Hairy McScary - Power Shrift attempting 3rd to 1st downshift

[AlCan]

Hi Guys,

My current daily, of the last few weeks, is the '13 MC TDCi DCT Wagon I've mentioned in relation to Cam Chain lubrication. That's seeming much improved now, but another problem has been rearing its ugly head.

"Randomly", averaging about once every 100-200km, during routine decelerations below about 25km/h, the transmission has been throwing a wild "downshift". Suddenly, instead of its gentle downshifting through the gears at just above idle speeds, it suddenly seems to attempt an early shift into first, and the engine revs up to 2,000-3,000 RPM. It's as if the Kick Down Switch has suddenly been activated. Fortunately, it's either in Neutral or the clutches are disengaged as, so far, it doesn't start powering into the back of the car in front. It's alarming all the same, and you can understand why anyone would be unhappy.

As I see it, the only way to sort this out is with FORScan, and now have a Windows version with an Extended (Free, 2 month) Licence - a great response to previous sanctions? Still figuring it out, and already discovered you apparently can't graph more than 12 traces, and you can't scroll up to view the lower ones. If anyone knows how, please let me know.

On my first crack at this I selected 14 PIDs, but fortunately, you can still access that data, even if you can't graph it.Took the car out yesterday, down a street with a mile of speed humps - the perfect excuse for lots of realistic slowdowns and speedups. On the first run, last hump, got a result. Saved it, figured I was damn lucky and headed home. Damn it if I didn't get a much bigger example just approaching a set of traffic lights. That time (the second since I've owned it), the trans got "stuck" in first gear and I had to crawl around the corner to get out of the traffic. Wanted to resume recording but it sorted itself out before I could do anything. Started recording again and it then did another "normal" example which I'm showing here, though not all the traces are visible.
https://photos.app.goo.gl/xCF7fpJZqVA4KTm28

Unfortunately, it looks as if the "GEAR_SEL" trace has a bug and doesn't show the gear steps properly, but it does show an unexpected shift into Neutral at the time in question. (The raw data shows the actual gear steps.) This coincides with the highest engine revs of the trip, and looking at the raw data seems to show that the firmware attempted to select a change from 3rd into 1st.

As we know, these two gears are both on the same input shaft and clutch, so such a change should not really be possible. That's to say, a Pre-select, Dual Clutch change would not be possible, though I guess, a single clutch 3-N-1 would, in theory. Maybe, it is actually implemented, but what's causing it to activate? I logged the KDS PID, but that's as it should be, I think. It seems to go active when in Park... Is that normal?

I can confirm that throughout this episode and the engine rev up, I didn't touch the accelerator and maintained my foot on the brake pedal. The engine rev up was obviously commanded internally, like it is during normal downshifts. Except this is a bit extreme.

So, can anyone suggest what the problem here is? I'm guessing that, like in Mondaveo's experience, this problem has existed through the past two or three ownerships.

One thing I notice from the raw data is that the (PCM) Engine RPM and the TCM Engine RPM data begin to differ by around 200 RPM during this craziness. Unfortunately, I can't seem to see which column is PCM and which is TCM (at least, not in off-line mode).

Anyway, could this be related? Any thoughts, anyone?

P.S. I didn't capture any new DTCs yet. Forgot to check after this 'successful' trip. (It does have a historical P0766:00-28 Shift Solenoid 'D' Performance/Stuck Off and a P0700:00-28 Transmission Control System (MIL Request), but these were from when I bought it, when it was suffering from very severe [undriveable] EGR issues. I assumed, maybe wrongly, that those aren't relevant to this.)

Event begins at time 55,384ms when Trans in 3rd gear, targets a change to 1st gear.

The engine starts to rev up at 55,424ms, but I don't know why the other Eng Speed trace was leading but now starts to lag. Is it that the TCM Engine Speed is not actually engine speed but clutch output speed? So clutch was slipping / disengaged?

