2005 V70 T5 Automatic 218,000km Rough Idle Diag Help Topic is solved

Slipshodcrowd · Post by **Slipshodcrowd** » 19 Nov 2022, 14:44

Hello everyone I woke up this morning to a rough cold start with a vibration that seems to shake the whole engine/air box all the way into the cab through the steering wheel, dash and e brake handle.

To set the scene. The other day it threw a ECM 614B Cam position code and was able to clear it and it hasn't thrown a new engine light yet, other than that no codes for the engine everything else is related to other electronic stuff like the DDM or Climate control. The car is due for an oil change ( burns about a liter over 4000km which i assume is cause its old and previous owner didnt do frequent oil changes) and at least the top engine mount is toast I can push on the bushing and move it around inside the mount w my finger (haven't checked the other mounts).

Now on to what happened in the morning
Cold start this morning, my battery is old so it had a slow crank which i expected, but when the revs dropped from around 1.5k to its idle it started to make a weird noise while just warming up at idle. When i give it some revs to like 1k rpm the noise went away or at the very least didnt get louder which gave me relief that it wasnt a knock inside the engine. When idling the whole engine shakes so bad that the air box and other bits move more than ive ever seen which leads me to think the idle is dropping lower than it should to nearing a stall, it also had a small sputter when returning to idle after giving it gas. I unplugged the MAF and nothing changed when i ran the engine again (Fuel consumption seems high at 12.5/100km which used to be 11/100km a month or so ago so i thought this may have been an issue or just a heavy foot on the throttle)

Somthing clogged or dirty? Just bad mounts and cold/old rubber bushings? Im at a dead end and wanna know if its time to sell or if i should bother doing the T- Belt as ive got it scheduled at a shop but dont wanna spend 2k on that if somthing else needs to be done first since id rather take my chances putting off the belt if somthing like the Throttlebody or MAF needs to be fixed first.

Post by **matthew1** » 19 Nov 2022, 15:13

Sounds to me like a cylinder isn't firing: coil, sparkplug, or wire.

Slipshodcrowd · Post by **Slipshodcrowd** » 19 Nov 2022, 16:07

matthew1 wrote: ↑19 Nov 2022, 15:13 Sounds to me like a cylinder isn't firing: coil, sparkplug, or wire.

Would this cause a check engine light?

Started it up an hour later and the noise i heard before at idle is gone and the vibration has calmed to what it was yesterday. Now idle is dipping when stopped from about 700rpm to 600rpm somtimes when retunring to idle after rev and somtimes when just sitting at idle.

Post by **br0dy519** » 19 Nov 2022, 16:27

Yes, you would get a misfire code for the corresponding cylinder. It sounds almost exactly what happened when one of my ignition coils died. Although rough idle can also be caused by a vacuum leak.

Slipshodcrowd · Post by **Slipshodcrowd** » 19 Nov 2022, 16:45

br0dy519 wrote: ↑19 Nov 2022, 16:27 Yes, you would get a misfire code for the corresponding cylinder. It sounds almost exactly what happened when one of my ignition coils died. Although rough idle can also be caused by a vacuum leak.

Hey brody, been a while. Seems your always around when ive got some woes.

Ill check my scan tool at work monday if the car makes it through the weekend to see if i got a code but no engine light.

The surge at idle almost reminds me of when my MAF went on my 03 v70 and it got so bad i had to drive without it plugged in or it would stall at a stop sign or light. My 05 doesnt stall yet but feels like it wants to for half a second and then comes back.This is the first time its idled poorly (ive had it drop once or twice on separate occasions at a stop sign) but its had some issues starting since i got it which could be the old battery but could also be the plugs and coils. Those 2 are still cheaper than a new MAF which may not even be the issue so ill start there and work my way up to the expensive parts, will also clean the throttle when i do the pcv soon since ive read it controls the idle as well.

Vibrations also got way way smoother in the cab when it was sitting in neutral instead of park so thats something.

Post by **scot850** » 19 Nov 2022, 18:18

Try disconnecting the MAF and see if the idle smooths out. If it does, check the connector is clean and not corroded, clean it with electrical contact cleaner, and then clean the MAF with MAF specific cleaner and see what happens. I don't think it is the MAF. I have tended to find they make the engine run rough and lose a lot of power/or stalls.

You really need a code reader on this as throwing parts gets expensive quickly!

Good Luck

Neil.

Post by **jonesg** » 19 Nov 2022, 19:03

bad coil will put the engine out of balance, the noise is from the bad engine mount.
Track down the coil by just unplugging each one , the bad one will make no difference to idle when unplugged.
Or use vida.

Post by **br0dy519** » 19 Nov 2022, 19:15

A misfiring engine is pretty alarming when it happens. It's almost like... "bucking", it does vibrate fairly violently. Hope you get this one solved, and like above I would not recommend throwing a MAF at it. I fell for that scam one time and bought one unnecessarily. jonesg suggestion is a good one above to troubleshoot without any scan tool. I'm still thinking possible vacuum leak. Although I am bias to that because I found so many vacuum leaks on my vehicle a couple of years ago I nearly had to replace all of the rubber in the engine bay. If you are planning to do the pcv, I would replace a lot of the vacuum hose tree near the purge valve while you're in there.

And change your battery if it's in question! Costco sells them for a good price. Check the date code on yours, if it's ~5 years old, it's a good time to change it anyway.

Post by **jonesg** » 20 Nov 2022, 05:05

"vibrations also got way way smoother in the cab when it was sitting in neutral instead of park so thats something."

no load in N, thats why I say top engine mount, stuff a screwdriver shank in it, I bet the vibration will change.

Slipshodcrowd · Post by **Slipshodcrowd** » 18 Dec 2022, 19:28

So the idle issue went away for a few weeks but has returned and is worse than before, now it drops low to the point that the lights flicker and its even stalled out once. Unplugging the MAF didnt change much if anything it made the issue slightly better so im happy i didn't go that route.

Talked my mechanic friend who knows more about stuff than me and he said it could be a fuel pump starting to fail so i think ill see if i can diagnose that properly, if its not the fuel pump im checking plugs next since ive ruled out air as the issue unless my exhaust cam sensor is going bad