V40 2001 Engine dies when it reaches operating temp.

royvidar · Post by **royvidar** » 06 Mar 2011, 00:34

I`m trying here for my mothers v40 2001 1,8 non turbo automatic. What has been done. Replaced timing belt and service belt, all filters and oil are all new. Camshaft sensor has been replaced from a previous episode. The car had been sitting for about a week, she drove about 130 kilometeres without any problems before parking it. Then as she was starting it, it started just fine and drove off. But once the engine got at normal service temperature, the engine suddenly stopped, just like you turn the ignition off. And would not start again. Then when engine cooled off, it fired like nothing had happened at all. And when the engine heated up again, same thing. Then I was watching it, while idle, just like the ignition was turned off. And no reaction. Starter turnes normally, but not firing. It gets plenty of fuel. The temperatureguage, does not show any sign of overheating. check engine light came on, so I read out the codes. Here it goes: Coil A/B, camshaft position sensor, mass air flow too high (something like that) And Some air temperature malfunction. And when I turn the key off, the fan started running. Just like it believes it`s overheated somehow..

I thought about the MAF sensor, but when the engine runs, and unplugg the MAF, the engine runs very rough, put it back, and it runs fine again. The camshaft sensor was broken a while ago, then it would not start at all, cold or warm. Replaced it, and have worked fine. I think the coils show up for something has shut them off. When I delete the codes it fires for a second and dies again. But after a few hours, fires up like nothing has happened, and runs smoothely until it gets hot, then the same *^"#%¤#!! I`m simply running out of ideas over here...

Any ideas would be VEEEEERY welcome ASAP. Thanks from Norway, Roy. (sorry about the poor english writing

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royvidar · Post by **royvidar** » 06 Mar 2011, 00:55

Just adding, I haven`t checked if it gets fuel, but the shop she had it in said it gets plenty of it, but my guess is that it is a bad sensor somewhere. And the engine fan stops when I delete the codes. The same thing happened when the camshaft sensor broke last time, the fan was running with key out, replaced the sensor, and everything was working fine.

royvidar · Post by **royvidar** » 06 Mar 2011, 21:50

No takers?

Post by **precopster** » 06 Mar 2011, 23:59

You need to be doing some basic tests when the car doesn't start. Unplugging the MAF and seeing that it runs rough while the engine is running, doesn't immediately rule this item out. You need to be unplugging it when the no-start condition occurs & then seeing if it starts with it plugged back in.

Is there a shraeder type valve on the fuel rail? If so can you press it after it dies to see if there is fuel at the rail? Fuel should squirt out.

If there is no fuel at the rail there are two possible faults; fuel pump is faulty or the fuel relay is faulty.

Again while the motor is dead: If the motor has coil on plug you need to be removing at least one coil and put in a spare spark plug, then turn it over and see if you can make a spark jump to the electrode while the plug base is grounded. If no spark write back and we'll go to the next step.

royvidar · Post by **royvidar** » 07 Mar 2011, 08:07

Ok, thanks, we tried starting it while the MAF unplugged as well. But I didn`t check the fuel rail, there is a valve there. I will try it as soon as I get to the car again, probably to the weekend. But the mechanic said that it drowned in fuel, so I didn`t check that myself. And I didn`t check if there was a spark when it was "dead", but the diagnosis said that coil A and B were shut down, so my guess is no spark when engine out. When I erased the codes, it fired for one second and shut down again, and when I didn`t erase them, completely dead. But I will do the manual check of this. Thank you so much for your response

royvidar · Post by **royvidar** » 08 Mar 2011, 10:08

I did read somewhere that a engine temperature sensor had stalled a engine on a similar car somewhere, i think it was u.s forum, but nothing about where it is located or what the diagnosis codes was... But the coolant temperature looked normal on the gauge though. Can this be an issue? Can it be the crankshaft sensor? oxygensensor? (lambda). But nothing of these in the diagnose...

Post by **jblackburn** » 08 Mar 2011, 10:11

This screams bad O2 sensor to me, but I would not replace it just yet on that assumption alone.

My test for a bad O2 sensor is to switch the front and rear sensors and connectors. Likely the cable for the front one will not reach all the way from the rear - but that is OK, just leave it in place. The car will get mad and throw a check engine light when it realizes it's not getting an input from the rear sensor, but it does nothing to affect how the engine runs.

Once the car warms up, if it stays running perfectly normally, you have found your culprit.

royvidar · Post by **royvidar** » 08 Mar 2011, 10:25

Ahaa, so the front has something to do with how the engine runs, but the rear doesn`t if I understand you correct? where is the sensors and connectors located? I guess one are located on the exhaust manifold somewhere Thank you and will give it a shot

Post by **jblackburn** » 08 Mar 2011, 11:13

Exactly - the rear is only there to monitor the efficiency of the catalytic converter for emissions testing purposes.

The sensors are located on top of the catalytic converter under the car - you will need to drive the front end of your car up on ramps or something to gain access to them.

On the S70, the connectors are directly behind the transmission at the back of the engine compartment; I don't know about the V40, but it is probably in a similar location. Located the sensors, then follow their wires back. Also on my model, you have to pull the red plastic part of the connector loose with a screwdriver, and then the plug will slide out from the connector - it is a bit confusing at first.

royvidar · Post by **royvidar** » 08 Mar 2011, 11:46

Ok Thanks

I`ll post when I have checked them