No Singleboost, never mind Doubleboost! Car trouble.

[northwest]

I am having issues with my little Astra van, it is a 1.7 diesel H series. Runs like a top usually but last week a problem manifested itself totally out of the blue as i was driving up the M62, I pulled out to overtake and then --- nothing.
The issue seems to be a lack of boost. We have had the MAF sensor disconnected but then it is absolutely flat, with it connected there seems to be a bit more driveability about it but it has no guts and is positively dangerous at a junction where I think I have enough of a gap to go for it! :-)
We have removed all the hoses from the turbo and spun it by hand and the vanes/spindle appears free moving with no side to side movement. We have run it with the boost hose disconnected from the outlet side of the intercooler and although there is pressure there there isn't the gale I usually associate with turbo boost. Frankly we are at a loss as to know what it is and my pal thinks it is a turbo fault, I am rather hoping it isn't.
There are enough really smart people on this forum to give me some pointers and a bit of clue as to where to look next, I hope!

 

[Blobber]

How about MAP sensor? think they used to be problematic, shame your not nearer you could have used my Tech2

 

[m_c]

Any fault codes stored?

I'd probably check the vacuum system. You should be getting at least -0.7bar at the turbo wastegate hose at idle. If not, then work back through the system.
If you are getting a good vacuum, then either T in the vacuum , or use a MitieVac to check the actuator itself isn't leaking.
Also check the actuator is moving freely, as the pivots were prone to seizing.

 

[Robert Weaver]

Would the wastegate seize in the open position? It'll be shut under vacuum, so boost pressure can build, then +ve pressure opens it to bleed excess. If it seizes open, it'll not boost, but if it seizes shut, the system could overpressure.

MIght not be a mechanical issue, like fuel pump or turbo. Pressure leak or map sensor.

 

[colnerov]

You've checked downstream of the turbo, what about up stream? Air filter blocked, hoses collapsed?

 

[minimutly]

Exhaust blocked?

 

[minimutly]

Would the wastegate seize in the open position? It'll be shut under vacuum, so boost pressure can build, then +ve pressure opens it to bleed excess. If it seizes open, it'll not boost, but if it seizes shut, the system could overpressure.

MIght not be a mechanical issue, like fuel pump or turbo. Pressure leak or map sensor.

Some (well one I know cos I have it here) is held open by a spring, how does that work??

 

[m_c]

Some (well one I know cos I have it here) is held open by a spring, how does that work??

Typically modern(ish) turbos are vacuum controlled via a solenoid, with vacuum used to close the wastegate, or in the case of VGT, move the vanes to full boost, with the default position being open/minimum boost.
I say modern(ish), because the latest turbos typically use pure electric wastegates.

Certainly on Northwests 1.7, it'll be vacuum controlled, but it could have either a wastegate if the low power option, or a VGT if the high power option.

 

[northwest]

How about MAP sensor? think they used to be problematic, shame your not nearer you could have used my Tech2

To be honest I was thinking MAP sensor too so I put my pals diagnostic kit on and this is what it showed:



Few gratuitous pics just to prove I too got dirty, hoses were an **** to get off and my pal wanted to know "which T**t did that" I reminded him that he actually fitted the new Turbo.......




Another of the diagnostic screen:

 

[northwest]

Certainly on Northwests 1.7, it'll be vacuum controlled, but it could have either a wastegate if the low power option, or a VGT if the high power option

I hadn't considered the vacuum so thanks for that, the more pointers I get the more success I am likely to have.

 

[m_c]

To be honest I was thinking MAP sensor too so I put my pals diagnostic kit on and this is what it showed:

View attachment 498340

That DTC would indicate a MAP sensor issue, but if the description is correct, possibly a wiring/connector issue rather than the sensor itself.
Check you have 5V, and a GND at the connector.
With it disconnected, the signal wire should have some measurable voltage on it. It's been a while since I worked on anything of that era, but provided the voltage is somewhere ~0.7 to 3.0V, it would indicate the signal wire is intact. If it's at full 5V, or 0V, then it's likely shorted to the relevant wire.

Does the live data show the voltage for the MAP sensor, or just the calculated pressure?

 

[northwest]

Does the live data show the voltage for the MAP sensor, or just the calculated pressure?

My bad, I didn't think to look but tomorrow is another day and I will be able to check all this tomorrow. As long as I have a list to work through I will be good to go.

 

[m_c]

If it shows the actual voltage, then that gives you a good idea what is actually going on, and you can bridge the signal to 5V or GND to see what the ECU is actually seeing.

If it only shows the boost pressure, then it doesn't help that much, as if it detects a fault, it'll likely only show a default value.

 

[ms08]

Boost hose off or split? Can you hear any leaks under boost. Blocked exhaust as above after checking everything else. Had this on Saab 900 where one of the boxes had collapsed internally preventing exhaust flow. Wastegate actuator disconnected from arm - again had this with rusty R clip meant the arm had dropped off the actuator....

 

[jmp49]

I had a turbo engine that wouldnt boost that drove me mad trying to find it, until I made plugs for the exhaust up, and a fitting for the turbo intake with a pcl connector on it, and pressurised it lightly to 10psi via a airline regulator.
Its much easier to trace boost leaks when its all under pressure, a split pipe can hide but when the hose blows up under pressure start leaking.
Pressurise it after filling it with a smoke machine might be better, but I didnt have one back then.

 

[Smallfry]

1.7 cdti. The boost pressure sensor is fixed on the inlet manifold. On the drivers side end of the engine behind and below the lifting eye.

Low input normally means a wiring fault or break. Might have become disconnected though, or not connected properly in the first place. Try unplugging and re plugging a couple of times and spray with contact cleaner if you have any. The pressure sensor itself can get blocked by carp in the manifold caused by the EGR system. Might be worth taking if off, one bolt but a bar steward to get at, and cleaning with some brake cleaner. DO NOT blow compressed air directly in the sensor hole though.

The EGR is the Achilles heel of these engines

 

[jmp49]

The EGR is the Achilles heel of any engines

There Fixed that for you. EGR is just a disaster introducing carbon into places it shouldn't be and causing issues that probably cause the engine to run worse in the longer term and emit more pollution as a result.

 

[northwest]

Well. The saga continues turns out it was the MAP sensor. 20 quid later and a replacement of dubious origin and we are all fixed Yay!
Drove home all happy relieved it is not the turbo and stop at the lights, literally at the bottom of the street.
Go to set off, foot on the clutch and straight to the floor!

My pal recons it is the slave cylinder in the gearbox :-(

Awaiting the arrival of Britannia rescue as I type this.

 

[colnerov]

Sounds like time to practice and perfect your clutchless gear changes.

 

[northwest]

ability to determine a faultSounds like time to practice and perfect your clutchless gear changes.

Did that from Birmingham to Teesside once! Only becomes really exciting in town.

Day started off great too, went to a friends place who has an almost clairvoyant ability to work out what the fault is. Rightaway deduced MAP sensor, ordered a new spurious origin one and off I went, I should have known the gods weren't done with me yet and they were just lulling me into a false sense of security. This was a pig to start. Had a bit of a play with and a chance to see up close and very personal some real exotica, this ran at Spa, very well too I was told:



The finish and detail of this car was exceptional:




This was a real wolf in sheeps clothing:




That was 365 Brake two feet away at silly MPH, fair rattled my teeth it did.



Ah well, need to work out how much this malarkey with the Astra is going to cost, I am not scrapping it so needs fixed.