I just learnt about the ECU relearn !

se13allmylife · Post by **se13allmylife** » 18 Jul 2011, 12:14

This past weekend I finally got round to changing my '95 20v 855's , timing belt , tensioners , waterpump , pcv system , oil ,filter and anti-freeze (phew

). After many hours and fiddiling I got it all back together , started it up and presto it ran like crap

! My first thought was a leaky intake manifold gasket but the OBD recorded no faults after 10 miles , number 1 plug was wet but changing it made no difference . I thought i'd check my Volvo workshop info last night before hanging myself and found a bit about re-learning the ECU after disconnecting the battery . Tried it this morning (start , get to running temp. , 1 minute idle in 'n' , 1 minute idle in 'd' , 20/50% throttle to reach top gear , cruise at light throttle a little , decelerate down through gears and brake to a stop) and all hail the info sheet she's now running smooth as silk . If i'm the only one who didn't know this then

, if not happy days all round . I won't have to get under it again now till I pick up my stainless exhaust at the end of the month

.

Post by **JRL** » 18 Jul 2011, 14:47

Learnt?

Post by **jblackburn** » 18 Jul 2011, 14:48

You might be surprised sometimes what a difference it makes.

When my MAF sensor went bad, I changed the sensor and the car ran afterwards - but it was reaaaallllyyyy slow until the turbo picked up, and I noticed black smoke out the back. Once I reset the computer, it instantly had its pep back.

I make it a general rule of thumb that after anything I change that might alter the air/fuel ratio (a sensor, air filter, vacuum lines, etc) I give the computer a hard reset like that.

Post by **dcarlson12** » 18 Jul 2011, 15:20

To Jblackburn:
When you say 'hard reset' are you saying to disconnect the battery for a while or ????

Post by **matthew1** » 18 Jul 2011, 17:11

JRL wrote:Learnt?

Learnt means exactly what learned does. They're 100% interchangeable. Now please go back to helping people with VOLVO problems and leave the grammar to me.

Post by **jblackburn** » 18 Jul 2011, 18:37

Exactly. You can leave the cables disconnected for 10-15 min, or do what I do and disconnect the negative cable then tap the brake pedal a few times and reconnect it.

If you have a 1999+, the negative cable must be reconnected with the key in position II and wait for the SRS light to go out. 1998 and earlier doesn't really matter - the key can be off.

turbozutek · Post by **turbozutek** » 19 Jul 2011, 04:43

Learnt = real, actual good English.
Learned = horrible, bastardised, lazy, wrong English incorrectly used in this context.

If you are the kind of person who spended ten dollars last night, then 'learned' is for you. If you SPENT ten dollars? You have a much better grasp of English. Learn works the same way as spent, as does spoil and a ton of other words, in this context.

/Off topic but still fun

On topic, my MPG shot up quite considerably after doing the reset and relearn on the engine ECU. I think the long term fuel trim on my car was messed up from when I had a faulty distributor cap on and the rough running became the ECU's way of life.

Chris...

Post by **Pauloil** » 19 Jul 2011, 09:09

jblackburn wrote:Exactly. You can leave the cables disconnected for 10-15 min, or do what I do and disconnect the negative cable then tap the brake pedal a few times and reconnect it.

If you have a 1999+, the negative cable must be reconnected with the key in position II and wait for the SRS light to go out. 1998 and earlier doesn't really matter - the key can be off.

Please tell more about this 99+ reset procedure: I thought just touching batt cables together for 10 sec reset the computer

Harpoon · Post by **Harpoon** » 19 Jul 2011, 09:29

What does 20/50% throttle to reach top gear mean? Does it mean give vehicle 50% of the gas pedal until you have gone through all the gears?
Thanks for this post. I have had this problem and never new what it was. I can't imagine how my vehicle will run now when I re-set it.

Post by **jblackburn** » 19 Jul 2011, 10:15

Paul - yes the battery cable method will do it too. Basically, any way that you can drain the residual charge out of the electrical system.

The key *should* be in position II on those models when reconnecting the battery again to avoid the possibility of triggering an SRS system fault (which, as we know, means a trip to the dealer). That's really the only special step you need to take.