1998 GLT V70 Hard start below 30deg/studders SOLVED

[stephansvolvo]

rspi,

So i replaced the sensor. this thing still wont start! Any other ideas??? I am at a loss.

Thanks Stephan

[Pauloil]

did you reset adaptives? did you take neg batt cable off during the job? if not, take if off now and touch it to positive cable, then reattach.

[stephansvolvo]

did you reset adaptives? did you take neg batt cable off during the job? if not, take if off now and touch it to positive cable, then reattach.

I'll give that a shot too. Man the frustration!
Thanks
Stephan

[stephansvolvo]

did you reset adaptives? did you take neg batt cable off during the job? if not, take if off now and touch it to positive cable, then reattach.

Missed this the first read. What are "adaptives"?

[rspi]

[erikv11]

Coolant temp sensor is pretty far down on my list of guesses for this problem. Since you just replaced it, make sure the wiring is in good shape near the plug connecter, and that the plug is making good contact.

p0172 is a MAF code but is almost always caused by a vacuum leak. Check the vacuum lines, especially the little elbow on the passenger's side of the intake manifold. It is hard to see, use a flashlight.

After that I would look at the MAF as was first suggested by jblackburn. A longshot but possible problem is the front oxygen sensor.

p0455 don't worry about for now, it is an SAS (emissions) code.

"Adaptives" just refers to whether the car's computer is running on default settings or based on how the car was running when you last turned it off. If you remove power to the ECU, e.g. by disconnecting the battery for an hour or so, those values will be reset (be sure to have your radio code first!). Some people like to touch the cables together when they are off the battery as insurance that power is drained from the ECU, but I've never had to do that and it would make me nervous to recommend it, I always imagine someone putting on jumper cables and holding the ends together

So now the car won't start at all, or just a hard start?

[stephansvolvo]

Coolant temp sensor is pretty far down on my list of guesses for this problem. Since you just replaced it, make sure the wiring is in good shape near the plug connecter, and that the plug is making good contact.

p0172 is a MAF code but is almost always caused by a vacuum leak. Check the vacuum lines, especially the little elbow on the passenger's side of the intake manifold. It is hard to see, use a flashlight.

After that I would look at the MAF as was first suggested by jblackburn. A longshot but possible problem is the front oxygen sensor.

p0455 don't worry about for now, it is an SAS (emissions) code.

"Adaptives" just refers to whether the car's computer is running on default settings or based on how the car was running when you last turned it off. If you remove power to the ECU, e.g. by disconnecting the battery for an hour or so, those values will be reset (be sure to have your radio code first!). Some people like to touch the cables together when they are off the battery as insurance that power is drained from the ECU, but I've never had to do that and it would make me nervous to recommend it, I always imagine someone putting on jumper cables and holding the ends together

So now the car won't start at all, or just a hard start?

As of last night it would start and then stall out. I did find the vacuum at the intake was off after I replaced the sensor and had it all back together. It should be replaced at that elbow. I'm going to try the battery disconnect and replace some of the elbows and lines I have seen that need replaced. Is there a place in repairs that show all vacuum lines?

[matthew1]

I once had a P0172 from the "evil" elbow vacuum connection on the intake manifold, near the thermostat (left side of engine as you're in front of the car).

https://www.matthewsvolvosite.com/forums ... 35#p213535

[erikv11]

Nice pics Matthew. That's the one.

Look through this thread, there are OEM diagrams for all of the vac lines (and there may still be a sticker under the hood of your car):
https://www.matthewsvolvosite.com/forums ... f=1&t=6941

Here is a link to a good diagram of just the vac lines in the SAS system, check those too:

[stephansvolvo]

I once had a P0172 from the "evil" elbow vacuum connection on the intake manifold, near the thermostat (left side of engine as you're in front of the car).

https://www.matthewsvolvosite.com/forums ... 35#p213535

That's the one. Thanks for the pic of this one. I never really thought of zip ties to secure the line thought it might get to hot.
Thanks