What did you do to your 850/X70 today???

[ASt85]

Took the cover off the C70 today, started first turn of the key after 5 month SORN, I had disconnected the battery before laying the car up for the winter. - the cab dehumidifiers hard hardly any water in the them, the boot area was bone dry with no water at all in the dehumidifier

It ran like a dream after a 15 minute warm up followed by an Italian tune up to sweep away the cobwebs/rust on discs etc to prepare for the MOT on Saturday.

[ITSv40]

Out of interest, was the battery disconnected for 5 months and if so does that not affect the ecu memory. I have mine connected to a smart charger so it is always on the button, but just curious.

[ITSv40]

I collected the under body bits and pieces from the powder coaters today and the new bolts etc from Volvo so have everything to hand to rebuild. The powder coating does look good - all done in satin black as per the original.

[StatusRed]

Fitted the newly arrived wheels and tyres to my C70, took it on the motorway for a test drive, good to see it's handling much better after it's pothole repairs and to have it back on the road

[ASt85]

Originally Posted by ITSv40

Out of interest, was the battery disconnected for 5 months and if so does that not affect the ecu memory. I have mine connected to a smart charger so it is always on the button, but just curious.

I am fairly certain the ECU memory is only dumped if the cables are shorted after disconnecting the battery ie a hard reset. It may have helped in letting the engine tick for 15 minutes followed by some highly varied and spirited driving, including a couple of stops with the ignition off, which would probably reset the ECU.

[ASt85]

Originally Posted by ASt85

It ran like a dream after a 15 minute warm up followed by an Italian tune up to sweep away the cobwebs/rust on discs etc to prepare for the MOT on Saturday.

Happy days, the C70 passed yesterday's MOT with no advisories, just waiting for better weather to get the hood down

[ITSv40]

Finished fitting the new hoses, bled the brakes and changed the fluid. Reassembled the suspension and fitted the tank straps. Now all to do is clean the wheels, wash the car and polish ready for the summer.

[SteveSarre]

Hi all,

As far as I know ...

If you disconnected the battery for 5 months, then I would think that the system would be completely discharged. That would have the same effect as disconnecting the battery then pressing the brake pedal.

But that doesn't delete the factory map settings in the ecu, it only deletes the trims.
If your trims are not large, ie if wear and tear hasn't meant that the ecu has to make adjustments from the factory map, then your car will run pretty well straight away.

When you are driving, the short term fuel trim is adjusted rapidly (at least every few seconds).
So you could find out about your trim state, by having Torque connected when you first start the car up. After a reset, you would expect to see 0% short term trims to start with, then if they go over +- 10% the long term trim is adjusted and the short term trims drop as appropriate. Eventually (when you have covered the full load, revs, throttle and temperature range), the long term trim will settle down.

Whenever you change MAF, plugs, fix vacuum hose leaks, air filter etc, I think it is a good idea to rezero the trims, and let it learn from scratch again.

If you keep an occasional eye on your long term trim, then if it changes, then something must have changed eg faulty MAF, plugs, O2 sensor etc

If anyone knows better, please tell me.

HTH
Steve

[ASt85]

Originally Posted by SteveSarre

Hi all,

As far as I know ...

If you disconnected the battery for 5 months, then I would think that the system would be completely discharged. That would have the same effect as disconnecting the battery then pressing the brake pedal.

But that doesn't delete the factory map settings in the ecu, it only deletes the trims.
If your trims are not large, ie if wear and tear hasn't meant that the ecu has to make adjustments from the factory map, then your car will run pretty well straight away.

When you are driving, the short term fuel trim is adjusted rapidly (at least every few seconds).
So you could find out about your trim state, by having Torque connected when you first start the car up. After a reset, you would expect to see 0% short term trims to start with, then if they go over +- 10% the long term trim is adjusted and the short term trims drop as appropriate. Eventually (when you have covered the full load, revs, throttle and temperature range), the long term trim will settle down.

Whenever you change MAF, plugs, fix vacuum hose leaks, air filter etc, I think it is a good idea to rezero the trims, and let it learn from scratch again.

If you keep an occasional eye on your long term trim, then if it changes, then something must have changed eg faulty MAF, plugs, O2 sensor etc

If anyone knows better, please tell me.

HTH
Steve

Hi Steve, I can't thank you enough for the excellent advice that you have provided.

The information about short and long term trim probably accounts for the slightly higher than normal tick over speed (approx 950rpm) which I had put down to the aircon as it does drop within a few minutes of startup. I hadn't thought of using Torque to check it on the run.

I'm lucky enough to have a DiCE (thanks to Cheshired5) but have not plugged it into the C70 since last June(2019) when everything appeared normal. It might be worth plugging in and then driving the car normally to get access to an even wider set of parameters.

Thanks again
Alan

[SteveSarre]

Hi Ast85

Yes I find Torque very useful.

And if you have Dice then you can monitor the turbo control valve duty cycle which you cant see through Torque. That can give more clues.

HTH
Steve