I have the previous Service Docket, serviced by a Ford dealer 20,000km ago. Says "REPLACED TRANSMISSION FLUID AND FILTER", Parts include 6 litres of "TRANS FLU 75W 936A", P/N 'AXT13LDC'. Sound right?

Can anyone tell me how to read Firmware levels / is there an update?

[AlCan]

See attached file for FORScan data snippet.

Change extension to .csv for viewing in Excel - wouldn't allow upload as .csv

[AlCan]

A quick update... (Sorry, still long, but I'm not Mark Twain).

At first, thought it might be the Longitudinal Accelerometer, for two reasons.
1. The PID values for LNAS (a TCM PID) were showing roughly 10 times those of LONGACC_ABS, so I thought the higher one might be faulty, making the TCM think it was experiencing a very rapid deceleration (sudden steep hill?) when it wasn't.
2. When I had previously changed the engine oil and removed the undertray, found that the rear engine/transmission mount had taken a good hit at some stage, with scrape marks on the 'leg' and tarseal tightly jammed into the space between the mount and the lower chassis strut. Thought that might have damaged the sensor.

After repeating the tests in the old 2011, also found the same ~10-times readings for LNAS. I still don't understand why, as both PIDs show units of 'G', but that ended that line of thinking

Then, noticed that the GISS traces seemed slushy and that there was too much clutch slip, so next, tried a Clutch Learn. That went very nicely and made a huge improvement to the smoothness of gear changes (but also seemed to make them noisier, with more clutch plate engagement rattle apparent - small price...). But it didn't solve the problem.

At least, the GISS traces now seem to match those of the 2011, so I'm guessing the GISS speed sensor is also not the issue.

Did more Searching and found I'm not (of course) the first to experience this problem:

https://www.talkford.com/threads/pow...g-down.317185/

In that case, it looks like he eventually fell for a new transmission, but doesn't report on how that went. I don't buy the worn 2nd gear synchro theory, as the OBD data clearly shows it's a planned downshift to 1st, without any prior issues with 2nd gear. I have no graunching into any gear and as he doesn't mention it either, assume the same for his.

[FWIW, I read a lot of posts on the Kuga forum and had to quit - they were so depressing! One case of three "trans" failures - roughly one per year or so. ]

To be continued...

[AlCan]

Happy New Year to all!

May 2025 be a Happy, Healthy and Prosperous one for everyone.


Regarding the Powershift, trying to be time efficient and keep it simple, I've tried one last trick for the year, gone full circle and started back at the beginning. One run down Humpy Track and back produced no issues, so maybe it's fixed. Only time will tell.

[AlCan]

Yeah, Nah!

Yeow! Another long one. I hope it's interesting enough to make it worth the read.

My attempt last night didn't fix it. A second trip and... Seems like another factor is "Fully Warmed up".

Thinking back to the original No 1 problem with the car - very bad EGR issues, restarted back there thinking that "disabled" (vac line off and plugged) maybe wasn't enough.

Pulled the vacuum actuator off (easy, 2 x T20 screws) to see where that was at. There is a lot of spring tension in that dashpot, and I already knew that the arm was returning fully and easily - really snaps back if you pull the vacuum line off at idle - and could see when I took the pot off that the valve shaft was fully rotated to the closed position.

The design seems sound, there's a few degrees of spare (spring-arm) rotation remaining, which keeps the shaft tightly against some hidden stop when closed. However, also saw some soot around the shaft bearing and thought it was a tad loose. Seems like it's a simple butterfly valve, and maybe there is some internal wear of the butterfly or throat so maybe it was still leaking a bit. Lots of doubt...

So, made a blanking plate and fitted that in, but on my second trip out, it played up again... Slightly. And again today, this time another "Big Rev" 3N1 downchange. (It actually completes the change but usually I'm stopping so it's hard to confirm.) This time, the traffic moved ahead in time so that I could calmly confirm it. Also took careful note of the leadup to this change. It's not what one might expect, at all.

The accelerometer idea seems to be blown out of the water, as in this case and two other major rev cases, the braking was gentle but variable, and the changedown seemed to occur when the brake foot pressure was declining or released. It has always taken me by surprise, which makes it that much harder to remain the detached observer.

