TTiD loss of performance low down

[carrera]

I have put 8000 miles on the TTiD now

One thing that has disappointed me has been the straightline performance. She's fine at motorways speeds, but very sluggish setting off from the lights.

As part of fixing the throttle body that failed, and replacing one of the boost solenoids (not faulty) I ended up doing some monitoring of the boost levels

On tickover the requested MAP is 1.2 bar. Actual is 1 bar, or just a little under

Having read https://www.uksaabs.co.uk/UKS/viewtopic.php?p=1380777 (thanks wrighar) I'm trying to figure out the best diagnostic strategy as I think the setup for the 9-3 and 9-5 are very similar

The engine essentially has little boost until it gets to 1500 rpm when it's halfway up the gauge and by 1750 rpm it's pulling strongly with the needle in the red. Data wise this corresponds to 2.9 bar MAP or 1.9 bar boost

It appears to me that this is a physical issue. Either the small turbo is underperforming, or the crossover valve isn't working correctly.

I have tried to remove the pipework with the crossover valve with the turbo in situ. Everything came off except the one bolt around the back where I just couldn't get an allen key/ bit into place

Having spend some time trying to understand how the TTiD arrangement works I "think" that the wastegate operates on the big turbo, while the variable vane adjustment also operates on the big turbo. I have also read that the small turbo's have a habit of going "weak", though new ones are only ~ £100

Any advice, knowledge or suggestions much appreciated. If I am going to have to remove the turbo etc, I would really like to be sure of the nature of the fault beforehand so I can simply remove / replace over a weekend.

When she's back to full performance, then I might consider getting her breathed on...

[carrera]

Just a little bump on this, to try & gain some better understanding of the mode of operation, before laying some spanners on her which means taking her off the road ?

[carrera]

I tried to get access to the crossover pipe in-situ. things were looking promising until I found one of the allen bolts, at the rear of the small turbo impossible to undo

Consequently, I'm still contemplating doing something about this.

Having gone back to this thread https://www.uksaabs.co.uk/UKS/viewtopic.php?t=139532&start=20 by wrighar, I am suspecting that I have the same problem with a weak dome valve spring. This would leave air to bleed away via the dome valve, rather than being forced through the small turbo

I knocked together this little graphic to help - the Speedparts original image is not orientated the way it is installed in the car & I don't want to have to do mental gymnastics everytime I contemplate this problem

I have been trying to search for a source for the spring only... I don't suppose anyone knows a source for these

[carrera]

I had a second hand unit delivered from lithuania this morning, off a ZD19DTR. Given that the power output is 185HP, rather than 190HP I was expecting that the spring would be the same as would be fitted to the A20DTR.

Frustratingly the item is incomplete, as it doesn't have the spring, so I'll be taking it up with the seller.

However, it has allowed me to confirm the assumptions in the diagram are correct with regard to operation & also get the dimensions of the spring. 20mm OD, length in situ 50mm, approx.

I have spoken to my usual source for turbo rebuild components & unfortunately they don't appear to have a source. Time for some further internet searching

[carrera]

An appeal to the collective mind....

I have done some data collection, which is accessible through GDS2, but not exportable, which makes it more difficult to analyse

This is a snapshot, for a 12 second period, for an acceleration run in 3rd gear (I think). Starting from 1000 rpm, because it will pull slowly from that speed, but the boost / torque doesn't really start to build until 1500 rpm+. Classical turbo lag

From reading around, this isn't a sequential turbo arrangement, but parallel. The small turbo has it's own exhaust gas feed, which compresses intake air, received via the big turbo compressor wheel to give boost in a responsive way at low engine speed, below around 1500 rpm.

