So yesterday my wife was driving the car and all was good. Then she shut it off for a minute or two and then restarted it and started driving and the check engine light kept going on and off and the car felt like it was almost dying then restarting. I checked the OBD codes and the diagnostics under the hood and there was nothing. Today I drove to the store and all the way there the check engine light and the upshift arrow kept going on and off. This time I had my OBD tester plugged in but nothing showed. When I drove home nothing went wrong and no lights.
What is going on? What could cause this?

 

The transmission light is a strange clue. I wonder intermittent loss of power to one of the ECM pins would cause that. When the ECM first turns on, those lights are on. then they go out. No code is set. What do you think?

If that's the problem, I know where I'd look first. I'd look at the "fuel injection main relay" plug. That is one of them on top of the radiator.

 

upshift light flashing can indicate car is in winter mode - so first check the button switch on the shifter is where you want it. There are several components which can trigger this happy meal of warning lights - PNP sensor (switch), ABS controller, connector/relays. First thing I'd do is the "shifter row" to see if that can clean up the PNP switch contacts (park/neutral position sensor is in the shifter assembly). Next is to see if you have any ABS warning lights coming and going. My early money would be on the PNP sensor.

 

But the check engine light and the upshift light go on and off at the same time.

 

Have you scanned for any stored check engine codes? My thinking in anything which appears randomly or intermittent is likely connectivity related - PNP sensors, relays etc have contacts that can get corroded and fail at temperature or randomly, ABS control boards can develop cracks in solder joints which open circuit randomly and the same can be with wiring and ground points.

 

You are partially correct on this. There were no codes anywhere. Last Saturday I was able to check it out and the entire issue seems to be because the fuel pump relay must have vibrated up because I pushed down on it and it pushed down about 1/32+ of an inch and the issue went away. I need to find a way of holding the relay down. 1/32 of an inch is not much and if this happens again I may need to pull the entire relay panel and check the fit of all the connections.

 

Reviving this thread because the engine cut out twice today and after bleeding off some fuel it started. The guy whose drive way I had to stop in front of walked over and said he was a foreign car mechanic and that he had seen this issue due to the pressure relief not opening and to much fuel pressure building up. Does any one know anything about this? How would I correct it if this is the issue? After I bled off some fuel at the end of the fuel rail the car started right up, I have had to do this before.
The guy I was talking to also referred to issues with the carbon canister.

I just went out and drove the car again and the check engine light kept going on and off and it kept feeling like it would die. I tried checking codes at the OBD reader but there were none so I went through test block A in the engine compartment but the only code I found was 223 using socket 1. I have not been able to find anything that tells me what socket 1 is for. socket 3 and 6 show no fault.

 

volvotips.com is a good source for the diagnostic codes

 

Next time it does this, try wiggling the key in the ignition switch. We had a very similar issue on our old 850 and it turned out to be a faulty ignition switch.....

 

I went out and drove it again and it would go fine on acceleration but when I would lift my foot off it would die and the re start. I keep going back to the idea of the fuel pressure regulator not working correctly allowing it to flood.

 

when my Daughter's 850 started to cut out, I replaced the relay first which seemed to help, then it happened again so I did the FPR, which again seemed to help, finally when it died again, I replaced the fuel pump and its been good for 2 months now.

 

Your idea would be incorrect. Injectors alone spray fuel or leak fuel into the cylinders.

If you have not figure it out in 3 months, it maybe time to pay someone to diagnosis and fix the car.

 

yep, typically the FPR presents itself as a long crank to start, not a cut out. the diaphram tears and leaks pressure out through its vacuum line - so you can test by popping off the FPR's vacuum line to see if fuel drips out. Long cranking is due to the pump needing time rebuild pressure at the rail. On the 850s there is also fuel injector relay as well up under the cowling that can can cause issues. Relays typically fail by worn contacts getting sticky (ie presenting as a cold start problem) or by overheating and losing their magnetism - but that's more typical of fuel pump relays when the pump is drawing too much current (and thus heating up a relay, particularly if the contacts are worn).

 

I was looking up the fuel injector relay on IPD but it does not come up under that name. Is there any other name for it? When I am having this issue with the car after I get it started it will sometimes stop as soon as I close the hood. That would indicate that maybe there is a loose connection that gets jarred when the hood closes.

 

Hmm. It is of course close to the hood latch. IPD has this listed as the "fuel system relay"


P.S. I just had a thought - it's likely there's a bad connection. If there is, then the relay won't fix it. The problem may be the wiring. The plug there has the round connectors that go bad.


You can buy the innards to fix that, see below, but personally I just bodge up something when they go bad.

 

I was thinking the same - Also curious what the symptoms of ECU contact issues would be on the 850s. Worth a try pulling the ECU and cleaning the contacts with electronics cleaner??

 

So if you look at my thread that I did about changing the radiator I had issues about that. I did find when you change the radiator you have to remove the relay carrier above it and that gave me a chance to check all the connections and sure enough the two of the connectors to the fuel system relay were not on tight and when I went to pull the connector I found those just touching the pins that they go on. I have re done all the connections and all seems to be good now. Also that relay carrier is now mounted properly so it doesn't bounce around.

 

I recently had a problem like this with my 960. It turned out to be the (+) battery cable connection to the main fuse box. The cast brass clamp was cracked and providing intermittent signal. I refashioned and cleaned the connection then used a hydraulic crimper to keep it together. All is well thus far.
Good luck!