97 850 T5 - Stalling, hard starting MVSOLVED dist rotor bolt Topic is solved

[jblackburn]

Sounds like a typical MAF sensor to me, however, check all turbo air hose connections for something loose as well - they easily blow loose from the clamps once the rubber gets old.

[keithf]

My code reader showed up yesterday. Unfortunately, the only codes captured were the misfire codes from a few weeks back: P1310, P0301, P0300. I've reset the codes, run the engine to operating temperature, but no new codes are showing up.

Additional troubleshooting:
- disconnected the MAF, which makes start to idle rough
- checked out the fuel pressure regulator - looks ok, no gas came out of the vacuum line. When I disconnect it, the idle changes.
- measured 12v & 5v at the Cam Position Sensor (note: the electrical connector on the cam sensor is brittle.)
- rechecked gaps on all 5 plugs
- did another look for broken lines, hoses, etc...
- realized that it starts easier when cold. After it warms up, it's more difficult to start.

I'm thinking that it's either the Cam Position Sensor or the Crank Sensor. I'm likely going to order both, and throw in the towel (tow it to my local Volvo specialty shop) if that doesn't fix it.

I'll let you all know what happens.

[850_olaf_nz]

more difficult to start when warm? could the CTS be having something to do with this?

edit: sorry, must better explain my thinking - when it's warm, where's your temp gauge? if the cts is mis-representing temp to the DME (eg reporting cool) it could be running too rich & contribute to your difficult starting. I've experienced this before. replaced cts at same time as MAF, and recently replaced failed CTS (5 years later) with genuine volvo part.

HTH

[E Showell]

Assuming CTS = coolant temperature sensor. You've got me mystified with DME, however.

[850_olaf_nz]

bmw-speak. DME = Digital Motor Electronics aka Bosch Motronic. sorry for any confusion!

yep, it's probably the cam position sensor (having slept on it some more) making the startng difficult when hot.

[keithf]

This is finally solved, though it was quite a random problem. The distributor rotor bolts had come loose, essentially creating a spark/timing issue. I guess a few months ago when I replaced the cap and rotor I didn't torque the rotor bolts down enough. While the solution was really simple, it took way too much time (and money) to find the cause. Lesson learned -- Double check torque on everything.

During my troubleshooting the problem went from "difficult to start and stalling" to "non-starting". That's when I gave up and had the car towed to a local Volvo specialist. They had the car for a week and put a lot of hours into solving it. Thankfully, they only charged me for a couple hours, as they were intrigued and took it on as a challenge.

[jblackburn]

That's something no one would have ever thought of!

Glad they were able to get it running again!