98 v70 base - rpm drop in idle

Anchorend · Post by **Anchorend** » 31 Dec 2013, 19:17

Hi all,
I have a 98 v70 base 181k miles. I've had a nagging issue since I got it about a year ago, when in gear and stopped it will go rough for about 5 seconds and drop approx 1-200 rpm, then recover and sound fine.Some days it won't do it at all, others within a couple of minutes of starting up then somewhat intermittently with no pattern. In the last year I've done spark plugs, wires, dist rotor and cap, cleaned pcv, throttle and IAC, new mass air sensor and both cabin and intake filter. Ive also ran a can of seafoam, as well well as a couple of injector cleaners(gum out, STP). I only use premium gas. Not sure what to check next..anyone have ideas?

volvospeeds70 · Post by **volvospeeds70** » 31 Dec 2013, 19:26

Get your alternator checked and diagnosed.

Anchorend · Post by **Anchorend** » 31 Dec 2013, 19:58

The lights dont flicker or dim or anything, its just the " shudder" in idle, but I'll check that when I do belts soon

volvospeeds70 · Post by **volvospeeds70** » 01 Jan 2014, 16:23

are you getting any check engine lights?

volvospeeds70 · Post by **volvospeeds70** » 01 Jan 2014, 16:27

I would check your coolant temp sensor also. normally they are on or near the thermostat housing.

Post by **jblackburn** » 01 Jan 2014, 20:13

Does it happen WHEN you're slowing down to a stop, or just randomly dips down when you're sitting there at a stoplight or something and have been stopped for a while?

If "yes" to my first question, inspect all vacuum lines, especially the one near the PS pump. This is a classic 5-cyl Volvo response to a vacuum leak.

Anchorend · Post by **Anchorend** » 01 Jan 2014, 20:26

No check engine lights, just had radiator and thermostat replaced, along with a couple of vac lines, but this had been happening before it.

No to the slowing down problem, sometimes when sitting at a light and sometimes even after starting and not having moved at all. It seems very very random. Sometimes not for a day or two, yesterday happened twice in 5ish minutes. I can feel the shudder in the steering wheel and also the vehicle shakes a bit. Have never noticed while driving. All other aspect seem to run fine. Accelerates well and runs fine under load and stuff

Post by **kcodyjr** » 01 Jan 2014, 20:29

How's your PCV system? Any pressure at the dipstick?

Anchorend · Post by **Anchorend** » 01 Jan 2014, 20:36

Pcv has been cleaned about a month ago, was hoping that would help but it didnt

Post by **E Showell** » 02 Jan 2014, 14:26

Been driving my car for years with the same niggling issue. There have been posts on here about this before. I think it drove JRL about crazy on one vehicle. I just live with it having replaced a bunch of stuff (unrelated to it) including an engine, and not having it go away. The only things I haven't replaced are crank position sensor and throttle position sensor, as well as air idle control valve, coil and fuel injectors. I have also not checked the alternator. Anything else, plugs, cap, rotor, vacuum, pcv, plug wires, etc. I've gone over and/or replaced. They have not managed to alleviate the issue. Never threw any codes as a result of this shake either. I have cleaned the throttle body numerous times and replaced the MAF as well as ECT and thermostat (all unrelated to diagnosing/treating this issue) to no avail. It is just annoying. I live with it.