Anyway, after last night's failure, got thinking again... Apparent facts:

The TCM seems to be doing something it has been programmed to do, albeit an exception to the general rule. It's not simply, random accident.

It is clearly (from the OBD Data) proceeding in a planned, timed and logical manner, and seems to complete its plan without fault. It changes from 3rd, through Neutral into 1st without graunching or breaking anything. For all I know, (as a long term former driver of crash boxes), it's actually performing a full Double-Declutch sequence, complete with appropriate engine rev-up, but I haven't yet found the PIDs which would confirm that.

Given that it must have been a whole lot of extra effort, time and money to implement this feature, it must have been regarded as worthwhile and important enough to do. I'm still thinking it's to solve a safety or driveability issue.

Suddenly hitting a very steep hill in too high a gear at low RPM might have been one, except that that scenario isn't playing out here. To the contrary, the decels in question are generally very gentle and drawn out. Not enough to reach the accelerometer threshold, I imagine. (That said, the observed behaviour suggests a fault somewhere, so the steep hill possibility is not necessarily ruled out.)

The problem, so far is that I haven't figured out what is triggering the activation of this exception.

For now, I've shelved the steep hill idea, but have found another that is looking even harder to pin down.

The first thing I noticed about the car (after sorting the EGR) in switching from the 2011 was that the brakes were noticeably weaker. Initially passed it off as someone fitting cheap aftermarket pads and, as you do, pretty quickly got used to it.

But now I'm wondering about the vacuum pump...

This is already too long so we'll get to that later as this is another big can of worms.

[AlCan]

OK, a bit more for those following this.

My latest notion is that a weak vacuum pump leads to weaker brakes. You have to push harder to get the same effect, which I'm gonna say, is kinda obvious.

Now this is where we lift the lid on that can of worms.

What's going to happen when the vacuum pump starts to fail, and its vacuum generation ability falls?

This is where we begin realise how difficult it is to discuss vacuum in quantitative terms, because it's a negative concept. In fact, it's a generally misused word, as according to Oxford Dictionaries, a vacuum is "a space entirely devoid of matter".

In other words, a vacuum is absolute. It's either a vacuum or it isn't, and if it is a vacuum, then the absolute pressure is 0. So, a vacuum pump and a vacuum cleaner are (now accepted) misuses of the word, since neither can create a true vacuum. Really, suction would be a better word, but never mind.

As above, when the 'vacuum' created by the engine vacuum pump is weaker, then the brake booster's effect will be less, so the braking effect will be less for the same pedal pressure.

Could this be what's triggering the transmission to jump down two gears? Maybe 'it' thinks the car is 'running out of brakes'?

I've been looking into this and have a done a search of 'All' FORScan PIDs but can't find any relating to "vacuum", nor anything likely, related to brakes. This brings out a few worms.

1. It looks like either:
a. FORScan doesn't know about it, or
b. There is no PID relating to the vacuum level, and/or

2.a. There isn't any sensor monitoring the vacuum pump output, so
b. There's nothing to warn of reduced braking effort or potential severe loss of braking ability.

3. Is there anything (Sensor/PID?) in the brake booster system that monitors or infers vacuum level?

A bit of Googling confirms that even the notorious Mazda CX-5 has a vacuum circuit sensor, and that failing vacuum brings up a DTC:

P258B Vacuum pump circuit/range performance

A few questions follow:

Do the Mondeos (or any Fords??) have a vacuum pump monitoring sensor, and, if they don't, why not?

I don't believe there is any vacuum feed to the transmission, but can anyone who's pulled them out confirm that?

If these unusual downchanges are not related to vacuum level, nor to accelerometer values, what other possibilities can we come up with?

Is there an inclinometer in these cars, and does it have a PID?

