1999 V70 Misfire Troubleshoot

cohomology · Post by **cohomology** » 05 Oct 2015, 20:08

Hi y'all, I just picked up a 1999 V70 XC for a song. Previous owner said it had a misfire but he had no intention to fix it. I took the chance since the price was too good to pass. Heck, even I have to do a head work the price is still not bad.

I took the car home and pulled the code. Sure enough misfire on cylinder 3. When I open the engine cover, first thing I noticed was there was lots of oil under the engine cover. So the PCV is clogged I guess. Then I immediately noticed what might be the cause of the misfire -- someone carelessly drove one engine cover bolt through the ignition wire, so the circuit was completely shorted! Still waiting for my compression tester to come and fingers crossed no need for a head work!

I have seen lots of discussion on the coil pack but had a hard timing finding info regarding the ignition wire bundle. I am wondering what my options are: replace the wire with some OEM parts or just solder it? Please advise! Thank you all!

Post by **kahl** » 05 Oct 2015, 20:33

If it were mine solder and shrink tube would solve the problem. Make sure the wires hold hands tightly then solder keeps them together.

cohomology · Post by **cohomology** » 05 Oct 2015, 20:40

I am only concerned that the tube will not block moisture very well. And if I need any patch wire, what gauge/whatever other spec should I be looking for?

cohomology · Post by **cohomology** » 05 Oct 2015, 20:42

Also I just noticed there are actually two black wires run parallel, should I keep them separate or is it ok if I mix them up?

Post by **rspi** » 05 Oct 2015, 22:12

Black wires are likely ground so that smashed wire may not matter.

Post by **rspi** » 05 Oct 2015, 22:13

Welcome to the site.

Veilleuxpbd · Post by **Veilleuxpbd** » 05 Oct 2015, 22:17

The oil in the engine cover *might* not necessarily mean a clogged PCV system, maybe the oil cap was never changed and turned into a rock, letting small amounts of oil out when the cams turn too fast. Mine had oil in but the PCV system was good (not perfectly clean but still had no symptoms and far from being clogged).
As for the wires that were damaged, maybe consider using 'liquid electric wire' between the solder and the heatshrink tubing; additional protection never hurts!

cohomology · Post by **cohomology** » 06 Oct 2015, 08:42

rspi wrote:Black wires are likely ground so that smashed wire may not matter.

so it is still possible that I am facing a head job down the road! my compression tester is on the way....

Post by **abscate** » 07 Oct 2015, 05:19

cohomology wrote:Also I just noticed there are actually two black wires run parallel, should I keep them separate or is it ok if I mix them up?

One is the HV ground and I think the other is 12VDC

You cannot mix them up.

Just cut, solder, and tube /electrical tape the repair. These are low current wires so they are easily dealt with

Try moving the number 3 coil to cylinder 1 to see if your misfire code moves
Pull all the spark plugs , take a picture and post here
Make sure the 10mm M6 bolts holding the coils are tight and clean, these are also the coil grounds
The 1999 on models hVe a lot less trouble with PCV blockage than the earlier P80 models as the long PCV tube is heated with hot coolant which keeps the vapors from condensing.

PatternFlyer · Post by **PatternFlyer** » 07 Oct 2015, 12:57

Best way to fix including water proofing.

use liquid tape and heat shrink tube over the solder joint.. I use liquid tap over the solder joint and wait until it dry before using heat shrink tape. Water going inside the tube is not going to cause any problems.