V70 1999 AWD Manual loss of power

[SteveSarre]

Hi

I am trying to work out what is causing a loss of power on my V70 1999 AWD Manual gearbox which I am bringing out of SORN (I bought it a few years ago and am finally getting round to it).

If you drive it gently you might not notice the problem, but if you drive it hard, it falters beyond about 2200 rpm, and power feels 30% down from what I would expect.

It has
B5254T engine (turbo but not T5)
120k miles
ignition stick for each cylinder
Electronic throttle module (which looks old)
New Volvo spark plugs
New air filter
Replaced all ignition sticks with good used (manufacture date 2005)

mpg is about 29
No diagnostic codes
No warning lights

It passed the MOT (replaced various bits such as battery, wipers, wheel bearings and tyres) and I have driven it about 300 miles on one long trip since bringing out of SORN.

I really cannot remember how it drove when I first bought it. Certainly at that time it had codes because of a faulty front O2 sensor, and some failed ignition sticks.

I have put in a new MAF (I had one around) and triggered a relearn. No change.
I have looked for vacuum leaks, and can see that various small hoses are powdery, which I will replace in due course, but I can't find any leaks.

I cannot use VIDA Dice to test the ETM because it doesn't have the post 2006 software loaded.

I have a known good ETM which I could put in, but am looking for an easier fix at the mo.

Where shall I start? Any ideas?

Thanks
Steve

[turboboy]

What sort of ignition system does your car have? I'm not familiar with the differences between years but my 1998 T5 has a distributor with a conventional rotor arm.

If it has a distributor it may be that the advance is not working properly, having stuck while in storage.

[Luxobarge]

Originally Posted by turboboy

What sort of ignition system does your car have? I'm not familiar with the differences between years but my 1998 T5 has a distributor with a conventional rotor arm.

If it has a distributor it may be that the advance is not working properly, having stuck while in storage.

OP states that it has individual coils for each cylinder, so it's the later ME7 engine type.

[SteveSarre]

Thanks both.

Yes I am wondering what might have deteriorated while it was in storage. On the other hand, it has driven for a few days now with no codes.

I have an infra-red temperature gauge around here somewhere which I will use to check the normal operating temperature.

I will replace the fuel filter because I might as well do that anyway, and I will change as many of the vacuum hoses as I can easily get to.

I have plenty of known good used parts (on or off other similar cars) but would like to do this systematically.

Steve

[SteveSarre]

Hi all,

Some progress.

I have replaced the fuel filter. The one that came out didn't seem very old, and when I emptied it backwards into a glass container, it didn't release a lot of dirt. Forward flow also seemed fine.

I fixed a broken vacuum hose to the evap canister in the lower front left of the engine bay.

I triggered a fuel trim relearn and there was possibly some improvement.

I then noticed that the thermostat was opening too early, and that the reported coolant temperature was about 15 degrees C below what I could measure using an infra-red temperature meter.

I changed the coolant temperature sensor and both ambient temperature sensors 9125603 while I was at it.

I think the most likely culprit for the loss of power and misfiring is a leaking or broken vacuum hose.

I will dig around, and see what I can find, replacing as much as I can. Hope I find the culprit.


Steve

[turboboy]

Originally Posted by Luxobarge

OP states that it has individual coils for each cylinder, so it's the later ME7 engine type.

Ah! The "ignition stick". I wondered what that was.

Thanks.

[Bigfella666]

Hello Steve hope you good

Your symptoms are v similar to those on my 98 R so look forward to hearing you have resolved so might assist me.

My gal needs a new cambelt for peace of mind but I doubt the timing is out and regrettably have not had time to further investigate since Easter !

[SteveSarre]

Hi Bigfella,

I am making progress and will report back when I am sure what is going on (and it is fixed).

Waiting for some parts to arrive.

Steve

[SteveSarre]

Hi all

I think I have fixed this.

I started to replace vacuum hoses, but ran out of hose. Have ordered some more. Take care when removing the old hoses from the TCV, they stick on pretty hard. Safest is to cut them off about an inch from the end, then working off the car cut/split the hose too avoid putting too much strain on the two fragile plastic TCV ports.

In the meantime, I did some reading up and then thought about putting in a known good turbo control valve (9473212).

SiRobb's video shows testing a (2 port?) TCV on a diesel, which is a slightly different part
https://www.youtube.com/watch?v=c2RLYw1ijWc

Andy Mechanic's video shows testing some 2 and 3 port TCVs but doesn't discuss the duty cycle (the valve is designed to rapidly switch on and off which provides an intermediate level of vacuum (not simply ON or OFF).
https://www.youtube.com/watch?v=c2RLYw1ijWc

I dug around and found 4 9473212 TCVs. The coding on the side seems to indicate date of manufacture eg 99T131 indicates 1999 presume day 131.
One of them had two of the ports broken off, so that was no good.
The other 3 both clicked when connected to 12V, but I wasn't clear how to test (which port to blow or suck on), so I connected a clean vacuum hose and blew. The click corresponded to the flow being turned on and off as expected. I was unable to test the duty cycle (rapid switching on and off up 70 times per second).

I then did two road tests. One with the original TCV and one with a known good used.

VIDA Dice graphical displays are attached.

Faulty (original) TCV:
With the faulty TCV when going through the gears up to 70 mph, the duty cycle % (black line) drops out and causes the boost to drop. That directly corresponds to what feels like a stumbling or misfire at WOT.

Known good used TCV:
the red line indicates engine RPM, accelerating through 3rd, 4th and 5th gears. Note that the duty cycle % does not drop out and the boost stays high. No stumbling or misfire.

The car is feeling much better now. Smoother response and more power.

I will finish replacing a few more vacuum hoses (the ones that are buried under the turbo intake tube) and see how it goes for a while.
I then may switch out my otherwise new MAF and revert to the previous one.


As I understand it, this is a fairly common fault above 120k miles, and it wasn't causing any warning lights. VIDA fault trace showed one fault
ECM-6805 Turbocharger (TC) control valve. Pressure too high. Permanent/Intermittent fault.

HTH
Steve

[SteveSarre]

So overall, to bring this car back from SORN I have replaced

front O2 sensor
radiator
clutch position sensor (it is a manual)
3 or more ignition pencils
5 Volvo spark plugs
Air filter
New power steering reservoir and hose
Oil and oil filter
Two front wheel bearings
Two front shock towers
Two front disks
New battery
Wipers (front, rear and waiting for headlight wipers)
Passenger door window switch pack
New MAF
fixed vacuum hose leak on top of evap canister
TCV valve
Vacuum hoses

Who says problems only happen one at a time?

Steve