'97 850 problems after ecu reset

PeteB · Post by **PeteB** » 31 Jan 2015, 08:15

We want to reset the ECU on my son's 1996 850 wagon, do they all have the Motronic 4.3 & 4.4 ECU?
Given the issues here, I don't want to have to do it 10 times to get it right.

Post by **erikv11** » 31 Jan 2015, 09:29

The problem with Misha's car is real but (1) it may not be the ECU, it may be something else and (2) to my knowledge no one else has ever reported these kind of problems in resetting the ECU. You are safe to do it.

Your US model 96 is either 4.3 or 4.4, you can tell by whether or not it has an air pump/SAS (those are all 4.4). E.g. check the vin at http://new.volvocars.com/ownersdocs/199 ... n1996.html

Post by **misha** » 31 Jan 2015, 10:03

My only solution is to try with other ecu.

I did a little research on this problem and found out that ecu is the same for manual & auto transmission.That's why these cars have a separate tcu for auto transmission.For manual...it doesn't matter and that's why there is only one ecu.

PeteB · Post by **PeteB** » 31 Jan 2015, 18:21

erikv11 wrote:The problem with Misha's car is real but (1) it may not be the ECU, it may be something else and (2) to my knowledge no one else has ever reported these kind of problems in resetting the ECU. You are safe to do it.

Your US model 96 is either 4.3 or 4.4, you can tell by whether or not it has an air pump/SAS (those are all 4.4). E.g. check the vin at http://new.volvocars.com/ownersdocs/199 ... n1996.html

We know that it has SAS because we just recently got a P0410 code, so that seems to indicate that it would be 4.4. Did the changes come all at once, does this mean that we do not have PCV - as I understand it the complex PCV was deleted at some point? Or can we tell this also by VIN?

Post by **Ozark Lee** » 31 Jan 2015, 18:49

They all have PCV, which is passive but the variations seem to be SAS and EGR. Some had neither SAS nor EGR, some had one or the other, and I think there were some versions that had both.

I think the product plate will give you more emissions related information than the VIN.

...Lee

Post by **erikv11** » 31 Jan 2015, 19:54

PeteB wrote:
erikv11 wrote:The problem with Misha's car is real but (1) it may not be the ECU, it may be something else and (2) to my knowledge no one else has ever reported these kind of problems in resetting the ECU. You are safe to do it.

Your US model 96 is either 4.3 or 4.4, you can tell by whether or not it has an air pump/SAS (those are all 4.4). E.g. check the vin at http://new.volvocars.com/ownersdocs/199 ... n1996.html
We know that it has SAS because we just recently got a P0410 code, so that seems to indicate that it would be 4.4. Did the changes come all at once, does this mean that we do not have PCV - as I understand it the complex PCV was deleted at some point? Or can we tell this also by VIN?

Like Lee said, it definitely has PCV.

If your US spec 96 has SAS (I agree, it should given the code!) then it is Motronic 4.4. and does not have EGR. You can also confirm EGR just by looking, look for this cylindrical doohickey on the driver's side of the intake manifold

The link I provided has never failed me for emissions info, give it a try with your VIN then ispect the engine bay.

Post by **misha** » 01 Feb 2015, 08:53

What are the symptoms of leaky intake gasket?

Also,if the engine is burning oil due to bad valve seals,could it be a reason for running rich?

Post by **misha** » 03 Feb 2015, 11:45

misha wrote:What are the symptoms of leaky intake gasket?

Also,if the engine is burning oil due to bad valve seals,could it be a reason for running rich?

What are the chances that stored codes remains stored in ecu even if battery is disconnected?

I want to say...if i disconnect battery for,let's say,replaced o2 sensor and i don't reset cel with a scan tool for it,does the code remain stored in ecu and because of a stored code for o2 sensor...ecu don't see a new o2 untill it is being reset with a scan tool?

Or...disconnecting ecu on our cars clears cel codes just like a scan tool do?

Post by **erikv11** » 03 Feb 2015, 12:03

Leaky gasket intake will behave just like a broken elbow on the PCV at intake: probably a p0172. If you suspect any leaks at all, try spraying starting fluid around the intake.

Burning oil should not make the car run rich.

Disconnecting the battery will reset stored ECU codes, especially if you touch the cables together while they are off (discharges any capacitors).

Post by **misha** » 03 Feb 2015, 14:49

erikv11 wrote:Leaky gasket intake will behave just like a broken elbow on the PCV at intake: probably a p0172...

What about an erratic idle,running like c*ap,stumbling,misfiring and alike symptoms?

How sure you are about codes reset with disconnecting battery?Obviously the CEL will reset,but are you sure about codes?

Somehow i'm stuck on this cel codes thing.