2000 S80 infamous hard to start issue

[aussieviking]

Hi all, long time reader new time member. Firstly let me say that this site has helped me greatly over the last 3.5 years as my wife and I also have an XC90 as our main car. Thankyou to all the contributors on here that go unthanked by the many people that just look through and find what they need and leave.

First of all I need to give a little backstory so please bear with me. Having had another Volvo for two years at the time I decided to get my feet even wetter by looking at getting a 2nd Volvo.. I missed out on some cheap S60's and then started looking at the dreaded S80 T6 model. Knowing full well what I might be potentially getting myself in to one day I made a purchase interstate for a very good price considering it had no transmission issues at the time and the body and interior are in great condition I thought I did pretty good.

Sure enough, a month or so after owning it I started getting transmission codes and getting locked in to third gear. VIDA reported that the third gear ratio was out of spec even after full line pressure apply. I tried a few things like trans fluid modifiers and just kept driving it avoiding third gear engagement using manual shift everywhere. Moving forward and being no stranger to working on cars in general I had already promised myself to attempt the transmission rebuild if I ever had the issue happen to me when I bought the S80.

So over the last 6 months on and off, I have removed the engine and trans, cleaned them both up as they were filthy, rebuilt one of the turbos due to excessive shaft play, performed a complete rebuild and upgrade of the transmission internals as well as install a shift kit, and reinstalled back in the car.

Present day: the car itself has now been hit and miss when it comes to starting since putting it back together. Sometimes it will start instantly. Sometimes it will start after 3 attempts. And sometimes not at all... walk away in frustration, then come back and it works. Edit: The car cranks and will continue to crank but will not fire up. The transmission rebuild on the other hand has worked flawlessly. This starting issue did not exist before the repairs.

So far I have checked the following -

• Fuses

• Engine timing and VVT hub spring alignment

• Cam position sensor

• Crank position sensor

• Rerouting of the cam and crank sensor wiring away, or back behind the starter motor with more shielding

• Fuel pressure (jumps to 40psi straight away after turning key to II)

• Spark plugs

• Coilpacks

• Engine grounds

• Battery is new as the old one went flat and couldn't be resurrected while I was doing the rebuild

• Key barrel antenna

• ETM operation via the VIDA self diagnostic test (all well within factory limits)

Any ideas what might be causing this but I'm not generating a code?

Next I'll be looking at backprobing the crank and cam position sensors to ensure they are actually giving the expected voltage, but I had tested them out of the car and replaced with another 2nd hand unit and they appear to function as expected on their own both the old and 2nd hand units.

When cranking it over on the DDM I see "no oil pressure" flash up for a second or two while trying to get it to start. Does anyone know if it might be a dodgy oil pressure switch if this could be telling the ECU not to fire? I'm not sure if this is one of the safeguards in place but it did cross my mind only earlier today.

This is really starting to get me as when the car does start up, it's instant and runs as smooth as silk... the transmission even smoother than butter on a warm summers day.

Any internet knowledge appreciated. I may even gather together a collection of pictures of the rebuild and post here in appreciation for all the knowledge I've gathered through this forum over time.

[DeadEric]

KOEO does fuel pressure shoot up to 40, drop a bit when the prime stops then hold steady or fade away?

[aussieviking]

KOEO does fuel pressure shoot up to 40, drop a bit when the prime stops then hold steady or fade away?

Hey thanks for the quick reply. Not remembering the exact details of my earlier fuel testing I just went out in to the cold and hooked up the gauge.

Interesting note... upon first turning the key to position II after hooking the gauge up the pressure only went up to 20psi and stayed there.

Turned it to off, back to position II and it shot up to 50psi. It took exactly 1 minute and it slowly dropped to 40psi and held there for several minutes. Attempted to start and it started instantly and shot up and held just under 60psi while idling.

Could the first 20psi lazy prime be when I would have had a no start condition? Or is this only because all the fuel came out the rail when I screwed on the gauge? I have left the gauge on and will check it in the morning to see what it has gone down to overnight and what the first turn of the key prime is, as well as if it will start upon that first prime.

[DeadEric]

I was thinking bad pressure regular, check valve or leaking injector.

I'm not sure what the fuel pressure specs are so hopefully someone will chime in with those.

[aussieviking]

Ok so things have gone in a different direction.

I checked the fuel pressure this morning and it started off at 25psi before touching the car. It also stayed on 25psi after turning to position II and after one successful start and one non-start. My wife noticed that when it did start I had got her to keep it on position II for a while because I was waiting to see if the gauge would shoot up.

Turns out that the gauge was stuck frozen or something so none of the readings I took this morning were accurate as it was stuck on 25psi for the mornings tests.

After testing four starts so far now, leaving it on position II for 15 seconds or so then starting it has worked every time. Two things could be happening during this time, the pump could be having trouble priming the rail, or the ETM is getting stuck during it's self test (this is the click-buzzing noise-click anyone may notice when they first put their cars to position II).

Fingers crossed I have nutted it out now thanks to a second pair of eyes on it.