98 V70 AWD-Idle dip when decelerating

[benpineapple]

Howdy, been having this issue for some time now. Problem is intermittent. It seems like it goes away for a bit whenever I do work on the car, but without fail comes back.

Idle dips down to 600-700rpms during the last few seconds of braking (around 10mph), and then goes right back up to 900 where it should be, once completely stopped. Issue only happens when in drive, decelerating in neutral does not produce the symptom. No error codes, CEL is not lit. Has not stalled out when exhibiting symptom. Can't tell if it feels like idle is dipping due to lack of fuel, or lack of air.

My best guess is that it's an electrical issue, but I'm not sure where to look. Buddy of mine thinks its a vac leak somewhere. All vacuum lines to and from the turbo have been recently replaced. Haven't replaced any other vacuum lines or check valves though.

I know this is a common ETM issue, but the 98 V70s do not have an ETM. As far as I know, the ETM was introduced in 1999.

Any help would be appreciated. Thanks!

[abscate]

Vacuum leak.

[crismit125]

I have this EXACT issue with my 98 glt, you have explained it perfectly. I have checked all my intake and turbo vacuum lines and they are all good, also the evap lines around the engine bay. I also tried a second IAC (idle air control valve) which fixed the issue for a day but it then came back. Soon when i change my oil and the car is off the ground im going to check the evap line that runs by the fuel filter in the right rear of the car. i'll be following this thread and update you on what i find.

[E Showell]

I've lived with this issue for years. Search "Campaign 81" on this site. It may be the answer. I haven't yet had it done to my car and am not sure the local dealership could still do it. I do know it would cost around $165 to have done so, for now, I choose to live with it. (Apparently, Campaign 81 is a Motronic software update).