Reset computer -positive cable to negative battery terminal?

stuartg3 · Post by **stuartg3** » 22 Nov 2010, 16:47

Anybody ever heard of resetting the computer by disconnecting the positive battery lead and touching it off on the negative battery terminal? I had a guy tell me that this car "learns" the driving habits of the operator and I may need to "reset" the computer by doing this.

The car is an '03 V70 (2.4L non-turbo) and it is running poorly. No power when you accelerate hard. Does not idle rough, starts easily. No check engine light and no codes from the OBDII tool. If you keep the accelerator floored, the car begins surging at about 4500 rpm.

I've replaced the plugs, cleaned the MAF, and cleaned the throttle body. I've got a tank full of injector cleaner running through it now, but am reluctant to think that the injectors are causing this because I would think that I would have a rough idle or missing coming from the engine. The other thing that the car does is to "stumble" off of idle if you floor the accelerator. Feels like the engine is flooding with fuel.

The fuel filter was changed 5K ago, but I am going to look at it (maybe remove it and try to blow through it). I am also going to check the fuel pressure at the rail (anybody know what the correct pressure should be?)

Thanks in advance for any help,

RaymanSean · Post by **RaymanSean** » 22 Nov 2010, 18:07

You can disconnect both cables and then after 30 min to make sure all the caps have equalized connect the two cables together for a a while to make sure that everything reaches the same potential this will clear all the volatile memory. I have seen it mentioned on this board to turn the key to position 1 before reconnecting. I do not know what this does but I assume it could not hurt, perhaps someone will chime in with the why. That should clear all the adaptive settings back to factory defaults. However, I doubt that resetting the adaptive parts will solve the stumble, the lack of power or the surge at 4500 RPM. I am not sure what the rev limit is for the car but you may be hitting it at 4,500 rpm which would be the surge. Lack or power can best be summed up as you have a 2.4 liter engine that is NA trying to push a V70 I would not expect to get over 60 mph in under 10 seconds from a stop. The stumble is probably a result of a build up in the throttle body there have been several post detailing how to clean it up. Hope this helps.

ctrobk · Post by **ctrobk** » 23 Nov 2010, 07:14

For what its worth, I am also driving an '03 v70 non-turbo. I was having very similar problems. It was really bad while going uphill. I thought it might have been a transmission issue because the OBD wasn't showing any codes either. Just a lack of power etc.
For me, it turned out to be my catalytic converter. It took my indy shop two days to diagnose the cat problem. Unfortunately for me, I already had over 80k, so I was out of the emission warranty period. I think it has since increased to 10yr/100k for emission issues.

Not sure if you have had the car since new, but if not a more sophisticated OBD can pull up the history of codes. Previous owner might have had the codes erased.

stuartg3 · Post by **stuartg3** » 23 Nov 2010, 18:41

ctrobk, that blows my theory that the second O2 sensor would have let me know if I had a bat catalytic convertor. I thought I had eliminated that possibility.

Well I'm really perplexed. I've got a trip planned - about 300miles total - but I'm still no closer to finding the problem and the timeline is too short to allow me to take the car to a shop. Does anybody have any thoughts on driving the car as is? Can I damage anything?

otis44 · Post by **otis44** » 23 Nov 2010, 19:04

If you think you are having emissions issues (cat) and your engine code is 64 you should have a 15 year 150k warranty on the emission components. If your vin/engine code is 61 this warranty won't pertain to your car. May not help, but just thought i'd mention it.

stuartg3 · Post by **stuartg3** » 23 Nov 2010, 20:53

otis44 wrote:If you think you are having emissions issues (cat) and your engine code is 64 you should have a 15 year 150k warranty on the emission components. If your vin/engine code is 61 this warranty won't pertain to your car. May not help, but just thought i'd mention it.

engine code is 61

stuartg3 · Post by **stuartg3** » 19 Dec 2010, 05:28

Verified that it was a clogged catalytic converter. Car runs like a champ now.

Thanks!

Post by **igel513** » 20 Dec 2010, 16:10

Stuartg3 How were they able to diagnose that it was the clogged cat. conv.causing the poor acceleration? How much did it cost u to replace it?

billr99 · Post by **billr99** » 20 Dec 2010, 16:52

RaymanSean wrote: have seen it mentioned on this board to turn the key to position 1 before reconnecting. I do not know what this does but I assume it could not hurt, perhaps someone will chime in with the why.

Actually you need to turn the key to Position 2 prior to reconnecting the battery. Also you attach the positive lead first, then the negative. Failure to follow this procedure could damage some of the electronic components, the CCM is the usual suspect. Its all part of the OEM-specified procedures documented in VADIS/VIDA.

Cheers,

Bill