[goz007]

All speculation on my behalf (maybe worth having a look through the workshop manual in the manuals section of the Forum) but I don't believe there would be any vacuum going to the trans, I believe it would be all electrical over Hydraulic, as for the vacuum sensor good point, but most of the Euro's do run a vacuum sensor & the Mondeo is built in Europe....but who knows, quiet possibly a cost savings measure....but interesting point... maybe kickdown could be monitored by brake pressure (but I really don't think so/or know, I also don't believe my SZ Tdci has a vacuum sensor either as the Early SZ S1 territory had terrible problems with its brake booster)

[goz007]

I also wouldn't be ruling out an EGR issue giving u the transmission issue, imo it would also be worth a transmission filter replacement (so if as your records say it will 1/give u piece of mind knowing it's been done & as it was done by Ford u should have a genuine filter in there 2/u can get an oil sample + squash the filter paper out & open it up & take a look)

[AlCan]

Thanks, good point, it's a European car... EURO5 and all that. Maybe they needed to cost cut a bit after all that expense.

I charted Brake Pressure and tested on hard braking, but it seems to be the opposite. It jumps down when you'd least expect it, usually at the end of a mild braked deceleration, at about 25-20km/h. Gently pumping the brake pedal - i.e. On/Off-On/Off braking seems to trigger it most often, so I figured maybe it was running out of vacuum. But if there's nothing to detect it... ?

Have to admit, got excited when the low vacuum idea occurred to me, but I'm starting to run out of ideas

I'll have a dig through the manuals.

[AlCan]

Will check out the tranny oil and filter, as we know that what the invoice reports isn't necessarily what happened, or if they did it correctly. MAYBE I need to be checking the fluid level!

Still can't get past the fact that I see the trans Targetting 1st gear from 3rd, and that it actually does it successfully! Anyway, as so often happens with these cars, it's not always what you'd think. EGR issues being a case in point.

Do you think blanking off the EGR valve (done) is enough, or do I need to do something more?

[goz007]

So u already have EGR blanked off?

[goz007]

If so & it hasn't been remapped with EGR taken out(I know a very experienced ECU remapper over in N.Z- if u want his details let me know) u will need to drill a 5/6mm hole in the blanking plate so as not to upset the ECU & start setting it of with faults, there is also a set of electrical test that can be done to it(check the workshop manual), I believe there is a plug-in u can buy to also delete the EGR & trick the ECU.

[goz007]

https://www.ebay.com.au/itm/32615099...mis&media=COPY
Or anthor option is buy anthor EGR valve Cable tie it to the engine & plug it into your loom & drive around with it & see if it sorts the issue.

[goz007]

https://www.ebay.com.au/itm/31605997...mis&media=COPY
https://www.ebay.com.au/itm/40484256...mis&media=COPY

[AlCan]

Originally Posted by goz007

So u already have EGR blanked off?

Yes, that's the last trick I tried on Tuesday - last day of '24.

Up until then, I'd been running with just the vacuum line disconnected and plugged, and the EGR dashpot port open. This meant the valve was closed, but not necessarily sealed, depending on its internal state. It was in the closed position, but as this behaviour was happening, wanted to eliminate that unknown.

For a bit more background, when I bought the car, it was effectively undriveable. It would kick and buck like a wild mule. It felt like the engine would suddenly and completely cut out - zero power - then continue, then cut again. It was terrible, worst around gear changes, and THB, it was scary to drive - I'm surprised nothing broke, it was that rough.

But simply disconnecting and plugging the vacuum line made it almost like new again. I drove it back (200k's) in TipTronic mode and it was almost faultless. (It may actually have done one of these 3N1 downshifts but I didn't know what it was at the time.)

[AlCan]

Thanks for the eBay links and other comments. Very interesting.

Looking at the 2011 valve (your first EGR link), it's the same as in my '11, but different from the '13 with this problem. In the '13, that light blue-grey coloured connector and wire etc is deleted. There seems to be no direct feedback circuit from the EGR valve actuator, and I guess it's all done from the other, black connector.

Regarding Remaps etc, up until now, I've been relying on what AlanM has said:https://www.fordforums.com.au/showpo...7&postcount=18 but I would be keen to talk to the Kiwi Remap guy you mention.

