850 Wagon wont start - possible 'limp mode'

Adsteph0408 · Post by **Adsteph0408** » 03 Oct 2016, 11:38

Hi,
I recently bought out 850 Wagon, new to Volvos, always had Volkswagons. It ran good, didn't pur like a kitten but always started and ran just fine driving to and from work (about 7 miles each way). Over the course of 3 months I only had one issue, which was an idle issue, it would dance around 1000 rpm, up and down but never stalled. This happened only twice and would correct itself very quickly. Now about a week ago at a stop sign the car started making a loud noise at idle, best way to describe is it sounded like I was driving a diesel. It had very little power and barely got home. My husband drove it, maybe a mile to see what I was describing, and it wouldn't go above 10 mph. It was then parked and now wont start. We have checked everything, it has spark, it is getting fuel, fuel pump is working. We replaced the spark plugs, I cleaned the throttle body. I'm puzzled, it has air, spark and fuel but just wont start. Battery is charged, and starter is functioning. If anyone has any idea please help. Thanks.
Also if it matters, it does have an oil leak, but we have always topped off the oil as needed.

Post by **misha** » 03 Oct 2016, 11:53

Try with unplugging Maf sensor's connector and start the car with it disconnected.
Are you sure you have a working fuel pump?
Sounds to me like fuel pump is not working.

Post by **scot850** » 03 Oct 2016, 11:57

Is your car a turbo or non-turbo? If it is a turbo it may sound like a diesel as a turbo pipe has blown or come off.

+1 to what misha says, have the pressure checked at the Shraeder valve on the fuel rail. Should be 43psi minimum.

Neil.

Post by **benpineapple** » 03 Oct 2016, 12:48

+1 to Misha +1 to scot850. Sounds like potential combined MAF and fuel relay.

When pump goes, it's gone with no warning. When the pump relay is going, it can act sporadic right up until it goes to the pearly gates. https://www.matthewsvolvosite.com/forums ... hp?t=52252 Try the procedure from that article where the fuel pump relay is pulled, and a jump wire is inserted between terminals 15 and 87.

MAF going bad could describe it running like garbage, and the idle dancing. misha's test (unplugging MAF) is how I identified a failing MAF on my car last fall.

Adsteph0408 · Post by **Adsteph0408** » 03 Oct 2016, 13:08

I have disconnected the MAF, doesn't make a difference. Also, I can hear the fuel pump running when the key is turned and I can hear fuel being sprayed into the engine. Will all this happen if the pump relay is faulty?

Adsteph0408 · Post by **Adsteph0408** » 03 Oct 2016, 13:11

Also, just checked the codes. A1 - 114 and A7 - 122.

Post by **misha** » 03 Oct 2016, 14:48

A1 is PNP switch code and A7 is Ect sensor code.

Both are a no start codes but with a1 the engine will not crank and A7 will crank but will not start because the ecu doesn't know how much fuel to inject since there is wrong input from coolant temperature sensor(ect).

Adsteph0408 · Post by **Adsteph0408** » 03 Oct 2016, 14:58

Is there a way to by pass the coolant sensor and see if it starts? Also would that cause it not to start because it doesn't know how much fuel it needs?

Post by **misha** » 03 Oct 2016, 15:23

No way and yes....that's exactly what it does.
The only problem is that you need OEM one or at least Vernet.

Aftermarket ones will give you the same symptoms.

Did you checked it's connector....harness side and ect side?

Adsteph0408 · Post by **Adsteph0408** » 03 Oct 2016, 15:39

We haven't, we will go try that now.