No Start Intermittent stalls 850

nathan chase · Post by **nathan chase** » 29 Oct 2010, 00:46

Hi all,
I have read alot of posts trying to figure this out.
The car: 94 850 196k n/a auto
Symptoms:

Long standing- hick ups under hard acceleration once every 2 months. just like it skipped a beat. doesn't bog down just most stops and then keeps on going strong. strange, like the whole motor misfires once and then keeps on going. Codes crank sensor (replaced, didn't eliminate issue but seemed to helped)

Last 2 weeks - stalled when at idle or coming to a stop sign or going over a speed pump, restarts immediately, so I checked spark plugs, did oil and filter and have an injector cleaner in the gas.

Today (rainy) - Stalled twice under gentle acceleration, once it restarted no issue, once it just about died, got bogged down and then picked up

Tonight (still rainy)- parked for 2 hours and then wouldn't start. didn't even struggle, nothing. turned fine. tried banging on the tank and below the back seats and it started then stalled after a minute. after stall I checked for fuel at the schreder valve at the end of the injector line, some gas came out, I don't know how much should come out but it wasn't a dribble but it wasn't a shooting squirt either. whats normal?
Tonight - once I got home I revved it and once it fell back down from a rev it would almost stall, struggle and recover ~1/2 the revs. didn't stall though. isn't idling really smooth but it never has. I didn't notice any arcing but the lights were on and I could therefore have missed it. Didn't sound like a misfire. heard ticking from injectors.

Possibilities:
Spark
-regapped spark plugs after stalling started to happen- could be shot, they have 6k on them
-don't know when distributor was done
-how can you test a coil?
-some loose electrical connection perhaps with Crank sensor or otherwise (I sure hope not, these suck)

gas
-Fuel pump
-Fuel Pump relay
-Fuel Filter
-bad gas (never had issues with this station or the injector cleaner is currently in the tank)

Air
-MAF sensor (cleaned 1 year ago)
-dirty Throttle body ( partially cleaned 1 year ago)
-EGR is not connected due to exhaust manifold mismatch when it was replaced 1 year ago, has run fine since
-PCV

My thoughts:
-Seems I have fuel at rail so could it really be fuel related?
-Has thrown codes for cam and crank sensors but couldn't this happen when the car stalls? it doesn't get a signal cause it stalls and therefore codes? or perhaps these circuits are failing intermittently, poor connection somewhere
-With the rain I am thinking it could be electical but where to start
-why did banking on the tank get it to start again
-it could be a due problem of fuel filter,replay, or pump as well as intermittent electical

Thanks for your ideas on how to proceed.

-nate

Post by **phils94850** » 29 Oct 2010, 04:43

It sounds like a cam sensor if thats the code you got.. id also check the fuel press. at the rail with a gauge. You can try disconnecting the MAF and see if it runs better, if so, you have a bad MAF.

If you smacked on the tank and it started again... you have a bad fuel pump.

Post by **jblackburn** » 29 Oct 2010, 06:58

I think you might be in need of a new fuel pump (or maybe just the relay?) as well. You should get a nice squirt out of it even after 2 minutes when functioning properly. If you're going to be replacing the pump, get a new fuel filter as well.

I think this is your main issue:

-Has thrown codes for cam and crank sensors but couldn't this happen when the car stalls? it doesn't get a signal cause it stalls and therefore codes? or perhaps these circuits are failing intermittently, poor connection somewhere

Try getting the cam/crankshaft sensors AS FAR AWAY as possible from the distributor/ignition coil wires. This may help, it may not. Zip ties do a wonderful job.

Your spark plugs should be fine, and if you don't see arcing, lets say your ignition coil is fine right now (unless you notice a loud zapping noise every time it fires).

Plug off or smash the end of the EGR pipe with pliers - that's a huge air leak if it's open. Try the MAF sensor trick as Phil suggested - even if it's been cleaned, these things fail all the time.

I'm sorry we don't really have a solution for you, but hopefully that should give you some more troubleshooting tips so you can track it down. Good luck!

nathan chase · Post by **nathan chase** » 29 Oct 2010, 14:04

So there is a really strong squirt of fuel from the valve after a few minutes of idling this morning. First time it started up just fine. randomly will stall after 5-10 minutes idling.

I moved the Cam and Crank wiring away from the distributor and it still stalls randomly.

Tried disconnecting the MAF sensor (Sensor right after the filter box) and it stalled when cold. Once warmed up it sometimes ran at a higher idle without the MAF connected but not any smoother or rougher, sometime just stalled. Recoded cam sensor intermittent and missing codes after stalls. How can I check if its the sensor or the wiring? It has also thrown the Crank sensor code in the past but I have replaced that sensor. could this be wiring somewhere? It almost stalls after a quick hard rev but struggles and recovers, shows CEL for a split second and recovers, only code then is RPM sensor missing sporadically. is the RPM sensor something separate to Cam or Crank sensors or is it just detecting the almost stall? it drops to like 500-600 RPM then recovers.

Post by **jblackburn** » 29 Oct 2010, 14:37

I was hoping that it would be something that simple - it is very odd to have both codes at once.

The cam sensor is a tricky one to test. The only test for the wiring is: pin 1 to 3 is 12V; 2-3 is 5V. 3 is the one towards the back of the car. Most of the time if you get a code for that sensor, the sensor is going - or just craps out entirely. Try to get your hands on a used one (junkyards are awesome) - they are expensive.

The crankshaft sensor should show >250 ohms at all times, and fluctuate as the engine is cranked.

The RPM sensor/crankshaft sensor are one and the same.

nathan chase · Post by **nathan chase** » 29 Oct 2010, 18:44

My neighbor has an 850 so I swapped cam sensors. before that I had driven to the store and it had stalled once and hiccuped a few times. With the neighbors sensor it ran fine. Drove it up and down the street with not issues for like 5 minutes. put back my old sensor and drove it for 5 minutes. it hiccuped once and threw the RPM code. I am pretty sure now that it is the cam positioning sensor causing the issue. The only used one I can get locally is from a '99 V70. anyone know if those are compatible? otherwise its $200 for a new one.

thanks for all your help