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1996 (corrected) 850 NA hot stalling

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

850oldschool
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1996 (corrected) 850 NA hot stalling

Post by 850oldschool » Sat Oct 19, 2019 2:07 pm

I've been working on this problem for a couple of months. It only happens when the engine is thoroughly hot, usually after at least 20 minutes. The car starts instantly and has full power until the problem occurs.

I first noticed it when I would be cruising at highway speed and then hit some dense traffic. After about 10 minutes of crawling in traffic the engine would have trouble idling, dropping down to where it was barely running or sometimes dying. When it dies it always starts right up, but will die again, unless I keep my foot on the gas and rev it up to about 1500. Often times it gets back to normal after a few minutes, and usually it's fine, but yesterday it lost power at speed on the freeway.

It's definitely OBD2 and doesn't have the onboard readout for the codes. There's never been a CEL with this. I don't have a scanner to read the codes, but I guess that's next. There's a lot of info on older options like vol-fcr, but it's hard to figure out what the best option is now, in 2019. Autel? Volvo850diag?

Any advice on diagnostic tools and troubleshooting would be much appreciated.



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SonicAdventure
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Re: 95 850 NA hot stalling

Post by SonicAdventure » Sat Oct 19, 2019 11:04 pm

Hi I have an n/a 96 850. I had been encountering the same types of problems, including the stalling and misfiring when warmed up.

I had bought the car off some people who had done recent work to it, and because the plug wires and igniter were brand new, I assumed the problem was one of the other spark-related sensors, so crankcase position sensor and cam position sensor. Both sensors appeared to be original. I had a mechanic check the car over after I bought it and he said it stalled at his shop one day. He confirmed it was a no-spark condition. But, he said it later started up fine and for the following several weeks after I picked it up it ran fine.

Since I was parting out my base model 98 V70 at the time and these two crank and cam sensors are the same, I decided to swap them one and a time and see if that had any effect. Did the Crank sensor first. After a week, problem came back. Did the cam sensor next, same issue.

Finally I decided to looking into the plugs and wires situation. The plug wires were “Plugs for Life” I think. I got some feedback here that the Bougicords were the only way to go. I was in the process of coming up with a plan to do the tune up when it stalled hard on me one night, throwing a Cyl 2 misfire and general misfires. The next day I decided to pull the distributor cap. It was filthy inside and full of fouling. The distributor itself was also very worn and old looking.

I decided to order a complete kit from FCP Euro and get a tune up done. I ordered a Bosch cap and distributor, BC wires and Volvo OEM Tri-Fire plugs which are the correct plugs for n/a 850s.

The “Plugs for Life” wires were fused onto the ceramic of the plugs and I ended up having to spend a half hour with needlenose pliers pulling the boots out before I could pull the plugs. The plugs in the car were Volvo plugs, but they were gapped at around twice the recommended gap of .028 or whatever spec is for these cars - they were also single tipped plugs. While they were gapped wrong, there were in decent shape and showed no unusual signs of fouling or physical deformation.

So, I got the right plugs in, got the Bougicord wires on and the new cap and rotor. The car ran fine for several weeks with absolutely no issues and slightly better fuel economy, maybe a 1/2-1 mile per gallon better than before.

However, after taking a drive one afternoon a few weeks after the tune up I put the car in Winter mode to Explain to a family member what it does. It was in winter mode for about 2 mins at low speeds. After taking it out of winter mode and while the car was idling in the parking lot, the car stalled. It started back up, and I proceeded to drive it 2 hrs home with no issues.

It has been virtually without hiccup since and that was probably about a month ago, including a 10 hr round trip drive to the beach two weeks ago. I was in some very heavy highway congestion earlier today and when the traffic loosened up, I felt what seemed like hesitation but I couldn’t really tell because I was still in start stop traffic. However no CEL or stalling. I then proceeded to drive it for at least 2-3 hours with several stops and back home and no issues.

There seems to be some correlation to warm engine temp and the stalling and we are not alone. After doing my tune up and seeing the problem all but eliminated, I have no clue how a car with poorly gapped plugs, a crap distributor/ situation and junk plug wires would be OK for the first 20-30 mins and then start stalling when warm. You would think that it would run crappy from the get go.

The coolant temp sender is something I am keeping my eye on, as I was told that also will cut spark if it’s on the fritz and thinks the motor is overheating. But, since the tune up, other than the one time, it has not stalled, and it is not stumbling and fumbling like it was prior to the tune up, cold or warm.

