200Tdi seems a little sluggish

We were not talking about maximum boost as you'll see if you read the posts properly. The OP wanted to know if he was producing ANY boost as he said. My test is easy cheap and works, I didn't say it would measure boost accurately but it will tell him if he's getting boost at all. Further, you said "It'll only produce boost under load." which is the most patently untrue statement in this thread so far.

Load has nothing to do with boost. Of course you'll get max boost under max load but not because of it.

I would really appreciate it if you'd stop slagging me off without good cause. Please, read the posts first. TonyB

On or around Sat, 16 Jun 2007 19:07:33 +1200, EMB enlightened us thusly:

I'm not arguing that it'll produce full boost off-load. But it's still a fact that just by rotating the engine pumps a goodly wedge of air through the impeller, which must generate some boost. The difference when it's burning fuel is that you not only get the balance of the input air going out of the exhaust but also the combustion gases.

You're quite correct that what you need to measure is maximum boost, and it'll only do that at full chat. Or, more accurately I suppose you need to measure the revs at which the wastegate opens, on a normal sort of engine.

On or around Sat, 16 Jun 2007 21:25:13 +0100, "TonyB" enlightened us thusly:

well, true. To check for "any" boost, you open the bonnet and rev it up to about 3000, and watch the outlet hoses from the turbo, which will get fatter.

However, it's pretty unlikely to produce no boost at all without other symptoms, so you really do need a max boost check. Since most of them regulate boost with a wastegate, knowing at what revs the boost stabilises at the preset level is also useful - if the turbo, for any reason, is a bit lacksadasical then it might still get to the book value for boost but not 'til a higher speed.

The LR workshop manual says the following for testing the boost on the

300Tdi. I would assume the principle (if not fugures) for the 200Tdi would be the same -->

"To check maximum boost pressure, drive vehicle normally, but in such a manner that full throttle can be maintained whilst climbing a hill with engine speed held steady between 2,500 and 3,000 rev/min. Under these circumstances boost pressure should read 0,95 - 1,09 Kgf/cm2 (13.5 - 15.5 lb/in2 )."

Colin

It won't produce any SIGNIFICANT AMOUNT of boost unless it is under load.

Why do you think Hugh's Volvo produced 'virtually no reading' whilst 'cruising' along merrily at 70 mph?

He wasn't slagging you off, you were the one that condemned his statement "It'll only produce boost under load", it was a helpful comment for the OP. :-)

Martin

On or around Sun, 17 Jun 2007 20:37:30 -0000, Colin Reed enlightened us thusly:

yes, indeed, that's how you'd check for maximum boost and note that it specifies the speed at which it should be achieved.

But it's true to say that the OP wanted to check for "any" boost, and for that you don't need to do the whole works. It might not tell you much, though, compared with a maximum boost test as above.

Tony

Hatchet, buried, and sorry if you took offence. However I have a turbo sitting on my bench that will 'produce boost' according to your test, but the moment it is subjected to any significant load will promptly bash the exhaust impeller into the housing and cease to turn (and thus no longer produce boost). Quite apart from which (as per another of my posts) a sticky wastegate (a common and relatively cheaply repaired problem) will not necessarily be diagnosed by your 'test'.

Max boost is the only way to tell if a turbo is working correctly - and most unburnt fuel problems only manifest themselves in an obvious manner at high boost pressures.

Sorry mush but that's patently untrue, on my old car you could tell the turbo wasn't working properly even when the car was not under load, with the engine in neutral, booting the throttle produced the most godawful sound from the turbo as it was missing an exhaust vane, the scraping sound was horrible. Testing for max boost is certainly important but to baldly state that anything else is worthless is just daft. You can check for some problems with a turbo just by spinning the thing by hand, every turbo problem does not need a max boost check to see if it's there or not. I've found a stuck wastegate by trying to move the thing by hand, no max boost check was needed to spot that one.

"Derek" wrote .............

That would do the trick, and yes, I've got lots of bits, mail me the list and I'll see if I can help you out.

Martin

Martin, thank you for your input.

Point one, the OP did not ask about "significant" amounts of boost, he asked about checking for ANY boost. My test would have told him that he was getting some boost or no boost.

Point two: I have already said, Hugh's Volvo produces little boost at 70 mph because he has a low throttle opening and low exhaust gas pressure.

