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850 ignition issue

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

pirateinavolvo
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Year and Model: 1996 850
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pirateinavolvo

850 ignition issue

Post by pirateinavolvo » Tue Jul 23, 2019 7:29 pm

My 96 850 non turbo glt wagon has an issue. When at times, starting the car with the air on it begins to run really rough. I am in sales and start and stop many times during the day. I shut the air off and drive it for a little and it will be ok. I changed the cap, rotor (was toast) wires and plugs. It runs great but it happened again. I installed the Bosch plugs, oem FRDPP. My tech suggested I install the volvo 8642661 plugs. I pull codes po300, po304 and po305. All codes are emission related. I also have an issue with my compressor working and then not working but I don't believe that has anything to do with why my car runs smooth for many start ups then all of a sudden it happens. My tech informed me that fuel on very hot days could not be entirely exploded and could cause the issue on start up. Any suggestions?
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Last edited by pirateinavolvo on Tue Jul 23, 2019 10:02 pm, edited 1 time in total.



Ozark Lee
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Ozark Lee

Re: 850 ignition issue

Post by Ozark Lee » Tue Jul 23, 2019 9:20 pm

Your codes are misfire codes. P0300 is a multiple misfire code and P0304 and P0305 are misfires on cylinders 4 and 5 respectively.

What did you gap your spark plugs at? Out of the box they tend to run about 0.040" to 0.045". Your Volvo wants a spark plug gap of 0.028" and it will run poorly of the gap is significantly larger than than. Beyond 0.030" is starting to get significant.

The car is also very picky about the spark plug wires. Anything but OEM (Bougicord) ignition wires will cause trouble.

The air conditioner problem is likely due to the clutch gap on the compressor. We have some simple fixes in the repair database. Search "bread clip fix" for details. Most of us have gone from bread clips to zip ties to accomplish the same thing and I think that gets detailed in the bread clip threads. The air conditioner and the misfires are usually unrelated unless there is something seriously wrong with the compressor and it is locking up. Even then that will usually present with a squealing serpentine belt rather than a misfire.

...Lee


'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

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Clemens
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Clemens

Re: 850 ignition issue

Post by Clemens » Wed Jul 24, 2019 6:48 am

just guessing: if the a/c compressor is on it´s way out, it could be additional resistance to the motor that could theoretically lead to a misfire if the spark isn´t good. I know I had a compressor with a shot bearing make the car almost stall occasionally.
To test if the AC compressor could be the culprit, test if the problem occurs when the AC is on but not working.

but then, I am just guessing here mostly. Definitely check the plug gap!


Summer: 1996 855 R
Winter: 1994 855 T5M
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pirateinavolvo
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pirateinavolvo

Re: 850 ignition issue

Post by pirateinavolvo » Wed Jul 24, 2019 8:22 am

Thanks! Plug Gap is .28. I filled up with premium gas and will see if that helps. When the AC is working it blows cold. I am sure it's the clutch. This misfire issue is a puzzle!



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greg850r
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Re: 850 ignition issue

Post by greg850r » Thu Jul 25, 2019 9:40 pm

Bosch cap and rotor, Volvo plugs, Bougicord wires to start. Clear codes and you have a good starting point. Pay close attention to the routing of all wires, including cam sensor wire. Keep in mind that misfire codes will sometimes not be accurate as to which cylinder, especially when there's more than one cylinder along with the random one.


05 Cross Country wagon
99 C70 Convertible
96 850R wagon
96 850T wagon
96 850 GLT 5spd N/A sedan
97 850R 5spd sedan
66 GTO 421SD 4spd
67 GTO 455 T400
02 Powerstroke 4x4
85 Yota 4x4
24' 454 Challenger
07 Softail Custom
02 Sportster Custom
Parts cars not included

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