1998 V70R Random Misfire Topic is solved

[fitz548]

Symptoms of a failing crankshaft sensor---- Acceleration Problems

As the engine speeds up, there needs to be adjustments to spark timing and fuel injection. Without accurate input from the crankshaft sensor, the engine control unit (ECU) can't make these adjustments as well as it should. This can result in slow or uneven acceleration.
Reduced Gas Mileage

Without accurate timing information, fuel injection won't occur as efficiently as it should. That means the engine will need to use more gas and your morning commute will use up more fuel than usual.
Engine Misfires

Lack of proper spark timing can cause a different problem: one or more of the cylinders may misfire. That is to say combustion may be disrupted. You will feel, and maybe hear, this as a brief stutter in the engine.
Rough Idling

You might feel that the engine runs rough or vibrates at idle, say, when you're sitting at a red light. This is similar to the above in that it stems from poor spark timing.
Stalling

As seen with rough idling, sometimes crankshaft position sensor problems are worse at low engine speeds. Sometimes the engine might even stall out entirely at low speed if the fuel injectors aren't giving it the fuel it needs.

[fitz548]

One thing i would like to mention and i think others had mentioned this also you need to check your fuel pressure at the rail it needs to be a minimum 44psi or higher anything lower than that is not good stock volvo fuel pump is around 400.00 stay away from the aftermarket junk like pro parts sweden they are junk parts. not sure if your car has the access panel for the fuel pump underneath the rear seat i have the xc model and shop had to drop rear suspension to put fuel pump in my car cost 1000.00 hopefully thats not the issue on your car thats why you need to check the fuel pressure at the rail or have it done

[fitz548]

one other thing i wanted to ask you was have you performed a stage zero on the car?

[Mriv1998]

I guess you could say it’s had a semi stage 0 lol because since I’ve got it in September I’ve done the spark plugs, wires, cap, rotor, had one vac line replaced. Also serviced the tranny and transfer case. Injectors were checked and I was told they were fine. This misfire has come back in a few different forms and I’m baffled every time since the obvious fixes

[fitz548]

fuel injectors get gummed up and when performing a stage zero sometimes you can get away with just putting techron in the fuel tank but its really best to have them removed and cleaned.also this--------------

Stage ZERO Tuning List:

Spark plugs
Air, fuel and oil filter service
Trans fluid flush
Inspect & replace vacuum lines and IC piping rubber
Upgrade to silicone hoses where possible
Test / replace 02 sensors
Verify proper fuel flow using a fuel pressure tester and replace fuel pumps if needed
Clean / replace injectors
Clean intercooler / intercooler plumbing
Compression and cylinder leak down test

[fitz548]

are you working on this vehicle yourself? i think i read in your first post that you were having work done to your car at a volvo shop and you wanted input from us to make suggestions to your mechanic on what to check while under the hood?

[Mriv1998]

I try to work on whatever I can whenever I can but I avoid going too deep under the hood. I’m bringing the car to my mechanic this Thursday to have the pcv done and wanted him to look at this misfire as well. Last time he had a look at it he changed a vacuum like which required him to remove the intake manifold (had I known then I would’ve had him do the pcv) and it misfired the second I drove it out the lot. After that I changed the coil myself and it drove great for a month until recently I brought it up to about 85 and it misfired again. Now it’s happening consistently and the code this time comes back as cylinder 1 after I clear it

[fitz548]

Its more than likely what i and Matthew suggested to you man,

its the crank sensor. did you read the symptoms of a failing crank sensor that i just replied with on your post? i did replace the fuel pump relay also for good insurance because it was the original on my car for the last 20 years. even my mechanic said its the crank sensor and he was right because i had replaced everything under the hood of my car everything----------big big money i am trying to save you from doing what i did and spend 50.00 and replace the crank sensor unless you would rather keep dumping money trying to figure this thing out i can guarantee you its the crankshaft position sensor just tell your mechanic to replace that and see what happens.

[misha]

Since the intake manifold was removed not a while ago....there is a possibility that intake manifold gasket is pinched somewhere.
It happens all the time.

[Mriv1998]

I appreciate the advice and trust what you’re saying. Also watched the video for the crank sensor and it’s definitely a job I can bang out after work. I’m going to do that before I bring it in that way I can see if it fixes the issue