2000 S70 awd - Intermittent Starting - Runs well after start

[Abneya]

OK guys.... I'm going to look into the "antenna ring" tomorrow but while i'm at it i'm looking for opinions and other things to look at. Here's the sequence of what has gone on. I'm getting ready to take the volvo on a road trip so i've been doing some maintenance. As this problem coinsided with the maintenance it would seem like they are connected - the problem is i've double check the stuff multiple times and its all done right. Here goes:
1. A few months back I had problems keeping the car running and was throwing 02 sensor and MAF codes. I replaced both 02 sensors with OEM/Bosch sensors and the MAF with a new Bosch sensor from FCP. (now.... that was just to let you know those three had been done... fast forward 2 months to now)

2. Had a leaky internal check valve in the fuel pump. Decided it was time for a new filter and aftermarket inline check valve.

3. Broke one of the lines trying to get the check valve in (from the pump to the filter, not filter to the engine). I ended up removing it all the way back to the metal outlet on the fuel tank - replaced and reran the fuel line and installed the inline check valve on the back of the new fuel filter.

4. Replaced all the spark plugs with new Bosch Yttrium plugs from FCPEuro (4-prong pre-gapped plugs).

5. Car ran fine for a day. Then it died on my while parked. It wouldn't start again. I had it towed to my house where i took the fuel stuff off and tested the valve, the line, the filter, the direction of flow for the fuel filter and the check valve and reinstalled. All were installed correctly.

6. I pulled the plugs out and double checked their color. THey were too new for any real color. I also checked the coil connection snugness. It was fine. I reinstalled the plugs and tried to start the car. No luck.

7. I checked the 15amp emissions fuse. It was blown. I replaced it and the car ran great..... for a day.

8. This afternoon it acted like it did before.... the car turned over just fine and turned over strong (new battery as well) but wouldn't start. Acted like no fuel. I checked the fuses but they were fine this time. I tried again and it started and ran fine.

9. Tonight it happened again. Wouldn't start in the grocery parking lot (actually started initially and then died immediately after .... like 1-2 seconds after). It would not restart. No blown fuse.

10. Came back tonight and it started right up after 2 tries (the first try it just turned and turned....second it worked like normal).


When it runs it runs great. When it is quirky it wont start at all. Could it be....

a.) The plugs
b.) antenna ring
c.) ecm issue?
d.) key chip issue (its an oem key)
e.) On the key thought - my remote key fob randomly stopped working... coincidence?

[nedro018]

hmm i have 95 850 NA but i had same issues...intermittent no-starts. for the wife (she drives it) it wasnt the FP circuit, i ruled that out. it wasnt the coil.

it was the camshaft position sensor. it took me 3 weeks to find it because you ever knew when it -wouldnt start- several times this was in remote parking lots. my 95 850 almost got sold under duress....several times. she was so pissed that i had to pick her up. i kinda was too, but i was more curious.

theres 3 things that cause no-starts in -my car- (95 850 NA): something wrong in FP circuit (2 relays, 1 fuse, the FP itself), or, 2 sensors and/or the coil itself. the sensors are the camshaft position sensor (CPS), and the crankshaft (or pulse) sensor. they provide inputs to the ECU and if the ECU doesnt see them, the coil will not collapse the field on the blue wire on the coil...which is what provides spark to the distributor. no collapse-no start.

i learned this the hard way because my CPS was -intermittent- it would start fine every morning. but during the day after the wife's classes (4+ hours) maybe...maybe not. the calls for pickup kept coming.

i read forums and saw that the CPS and crankshaft sensor (CS) can cause this. i went to my local junkyard and was only able to find the CS sensor so swapped it. first. all was fine for about a week. another call by the happy wife with desire to sell the car. i found the CPS sensor for my car in another city's junkyard. i kept it and waited until next failure...which happened about 2 weeks later...in my garage! no-start. i replaced the CPS in 5 min. -start- put old one back in. -no start-

the CPS was failed and it was temp related.

if you have a 94-98 volvo 850 that you maintain well and want to take a long trip, and your normal maint areas are adhered to (CS belts/all pulleys/tensioners, water pumps, etc), and you dont want a no-start condition, you have to keep these sensors/relays in the car at all times because they are -no start- areas: camshaft position sensor, crank shaft position sensor (pulse sensor), the 2 fuel pump relays (2/32 and 103...2/32 -feeds- 103). then there's always the fuel pump itself, but if that dies on a trip with the wife this 850 is gone. hopefully it happens in town cause i have a spare in bench stock!

best of luck.

[mikealder]

9. Tonight it happened again. Wouldn't start in the grocery parking lot (actually started initially and then died immediately after .... like 1-2 seconds after). It would not restart. No blown fuse.

That description is a classic symptom of the immobiliser aerial ring, mine used to do this until I cleaned the contacts and it has been fine since, get the car scanned for any fault codes and if P1670 is listed it is immobiliser communication error which points straight at the immobiliser aerial - Mike

[Abneya]

So you can clean the contacts and not replace?

[mikealder]

I enquired about a new one at our local Volvo indie garage and they were £38 (UK) but the garage owner suggested I tried to clean the contacts in the wiring loom connector and the socket on the aerial ring, a small disposable nail file worked a treat and it's not failed for around two years since I cleaned it - Mike