2006 XC90 fwd 2.5t won't start hot
Username
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    Results 1 to 11 of 11
    1. #1
      Junior Member
      Join Date
      Jun 2020
      Posts
      9

      2006 XC90 fwd 2.5t won't start hot

      Can I post yet?

    2. Remove Advertisements

      Advertisements
       

    3. #2
      Junior Member
      Join Date
      Oct 2017
      Location
      New Hampshire
      Posts
      667
      Apparently...
      John C
      ---------------------
      2011 XC90 3.2 175,000 miles and counting...

    4. #3
      Junior Member
      Join Date
      Mar 2014
      Posts
      241
      It could be the coolant temperature sensor. Check to see if there is spark, then remove a spark plug to verify if it is fuel soaked. If the ECM thinks that it is cold, it will dump too much fuel.
      2004 XC90 2.5T FWD + 2006 XC90 2.5T

    5. Remove Advertisements
      SwedeSpeed.com
      Advertisements
       

    6. #4
      Junior Member
      Join Date
      Jul 2014
      Location
      Omaha, NE
      Posts
      365
      1+,

      No start when HOT is usually a problem with the ECT sensor.

      The thermostat and ECT combo is sold together.
      Use only Wahler brand.

      I wrote a DIY in matthews volvo forum for my 2005 XC90 2.5T w/o the need to remove the PS Pump.
      Basically removing only the upper housing and swap the tstat + ECT over.

    7. #5
      Junior Member
      Join Date
      Jun 2020
      Posts
      9
      Just typed a huge post and lost it... Anyways I kept getting messages that my posts had to be approved by the mods since I am new and didn't realize they eventually went through.

      Car cold starts fine, and restarts fine immediately after shutting down hot. Let it sit 5+ minutes, forget about it, try again tomorrow. It will just crank until the cows come home. Charging system 14.79v driving around, relatively new Odyssey battery that passes load tests, original Bosch starter that was rebuild recently and cleaned out last week by me.

      Cole's notes... New crank sensor (Beck Arnley box, says Denso on it), new fuel rail pressure sensor (Bosch), lengthened and relocated crank sensor and rear cam sensor wires away from starter. No change. Coolant temp sensor is working fine. Resistance has been checked against temp and it appears to be fine comparing it to graphs I found on a Jaguar forum which use the same sensor. This car has the fuel pump module inside, and it looks like new still. It has been ruled out, hair dryer didn't affect it. Every ground I can find has been cleaned even though none of them looked suspect, as well as power connections.

      Has anyone had a catalytic converter do this to them before? The engine runs smoothly, but it sounds like it is misfiring at the tailpipe, and it smells like rotten eggs there too. It is like a puff puff puff rather than just a steady flow of exhaust coming out. I just put it on my lift and hit the cat lightly with a rubber mallet, and it sounds like the substrate is rattling around inside. It likes to throw a P2195 code consistently if the car idles for long periods of time, and I replaced the O2 sensor with a Bosch recently and it still does this. Thinking possibly the cat is partially plugged causing this? Very weird, doesn't have an rpm limit or feel like it is way down on power, and temp gun reading of it with the car running seemed to be ok.

      Your help is appreciated, thanks!
      Last edited by euro-trash; 07-05-2020 at 02:11 PM.

    8. #6
      Junior Member
      Join Date
      Jul 2013
      Location
      Georgia
      Posts
      202
      Quote Originally Posted by euro-trash View Post
      Has anyone had a catalytic converter do this to them before?
      No, you are chasing the problem with the replace parts technique. Can get very frustrating and expensive. - download and install the factory service manual (VIDA, the software is free on sweedspeed) You could use it to give you suggestions to solve your hot start even without scanning the car with a DICE unit attached.

    9. #7
      Junior Member
      Join Date
      Jun 2020
      Posts
      9
      Quote Originally Posted by hoonk View Post
      No, you are chasing the problem with the replace parts technique. Can get very frustrating and expensive. - download and install the factory service manual (VIDA, the software is free on sweedspeed) You could use it to give you suggestions to solve your hot start even without scanning the car with a DICE unit attached.
      Yeah, that's what it looks like, but these were educated decisions. The fuel rail pressure sensor was showing 79 psi in the rail on a Snap-on scan tool during heat soak when my gauge would show it only getting up to 56psi hot. The crank sensor was tampered with by a previous owner as it was installed without an o ring on it and had shards of metal stuck to it with a pin hole in the end of it when I removed it.

