cables themselves).

Kevin

 

[iantt]

I refer back to my earlier post regarding connector pins being a tight fit, how did you check they were ok? To check correctly you need the opposite type connecter and insert in each pin and feel for tight fit. If you think there is an issue in the area of connector, get your dealer to just put on a new one and not a loom. Dealers have a box with alsorts of connectors available now. That connector may or may not be available,

[Tdci-Peter]

8 hours ago, SwanseaS1600 said:

or testing the throttle body itself?

Testing the throttle body is dead easy, all that is needed is a variable power supply & a multimeter. It is not a fancy electronic thing, just a motor and a pair of position feedback pots. Apply some voltage to the motor, see if the vane moves, and check the two pot outputs. (This assumes it has the 6 pin connector as in the drawing I have). Unfortunately this ideally needs to be done on a workbench, ie out of the car.

So for a garage to do it, it would cost almost as much as fitting a new body. And they would have no procedure for it. I suspect most of this work is done "by the book" these days, especially in main dealers with contractual arrangements with Ford. And the "book" is far from perfect.

One worry is that the fault could be in the connector, or in the wires where they are crimped to the connector pins. Ian (above) is also suggesting this. The fault does seem to be close to the connector, either inside the body, or outside.

I wonder if it would be possible to support the cable in some way near the connector. A piece of stiff steel wire, ty-rapped to the throttle body, and to the cable, say? Supporting and bending the cable to one side may make the problem better, or worse. If worse, bend it the other way. Either way moves the diagnosis forward.

If the body was hard to remove, or testing revealed no fault, I would test through the cable from the pcm end. The motor should have rather low resistance, and the pot connections have well defined resistances,  then wiggle the connector & cable to see if I could induce changes.

It is interesting that Ian suggests that dealers might be able to renew a connector, rather than change a loom because of one bad connection. He has good knowledge of these things. That is certainly worth a try.

How far away is you next nearest Ford dealer, or other trustable garage? A few phone calls and negotiations might pay off.