'99 V70 CEL flashing

obayha · Post by **obayha** » 08 Jan 2016, 10:38

It was foggy and damp this morning and the car started out not firing on all 5. The CEL started flashing for about 1 min then went off.
Heading up the ramp to the interstate, had to give it a little extra push and the CEL started flashing again. Stayed flashing for about 5 mins, then off.
Drove my 45 miles to work and on the off ramp, light started flashing again.
Light never stayed on, just flashing.
This has happened other times, not the light flashing just the not firing on all 5, but only on start up and when weather was damp and not driven for a few days.
I am thinking coils and or wires to be the problem. Any other thoughts?
Are coils replaced as needed, or all 5 at once?
Thanks for any help and direction.
Shane

Post by **kahl** » 08 Jan 2016, 11:12

Similar thing happened to my 2000 V70XC. Could feel it missing on a cylinder, very pronounced on acceleration. During accelation is when the CEL would flash. No CEL light, when I checked with a code reader I got P0305 as pending. Changed out coil pack and every returned to normal. My thought though may be incorrect is that the knock sensor was triggering the flashing CEL light. P0301 through P0305 denotes a misfire in one of the 5 cylinders. Could be coil pack or spark plug. Cleared the pending code with the scanner.

Post by **abscate** » 08 Jan 2016, 12:06

The misfire by cylinder codes are not reliable - especially if there is rough running. Once you get a misfire code, pull the plugs and do a compression test to see which one is the culprit.

Shane - replacing one coil is fine on a daily driver. I carry one old spare in each car. There are test measurement threads in the Forum but they can pass these and still misfire.

obayha · Post by **obayha** » 08 Jan 2016, 12:28

So even though the CEL is not on, you can still have a code to be read?
I will stop on the way home and let them read the code and go from there.
I have 2 gift certificates from a Volvo dealer in South Carolina, that is why I was wondering about buying one or replacing all.
These certificates would not buy 5, but could get me one or two.
Thanks
Shane

Post by **abscate** » 09 Jan 2016, 06:10

You can have a pending one which a decent scanner will catch. That's useful for focussing on the right cylinder. But, pulling the plugs and looking at them and the coils can also help nail it down if you don't have a scanner

Post by **FLXC90** » 09 Jan 2016, 13:54

Don't know about others' experience, but on my XC90 I have gone the nickel and dime route over the last two years, and 35k miles, replacing one at a time. I am now starting to get repeat failures on Autozone/O'reilly's house brands. Five of 6 were still OE when I bought it. Currently have one Bosch coil on order through eEuroparts. I guess I'll go through and replace all 6 of mine as quickly as funds allow. I'll keep the generics as roadside spares, but I don't have faith in long-terming them though.

Shane-the flashing CEL is the dead giveaway indicating misfires. It's just necessary to read where you have them and start investigating from there.

Post by **precopster** » 09 Jan 2016, 14:55

With the last 4 coilpack failures (including one on a customer's car) the OBDII system was spot on with which cylinder to target.

On two of them once I peeled the rubber boot from the coilpack body I could see a hairline crack in the body in both instances. The other 2 had no identifiable marks on the coilpacks. I even swapped the rubber boots and they still misfired.

Obayha even a simple ELM327 connected to a cellphone will give the correct misfire number. For $15 it's a no brainer to have one in the glove compartment.

obayha · Post by **obayha** » 09 Jan 2016, 15:15

In between the rain showers, I got to take a look at the engine.
Raised the hood and pulled the cover from the coils and the fuel rail. Started the car and pulled one fuel rail wire at a time, seeing which one caused no change in RPM. Number four caused no change. My simple test was to change out number 4 with number 5 and see if number 5 was bad. It was, so that told me it was probably the coil pack from number 4 now on number 5.
Purchased a coil from local O'reiley's that has lifetime warranty, so we see how well that goes.
Running on all 5 now. Cost was about $52.00.
Thanks for the help
Shane

Post by **precopster** » 09 Jan 2016, 18:36

Great thinking with the diagnosis. Old school and correct way to do it even without OBDII . Glad it worked out and running well now.

Post by **abscate** » 10 Jan 2016, 06:24

If you don't have ObD you try OBDa, life goes on......

Nice work, Shane.