Point three: The statement that "It'll only produce boost under load" is not helpful, it is wrong.

Point four: Call me touchy if you like but he said "FFS" and told me effectively to shut up unless I knew what I was talking about. If that isn't slagging me off I don't know what is.

Point five: Perhaps you could explain then, why an engine turbo is affected by load on the engine to any degree and why my

300 TDi produced enough boost at rest with the pipes off to almost prevent me from holding my hand over the pipe? Would that be considered "significant boost" ?

TonyB

Thanks Mike, I did a bit as it happens.

However I have a turbo

** Point taken and I accept that my test is not an accurate one. I would not attempt to explain the oddities of your bench turbo!

Quite apart from which (as per another of my

** I can understand that too, hopefully we have an agreement at last!

TonyB

"TonyB" wrote..............

If there was no "significant" amount of boost, it would be a waste of time fitting the turbo in the first place, and it needs to be checked under load. Yes, I concede your test will show the turbo is actually working to a degree, but it needs to be checked more accurately.

What are you trying to say here? Why do you say that Hugh is under a misapprehension?, you have made the same statement which is correct. And after making that statement, how would do you think you would generate the boost in that situation, say, to possibly overtake something? and would the engine be then under load? And why does that alter the boost?

Dare I say this? FFS Significant is the operative word, it is a waste of time running an insignificant test therefore the engine needs to be under load to test for boost pressure. Your comment was/is wrong.

I don't think you have a right to be 'touchy' when his response was quite appropriate after you effectively told him he knew nothing when he obviously does

Do you see a relationship between governor or potentiometer? fuel? exhaust gases? proportionate increase in boost?

and why my

Not really. :-) But I knew what you meant.

On or around Mon, 18 Jun 2007 20:21:44 +0100, "TonyB" enlightened us thusly:

it's got shagged bearings, and I bet if you installed it in a motor it'd scream nicely?

It sure does.

On or around Mon, 18 Jun 2007 09:46:45 +0100, Ian Rawlings enlightened us thusly:

True enough. There's also the point that the max boost test will tell you you're not getting the boost you should but not necessarily why...

On or around Mon, 18 Jun 2007 09:46:45 +0100, Ian Rawlings enlightened us thusly:

I think it needs taking in context. The OP stated that the vehicle felt "a bit sluggish". A mechanically fscked turbo which screams at anything over

1500 revs rather tends to self-diagnose: in that case, OP would have posted "my turbo makes a godawful noise[1], I assume that means it's shagged".

The question as originally posed suggests that maybe it's not boosting as well as it should, and to test that, you do really need a maximum boost test as EMB said.

In message , Austin Shackles writes

We've also not mentioned the third component which is the intercooler.

This is IIRC an 89 RR. Could be the intercooler radiator is bunged up and in need of a (gentle) washing.

Fine. That's all I said, we agree.

** What I am trying to say here is Hugh's Volvo produces little boost at 70 mph because he has a low throttle opening and low exhaust gas pressure. I think that is clear enough.

Why do you say that Hugh is under a

** I said Hugh is under a misapprehension because he said " I was surprised to note that that cruising down the motorway at 70(ish) there was virtually no reading at all."

Clearly Hugh expected a reading otherwise he would not have been surprised that there wasn't one. I would not have expected a reading at a low throttle opening therefore I think Hugh is under the misapprehension that a high speed should result in him seeing a high boost reading.

you have made the same statement which is correct.

**No, Hugh was surprised at his reading, I wasn't.

And

**The increased boost is generated by an increase in exhaust gas pressure, this occurs when you put your foot down to overtake, thus putting more fuel through the engine and increasing the revs.

and would the

** The engine would be under more load, yes

And why does that alter the boost?

** I didn't say it does. ** Nope, the OP did not mention significant he said "ANY" boost. The engine does not have to be under load to test for any, or for that matter, significant, boost. My test will produce enough boost to virtually stop you holding your hand over the outlet pipe, I know it does I have done it, if you don't believe me go and try it. that amouint of boost certainly qualifies to answer the question of "any" boost and to my mind also answers the question of "significant" boost. ** I did no such thing, I said "Not quite" and explained why in polite terms, his response he now concedes wasn't right but at least Mike went out and tried the test. ** You'll have to explain that one properly, don't forget you are dealing with an idiot here. ** You'll have to explain that one too.

TonyB