1998 V70R Random Misfire Topic is solved

Mriv1998 · Post by **Mriv1998** » 06 May 2020, 03:51

Hello All,
This is my very first time posting in any sort of forum but I’ve read through many threads to try and find the root cause of my issue and am finally deciding to just ask all of you experts for help.

I have a 1998 V70R with 156k on it since September of 2019. I absolutely love the car but it was clearly maintained by a non Volvo expert. I’ve been dealing with a random misfire since I’ve got it and have done all the basic stuff to fix it and each time I get something fixed it drives great then all the codes for the random misfire start to pop up. This has been extremely frustrating because I haven’t been able to drive the car as an “R” model so to speak.

I usually have my car worked on by a local Volvo/Saab expert and am bringing it to him soon to have my whole PCV system done as soon as the parts come, and would like him to look into this misfire issue that’s been a pain in my butt since day one so I really need your help suggesting things to ask him to check while under the hood.

Here’s a list of all the misfire related repairs I’ve had done.

Spark plugs, cap, rotor, wires, and coil (all oem Bosch parts except for the wires I opted for the IPD “performance wires”)

Had the injectors all looked at and they were fine, I’ve even used Techron fuel system cleaner (recommended by the mechanic) which didn’t seem to do much

I also had a vacuum line replaced which was shattered into pieces when they removed it.

If I missed anything please let me know I need every suggestion possible

Also welcome to suggestions regarding other things I should have done while they replace the PCV.

Post by **misha** » 06 May 2020, 12:21

What spark plugs you have in it?
Don't know about ipd wires...but nothing except Bougicord will not last....even for the Bosch wires,there are reports that they won't last.
When misfiring occurs...does the CEL flashing?
Does the car really misfiring or there are just codes for it?
What scan tool you use for diagnostic and what are the actual codes?

Post by **matthew1** » 06 May 2020, 12:28

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Mriv1998 · Post by **Mriv1998** » 06 May 2020, 12:33

The plugs I have are genuine Volvo for my model. The cel does flash at random times... mainly when it’s driven hard (around 80mph) it also sputters at times when idling. Yesterday I had the cel flash on me when I was going 60 at 2K rpm.

The codes I get are usually p0300 (random misfire) with either another code for a specific cylinder or just the code for random, it varies each time I scan it and clear it. I’m using one of the higher end scanners from Harbor freight but these are the same codes my mechanics get on theirs when they’ve scanned for me.

Thanks for the quick reply!

Mriv1998 · Post by **Mriv1998** » 06 May 2020, 13:49

Update... I just drove the car for 40 min and came back and did a scan, the only misfire code I get is p0301. The car at 60 would go just over 2K rpm then drop down. It’s idling pretty rough as well

Post by **misha** » 06 May 2020, 13:53

I asked about spark plugs because there are two kind of Volvo spark plugs....triple prong for n/a (excluding turbo)and single prong for turbo models.

V70 R should be M4.4 ....and you should have SAS system.
Stuck open SAS valve will make this kind of problem...random misfire...because it lets moisture from condensation into the intake...which must go through the exhaust.

Did you have this problem before spark plug wires replacement?

Turbo engines are highly sensitive about vacuum leaks.
All vacuum lines must be checked and replaced if necessary.

Post by **misha** » 06 May 2020, 13:57

Mriv1998 wrote: 06 May 2020, 13:49 Update... I just drove the car for 40 min and came back and did a scan, the only misfire code I get is p0301. The car at 60 would go just over 2K rpm then drop down. It’s idling pretty rough as well

Could be strange question...but are the wires connected correctly on cap...correct firing order?

Mriv1998 · Post by **Mriv1998** » 06 May 2020, 14:03

I do have the code for the sas pump and have been planning to do the sas delete/bypass once I had the time to... ive asked so many people and they said that has nothing to do with the misfire although I really thought it could be a cause...

As far as the plugs I have these:
https://www.ipdusa.com/catalog.asp?sku=113440

And yes.. my wires are connected properly to the rotor

Mriv1998 · Post by **Mriv1998** » 06 May 2020, 14:04

Cap* not rotor

Post by **misha** » 06 May 2020, 14:22

What you can check about SAS valve....
Remove the bigger hose from sas valve which goes to air pump,put a shorter one and try to blow or suck air through it...it should be closed either way.
Also remove the air filter cover and check if there is a moisture in the housing,filter or Maf.

The best timing to check for moisture is when the car develop random misfiring.

Stuck open SAS valve CAN and WILL cause random misfiring because the moisture will be sucked into intake.
All other failed sas components would not make this kind of problem...but stuck open sas valve would.
I had this looong time ago with my car...but only at full throttle accelaration and i had just a short misfiring along with a flashing CEL.

Water from condensation,because of stuck open sas valve,killed TWO Maf sensors back then...untill we figured out where the water is comming from.

You said that only codes you get are misfiring codes?
Now we have additional sas system codes.

Are there any other stored or pending codes?