      If you can provide me with a link to the software I would appreciate that. Regardless, this cat is not in good shape. Who makes one with a quality flex joint that isn't going to fall apart? I dislike Walker brand products, but it's the only name I am familiar with on Rock Auto that is available.

      When I had the Snap-on scanner on it, it appeared as though everything else was functioning as it should. I should have looked more closely at the rear o2 sensor voltage, but it hasn't thrown any codes indicating catalyst efficiency is down. It had the hidden Volvo codes stored on the CEM, BCM, and ECM. Most of them appear to have been set by me working on things or running the battery dead cranking it. 24BO is the only Volvo code that has reappeared.

    10. #8
      Junior Member
      Join Date
      Jul 2013
      Location
      Georgia
      Posts
      202
      Quote Originally Posted by euro-trash View Post
      If you can provide me with a link to the software I would appreciate that.
      It's in technical and faq's

      https://forums.swedespeed.com/showth...-Download-Link

    11. #9
      Junior Member
      Join Date
      Jun 2020
      Posts
      9
      Well, I put my step drill right through the bottom of the down pipe since the cat is rattly inside and needs to go anyways and this was free to try. Still doesn't want to start after a heat soak, but it didn't set the upstream oxygen sensor code while idling. Through the hole it wasn't a steady flow of exhaust coming out either at idle, but better than at the tailpipe before the hole. Starting to suspect a cylinder down, so I'm going to do a compression test and put my inline spark tester under each coil, I know #1 is firing. Going to check to make sure all the injectors are firing too. The plate and insurance are off it now and it has been replaced by a minivan. Not entirely sure if VIDA will work on my laptop or not at this point.

      Pulled some cam sensors and injectors off an 04 v70 2.5t at the junkyard since these Volvos are generally few and far between in my area. If anyone else has dealt with a problem like this I'd be interested to hear what the fix was for you. I'm going to keep plugging away at this.

    12. #10
      Junior Member
      Join Date
      Jun 2020
      Posts
      9
      So I'm suspecting the coolant temperature sensor is the culprit as I was able to get it to start with a 2200Ω resistor in place of the sensor when it was refusing to restart. This is essentially lying to the ECU and telling it the engine is 80°F when it was in fact 196°F. At 196°F CTS resistance was 250Ω, and at 190°F it was 262Ω. Gauge in the car read in the middle when hooked up to the CTS @ 196°F, with the resistor it was showing cold so that takes the wiring out of the question.

      Based on this graph, it looks like the CTS is good, but who knows maybe mine is 50Ω out and it's throwing the fueling tables off?

      TempSens.gif

      From here: http://www.jag-lovers.org/xjlovers/xjfaq/testcts.htm

    13. #11
      Junior Member
      Join Date
      Jun 2020
      Posts
      9
      Hey guys, it seems as though the coolant temp sensor was the issue all along. At 195°F the new one reads 225Ω vs 250Ω of the old one, so it was in fact reporting to the ECU the engine was slightly colder than it was, making absolutely no sense whatsoever as the car started hot with a 2200Ω resistor. The tip of the old CTS has corrosion on it, this is all very reminiscent of the small amount of oxidation on the flame sensor in my furnace years ago that caused it to light briefly and go back out. I am going to clean this one off and keep it in the glovebox along with a 2200Ω resistor and 225Ω resistor should issues arise with my ultra cheap Ultra-Power TX40 replacement. Shipped from Rock Auto this sensor was under $6.

      Seems crazy that a 25Ω difference is enough to cause this problem on a sensor with a 2200+Ω range...

    14. Remove Advertisements

      Advertisements
       

    Similar Threads

    1. 2006 XC90 fwd 2.5t won't start hot
      By euro-trash in forum XC90 (2003 - 2014)
      Replies: 1
      Last Post: 07-07-2020, 09:36 AM
    2. Car won't start when hot
      By foReveR in forum R Forum (2004-2007)
      Replies: 9
      Last Post: 06-03-2013, 04:28 PM
    3. My 99 v70r is overheating! please help! HOT HOT HOT
      By beardo265 in forum R Forum (2004-2007)
      Replies: 7
      Last Post: 09-26-2007, 03:33 PM
    4. Radio/Climate Control Panel...Hot, Hot, Hot!
      By Mr. Kotter in forum XC90 (2003 - 2014)
      Replies: 3
      Last Post: 09-27-2004, 02:54 AM