This happened to us the day before yesterday. I will not be able to get the codes read until Monday the 5th of March. Just trying to find out if this story sounds familiar to anyone here.

Weather conditions were just a few degrees below freezing, with moderate blowing snow and accumulations on the roads of up to 5-7 CM of mixed slush and fresh fallen snow.

Car was fully warmed up with everything initially operating perfectly. Approximately 30 minutes/50KMs into the trip and at a steady speed of 100kph, a single sharp clunk was heard and felt from the engine/transmission area accompanied by an initial engine speed drop of a few hundred RPM, then temporary increase before settling back to normal cruise RPM. Repeats of this clunk/RPM oscillation were noted, with increasing frequency and amplitude. Disengaging cruise control made no difference as did varying vehicle speed or manually selecting different gears. The time interval between clunks/RPM oscillation events soon decreased to possibly one every 3 to 5 seconds making the car unpleasant and unacceptable to drive.

As the decision was made to pull over, the restricted performance message appeared intermittently (flashed on/off possibly three times(?) followed by the engine cutting out completely as we exited the paved road and rolled onto the soft shoulder. No yellow or red caution lights or other messages appeared.

Attempts to restart the engine were initially unsuccessful as it would start only for a second or two, then die again. Sitting on the side of a major four lane highway in a snowstorm is not a pleasant or comforting experience, especially with SWMBO and my parents on board.

After sitting for approx 10 minutes waiting for the auto club tow truck, another attempt was made to start the engine and this time it fired right up and operated normally. We pulled out onto the road again, expecting to limp to the nearest exit. To our surprise the car operated 'as advertised' and we continued the journey hoping to make it to a larger town another 75 KMs away where a decent garage could be found. During this time, only one or two other 'clunk/RPM oscillation' events occurred.

The decision was made to stop for a break and evaluate whether to continue or not to our appointment, which would take us off the wet slushy highway and onto plowed but 'dry' snow covered roads. It was also thought that if moisture was causing the events, letting it sit with a hot engine would dry things out.

Long story short, after a half hour rest we carried on another 100KMs to our destination with NO futher clunk/rpm oscillation events.

The return journey was done partly on wet slushy roads with a few isolated single 'events' occurred and partly on dry clear roads where NO events were encountered. I've attempted to recreate the events today but was unsuccessful.

I had initially thought that the transmission torque converter had packed it in but don't beleive that a failed unit would also cause the engine to quit nor would it cause the car to buck and surge so violently. I don't think that it would somehow subsequently 'fix itself' and operate perfectly again.

Any similar experience other posters have had would be very helpful.

Thanks

Mike

 

Sorry to hear about your experience. The 2 things that come to mind are as follows: a transmission issue/internal failure or a tensioner issue. I would lean more towards an issue with the transmission. "Restricted Performance" I believe is typically transmission related. My Jag drove decently with some rough up shifts and the internals were shot - called for a rebuilt trans - $3,600 later. You should have some codes stored that should lead you in the right direction, hopefully. I wish you the best of luck. Please let me know how you make out.

 

Could it have been water in the fuel?

 

Like most technical things, intermittent problems are the worst to diagnose. If it were transmission, why would the engine have quit and refuse to restart for 10 minutes? The car now drives smooth as silk so aside from some codes that I'll hopefully get on Monday, there's no sign that anything unusual ever happened.

Possibly, but the clunk felt far more violent than just a random misfire on one cylinder. The round trip was done on the same tank of gas, over 400 KM. The latter part was absolutely fault free, the only key difference was drier roads.

I'm thinking water in a connector- but which one where?

Thanks for the responses so far.

 

Did you check for codes?

 

Mikey, this event sounds moisture related. The "S" is sensitive to moisture about the throttle body connections, etc. As she warmed up from sub-zero conditions, the melting and/or condensation of atmosphere in and about electrical connectors can cause minor intermittant shorts. As she warmed up the condensation evaporated not causing further engine and trans, cut-outs.

 

You have been jaged! I agree most likly moisture related.

I have had intermittent restricted performance lights here and there. It never went into limp mode and always drove just fine but triggered an array of lights none the less. The denso ecu and harness are impressive when it works, unfortunately it's so invasive that any little thing causes a whats wrong with this thing now moment. I would guess its ok now.

I know it isn't comforting as I feel the same way. My car has been 100% since I purchased it but it leaves a sense of worry when at any moment the ecu could have a "jag moment" with no real rhyme nor reason!

 

What a horrid experience!

Flashing MIL is catalyst-damaging misfires occurring then and there. (Unless there's another time it flashes but I don't recall one.)

Maybe an iced-up TB (throttle body) or water on its connector?

The TB is (meant to be) heated to prevent it, however. And I'm guessing you were out in non-special weather for your car's usual environment.

Since it cleared it's quite likely it was moisture that dried with remaining engine heat.

I suppose water almost anywhere might be the cause, from drips onto the PCM to the TCM wiring to ... well, anywhere. (You are of course right that intermittent faults are a nightmare.) Water can drip from hood nozzles that decide to leak and of course past the windscreen cowl (we say scuttle I think) as well as so many other places in that sort of weather.

The PCM doesn't like a catalyst breaking up or blocking, in case it might be that.

If you can grab an OBD tool with live data (infamous USB elm327 LOL) then as well as pulling codes at least check the fuel trims. Not because I think they'll be off but because it's so easy to check!

I'd say tensioners: very very unlikely.

Could be worth checking the 2 shifter bolts on the ZF trans side.

Be sure to check for water/damp in the trunk.

 

Could water/slush have been sucked into the combustion chamber? The Mini has this problem in certain weather conditions...


Regards
Fritz

 

I still ask for the codes if you have any. Condensation is an enemy of the car and it is well documented. Checking the TB plugs is a good start but often accompanied by codes. In my opinion, if moisture was the problem it would take more than 10min for it to dry and recover with no restrictions. The one situation I recall so vividly is the knock sensors. I had 2 fail not at the same time but both times no codes were set and the RP was intermittent and I felt at the time it was controlled by the weather conditions. I did capture the codes on the second fault when I had my OBDII code reader connected as I was driving. However, this does not account for the no start for 10min. When the car goes into RP the RPM’s will be reduced to around 2500 so if your car was in an acceleration mode and RP was triggered it would be an event that may make a little noise and stun the driver. I also had RP & FS mode caused by the TB but the engine shut down but restarted and I was on the road again with no errors two times the third time it threw a code. As for the no start I am thinking that the shifter may not have been in “N” or “P” all the way or water in the fuel. Reading the codes will provide additional information. Just my .02¢

 

Thanks for the suggestions. Hopefully I can get to the garage today for the codes. The driving conditions were certainly not anything new or unusual for Canada, or for this car. Done it dozens of times over the years.