Running and Emissions Questions for an '01 C70

[CutterComp]

Quick backstory: I'm working on this car for a friend to get it back on the road. 2001 C70 2.4T, convertible, automatic, 98k miles. Car sat for at least two years, was neglected before that. So far I've done brakes all around (calipers, pads, rotors, and fluid flush), new Conti tires, replaced rodent chewed hard fuel line, fuel filter, cabin filter, spark plugs, air filter, oil filter, oil change, MAF cleaned, water pump, timing belt, tensioner, idler, coolant flush, coolant level sensor, power steering fluid flush, and a bunch of other smaller cosmetic repairs. I told him I would get it through PA state inspection for him and now that I have the car up and running/driving, I'm starting to question my promise... haha. Here are the issues I still have:

1) ETM light is ON fulltime (car has a yellow sticker on the ETM itself, I gather that means it's been updated. Throttle response is funky, but not sure if it's due to other issues I'll mention in a sec)
2) Car gives only one DTC: P0234 for an overboost condition. Returns after clearing it. I would assume the culprits here would be the electronic boost control solenoid or a torn vac line? The vac lines are definitely dry rotted, but no holes/rips I can find. Solenoid itself appears to be a China made replacement. Boost while driving seems to come on heavy at low RPM and quickly fall off by 4k RPM. Definitely uneven power delivery.
3) Car will not rev over 4k RPM at idle. Is that by design?
4) Shows 3 emissions readiness monitors not set: evap system (I replaced two hoses by the fuel filter that had torn), cat converter, and oxygen sensor. I was thinking I would space out the secondary 02 sensor and see if the cat converter monitor sets. Don't know where to start for the evap issue. My cheap code reader has no ability to run tests on a Volvo.

Any advice from those more experienced in Volvo land than me would be appreciated. Thanks.

[scot850]

Did you drain and replace the fuel? Bad fuel will not help if it has been sitting for a long time.

A yellow tag/label on the ETM will not guarantee the ETM is not funky. These could have been replaced early in the cars life and may be failing again.

Evap/emissions system issues do take a while to clear or set their codes. Some of the codes may not be possible to erase with a basic code reader. There is a specific cycle which is hard to replicate to help set the monitors on these cars. May be worth checking if any of these are waveable at testing of a car of this age. I have read some states are more lenient on older cars.

If you have replaced the 2 hoses at the carbon filter and fuel filter area then those are usually the 2 issues with the evap system, but there is a pipe that runs to a valve on the slam panel by the radiator if it is similar to my car.

The cheap non-Volvo TCV (if I understand correctly) does have a small valve in it and it may have stuck with sitting or just be bad. However, before consigning it, make sure the 3 pipes are sound. They are prone to cracking with age and one is hard to see all the way as it goes under the turbo. If they are crust, then recommend you replace those as a matter of course.

Neil.

[CutterComp]

Thanks for responding, Neil! I'll give my answers below.

Did you drain and replace the fuel? Bad fuel will not help if it has been sitting for a long time.

The tank was nearly empty fortunately and I figured filled up with fresh fuel it would be okay. At this point, I probably have 30 miles on it since adding the new gas.

A yellow tag/label on the ETM will not guarantee the ETM is not funky. These could have been replaced early in the cars life and may be failing again.

I certainly believe it could still be bad, even with a replacement. That said, I would assume bad or failing components of the ETM system would throw a DTC that would show on the code reader?

Evap/emissions system issues do take a while to clear or set their codes. Some of the codes may not be possible to erase with a basic code reader. There is a specific cycle which is hard to replicate to help set the monitors on these cars. May be worth checking if any of these are waveable at testing of a car of this age. I have read some states are more lenient on older cars.

If you have replaced the 2 hoses at the carbon filter and fuel filter area then those are usually the 2 issues with the evap system, but there is a pipe that runs to a valve on the slam panel by the radiator if it is similar to my car.

Glad I'm at least on the right track here. I'll have to take a look for the pipe at the front. PA allows one emission monitor to not be set for a 2001. So I have to find a solution for at least two of them.

The cheap non-Volvo TCV (if I understand correctly) does have a small valve in it and it may have stuck with sitting or just be bad. However, before consigning it, make sure the 3 pipes are sound. They are prone to cracking with age and one is hard to see all the way as it goes under the turbo. If they are crust, then recommend you replace those as a matter of course.

I think I will just replace the boost solenoid and 3 hoses all at one shot. The hoses do seem a bit tough to access around the side of the block


Neil.

[scot850]

Old fuel could still have been an issue and moved crap into the pump and injectors.

Have you done a fuel pressure test? There is a Shraeder valve on the fuel rail near the injectors. This should be around 50+ psi for your year of car. Mine was measured by the dealer at 60psi when new.

I would expect that a DTC should be thrown if there is an issue. I don't have a basic level code reader to know what it would show, but I would think it would show something? I am assuming you have tried re-setting the ETM with the code reader or did I read correctly you said no codes were showing but the light is on?

I just recently had an issue with my car with evap errors and it was on one of the 2 hoses you replaced. The pipe was OE Volvo and was only 6 years old!

The dealer ran a smoke test on the system to find it as it was a small crack.

Check all your turbo hoses and intercooler for leaks, loose pipes and cracks in the intercooler.

Neil.

[misha]

3) Car will not rev over 4k RPM at idle. Is that by design?

It will not...it's designed that way.
If you floor the gas pedal and keep it there...rpm will bounce up to around 4k...back and forth.

[CutterComp]

Thought I would post an update in case it is helpful to others in the future. I bought a new Pierburg boost control solenoid and new 6.6mm vacuum line. I was able to replace 2 of the 3 vac lines from the boost solenoid. The third line runs to the turbo and was absolutely unreachable without some significant disassembly, so I let it be. I also bought a new secondary 02 sensor because I found the original had melted wires where they jointed the sensor body. I installed the new sensor with a spacer I was able to machine for fit on the lathe.

These two repairs made a great improvement. The car drives MUCH smoother and no longer gives an overboost code. The oxygen sensor and cat converter readiness monitors are set and good to go. The EVAP monitor is still not set, but again, in PA I'm allowed one not set.

The ETM light seems to come and go now, but I don't experience any negative symptoms so for now I'm calling it good. The car should pass inspection.

Thanks for the help everyone.

[RickHaleParker]

2) Car gives only one DTC: P0234 for an overboost condition. Returns after clearing it. I would assume the culprits here would be the electronic boost control solenoid or a torn vac line? The vac lines are definitely dry rotted, but no holes/rips I can find. Solenoid itself appears to be a China made replacement. Boost while driving seems to come on heavy at low RPM and quickly fall off by 4k RPM. Definitely uneven power delivery.

ECM-6805 (P0234) (Turbocharger (TC) control valve. Pressure too high. Permanent/Intermittent fault


Condition
If engine speed (RPM) is above 3500 rpm and the engine is operating at a high load, and if the boost pressure (from the boost pressure sensor) is higher than a designated value, which at maximum boost pressure is approximately 20kPa (2.9psi) above normal boost pressure, this is interpreted as a fault and diagnostic trouble code (DTC) ECM-6805 is stored.

Substitute value
Reduced boost pressure

Possible sources

• 1. Hoses between turbocharger, turbocharger control valve and pressure servo are loose or are blocked/damaged
  2. Faulty turbocharger (TC) control valve
  3. Faulty boost pressure control (BPC) valve pressure servo
  4. Sticking boost pressure control (BPC) valve

Fault symptoms
none