Soooo....what does all this mean for you? Well first, check your basics and move out from there. What is the age and condition of the primary sparking components, I.e plugs, rotor, cap, wires, igniter? If they are questionable or more than 5-7 years old assuming normal driving conditions it might be time for a tune up. Other than the pain of removing the battery and airbox, doing a tune up on these cars is pretty straightforward and can be done with a spark socket, torque wrench and a couple of screw drivers and hex head bits - no big deal. Plugs easily accessible right through the top of the head and with the hood flipped up to 90 degrees there is very little gymnastics involved.

Next would be air and fuel. Confirm that the fuel pump is priming by putting key in On position and listening for a 2 second hum from behind the passenger side rear seat. The red fuel pump relay in the relay panel in front of the driver under the hood is sometimes a stalling culprit. Assuming no fuel issues such as clogged lines or dead fuel pump, consider the fuel injector relay, which is above the radiator.

Next would be air. MAF could be an issue, as could physical blockages in any part of the air intake system, including clogged air filter or tubes disconnected or jammed. You may also have a vacuum leak; has the intake manifold gasket been replaced recently?

Another issue could be exhaust related such as clogged catalytic conv., or O2 sensor(s) but that should throw codes when it starts to fail.

Please keep us in the loop as I know I am not possibly covering every possibility and I know these cars are semi-complex, but at the end of the day, they are “just” machines...meaning, if the conditions are correct (air, fuel, spark, exhaust), they will run until the conditions are not correct.

Good luck,

Sonic



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Re: 95 850 NA hot stalling

Post by 850oldschool » Sun Oct 20, 2019 2:03 pm

Thanks for the thoughtful reply!

The cap, rotor, plug wires and plugs are all less than a year old, only the coil is original. The wires are Bougi's and the plugs are Volvo. It starts immediately, before it even completes one revolution, and I'm still amazed at how smooth it idles. Whether it's stalling or not, when you put the pedal to the metal it gets up and goes. The fact that it runs so well for the first 20 minutes might rule some things out, or maybe not.

As I said, my first thought was IAC, which I replaced with a used unit (along with both it's hoses), no guarantee the used one is any better than what I took out. The next thought was fuel pump relay. When it started cutting out on the freeway 2 days ago I swapped in the brand new genuine Volvo one I always carry in the glove box along with a T20 torx driver. Never missed a beat driving 20 miles home, but then an hour later I took it out for a run on the highway followed by some crawling in traffic, and got the problem to come back.

It's really unnerving when the power steering stops working.

Recent work also includes a new vacuum tree and o-ring, plus the accordion intake tube, which did have a crack in it, plus a flame trap o-ring.

I've got a large battery in it which occasionally slides and knocks the intake air tube off the airbox. Ive been wondering if sucking hot air from the radiator might be throwing the mix off, kind of like when the preheat valve is stuck and drawing hot air in from above the exhaust manifold. I've got a scan tool on the way, so soon I'll have access to codes and live data.



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Re: 95 850 NA hot stal

Post by abscate » Sun Oct 20, 2019 3:05 pm

Check out the Engine coolant temperature sensor (ECT) and see if the resistance is in range.


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850oldschool
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Re: 95 850 NA hot stalling

Post by 850oldschool » Sun Oct 27, 2019 11:04 pm

I cleared the codes and the ones that came right back are:

EFI-433 rear knock sensor
EFI-444 accelerometer
EFI-445 SAS pump

I didn't check resistance of the ECT sensor, but the coolant temp reading on my scanner has been in the 98-103 range, which seems normal.

I watched the live data from the MAF and when the engine was idling smoothly it was fluctuating between 3.3 to-3.9 g/sec. After the cooling fan had run several cycles it started idling a little rough and the range moved to 4.5-8.5 g/sec. One time the idle went down to about 300 and recovered and the MAF number spiked to the upper teens. It did the same thing again about 5 minutes later, but died. That time the MAF graph was spiky and the peaks were around 20 g/sec.

It died when I was parking after a test run and it wouldn't start without stepping on the gas. It wanted to die unless I revved it above 2000, when it smoothed out and ran OK above that speed. It started right up 60 seconds later and it idled perfectly.