There's then a bypass valve in the pipework, which when it opens diverts intake air away from the small turbo to allow the big turbo to build flow and pressure. Having examined the Z19 component, I think this diverter valve acts in a similar way to an old fashioned wastegate valve, probably using two different diameter springs. (edit: no only one spring, ilustrated here https://www.uksaabs.co.uk/UKS/viewtopic.php?t=139532&start=20 )My premise is that these springs have gone weak, meaning that the small turbo is permanently bypassed, so it may as well not be there. Indeed on idle, the boost request is 1.2 bar, while the actual is 1.00-1.05

Here's the graph of the data, which I have annotated to help interpretation

The red arrow highlights the deficit in actual boost delivered

The orange arrow shows the delay in reaching target boost levels

In simple terms, the boost control looks very weak, with considerable lag on both building of boost and control when reducing it

From previous work I am happy that the boost control valves, which control wastegate and vane angle on the big turbo are working correctly

Thoughts ?
 

[carrera]

I found a new crossover valve arrangement for the 9-5 NG on ebay, and decided to put my hand in my pocket & pay for shipping from Germany. It arrived today.

By way of note I'm sure that the 9-5 NG TTid has the same spring as the 9-3 NG TTiD

After a few hours wielding 4mm allen keys, bits & other tools the top part of the pipe incorporating the dome was removed & the new one put into place.

I took some measurements & the old one did seem to be a little bit on the weak side, about 1mm less extension of the spring when the weight of the dome valve was placed on it. Not much. I was able to spin the small turbo, but it didn't seem to be as free as it should be. No contact with the housing and only a small amount of play, so it may be that this has become lazy, as they apparently do.

Everything was put back together & I drove home normally. The car seemed a little bit more responsive, ran on lighter throttle settings & felt smoother. Conscious, that it might be nothing more than me thinking the car was better having done some work on it, just like a freshly washed car sometimes seems better, I decided to carry out a little 0-60 test on the basis that that the stop watch doesn't lie.

She was much quicker than before (seconds, not tenths) & most significantly delivered a time in line with manufacturers specs 

Further low engine speed testing showed that the pickup from 1000-1500 rpm is much better.

If I get a chance I'll try & log some data for comparison

[carrera]

Well, that didn't last, the very next day, she had reverted to type, so I have concluded that the manual spinning freed the bearing up a little, which was fine from cold, but once it had cooled down again the spindle was effectively frozen again.

Anyway, that's the theory, so time to put some £££'s behind it

New shiny bits to fit

The suppliers were out of stock so Turbo Rebuild took my number & said they would call back when they had stock. Encouragingly, the lady said, which turbo do you need, the small one ? "Yes", ah that's ususally the one that fails.

Anyway, I placed the order Friday afternoon, for delivery today. It arrived Saturday morning, but I had other plans for the weekend, so today is the day.

Armed with prior experience from replacing the inlet pipe & dome valve I have decided I "should" be able to do this in situ, without touching the exhaust manifold

Wish me luck, the bonnet is up, allowing the car to cool down a bit while I have a coffee

[carrera]

Well the job is done & I have been out for a test drive

Disappointing

When I removed the old turbo, there was no play & it span easily enough by hand, and by using the air compressor

When I started this journey, I thought the small turbo could only be removed with the exhaust manifold & everything else. So investigations prior to buying parts would mean the car would be immobile & off the road until parts arrived. Now I know that it's actually very easy to remove & replace in situ. The "difficult" allen bolt on the underside does not even need to be touched, neither do the other two that hold the trumpet portion onto the diverter valve bit

A couple of photos:

The first showing how the car looks with the trumpet & diverter valve removed. 13 bolts in total including the heat shield & intake pipe holder

The second shows the exhaust manifold after the turbo was removed

So, I'm back to square one with this problem. Wish I had another TTiD to compare with, just in case this one is behaving normally. I'm expecting that the car will pull like a train from low down, like the 120hp 2.2 diesel does, rather than bogging down below 1500 rpm

[carrera]

Steps backward & forwards

Returning home a couple of weeks ago the car droppen into full limp mode. Max 60mph & slow getting there. I cleared the codes & continued, but there were furter errors

I had a P2282, just the once, so I cleaned the MAF with brake cleaner, best I had. This has not recurred

Then I tested the solenoid valves for the turbo. No apparent errors, but fitting the previous solenoid restored the low down torque

Next was a P0299 that started to pop up, underboost for more than 6 seconds. This keeps on coming back. The vacuum pipework looks good & the vac from the pump is well ahead off minimum spec.