Apart from this problem, which may be unrelated, I can't say I've had any trouble since plugging the vac line. The engine itself starts perfectly (apart from cam chain noise!) runs very sweetly, has plenty of power. Hard to say regarding fuel economy as it's summertime and the aircon gets run...

I did see a number of laser cut plates for sale on eBay, especially by a guy called bertye1958, https://www.ebay.com/str/bertye1958 but he might be on holiday at the moment.

Similar or identical to this, but his photos and installation details were much better.https://www.ebay.com/itm/365062909646

They both claimed there would be next to no negative consequences to blanking. I can imagine an '11 model EGR valve might set DTCs, with that extra connector there, but so far none in the '13.

However, there's another thread on TalkFord (that probably confuses the issue by mixing up different engine models):https://www.talkford.com/threads/egr...for-it.246729/ All in all, it's a bit unclear, but thinking about it again, I'm pretty sure that these changedowns are nothing to do with EGR. The reason I say this is that, for the data snippet I've uploaded at least, when the change to 1st gear was targetted, the brakes were On (Hyd pressure 1166.7kPa), the throttle position was 0, the engine was in overrun (RPM = 1028), so I believe the fuel injection value was also 0 (I started to record it in later runs), so I'd say there was effectively no exhaust gas to recirculate - just warm air - and no fuel burn to dampen. Even if the PCM said EGR On, how much effect could it have had? The turbo would be idle, exhaust pressure near zero, power output 0, torque negative.

I'm truly puzzled. Must be something Proprietary? But still - Why?

I'll have to do more Data Logging and try to capture more of these events, but it seems to me odd that so few people have reported this problem, especially as there must be thousands of blanking plates installed by now, mostly without Remaps.

I so thought I was onto it with the vacuum pump but it's very hard to connect any dots there, now that there doesn't seem to be any vacuum monitoring. Maybe I'll find myself an empty outdoor area and try disconnecting the vacuum supply to the brake booster... You never know, there might be an inferred calculation happening that's triggering this.

OKAY! Another thought.

That random Water Detected in Fuel turned out to be a false alarm. But around the same time, a General Electrical Failure was flagged:

===PCM DTC P1139:01-27===

Code: P1139 - Water in Fuel Indicator Circuit

Additional Fault Symptom (:01): - General Electrical Failure

Status (-27): - DTC Present at Time of Request - Malfunction Indicator Lamp is Off for this DTC


Module: Powertrain Control Module

Maybe this is actually the key to it all - a dodgy connection lurking somewhere?

Oh Joy!

I will have to become more religious about checking for DTCs before Switch Off.

[goz007]

I'm not sure of the connection between EGR & Transmission-im sure ive seen other members on here talk of it(must be something in the Ford programming & the way the ECU/Ms talk to each other-the SZ Tdci also do strange things with there faults/fault codes, were fuel codes & EGR codes intertwine- the car throws a fuel code at u & can end up being an EGR issue) the other thing I would ask is has the battery been checked/charged/load tested.... batteries do crazy things & can appear fine but are not, I had a Territory recently giving random faults & going Into limp mode, switch the car off and most times away it would go without any issues, battery 12.7v at rest ,charged & load tested was showing 640cc ample for what it needed( but battery was actually 760cc) so in all reality good battery, but still I've seen it before with anthor car.....I just put in a new battery, car was randomly giving faults at least 3to4 times a week, battery fitted over a month ago, hasn't faulted since....I still believe getting another EGR valve & plugging it into your loom & Cable tie it into place & driving around like that would also be anthor good test....As for the Remapper, check out Peter James tuning-tell him Peter from Sydney told u about him.

[goz007]

I'd be checking member Mondaveo for his posts I think you might find the transmission/EGR relations in some of his write-ups.

[AlCan]

Hi goz,

Many thanks for all your input. I will talk to Peter next week.