I don't know if these readings are cause or effect. Common sense says that if the RPMs decrease, the volume of air moving through the engine would be lower and a properly functioning MAF should report a smaller number.

I'm really thankful for the lower ambient temps, it's been stumbling and dying a lot less.



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Re: 95 850 NA hot stalling

Post by 850oldschool » Mon Oct 28, 2019 5:03 pm

Today I drove it to the tool store (Delegard Tool in Mpls.-recommended!) to buy this:

http://www.langtools.com/sku-74853-smal ... e-adapter/

Which they had in stock for about 12 bucks, so now I can easily hook a fuel pressure gauge up. After about 10 minutes of hot soak while I was in the store I came out, started it right up and then it stalled out about a block down the road. Strong smell of unburned fuel. Restarted, but needed help from the gas pedal for about 10 seconds, then didn't miss a beat the whole way home.

I let it idle in the driveway when I got home watching the scanner and after about 3 minutes the idle trouble came back. The MAF reading spiked and it died.

So, I'm rolling the dice on a Delphi AF10311 MAF probe which I found for about 82 bucks. It even comes with the proper security pentalobe bit and a couple of new screws. I searched here and can't find any mention of it.



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Re: 95 850 NA hot stalling

Post by RickHaleParker » Mon Oct 28, 2019 5:45 pm

1. Idle problem: Clean the Idle Control Valve and check for leaks in the air induction
2. Clean connector and check wiring to Knock Sensor for shorts and opens.
3. Clean connector and check wiring to Accelerometer or shorts and opens.
4. Hook the SAS pump directly to 12V see if it runs or if it is dead. (1)

If you find water in the SAS pump, it has not run for a long time.
The water is from condensation that accumulated because the pump never came on and blew it out.

(1) I cut a SAS pump connector off a junk yard P80 so I could do this test with the pump still in the car. Cut the wires as long as you can.
Last edited by RickHaleParker on Mon Oct 28, 2019 7:02 pm, edited 2 times in total.


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

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Re: 95 850 NA hot stalling

Post by erikv11 » Mon Oct 28, 2019 6:49 pm

1. Could be a ton of things. Since you already swapped the IAC I agree with your earlier post that IAC is very unlikely but it never hurts to clean things (except the MAF - don't waste your time or $$ trying to clean a bright shiny MAF!). At least this one could relate to the hot stalling.

2. It is basically never the knock sensor that is the problem with knock sensor codes. Rarely it is the wiring or connector for the knock sensor so check that, but almost always the code coms from stumbling or misfiring. Fix that first and your knock sensor codes will in all likelihood go away - I wouldn't bother with it for now.

3. See Rick's suggestion.

4. The water accumulation is not because of pump problems, it is because the solenoid fails and gets stuck open. Then condensation accumulates and kills the pump. However like (2) the SAS problems are irrelevant to the hot stalling. Fix that first, then do SAS delete.

A problem that shows up after heat soak is basically guaranteed to be an electrical/electronic parts, if you hadn't already figured that out.

Checking the ECT is a good suggestion. How is the battery positive cable end, does it get hot after running? Are the grounds good?


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

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Re: 95 850 NA hot stal

Post by RickHaleParker » Mon Oct 28, 2019 7:12 pm

abscate wrote:
Sun Oct 20, 2019 3:05 pm
Check out the Engine coolant temperature sensor (ECT) and see if the resistance is in range.

Temperature : °C (°F) - Resistance Ω
0 °C (32 °F) - 7300 Ω
20 °C (68 °F) - 2800 Ω
40 °C (104 °F) - 1200 Ω
80 °C (176 °F) - 300 Ω
100 °C (212 °F) - 150 Ω

Vida: [Information]/ [Product specifications]/ [Specifications, electrical electronic]/ [Electrical system]/ [Specifications, electrical components]/ [Sensor]
Last edited by RickHaleParker on Mon Oct 28, 2019 7:25 pm, edited 2 times in total.


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

850oldschool
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Re: 95 850 NA hot stalling

Post by 850oldschool » Mon Oct 28, 2019 7:18 pm

Thanks for the tip on the knock sensor!

I'm reading ECT data on my scanner for both temp and voltage. Temp is between 98 and 103 and voltage is around 2 volts. Can I trust that? Also reading IAC data which is close to the MAF numbers at idle and the range where you expect the IAC to be operating.

Can I rule out the accelerometer as a cause of stalling?



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