V70 2001 Ignition Coils/Spark trouble

Gonefishin · Post by **Gonefishin** » 27 Jun 2010, 21:59

Hi guys,

I am writing about my 2001 V70 2.4L Turbo, 166,340 miles. Yesterday I was doing some maintenance and decided to pull the coils and plugs to inspect them. I noticed that all 5 coils have hairline fractures in the plastic around the windings. The NGK double platinum plugs were also worn down and I measured the gap to be .040". Thinking that I my performance might be suffering from the large gap, I re-gapped them down to around .028" and reinstalled to test. When I tried to start the car it ran very erratically (rough, like it was missing a lot) and died after about 10 seconds. So basically, I screwed something up and can't figure out what it is. The car was running fine before I pulled the plugs.

Next I ran down to the store and picked up some autolite platinum plugs because they didn't have the Bosh Platinum 2+. I gapped those to .028" and installed. Same problem. I've removed, inspected and reinstalled the plugs and the coils three times. I have also examined all the wires and connections and all appear fine- no kinks, pinched wires or loose connections.

Now the plugs have black soot on them from unburnt fuel. Peering down into the cylinders I can also see that black residue. All five plugs and cylinders are the same (black gunk). What could I have messed up? Now I wish I had left good enough alone.

It doesn't make sense to me that before the coils and plugs were fine, but now the car won't run. Oh, and one other thing, after I shut off the engine I can hear the spark plugs continue to fire for 8-10 seconds. Is that normal?

Gonefishin · Post by **Gonefishin** » 27 Jun 2010, 22:09

Update-
It is night here so I started the car to check for arcing- none visible that I could see with my head down in the engine. Oh and the clicking after I shut the engine off isn't the plugs, it is coming from just to the driver's side of the engine. What is that noise from?

Gonefishin · Post by **Gonefishin** » 27 Jun 2010, 22:28

Ok one more thing. One of the boots was cracked because it was sitting in oil and the end broke off. Would this cause it to arc to the spark plug tower wall and create this major rough running?

Post by **cn90** » 27 Jun 2010, 22:52

? Pinched wiring.

Scroll down to the post I made on May 22, 2010 (2nd page):
https://www.matthewsvolvosite.com/forums ... =1&t=29712

Post by **jblackburn** » 28 Jun 2010, 07:34

Are you actually pulling misfire codes from it/do you have a check engine light?

The unburned fuel actually suggests to me that you might have a bad fuel pressure regulator. Unfortunately, I don't know the configuration of the P2 cars very well to tell you where to look for that. It is my understanding that it changed between yours and my '98 model.

Gonefishin · Post by **Gonefishin** » 28 Jun 2010, 09:11

Thanks cn90, I did read that previous post and checked all my wires-all look fine, no pinches. They are sitting down low where they won't be pinched by the black plastic cover.

Ja- why would the fuel pressure regulator go out right when I change the spark plugs?

Gonefishin · Post by **Gonefishin** » 28 Jun 2010, 22:59

Update: After replacing the damaged coil-plug boot, the car randomly started working again. I took it for a spin about 10mi RT. At first it seemed really peppy and got to 100mph no prob. Then I got off the freeway and it died at a stoplight. The power also seems to come and go. After it died at the stoplight it seemed a little sluggish. Next I tried testing it under a little load and turned the AC on. It then died (while stoppped) after the AC had been on about 1 minute.

Any ideas?

Gonefishin · Post by **Gonefishin** » 28 Jun 2010, 23:01

Oh, I thought I also might mention that when I turned the AC on, the RPM's started bouncing rapidly between 800-1200 (automatic transmission). ???

boiseone · Post by **boiseone** » 29 Jun 2010, 09:58

How old is your MAF sensor?

Gonefishin · Post by **Gonefishin** » 11 Jul 2010, 15:54

Followup:

It appears the problem was a loose connector to one of the coils. After reseating all of the connectors, the car runs better than ever. Thanks.