Meanwhile, had to run into town at lunchtime. Started logging on the way back, and soon snagged the worst example I've had so far, on a 4-lane road. Had to slow for traffic and she jumped 3rd to 1st and got "stuck" there. Revving along at 20km/h, I had to shove into the left lane and off into a side-street, although it found 2nd just before the turn.

This time, I remembered to check for TCM DTCs pronto...

===TCM DTC P074A:00-27=== Code: P074A - Unable to Engage Gear 2Status (-27): - DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC


Module: Transmission Control Module Freeze Frame #1:

-EVENT_TIME: 371491145 s (Fri Jan 03 13:34:56 2025) -Event time

-TOTAL_DISTANCE: 134446 km - Total Distance

-MODULE_VOLTAGE: 14.3 V - Control Module Voltage

===END TCM DTC P074A:00-27===



You might say this changes everything.


I've had a quick look at the graph, TCM PIDs especially, and they don't seem to show any attempt to "Target" 2nd gear. TGT_GEAR simply drops from 3 to 1, but that happens after GEAR_SEL hits Neutral, which happens after the engine starts to rev up, which happens just as foot-off-brakes.
Whether the brakes had anything to do with it, the TCM apparently knew it was planning to change into 1st as soon as it started to rev up the engine, while TGT_GEAR was still 3. Now suspecting that TGT_GEAR is completely misnamed, just to confuse us. To me, a Target is what you're aiming for, not what you actually hit, so I've been misunderstanding what it was showing us. German designed, probably Lost in Translation, but maybe TGT_GEAR should really be called NXT_GEAR to indicate that the gear is actually engaged and ready to be used.

Also from the data captured, can see that just before the engine started to rev up, the accelerator was at 0, the engine fuel was 0, MAP is at atmospheric (100kPa), and the brakes were still only lightly (166.7kPa) on. There seems to be nothing to show that the TCM was attempting to engage 2nd gear at this point or earlier. That must all be happening inside the mind of the TCM and no PID for that is exposed.

To take all this any further, I imagine we would need to capture the HS-CAN Bus data, as there would have to be a command from the TCM to the PCM to "Rev Up!" But I don't think that would get us any further ahead.

It really does seem like the transmission is having trouble engaging 2nd, and that 1st is the last resort. Maybe all that kicking and bucking did do it some damage.

[AlCan]

Service Manual:

https://fordforums.com.au/wsmpub/lw2f/307-01a.html

P074A - INSTALL a new transmission

[Peter B - CV8]

I would assume that the EGR also functions under tiptronic mode, but you say the car drives fine when using tiptronic. Sounds like the fault is within the mechatronic unit of the transmission ie it's a communication issue rather than a mechanical issue.
If your thinking of changing fluid, then most certainly also drop the transmission sump & inspect for debris & change the filter.

[AlCan]

Hi Peter B,

Thanks for the comment / question. Currently, the EGR is as disabled as I can make it. The vacuum line is disconnected and plugged, but when I wondered if that was enough, I made and installed a blanking plate as well. I'm fairly sure it's nailed shut now!

And all the logs I've looked at suggest that before the Self-initiated Rev Up, the "Neutral" gear confirmation and the subsequent 3N1 changedown, the engine was overrunning with no fuel input, the MAP at atmospheric, and the brakes off or at very low pressure. Even if the EGR was working, what effect would it have, with no exhaust gas pressure, no intake pressure and only warm air coming out the exhaust ports?

So, I'm happy to put the EGR on the back burner for now, but as we've seen, when things go wrong with these cars, the symptoms often don't make sense. I still don't understand why the EGR causes such problems...

As I mentioned earlier, I'm going around the whole loop again. The first thing I did was disconnect the EGR. That took it from completely undriveable to acceptable, with only this occasional 3-to-1 downshift to worry about.

Then I went down the weak brakes, weak vacuum pump track. Maybe the system was thinking "Running out of brakes - Let's Panic!" But there doesn't seem to be any vacuum monitoring, so how can that work?

As I'd drawn a blank with the EGR and Vaccum pump ideas, thought I'd work through it again, dotting the 'i's.

