Loosing power and overboosting turbo

[Rich.]

Hi all,

Im coming from the UK forum with a problem in stuck with and just cant get to the bottom of. Its been 2 weeks now and im not getting too far. I have a 2006 D40, 2.5td auto. EGR blanked when i got it 5 years ago. Now on 120k miles.

So to start from the begining, 2 weeks ago i serviced the truck. Used it for a week no problem. Friday afternoon, drove to work and back fine. Packed up the truck to head away for the weekend and as soon as i pulled away i knew something way wrong, seemed sluggish, unresponsive and down on power. As soon as i got on the motorway i sturggled to get to 60mph, wouldnt go to 70. Got home and found out there was no boost. Went through all the vac hoses and all seemed fine. Got a second hand boost solenoid and no difference. Turned out that was faulty too. Got a 3rd boost solenoid and suddenly i have boost back. However i had very little power low down. I thought this was out of boost range and that it migt be a fueling issue, plugged it in to live data and the fuel rail pressure seemed erratic, so i fitted a new SCV and it stabalised a lot and seemed to give me a little more power.

However im now geting overboost fault codes and the truck still doesnt dive right. It seems very slow to respond still and its still down on power until i get to 2500rpm, it then shoots off then dies off again at 3000rpm. Running live data whilst driving it it was spiking over 30psi at some points. Ran live data and watched fuel rail pressure and boost pressure whilst it was going up a hill in the rev range that seemed down and there seemed to be nothing too abnormal there compared to when it was at 2500rpm and flying along, boost was around 21psi which is where i would expect it.

The big thing it isnt doing and i dont know why is that the actuator isnt bouncing. When you start the truck it pulls all the way in, but just stays there, im told its supposed to bounce. I ran it on the drive in park with live data going through the rev ranges and comparing the boost to the service manual, apart from a spike over 30psi at 2500, the boost pressures were exactly where the service manual says they should be.

So now im a bit stuck, seems to be able to generate boost, Yet feels like it isnt fully.. Theres no smoke and it still ticks over perfectly. I tested the actuator by starting the truck, clamping the vac hose to it then pulling it off the boost solenoid and it stayed retracted, diddnt drop. If that was leaking vac pressure i would have expected it to have slowly dropped?

Only things i can think of, but all of them seem like a stretch is;
Vanes on the turbo siezed (actuator moves up and down freely and smoothly with a prybar on it)
Boost/intake manifold pressure sensor faulty (seems to give good readings when sitting on the drive comparing it to whats expected in the service manual)
MAF?
Hole in intercooler/turbo hoses (surely wouldnt reach 30psi of pressure if it was)
3rd faulty boost solenoid valve? (Should i just buy a new one? I saw the current one on the truck it came off running in neutral and it was boosting properly when revving the engine, never drove it though)
Some other engine sensor im not thinking of?
Bad connection somewhere?
Fueling/injector problem after all?

Any one have any clues? Both to why its overboosting and to why it feels down on power?

I should also add, it seems to get a little better once its warmed up. Also, if its completely cold (i.e not been driven for 5 hours or so) the first time it moves it barely does, foot to the floor and it crawls at 3mph with the revs at about 1000rpm, after a few seconds they start to pick up and then after that it revs fine again. Its been doing that for a month or so now.

Thanks in advance
Rich

 

[Old.Tony]

Welcome to the forum.

Sounds like a raft of issues there, here's what I'd do to make sure everything was as good as it possibly could be before looking to spend serious $.

1) Remove, clean and reinstall the intercooler. Petrol is good for the job, just make sure you drain it out as much as you can and let it sit for an hour before reinstalling.

2) Unplug, clean the electrical contacts and reinstall the boost pressure sensor (low on the right hand side of the car on the intercooler piping).

3) Remove, clean and reinstall the MAFS (rear of the air pipe just outside the air filter). Don't drop it, don't poke anything in the hole in the end where you can see some electronic components. Use a good electrical contact cleaner, spray and watch the black stuff come out.

4) Undo the EGR valve and remove and inspect the blanking plate. There have been a couple of reports of people with 'soft' plates (eg aluminium, thin mild steel etc) having holes melted in them. Reinstall with your equivalent of Permatex Ultra Blue Sensor Safe Gasket Cement.

5) It's also worth disassembling your throttle body (on the intake manifold) and cleaning it, while you're looking around take a peek inside the manifold looking for black masses of EGR soot with oil. You'd really prefer to extract the muck out the intake manifold, rather than trying to blow it into the cylinders.

6) Disconnect the battery (use a jumper pack to maintain power to the vehicle's electronics) and clean the terminals really well. After reinstallation, spray the terminals with battery terminal sealer. Go over the primary connections, making sure the ECU (right hand side inner guard high on the top of the wheel arch) has a good earth - some D40s have had dodgy earths on the ECU causing all sorts of hard-to-explain problems. A bad battery can also do this - give your starter battery a run with something decent like a C-Tek multistage smart charger. I do recommend C-Tek, I have one and have recovered batteries with it in the past.

After this you're spending money. Yes, most cars' actuators move a little at idle and if yours is pulling all the way in it'd be interesting to know if there's any smoke coming out the back of your car under hard acceleration (at any stage, from idle up to 4,000rpm under load). It doesn't work in neutral, the car knows it's not going anywhere so it won't prepare (spool up) the turbocharger very much unless you're actually needing it.

I'd spend money in this order:

1) Replace all of the vac hoses. Should cost about $20 (what's that in UK, about 6 quid). You'll have a little left over from 3m of 3mm vac hose.

2) Either run a can of Liqui Moly Fuel System Treatment through a tank (see results in 100-200km) or do a Liqui Moly Diesel Purge. You should get change from $30 for either (that's about 10 quid).

After this is the serious expense. SCVs are a known sore point and affect fuel delivery. Your experience with the fuel rail pressure variations would indicate this as a possibility, but a clean of the system won't hurt.

Turbochargers are not often a major issue but it's worth checking. The spindle inside should have very little play, and you need to check the inside of the hose on the pressure side - you're looking for fine metal particles in the smear of oil you should see on the inside wall of the pipe. If you see particles and they're silver, chances are your turbo's compressor wheel has been rubbing the housing and detonation isn't far away. If you see gold flecks, your bearings are collapsing and turbocharger detonation is even more likely. You can get bearing and seal kits for the Garrett 2056V which should be what you have.

That's a fair bit of playing. Hopefully somewhere along the line it'll fix the problem without a new turbo!