XC70 sudden jerks at road speed

vah · Post by **vah** » 15 Nov 2020, 02:38

Hi,

I have problems with XC70, 2003, AWD, automatic transmission. At road speed - 90 km/h it gets sudden very short jerks that appear to be originated from the drivetrain. Does not show any error codes nor illuminated check engine light. Effect appears at driving on both, 4th and 5th gear, in full auto and manual. Gearbox does not change the gears during the moments when the jerks appear. Gearbox fluid level is OK. To get the effect, at least 20 minutes of driving is needed. Problem disappears at slowing down and at city speeds - 50 km/h.

Any experience here with such problem?

Post by **jonesg** » 15 Nov 2020, 05:20

might be pinging.

Post by **oragex** » 15 Nov 2020, 06:53

No codes with a good scanner ? It's hard to suggest a single thing because you may receive several suggestions and start replacing parts with no success. I would suggest trying to find used parts for not much money if you go this way. Things that may go bad are (google up) PEM, FPS, ignition coil (use only bosch and replace only the faulty one, and also inspect all spark plugs), DEM (awd module). Also inspect closely all wires going to the ignition coils and near the connectors and the ground cable behind the timing belt cover

Georgeandkira · Post by **Georgeandkira** » 15 Nov 2020, 09:50

How many kms/miles are on this car?
Changing your fuel filter, if it's old, is "always" a good/smart thing to do.
If you do this yourself it's an inexpensive maintenance operation.
Changing one frequently doesn't cure problems but you will be SO happy if a new filter cures yours.

Post by **SuperHerman** » 15 Nov 2020, 12:44

What scanner are you using? There may be codes and your scanner is not showing them. Many OBD-2 scanners only read the engine - this leaves the transmission and braking system undiagnosed (as well as other systems). Both the transmission and braking systems could cause what you describe.

Post by **E Showell** » 17 Nov 2020, 10:34

There was a poster a while back who described a skipping sensation like driving over a garden hose. I believe he traced his issue to the Haldex system. It would be worth searching for that thread.

vah · Post by **vah** » 20 Nov 2020, 01:58

Hi,

thanks for the feedback! I used some scanhub device + the auto gearbox shop used some of their professional tools (no idea exactly what's the make). However, there are updates - after removing the AWD fuse and rerunning the test, problem disappeared. When the fuse was re-plugged, problem appeared once more. Thus, Haldex for sure seems to be the issue. Current recommendation from diagnostics was that the DEM module + solenoids should be replaced ... + of course oil & filter changes. Let's see how it goes ...

Post by **oragex** » 20 Nov 2020, 05:54

For DEM Xemodex.com can fix it if it's not too damaged, but it's expensive. May also search "electronic module repair service" on Ebay, ask the sellers if they can fix it.

tyburn · Post by **tyburn** » 26 Nov 2024, 20:50

I seem to have the same problem. Infrequent, and only after driving for a while - maybe an hour. Car SLAMS HARD like a hammer blow - instantaneous, and then back to normal.

There appears to be a somewhat low alternator voltage, and I wonder if this could be contributing - gong to replace that.

The last time the slamming happened, I was on the freeway - one slam, then a while later another, and then a couple more closer together. Then as I got home, it even happened at slow speed when approaching my home. This time all power seemed to be lost to the dashboard and center console.

Turning off the key and putting it back seemed to reset that.

I removed the CEM and it looks absolutely pristine - no sign of any moisture or anything, pins perfect, etc.

This car was purchased at auction by the previous owner, and I have replaced the engine, transmission valve body, right suspension, radiator, front bumper (yes, welded on). It's a wonderful smooth drive and feels really strong...WHAM!!!

tfo · Post by **tfo** » 29 Nov 2024, 10:54

same here, seems to be a transmission issue with mine ('07 XC70 auto) as well.

my symptoms only start up once i've been driving for a while too. when in 3rd gear (manual or automatic mode) the trans will violently shift into 4th with a loud clunk, and then not be able to shift into any other gear afterwards. when shifting into neutral, there's a similar loud clunk every time. shifting into drive displays "4" on the dash where "D" would be.

this will happen when torque is being applied in any way- with little throttle, a lot of throttle, or engine-braking down a hill.

the in-the-moment solution is to shift into neutral, turn the ignition off, and then start the car again (either while driving or parked), and this lets the car shift again. some sort of computer reset?

i've also noticed this behavior with the two computer modules accessible from the engine bay (assuming ECM and TCM?) being hot and fans running, OR being cold.

VIDA has also thrown a code for this before; TCM-002F Lock-up function Slipping or not engaged. it doesn't put it into full limp mode either, just keeping it in 4th until a new operation cycle (ignition off and on).

anything else i should check / check my sanity against before thinking of solutions?

-tfo