So, my first suspicion was that maybe, despite the EGR butterfly valve shaft seeming to be completely closed, the valve might be worn internally and still passing enough exhaust gas to cause this changedown problem. Blanking it would confirm, but made no difference.

So, now that it's blanked off, I'm happy to move on to the next thing.

I've done the Clutch and Shift Fork Learns, and the clutch operation is much better but the problem changes seemed to be the same.

So, just for the hell of it, took the car out this afternoon, headed to a quiet industrial area where I could slowdown and speed up at whim. Just about there at not even fully warmed up when the car threw a right tizzy. Slowing down for a sharp left turn (in Auto mode), she suddenly revved up to 3,000 RPM and dropped into 1st.

And stayed there for a very long 27 seconds, with cars piling up behind me. Even changing into TipTronic mode didn't seem to help. Or maybe it did, as it came out of it into 2nd just near the turn into the nearest side street.

Stopped and saved the log, and checked for the DTC. There was NONE! And Yes, I did click the icon at the bottom left of the DTCs page, to force an All Modules query, but nothing.

Now, as I write this, a completely new idea occurs to me.

I know these cars are fitted with a Steering Angle Sensor, which (also?) inhibits changedowns while in a corner (in Auto mode anyway). Maybe the SAS is up the creek and preventing a changedown for too long.

I presume this Inhibit isn't Active when in TipTronic mode. Certainly, I haven't yet had the problem in TT-mode.

Or, maybe it's a Firmware bug, possibly due to having "Out-of-Step" updates installed, or something else unpredictable.

Anyway, gotta go now, but wanted to report what happened during my Test Drive. Maybe later.

[AlCan]

Ok, so I got to the industrial area and drove around and around, first in Auto mode. After the earlier whopper 1st gear episode, didn't have any further problems. That said, about all of my testing occurred in a straight line, as the Steering Angle possibility hadn't yet occurred to me.

Then did a stint in TipTronic mode, and again, no issues.

Since it was a warm day and things were getting hot, thought I'd test that out a bit too. Spent time stopped idling to increase temps until I got tired of it.

Got the ECT (Engine Coolant) Temp up to 95°C but the fan didn't cut in. Not sure what temp that's supposed to happen, but that's when I noticed that the good old analog (stepper motor driven) temperature gauge is BS. Even at 95°C (in FORScan), the needle was sitting at 79 on the dial. Don't know what use that is.

Got the TFT (Trans Fluid) Temp up to 92°C. There was no warning or DTC or anything else, though the TCM's behaviour may have changed a little. It's supposed to do something to reduce the temperature in these situations. Evidently, the earlier link about 82°C being hot for the TFT in an S-Max doesn't apply here.

Anyway, even at these temps, I didn't have any further bad transmission behaviour.

Also took at look at the TF cooling circuit. It runs from the External Filter Housing (Base) through the heat exchanger that's bolted to the Radiator and back to the filter housing.

The Coolant circuit through this heat exchanger appears to be in parallel with the radiator, which basically means that once the TF temperature is high enough (for the TCM to enable the cooling circuit), the Trans Fluid Temp is tied to the Engine Coolant Temp, all regulated by the Engine Thermostat.

Also checked out the trans fluid pipes for temperature difference simply by touch and figured that one pipe is somewhat hotter than the other, suggesting there is fluid flow through the heat exchanger.

Will dig into the Steering Sensor thing...

