1898 V70 occasional skipping at cruising speed, bad Ignition plug wires Topic is solved

5rivers · Post by **5rivers** » 06 Sep 2018, 10:31

Greetings!
I've repaired a few things to my newer V70 so it does not stall, managed to get unstuck the transmission dip stick, changed the oil and filter, changed the transmission fluid, removed a broken distributor cap bolt, changed out the spark plug wires (Bougicord), cap and rotor (Bosch) with what I had in older (now parked) '98 V70, put in a used (Bosch) MAF, and found a few vacuum leaks and repaired those. There is probably more that I have done that I'm am forgetting.

But, the reason for my post is that when I am at cruising speed (between 65-70 mph), the car will occasionally skip, like it is not getting an even flow of fuel. The fuel filter is about a year old, and I have not taken off the fuel injectors. The regulator (that is under the fuel rail) was replaced about 2 years ago.
I am not sure what to tackle next.

Have been trying to get the monitors to reach the ready stage (they finally did-hooray!) to pass inspection, but while sitting at a rather long traffic light recently, the check engine light came on. The code is P0131, which refers to the front O2 sensor. I removed that and cleaned it, the wiring looked good, no cracks. I wonder if there is another vacuum leak I should be looking for.
Could this also contribute to the skipping?

Plus, when the car is between 45 and 50 mph, the car seems to run rough, like it is struggling. Almost feels like the timing is off, but that is a guess on my part. It is not skipping like at higher speeds, just running rough.

I need to solve the CEL to pass NYS inspection, soon!!

Appreciate any suggestions on the above!

Post by **abscate** » 06 Sep 2018, 13:24

Did you replace that vacuum elbow on the pass side, under the intake Manifold?

It sounds like we need to get my smoke tester on it to find the leak. Are you closer to me now?

I have a cabin in Lewis country but its really hard to find.

5rivers · Post by **5rivers** » 06 Sep 2018, 13:29

The infamous vacuum elbow is properly seated, no leaks there!
I am near the intersection of Franklin and St. Lawrence Counties and the mighty St. Lawrence River!
Am about to piece together a smoke machine myself!

Post by **abscate** » 06 Sep 2018, 14:31

Remember not to smoke your MAF - it is delicate and won't like smoke.Pull off the snorkel and put a plastic bag/rubber band over it to close it off.

And don't try to pump smoke the wrong way through one way valves - that goof has already been done here by a very close friend.

5rivers · Post by **5rivers** » 06 Sep 2018, 15:57

Appreciate the advice!

Post by **misha** » 08 Sep 2018, 01:58

'98 n/a don't have fuel pressure regulator under the fuel rail...it's fuel pressure damper(it doesn't have a vacuum line).
Being a M4.4...FPR is at fuel filter area....BUT i don't mean that FPR is the source of your problem.
When fails it usually leaks fuel into vacuum line causing pretty rich mixture.

Spark plugs are not on your replaced item list...and o2 sensor might be the culprit since it throwed the code after the vacuum lines had been replaced.

Post by **erikv11** » 08 Sep 2018, 07:51

As a related note, how did you clean the O2 sensor? The domed metal shield that you see when you look at the removed sensor is just a shield, the ceramic sensing surface is underneath and inaccessible. A simple surface cleaning does nothing relevant.

My thoughts: vacuum leak, O2 sensor (is it Bosch, not the universal style?), MAF (is it Bosch?).

5rivers · Post by **5rivers** » 08 Sep 2018, 21:09

Greetings!
The spark plugs are Volvo and I am pretty sure I cleaned those before re-installing them, but maybe they need another cleaning and re-gapping. I put a propane torch to the O2 sensor for a few minutes, that seemed to help burn off the deposits on the inside of the metal shield/sensor. I'll have to take a closer look at the sensor to see if it is Bosch OEM part (the detail on the bill/statement indicated an OEM part; but I'll look again).
Appreciate your replies/questions!

Post by **abscate** » 09 Sep 2018, 02:56

Kally..an O2 sensor won’t cause a high speed miss or skip.they are slow adjustments to the mixture for efficiency.

It sounds more like a bad plug , wire, maybe inspect your new cap for carbon tracks?

I’ll see if I can find an old set of plugs to try a swap out for testing.

Lastly on the possible list

Misfiring fuel injector

Sticking valve.

Post by **wizechatmgr** » 09 Sep 2018, 03:15

Sometimes if you use an old timing light you can spot a bad cap/rotor/wire or at least identify which cylinder.