850 1995 Idling up and down Topic is solved

[manovlov]

Do not unplug the connector while engine is running!

I unplugged the MAF sensor, before start the engine, then ruan engine : 30/40 seconds, normal before stop.

If the idle is stable and runs better with Maf unplugged than it is bad.

I agree. I don’t think the corrosion would be a enough good reason to make some issue. But I’ve seen corrosion the sensor, so it may be the same on the connector…

In your case....since you did a pcv job recently...i would check if there is a vacuum leak somewhere.

Pcv valve,intake manifold,vacuum tree,main big plastic hose from air box to throttle body,fpr vacuum line.

Since the replacement of the PCV kit, I’ve driven 200 kms without a issue. I’ve checked the vacuum hoses this evening. Everything looked fine. But I didn’t plug in the main big hose from the air box to the top of the radiator. Not sure it may be a issue for the test. I can be wrong on that point.

Read the codes and post them here so we can see what's going on.
Did you plugged in a TPS sensor connector after pcv system replacement?

I will do that tomorrow midday and post the codes.

Did you plugged in a TPS sensor connector after pcv system replacement?

I don’t know what a « TPS sensor connector » means. The MAF sensor is an OEM. May be 22 years old...

[misha]

When you removed intake manifold to service the PCV system...you needed to disconnect TPS(Throttle Position Sensor) connector to be able to remove the manifold.

Did you re-connect it after putting the manifold back?

Maf sensor connector almost always make problems at this age.
Plug it in and out a few times to clean the contacts and see if problem go away.

Disconnect the negative battery terminal for 10-15 min in order to reset fuel trims.

Did you performed ecu re-learning procedure after you re-connect the battery when pcv job is completed?
http://www.volvotips.com/index.php/850- ... rocedures/

The procedure is more important for cars with automatic transmission but cars with manual should also learn the initial idle speed and fuel trims.

[manovlov]

I think so. You make me doubt. Could the engine have worked perfectly during 200 kms without this connector plugged ? I don't suspect also a issue with the injectors seals, because it should have "misfire" since the first kilometer, i think.

[misha]

Some codes needs time to be set...the others are instant....depends of which dtc is stored and which sensor is at fault.

[misha]

To cut this agony...read the codes and we will see what is going on.

Read the codes from both...Engine ecu(A2) and ignition ecu(A6)...since your car have them separately.

[manovlov]

Codes read today :
For codes A3 - 311/312, I've cleaned up brakes recently. I will replace sensors by new ones soon.

Codes 850 02-1995.jpg (61.95 KiB) Viewed 442 times

I've ordered the sensor and will replace this week.


Other jobs to come :

PART N° 133 2454

IMG_4098.jpg (35.02 KiB) Viewed 439 times

PART N° 138 9628

IMG_4099.jpg (32.15 KiB) Viewed 439 times

PART N° 913 5137

IMG_4097.jpg (33.42 KiB) Viewed 439 times

PART N° 913 5990

IMG_4100.jpg (28.1 KiB) Viewed 439 times

[scot850]

I can't recall if the sensors are the ones that have the wire clipped to them on a connector or are solid wires. If they are the solid wires, then they can break internally. If it is the ones with the clips, again make sure they are clean at the contacts and pushed fully home.

Also check the cog wheels/reluctor rings on the end of the axle in the hub where the sensors read for cracks/rust build up/ dirt that may cause issues for the sensors reading the rings.

Neil.

[scot850]

I can't recall if the sensors are the ones that have the wire clipped to them on a connector or are solid wires. If they are the solid wires, then they can break internally. If it is the ones with the clips, again make sure they are clean at the contacts and pushed fully home.

Also check the cog wheels/reluctor rings on the end of the axle in the hub where the sensors read for cracks/rust build up/ dirt that may cause issues for the sensors reading the rings.

I would look into the 141 and 122 for your engine issues. 122 may be the engine coolant sensor (ECT) at the thermostat, I am not sure on what 141 is triggered by as you car is not fly by wire. I'll have to do some research!

You may want to reset the codes and see what comes back incase they are old codes that were not cleared and see if they come back.

Neil.

[manovlov]

Salut Neil,

I'm sure they're OEM ones. I will replace them by new ones anyway. I've decided to order and replace also the throttle position sensor, for the same reason.

[manovlov]

I would look into the 141 and 122 for your engine issues. 122 may be the engine coolant sensor (ECT) at the thermostat, I am not sure on what 141 is triggered by as you car is not fly by wire. I'll have to do some research!

You may want to reset the codes and see what comes back incase they are old codes that were not cleared and see if they come back.

Neil.

Yes, good idea. I will have a look on the forum about how to do that.

Once you have read all the codes, push the button for that port for 6 seconds. It will then flash at you, and hold it for another 6 seconds.

When you push the button again, it should flash back a 1-1-1 at you.