S70R Low boost when hot?

[galion]

Hi all,
Im Having problems with my 1998 S70R

At start up, only when cold, it has an agressive acceleration, I can really feel the boost building up at about 3000 rpm. Very fast!

But... few minutes later, when the car starts reaching its adecuate temp, it turns sluggish and less responsive at all RPM range, I can even hear a slightly different exhaust note. At this time, the car stills runs OK, no hesitation at all nor rough idling, but theres no more "kick my back to the seat" feeling.

I can also hear a slight hissing sound coming from inside the dash (back of the instrument cluster) but I guess if theres a vac leak there, it has nothing to do with the turbo performance. Right?

What about a clogged Cat?, though not OBDII codes thrown from the Cat Sensor.


Any hints? Thanks

[mikezero]

thats turbo car's for u, all petrol turbo's ive had, have done that

[pzorb]

Maybe heat soak? Check the intake for leaks of hot engine bay air?

[siamblue]

Galion whereabouts are you? what temps are you running the car at?

as above sounds like heat soak.


Gary

[BlackBeast]

What air filter do you have? Standard? Cone?

[galion]

Thanks

Filter is new, standard type.
Ambient temperature is 75 F

Just neasure boost while hot, its about 6 psi at full throtle, with pikes of 7 psi. sounds too low to me.

Actually the engine bay seems pretty hot to me, I can hardly touch the hood or fenders.

[siamblue]

You would be surprised at how quick these crs soak up the heat, at the Avon Park 1/4 mile I did 4 runs all day, the first one car felt fine but after sitting in the traffic you could feel the car was getting slower after every run, and that day it was very mild in England,
So running at 23 degree C around town will sure get too the car.

Gary

[galion]

I checked the Air Mass Meter as someone suggested; I found that the clamp of plastic hose that exits the AMM was totally loose, then I cleaned the contacts at the plug, and went for a drive.

As Usual; At start up when cold, the car was very powerful; so I kept on driving waiting for it to warm up and expecting to start loosing its boost, BUT it never happened!!! I kept test driving for the rest of the evening without any problems.

Now I dont know what does it have to do with the symptoms I described early, Do you?

By the way, I still hear a hissing sound ( Bpsssssss...) while the turbo starts to build up its boost, Maybe thats the way it should work.

Thanks

[BlackBeast]

Its probably cause you've been boosting from cold and the turbo is slowly wearing out!

[galion]

I know boosting when cold is not good for the turbo; but just did that a few times only for testing purpouses.

I think the problem had something to do with the MAF Sensor false reading.

Intake air was by passing and not going throught the MAF due to the loose hose and clamp, that would result in a lean mixture when hot, with the described lack of power at full throtle.

When cold, MAF reading is not that important, mixture is rich so no boost problems were present at all.

what do yall think?
Thanks