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2002 V70 - rough idle

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive "P2" platform cars.

2001 - 2007 V70
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MilesM
Posts: 10
Joined: Tue Jan 01, 2019 4:49 pm
Year and Model: 2002 V70 base
Location: Saskatchewan

2002 V70 - rough idle

Post by MilesM »

Hello all,

I recently acquired a 2002 V70 base model for the princely sum of $600 Canadian dollars. When I bought it, it ran, but rough. Here's how far down the rabbit hole I now am:

- Xemodex rebuilt ECM (it now responds when you step on the gas pedal)
- New MAF sensor
- Replaced MAP sensor (used)
- New upstream O2 sensor
- New plugs
- 1 new coil
- new PCV lines (box to head, box to block x2)
- New timing belt, idler, tensioner and water pump
- Coolant flush and refill
- Oil change

- I've tried to find any vacuum leaks, but haven't sound anything obvious so far.
- I'm now finding that I have the dreaded low oil pressure warning, so I've ordered the O-ring kit and will drop the pan to sort that mess out when it comes.

As it stands now, the car starts and runs fairly well although the idle can be a bit rough when cold (it's winter here, so -15°C or so is my starting point). Sometimes it's rough enough to throw a P0300 code, but not consistently. Until it warms up, I have to tap the accelerator to keep the engine from sputtering and I have a hard time keeping it at a constant rpm as it jumps all over the place. once warm, the system seems to settle down and idles nicely.

I have driven the car up and down my driveway, but I haven't got it licensed and insured yet so I can't really take it on the road. I can get up to about 50km/h or so on these tests (I manage to get into second gear), but the car lacks power and doesn't rev up very far under load.

Once the car is completely warmed up and has gone up and down the driveway a couple times, the oil pressure light comes on and I shut it down.

I've ordered a Vida/Dice from eBay, but until it comes, does anyone have any suggestions as to where I should look for problems that would cause the lack of power and the weird idle when cold?

This is a bit different from my last Volvo, an old '82 244...

Thanks,

Miles
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RickHaleParker
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Re: 2002 V70 - rough idle

Post by RickHaleParker »

Clean out the Idle Air Control (IAC) valve.
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Re: 2002 V70 - rough idle

Post by erikv11 »

Engine Coolant Temperature (ECT) sensor is also a possibility. VIDA will help with diagnosing that, however, so may as well wait. I don't know the ohm-temperature graph for a P2 ECT but if you can find that info, that's a great diagnostic route. Or grab one from the junkyard and swap. And since cleaning is cheap, I'd start with the IAC anyway.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'07 XC70, 170k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
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Re: 2002 V70 - rough idle

Post by abscate »

erikv11 wrote: Thu Jan 03, 2019 7:44 am Engine Coolant Temperature (ECT) sensor is also a possibility. VIDA will help with diagnosing that, however, so may as well wait. I don't know the ohm-temperature graph for a P2 ECT but if you can find that info, that's a great diagnostic route. Or grab one from the junkyard and swap. And since cleaning is cheap, I'd start with the IAC anyway.

That graph is cross referenced in my P2 Maintenance Log (2005 V70 NAM M56 (separate Forum) or perhaps in my P80 (1999 V70 T5) log, in case searching isn't fruitful
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MilesM
Posts: 10
Joined: Tue Jan 01, 2019 4:49 pm
Year and Model: 2002 V70 base
Location: Saskatchewan

Re: 2002 V70 - rough idle

Post by MilesM »

I thought that the IAC function was controlled by the ECM on these non-turbo models. In any case, there isn't a valve unit on the driver's side of the engine like on the turbos and I haven't found any photos.

Image

I guess I can wait for the the VIDA to check the ECT. Would a problematic ECT show any issues at the temperature gauge? mine seems to behave normally... I might pick up another ECT next time I'm out at the wrecker, but its probably not worth going out there just for that (about 45 min drive one way).

Thanks,

M.
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Re: 2002 V70 - rough idle

Post by XC70Rider »

Installed the timing belt tensioner in this frigid weather? You must have a heated garage!

I need to wait until it reaches 50f again so my garage can warm up to 70f until I tackle the timing belt.

It's well worth purcashing the VIDA/ Dice unit. I installed it on a refurbished laptop I got on ebay for $136 USD last week. If you do purchase one download and install Rick's Repack:

viewtopic.php?f=40&t=83834
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erikv11
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Re: 2002 V70 - rough idle

Post by erikv11 »

MilesM wrote: Thu Jan 03, 2019 11:44 am I thought that the IAC function was controlled by the ECM on these non-turbo models. ...
I thought the same thing, but https://www.fcpeuro.com/products/volvo- ... 70-1275634.
MilesM wrote: Thu Jan 03, 2019 11:44 am ... Would a problematic ECT show any issues at the temperature gauge? mine seems to behave normally...
They do when they fail, pretty reliably. And throw a CEL. So the idea is maybe it is only a little out of spec, giving wrong air:fuel mixtures.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'07 XC70, 170k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
MilesM
Posts: 10
Joined: Tue Jan 01, 2019 4:49 pm
Year and Model: 2002 V70 base
Location: Saskatchewan

Re: 2002 V70 - rough idle

Post by MilesM »

OK, I still can't quite figure out where that IAC would be hiding on this car. I did see other references to it being integrated into the ECM. In any case, I'm waiting for parts so I can do the o-ring job and warmer weather so I can re-adjust the timing belt (my garage is sort of heated with a space heater - it was probably 5°C when I was working out there). Once I'm to the point where I'm not (as) worried that the motor will explode on me, I'll probably be able to do more actual road tests and maybe limp it in to the local shop (while I'm waiting on the VIDA-DICE).

In the mean time, work will be interfering with my tinkering...

Thanks for the suggestions,

M.
MilesM
Posts: 10
Joined: Tue Jan 01, 2019 4:49 pm
Year and Model: 2002 V70 base
Location: Saskatchewan

Re: 2002 V70 - rough idle

Post by MilesM »

OK, so I have my Vida/Dice now working and I'm seeing a few things to rule out some possible culprits: 1) ETM - desired and actual throttle angle are synchronized and doing fine. 2) Mass air flow and Manifold absolute pressure are giving consistent readings without any unexpected blips along the way (basically flatline at idle, moves with engine speed) 3) I'm getting misfires on cylinders 1 and 5 so I changed all the coils. That seemed to help, but they still misfire until the engine warms up (and it's still bloody cold out!!).

I'm wondering about the periodic (mostly downward) spikes in the ECM-actual spark advance line. Anybody know what I should look at now? I drove the car up and down the driveway again (enough to shift into second), but it seems to lack power when I step on it. Thoughts?

What other graphs should I be looking at?

Thanks,

Miles

Image

Image
MilesM
Posts: 10
Joined: Tue Jan 01, 2019 4:49 pm
Year and Model: 2002 V70 base
Location: Saskatchewan

Re: 2002 V70 - rough idle

Post by MilesM »

ECT seems fine as per this graph (blue line) - solid just above 60°C

Image

Would a failing VVT solenoid behave like this? Cam position sensor?

Thanks,

M.
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