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Discussion Starter · #1 ·
New to this forum and new to Volvo' s as well.

Actually I've had some experience with older Volvos; good friend had a couple P1800s, I owned an early 70s(?) 211 and later an eighties 4 door.

If I remember right I think the 211 had twin carbs that needed balancing every so often.

I digress. Just bought a 2001 (had reams of maintenance/servic records) V70 2.4t.

Shortly after I bought the car I drove some friends to the airport (about 40 miles, mostly freeway).

Shortly after dropping em off the cruise control quit workin and car started to vibrate, especially @lower rpms/under load and the CEL came on.

Few days later took the car to autozone and scanned for trouble codes and the printout said misfire cylinder. #1.

After a lil research I bought five new plugs and a Bosch ign coil.

Replaced the coil and plug on cylinder 1 and no change...

Took car to local repair shop and they said that I had a bad #1 coil...verified (so they say...) by swapping w/ cylinder #2.

Wife went to parts store and bought a no-name-brand coil. Installed coil and same result.

Miscellaneous trivial info:
Car seemed to run rougher while driving it home from the shop than when driving it to the shop?!! It even sounds different.

Visual inspection of wiring revealed nothing. I'm gonna find a wiring dia. ( I hope), buy a multimeter and check associated wiring.

What are the odds of receiving two bad coils?

If wiring is good would the next most likely suspect be the ECU (Computer, black box, etc.)?

Thanx in advance for any help.

Take care and stay safe
Roger

P.s. also cleaned connector and ground
 

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2004 V70R M66 | 2013 C30 M66 | 1996 855 AW42
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Check compression

And get genuine coils


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Bad ignition wiring harness? The insulation gets brittle over time.

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Took car to local repair shop and they said that I had a bad #1 coil...verified (so they say...) by swapping w/ cylinder #2.
I would try to replicate this, swap coil #1 with any of the other 4 and check for codes. If 1 is still bad then you have another issue. Doubt a new Bosch coil (and an aftermarket) is bad but not out of the realm of possibility.
 

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Discussion Starter · #6 ·
Thanx director fer sharing yer thoughts. That's my current plan; swap stuff around, and, since it's a recent purchase, gonna check compression, associated wiring and replace other 4 spark plugs.

Hope you and yours are having a great summer

Take care
Roger
.
 

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Before you spend any more money and time replacing hardware, you’ll want to rule out a fuel contamination issue which is surprisingly common in older cars. Condensation and other moisture can build up in the tank gradually or immediately after a fillup due to a single tank of bad gas. It can cause severe misfires and a variety of codes and can feel quite like a coil problem. Related codes can be a result of those misfires and not necessarily point to the cause.

Anyhoo, add a fresh tank of gas and add to it a bottle of yellow marine grade HEET, available at car parts shops and hardware stores that service gas yard equipment. It’s a fuel treatment that’s an extremely effective water dispersant (“dry gas”) and can fix a moisture-related misfire situation almost immediately if that’s the cause. I’ve had that situation come up with multiple vehicles over the years especially with the inconsistent fuel quality in my area, and a bottle of HEET has fixed most of those issues often after replacing hardware to no avail. Try the HEET first. No amount of “tune up” stuff will fix your issue if water in the tank is causing the problem.
 

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2004 V70R M66 | 2013 C30 M66 | 1996 855 AW42
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Before you spend any more money and time replacing hardware, you'll want to rule out a fuel contamination issue which is surprisingly common in older cars. Condensation and other moisture can build up in the tank gradually or immediately after a fillup due to a single tank of bad gas. It can cause severe misfires and a variety of codes and can feel quite like a coil problem. Related codes can be a result of those misfires and not necessarily point to the cause.

Anyhoo, add a fresh tank of gas and add to it a bottle of yellow marine grade HEET, available at car parts shops and hardware stores that service gas yard equipment. It's a fuel treatment that's an extremely effective water dispersant ("dry gas") and can fix a moisture-related misfire situation almost immediately if that's the cause. I've had that situation come up with multiple vehicles over the years especially with the inconsistent fuel quality in my area, and a bottle of HEET has fixed most of those issues often after replacing hardware to no avail. Try the HEET first. No amount of "tune up" stuff will fix your issue if water in the tank is causing the problem.
Fuel contamination would result in consistent misfiring across all cylinders

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