Greetings from germany and a question about high idling my V70R

[Hamburger]

Greetings from germany!
My Name is Alex and since march this year i'm driving a Red 06 V70R.
I drove it nearly 7000km since without any major Problems, also i repaired a lot ever since, like the whole rear Axle, the PCV System, several brakes lines and so on.

The time has come that the R needs "TÜV" (is it DOT in the other states?)
For the TÜV i need to pass the emissions check where the engine needs to rev between 2.5 and 3k rpm steady for about 20s.
Now comes the fun part, my engine does rev and first Pass emissions, then it starts so run faster, test failed since the 25s Holding time for the rpm aren't passed.
It idles good, no hunting or else, only if you want to rev it in this range it gets faster and eventually starts to go up and down in a range of 500 to 750 rpm, failing the test.
I got no Codes in Vida leading me to an issue, no Vakuum leaks (checked with fog) or exhaust leaks. In the short Holding time of the rpms it passes its emission range, untill it starts pulsing in rpm.

While driving there is no problem, fuel consumtion bewteen 8.5-12l/100km, no shaking or misfiring, even during hard pulls.

One thing i noticed is, if iˋll engage my AC, the rpms are steady without the pulsing.

Any ideas what can cause this issue?

Thanks - Alex

[matthew1]

Welcome to MVS. Can you re-phrase what is happening?

My understanding is it revs to 3k without problem for 20 seconds, then goes up higher than 3k at the 25 second mark without additional input on the accelerator?

This is in neutral or with load?

[Hamburger]

Hi Matthew,
I'll try to be Mode specific

For the TÜV the car needs to rev between (not a specific rpm) 2k and 3k, Holding any rpm in that range for 20s.
Once the guy doing the test revs it and holds the Pedal still, the engine starts to rev higher, like to 3.5-4k, then drops to 2 (withou releasing the pedal or any other influencing) and starts to jump to 3.5-4 again.

This is all under no load, while driving i never experienced this.
Rolling, switching to neutral and trying to hold any rpm shows the same case.

I tried this with a scan Tool hooked up, the Pedal Signal is totally still, no difference in % to See.

[matthew1]

This is a tough one, Hamburger. I'll think about it.

My initial reaction is that it is not spark, not air, but maybe fuel.

[volvolugnut]

Have you checked the STFT (short term fuel trim) and LTFT (long term fuel trim) under these conditions? This may give a clue for someone here at MVS.
volvolugnut

[firstv70volvo]

Hi Matthew,
I'll try to be Mode specific

For the TÜV the car needs to rev between (not a specific rpm) 2k and 3k, Holding any rpm in that range for 20s.
Once the guy doing the test revs it and holds the Pedal still, the engine starts to rev higher, like to 3.5-4k, then drops to 2 (withou releasing the pedal or any other influencing) and starts to jump to 3.5-4 again.

This is all under no load, while driving i never experienced this.
Rolling, switching to neutral and trying to hold any rpm shows the same case.

I tried this with a scan Tool hooked up, the Pedal Signal is totally still, no difference in % to See.

For this condition keep looking at live data and look at more parameters when the rpm is changing, if pedal signal is stable, monitor the throttle position (expect it to be steady), monitor the O2 sensor output along with short term fuel trim level, monitor MAP, monitor if in closed loop or open loop mode, make sure A/C is off, engine up to temp. Basically use live data as the pedal position is stable for 3k rpms and look for any parameter that is changing with rpms that you'd expect to be stable/steady.

[Hamburger]

Morning, since the Flu got me, i have some time on my hands...

what is saw, the ECM switches from Open loop to closed loop everytime the rpm drops...

i will try to make a video from live data, just need to wait a bit, not everyone here loves 5cyl revs in the morning

[firstv70volvo]

Morning, since the Flu got me, i have some time on my hands...

what is saw, the ECM switches from Open loop to closed loop everytime the rpm drops...

i will try to make a video from live data, just need to wait a bit, not everyone here loves 5cyl revs in the morning

The car should remain in closed-loop mode once the O2 sensors heat up and some other conditions such as a minimum coolant temp or a set time period set by the ECM. If the car isn't staying in closed-loop mode, monitor the o2 upstream and downstream sensor signals (live data) and also the fuel trim levels. I don't know all the possible conditions that will take it out of closed-loop mode but the o2 signals or fuel trim levels should provide a clue. I've read if the ECM can't trim the air-fuel mixture correctly because of a o2 sensor, large fuel or air leak problem it will go to open-loop mode. Your ECM switching between OL and CL is a good starting clue to help find the source of the problem.

[Hamburger]

Alright, i've filmed some footage from today.
Just uploaded it and there was a second video, another guy, same car, same problem... whonder why i didn't found it earlier...

my video:

I drove it kind a lot today, reseraching here and there with revving it, one thing the ecm told me is ecm 640C.
I Searched that code, in conclusion with the second Video i found, searching for my own one ( searched " Volvo V70R high idle") i think that my throttle body is telling me that she had enough...

fast backward to me buying the R, unseen 650km away, the car ran like shit, but there were so many faults, after getting rid of them it drove good and i thought the tbm was fine, untill today. (by the way, i paid 6k für the R)

after some garage beers i think, that alle the bouncing of the ECM data/parameters are from the TBM? like what was first, chicken or egg?

[firstv70volvo]

Alright, i've filmed some footage from today.
Just uploaded it and there was a second video, another guy, same car, same problem... whonder why i didn't found it earlier...

my video:

I drove it kind a lot today, reseraching here and there with revving it, one thing the ecm told me is ecm 640C.
I Searched that code, in conclusion with the second Video i found, searching for my own one ( searched " Volvo V70R high idle") i think that my throttle body is telling me that she had enough...

fast backward to me buying the R, unseen 650km away, the car ran like shit, but there were so many faults, after getting rid of them it drove good and i thought the tbm was fine, untill today. (by the way, i paid 6k für the R)

after some garage beers i think, that alle the bouncing of the ECM data/parameters are from the TBM? like what was first, chicken or egg?

Based on the code I'd take a look for any air leaks between the turbo and throttle body and also take a look at the boost pressure signal while the rpm fluctuates. You may also want to pull the boost pressure sensor and just check for build-up, there's an opening in the sensor that can become clogged up and cause faulty pressure readings.

ome VolvoECM-640C
Volvo Volvo DTC ECM-640C
Make:
Volvo
Code:
ECM-640C
Definition:
Turbocharger (TC) Control System, Signal Too High
Description:
The diagnostic trouble code (DTC) is stored if the ratio between the measured boost pressure (measured value from the boost pressure sensor before the throttle) and the calculated boost pressure (calculated value after the throttle) is incorrect. The diagnostic trouble code (DTC) can be diagnosed when the engine is running and the turbocharger (TC) control system is not active.
Cause:
Air leakage downstream of the turbocharger (TC) (between the turbocharger (TC) and the electronic throttle unit)
The boost pressure sensor has come loose (measures the atmospheric pressure)
Damaged boost pressure sensor.
Damaged check valve to crankcase ventilation.