Reading arounf took me to the MAP sensor. Removed that & it was covered in thick diesel residues. Cleaned with petrol, replaced, but no difference

Next area was to ty a forced DPF regen. It shouldn't need it because the mass is apparently 6g, and only 16% full. I couldn't force a regen with the GM software. The 6g and 16% do not seem consistent with each other. I'm getting a reegular P2458-57 DPF regen code.  It happens under hard accelleration, which is expected, but also on the overrun. She generally plays nicely if I tickle the throttle.


So, for the second week I am back in the Dame Edna.

The data seems to show Requested boost at idle is 1.2 / 1.0 bar, full chat 2.9 vs 2.4 bar

I'm thinking of replacing both boost solenoids, because they are cheap for s/h items & they will be here for Saturday when I can look again.

Perhaps I need to remove the DPF fo a manual inspection / clean

It's been a frustrating 2 weekends, because I don't have the time really, but at least if it gets worse, I might be able to find the underlying problem

Any suggestions or ideas ?

[carrera]

Found It !

I haven't used this car for about 6 weeks. She threw a CEL & went into limp mode on the way home one week, so couldn't rely on her.

Various error codes, including MAF, low boost, so with limited time I reluctantly have gone down the replace cheap parts route, meaning I have now got spare turbo solenoid valves, MAF, MAP sensor etc.

Lots of time watching the engine parameters, and started having an uneven idle when cold. After having a nosey around I spotted that cylinder 1 apparantly had no compression, according to the diagnostics. The very expensive glow plugs have pressure sensors in them. Swapped one out & the pressure was back, along with smooth idle. Apparently, the ECU uses the peak pressure reading to help manage fuelling.

Last weekend I though she might be sorted, she was picking up from low speed better, but after 4 seconds constant acceleration, I would get an EML for boost below requested, which was confirmed by watching desired vs actual MAP readings. So, could this be a boost leak.

Well, yes it is, but to get to it I needed to remove the front bumper. Inlet was fine to the IC, but this is the exit pipe. Split on the underside, where it could not be seen.

Now I just need to figure out how to remove this clip and where to source another hose

[carrera]

Oh, forgot to mention 3 weekends removing the DPF, taking the wrong approach in my attempt to get access for a DPF cleaner which resulted in destruction of the temperature sensor, which meant removal of the DPF,  drilling out the remains of the clamping bolt, which coudn't be drilled out because the remnants of the probe were spinning with the drill bit, preventing cutting of the metal

Anyway, probe threads were retapped, holes drilled at the rear for bolts having cut the studs off to remove it & cleaning of the DPF with flushing water.

DPF's are unobtanium, due to them being a combination of being a Saab (Insignia is different) and AWD

Reclaibrated the DPF and all seemed good last weekend

Plus I still have the DPF cleaner if I need it.

[carrera]

Parts are ordered

The OEM part is £227.92 + VAT from Bill, ouch

So I bought aftermarket, one with 10 years guarantee, which was on offer for £18

Paired that with a full stainless Mikalor clamp as the original ones are single use & need special tools. Mikalor are very very good. £13 each

[sgould]

Are you sure those hose connections aren't reusable?

It looks awfully similar to the ones on the 9-3 Carlsson heater connections.  Flip up the wire clip and pull apart.

[carrera]

Ah,

The top connection comes pre fitted to the pipe. It is similar, but not the same as the ones you have photographed. Almost unique I would say, you have to lever up the two ends of the retaining wire to allow a centre deformation to pop out. Every aftermarket pipe has this fitting

Easy when you know now, or have in in your hand.

It's the intercooler end which has the factory fit one time only fittings. Even worse than the crimp type often used on CV joints. Most people would use a jubilee type clip, but I know I will have no leakage problems with the Mikalor. They have solved slippage problems on no ridge silicone boost hoses before now

[sgould]

I realised after I had posted that, if the pipe had split, the connection is the bit that's fixed permanently to pipe, so not reusable.

As to the Saab price v aftermarket, did you see my post earlier on the "Things that annoy me" on UKS?  I found the same price disparity on several parts.