This forum has been really useful for looking up problems. Since I bought my V70 I keep looking up my problems here, so big thanks for the members for all the help. Here’s an issue that’s driving me crazy and I can’t seem to find a solution for here.
My 07 V70 D5244T4 with TF-80SC auto transmission loses power intermittently. It happens when cold or hot, can’t really tie it to anything specific.
I have a VIDA with DICE, and I’m looking for guidance on what to check to catch this problem. Shops weren’t really helpful since there are no trouble codes and can’t reproduce the problem on demand.
I have these symptoms, and don’t know if they are related in any way:
1. Brakes behaving weird
With the engine running the brake pedal can be pressed to the floor 1 and 1/2 times before it stiffens. I tried to repair this first since I thought the brakes were sticking causing the power loss. Dealer measured braking power and test driven the car, says all good.
Sometimes the brake becomes stronger. Like when you press the usual amount but get greater braking power.
(Refurbished all calipers, changed flex hoses, replaced brake booster pedal side O ring, bled 4 times, with VIDA activating the ABS unit, booster holds vacuum, engine mounts replaced.)
2. Very bad intermittent vibrations
Sometimes the whole car vibrates very bad. Sometimes not at all. Like the power loss problem, I haven’t been able to tie this to anything.
(All 5 engine mounts replaced, whole system holds vacuum, tested the solenoid that controls the mounts, OK.
3. Unstable cruise RPMs
Traveling with cruise control set at around 100kph (60 mph) with 6th gear around 2000rpm. The revs fall 150-200 rpms then get back up. This continues until I set a higher speed. You can feel the car accelerating then letting off, then repeating this.
4. Slight shake/vibrations at 2000 RPM
I can feel very slight vebrations or jittering when cruising on the highway. A previous diesel car had this and it turned out to be failing injectors.
I measured leak off, but none of the injectors were above VIDA spec.
The corrections were below 1mg/cycle at idle for all 5 injectors. For 2 injectors around 6mg/cycle under load @ 2000 RPM the rest are around 1. The two with the higher correction are neighbouring ones, one positive 6mg, other -6 mg. Not sure how to interpret these.
5. Power loss.
This can happen right after a cold start in the morning or after a highway drive, doesn’t matter.
Feels like I’m towing something heavy. I need to press on the throtte much more than the usual to achieve the same output.
Sometimes the opposite occurs and the car becomes very agile, and accelerates much easier.
Sometimes the car operates somewhere in between these. Not fast, not sluggish.
Of course no DTS stored.
- Turbo vane arm moves, EGR valve moves, SWIRL moves, throttle moves when actuated with VIDA.
- Fuel pressure and manifold pressure rises and falls with engine load, they follow the desired value plotted alongside them.
- Measured the wiring harness connections of all sensors to the ECU pins, all good even when moving and twisting them.
- All injectors have the correct coil resistance.
- Dealer leak tested the intake, no leaks.
SWIRL changed a year ago. EGR cleaned and tested, throttle cleaned.
Changed fuel pressure sensor, DPF diff. pressure sensor, O2 sensor replaced
I can’t even decide wether the problem is brake, transmission or engine related.
Can anybody help with what live data I should look at, or what needs to be checked out to eliminate causes?
Any help is appreciated!
I can head out and make measurements any time with VIDA.
Thanks!