[andrewpen]

Hi all. I have a 2001 manual convertible 2L Low pressure turbo. When we got it a few years ago it ran fine and had plenty of power (not like the 9-5). My partner drives it and learnt to drive a manual on it so it has had a new clutch since. For a while she has been complaining about low power particularly getting up hills. I haven't taken it too seriously but recently test driving it I am wondering if the turbo is still working. I can't notice it at all. It has no turbo gauge (I bought one on ebay but have not fitted it yet). It runs smooth, no smoke, no missing and nice and quiet, just slow compared to how it used to be. I am going to clean the MAF sensor today. Any ideas about what it could be? also any advice on installing the turbo gauge to see if it has boost?
It seems to be the same in all gears.

Update: I connected the turbo gauge tonight. I tried it on the vacuum hose from the throttle body to the solenoid valve - did nothing. Then tried it on the vacuum hose from the inlet manifold to the solenoid valve. It went from - 30 in Hg at idle, normal smooth running to about zero or maybe less than 1 PSI at full throttle up a hill. Just wondering if there is a non return valve in the tapping from the inlet manifold. If there was then my reading would be meaningless. Is there a special place to connect the gauge?

 

[andrewpen]

Update.

I have now used the same Gauge, connected the same way on the 9-5 and I get just under 10 PSI boost, but still get nothing on the 9-3. Anybody know what could cause the turbo to have no boost at all?

 

[Mimmi]

Have you checked wastegate and its rod?

 

[andrewpen]

I checked from the outside

I have checked that the rod is pulling the lever shut, from outside but yet to pull off the Cat to visually check the waste gate. I pulled off the rod and the lever was stopping at a point where I had to pull the rod against its spring a couple of mm to reattach it. I intend to get the cat off to at least check that the turbo can spin freely and the waste gate is closing.

 

[BobSaabit]

I don't know much about the LPT setup... does it have a hose to the wastegate? If so, disconnect it and take a run. See if you get any boost. Next step would probably be a visual check of it. The bottom downpipe bolt will be a PITA to remove if you have an upper cat on that car, but the other two are easy.

 

[Mimmi]

Yes T7 lpt have also BPV and Trionic controls it.

 

[BobSaabit]

Yes T7 lpt have also BPV and Trionic controls it.

Thanks, Mimmi.

So to the OP, try the test I mentioned, see if you get full boost. It should run into the red zone with WOT in 3rd gear... but with your problem and your gauge, you should be able to detect it well before that. FYI - you will hit fuel cut if you run it WOT hard enough (which is like hitting a brick wall when the engine shuts of)

 

[andrewpen]

Thanks,
I tried with the hose to the waste gate off and also blocked off the bypass tube. Still no pressure.
At this stage my next possibilities are that the turbo is not spinning or that there is a leak, or blockage in the inter-cooler.
Any experience of either possibility?

There seemed to be a bit of oil in the by pass tube but not enough to make the car appear to be burning oil, ie no smoke from exhaust on start up like you get when the turbo is on the way out.

Do turbos seize? and if so can this happen and not lose all the oil as happens when they blow seals?

 

[jakejm79]

I had one turbo that had seized but it had been sitting for a while and it also smoked too.

You can try pulling the DP off, that way you can check to see if the turbo actually spins and also test drive it to rule out an exhaust blockage.

You could also blow air in with a shop vac to the turbo intake pipe and then verify you have good flow out at the throttle body.

 

[BobSaabit]

^ and while you have the DP off, you can check the wastegate visually.

 

[andrewpen]

Thanks Guys.
I will try to get the DP off over the weekend.

 

[andrewpen]

Success!

Unbelievable success. I took out the front oxygen sensor (before the precat) and tested it and the turbo gauge shot up into positive territory. I figured that that was proof that the exhaust was blocked. I took off the front section of the exhaust (precat and the main cat) and emptied out the precat. It looked fine on the surface, but about 15mm below the surface it was melted and completely blocked. Below that it was good again. somehow it must be burning unburned fuel and maybe that is a hot spot. I left the main cat as is and now it goes like a scalded cat. The check engine light is on but this could be left over from when I was running without the O2 sensor.

Does anyone know if the 2 sensors will now have a problem as they no longer have any catalyst between them?

Anyway thanks for those who made suggestions.
Is there some way I should tag this as I wish I had been able to find this when I originally searched and think maybe others may find it useful.

 

[BobSaabit]

The upper sensor is pre-cat and tells the engine how the mixture is burning. The ECU uses it to tune on the fly. The lower sensor is post cat and tells the ECU whether or not the cat is working correctly.

I have a feeling you will not be able to get rid of the CEL for the post-cat sensor with no cat in there. You do have some options... You could get a used stock downpipe or a used one. Or you could tune the ECU to shut that sensor off. Or you could get a performance downpipe with a race cat and that would probably take care of it.

 

[andrewpen]

Problem solved

Engine Light went out after a day or 2 so all good now.