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1998 V70R Random Misfire Topic is solved

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

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misha
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Re: 1998 V70R Random Misfire

Post by misha »

What coil module on a '98?
There is coil behind airbox and cap & rotor.
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Mriv1998
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Re: 1998 V70R Random Misfire

Post by Mriv1998 »

Behind the air box
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Re: 1998 V70R Random Misfire

Post by misha »

That's the coil...one piece part.
Some calls it ignition coil module...but it's sold and replaced as a one piece part.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
Mriv1998
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Re: 1998 V70R Random Misfire

Post by Mriv1998 »

Yes I misspoke, regardless I had that replaced and it’s still misfiring
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Re: 1998 V70R Random Misfire

Post by misha »

Do what abscate adviced you to do...if the code move over to another cyl....it's the spark plug.
It could be a wire on that cyl.too...fuel pump relay.
Did you checked SAS valve?
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
Mriv1998
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Re: 1998 V70R Random Misfire

Post by Mriv1998 »

I have some free time today to look at those things... the spark plugs are easy to move around I’m just wondering if there’s any suggestions on how to actually test the wires like with a multimeter? (I work with electronics). Also is there a guide somewhere on how to check the sas valve?
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Re: 1998 V70R Random Misfire

Post by matthew1 »

Because you changed the spark plugs and still get the code, the chances of it being a defective spark plug now are very low. That probability would work like this: (chance of a bad spark plug before) X (chance of it being a bad new spark plug). So let's just say that would be 20% X 1% = one fifth of one percent. Plug in (no pun intended) whatever you think those numbers are, you'll still get a low probability. I wouldn't look there.

New wires = the same low probability.

I doubt it's spark, unless the symptoms are different from pre- new parts to post-new-parts, but it doesn't sound like this is the case.

I'd really look at fuel then crank position sensor.
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1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
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Re: 1998 V70R Random Misfire

Post by fitz548 »

Great advice on the crank position sensor i am pretty sure replacement of that and the fuel pump relay cleared up my issues. the other thing i forgot to mention also is that i replaced my fuel injectors also with brand new units they were not cheap but i wanted to get this figured out i did throw alot of money at it which is not really good to do but now my car runs like new crank sensor is cheap like 50.00 and fuel pump relay is also cheap like 30.00 you can install both of these yourself
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Re: 1998 V70R Random Misfire

Post by abscate »

Mriv1998 wrote: Tue May 12, 2020 5:42 am So you’re saying I should check the plugs again by swapping?
Try swapping a plug and wire to see if you can get the random misfire to change cylinders. These things are frustrating but patience will track them down.

Pop off your firstributor cap and make sure it is squeaky clean inside. A bit of oil vapor can ruin your day.
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Mriv1998
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Re: 1998 V70R Random Misfire

Post by Mriv1998 »

very interesting to hear that it could be the relay and crank sensor. I did some research and the common symptoms associated with those two parts is engine stalls and trouble starting which I am not experiencing. But you guys are the experts so I can give those a try a
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