[goz007]

The EGR effect is a strange one(I've no answer here-same as with the SZs)and imo it's linked as through different ecms all talking to each other & making different systems do different things from the feedbacks they all receive & coralate(same as what U are thinking) my thoughts here though differ to yours with the disconnecting of the EGR, imo this will be sending different messages by it being in this state, if it's still plugged in then it also really confuses the system more, if unplugged then its going to put other faults in(this is the reason I make the suggestion to strap or tie a good knowen valve to the engine & hook it all up as if it were fitted to test the EGR theory) other than that the battery will also play a big role in random issues & faults & as I said earlier even a battery that is still logically testing ok & seem good may not(as I just discovered recently with the SZ that was giving random faults)

[goz007]

As for oil temp, imo as long as it's within about 5deg of coolant temp I don't think there is any issues, I think the absolute most U would want to see oil temp would be about 110/120 deg after that I would be expecting gearbox damage... temperature would also be heavily dependent on ambient temp & transmission load & vehicle load, so unless U were towing a heavy trailer/boat on a hot day up a big hill I wouldn't be expecting to ever see 110/120deg, but the temperature U described I would think this quite acceptable

[AlCan]

Hi again Goz,

Thanks for your comments about oil temps. Very helpful and reassuring.

Thinking more... on the results of the driving around today, including the one testing the SAS.

I see a strong correlation with braking. Virtually all the testing today was without much braking, mostly natural (hills) or engine braking - and had no jump downs.

Both the two occurrences today were closely associated the light or moderate braking, during or just prior to the jump down.

Interestinger and interestinger ...

[AlCan]

Continuing along the Electrical line...

Looked at battery today. Label might indicate 5yo. Even so Battery Load Tester put it well into Green for 800CCA battery, still in the Green for a 1,000CCA. Spins the engine over very nicely. But could still be dodgy. Will let you know.

Also found four Wiring Harness Earth lugs approximately under the Air Filter box. Undid, cleaned and retightened.

And no difference...

But as you say, if I don't test and it's suddenly fixed, likely never know the cause.

I'm gonna get a vacuum gauge next.

[goz007]

As for the earth question, i.m.o 100% can cause issues & the same as U describe the hotter the wires get the harder to move the current pushing IR through the roof untill the circuit fails....as for the battery, yeah like I said, I've seen it 2many times the most recent was that SZ 760cc testing as a good battery indicator in the battery also solid green(but really that's just a false sense of security as it's only looking@1cell)but CCA was testing around 640 but battery test matching(expensive well known brand)was saying good battery) also struck another one that sticks in my mind on a Mazda 800cc battery, battery testing good & showing 780cca green indicator green 12.8v@rest car would start & drive perfectly, drive for hours without any issues, park it in the sun(was hot & summer@the time) it wouldn't start, park in the shade & it was ok... checking battery when it had the no start issues battery was still checking good, eventually after many attempts to diagnose (left it@anthor mates workshop as he found the situation quite funny & wouldn't believe me-until it did it to him(it was his sparky who said battery is U/S we laughed at him, he laughed back at us-car was in its no start state-had been driven out of the workshop sat in sun all day & then wouldn't start, sparky said I bet U a carton of carona that I'll put a new battery in & it will start.... well he took home a carton of carona.) although both these car are different to your situation(also both these cars were different to each other as well) the point being that with these modern cars that run a high demand on the power supply from a battery can play havoc with there modules.... batteries do strange things & batteries aren't made like they use to be & aren't really made to last any longer than 3yrs.....i.m.o 3yrs smile & be happy as uve done well

[AlCan]

Hi Goz,

Thanks - yes, I'm looking at putting another battery in just to see what happens. Will let you know for sure! Hah, a heat sensitive car battery. Must have had a crack or loose joint inside. Lucky it didn't go BANG! I've seen the result of a truck battery that did that. Ugly, stinky mess! Lucky no one was nearby at the time.

Also, rang PJ yesterday. He sends his best regards. What a thoroughly decent and helpful chap. A Jag man. We had quite a chat. Sounds like he's doing well. Gave me 4 options, all very sensible, will send pricing. He thinks it might be a solenoid problem. Anyway, for now I'm going to drive in in Manual mode, as so far, that's been fine.

But it's all a bit weird. Manual gear changes must use different routines inside the TCM, or why don't they mess up sometimes too? Maybe they will... ;-(

[goz007]

Yeah PJ is ok for a winging/whining X pom(hahaha).....nah he's a top guy, been tuning/remapping for over 25years, has tuned for some of the biggest tuning houses & race teams in Europe....he knows his stuff.