1999 V70 NA MT w/ hard to figure out idle issue

MrKrypton · Post by **MrKrypton** » 16 Dec 2019, 11:50

Hi Guys,

Sorry for the long story, but I'm having a hard time figuring out a persistent issue with my V70 and I'm stumped. Purchased the car last summer when I moved on from my long time MT 850. Reading the forums one issue that constantly kept popping up was the ETM. I removed it and had it rebuilt by XeMODeX as I seemed to be having idle dips when I coasted up to a stop in neutral. With the rebuilt unit I continue to have idle drops. Seems to be most common when the engine is just coming up to temperature for the first time that day. From there on it's a 50/50 proposition as to whether it acts up again that day. A month ago it threw a CEL but continued to drive fine. A week later on its first start of the day, it threw a ETS light with poor idle and the smell of unburnt fuel. I had it towed to a Volvo Indy and they replaced the CTS with a used unit. They found no faults with the ETM. They did find an active IMM-321 fault (might be related to the door chime and courtesy light fuses I pulled months ago), and a non-active ECM-4038 & 250A fault. Drove the car home and it still had coming to a stop idle issues in neutral.

Took the car to the Volvo dealer and they found no codes, performed a test on the ETM that it passed and said the PCV system is OK. They could not repeat my idle drop issue despite it being a multiple times a day occurrence for me.

Ultimately I'm hoping someone has a few leads or some insight as to what may be occurring. I have the ability to wrench and have done a few repairs on this car including the ETM install, but will send the work out this time of year for anything big. Tiny, unheated garage in December Calgary is unpleasant.

Thanks for your time,

Mike

Post by **RickHaleParker** » 16 Dec 2019, 16:41

Smoke test the intake system for leaks.

Empigt · Post by **Empigt** » 16 Dec 2019, 17:01

Starting fluid around your vacuum lines and intake gaskets to check for leaks works too. If it revs up you are close to the leak.

Post by **abscate** » 17 Dec 2019, 05:09

What’s the CTS unit they replaced?

MrKrypton · Post by **MrKrypton** » 17 Dec 2019, 12:54

Thanks guys,

I'll either get it smoked tested or play around with some starting fluid. Probably not uncommon for a vehicle this age to have a few intake leaks. I do suspect it has a slight exhaust leak at the flex joint on the exhaust manifold.

CTS is the coolant temp sensor.

Mike

Post by **abscate** » 23 Dec 2019, 06:40

The drop or stumble on run-down (foot off gas, gear in neutral) is indicative of a vacuum leak on ETM cars, I remember figuring out exactly why this, as on an ETM car the throttle closed position is negotiated between the ECM and ETM in software. My CRJS has flared up and I can't find my documentation on this though.

You do have an Idle Air control valve on a 99 NA though, at least if it has DENSO engine management. Good place to check for leaks.

You either build a smoke tester or remove everything and do a Visual Audible Tactile (tm) inspection - in which case you just put new hoses on anyway.

MVS will give you a mild keyboard shock if you post any phrase sufficiently close to

"I looked at the vacuum hoses and they look ok"

Post by **volvolugnut** » 23 Dec 2019, 09:15

Rule Number 2 of Volvos: Vacuum leaks are invisible. They cannot be found where you are looking.
volvolugnut

Post by **matthew1** » 23 Dec 2019, 09:20

abscate wrote: ↑23 Dec 2019, 06:40
MVS will give you a mild keyboard shock if you post any phrase sufficiently close to

"I looked at the vacuum hoses and they look ok"

Vacuum leaks are difficult. That’s putting it gently.

Post by **RickHaleParker** » 23 Dec 2019, 14:19

volvolugnut wrote: ↑23 Dec 2019, 09:15 Rule Number 2 of Volvos: Vacuum leaks are invisible. They cannot be found where you are looking.

Vacuum leaks violate the laws of quantum physics ... they cease to exist when you observe them.

Post by **smacknab** » 30 Dec 2019, 13:44

Following this as i also have idle dips when coasting to a stop in neutral, on my 99 s70 na with manual transmission. Hope to hear what you find!