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Discussion Starter · #1 ·
Hi,

As you may know I've got a my1992 9000 CD 2.3 Turbo Auto Griffin.

I got it MOT'd yesterday, new brakes fitted (Trent Saab Stage 2 whoo hoo), and at the same time a big service.

Which consisted of the following :

New oil (Shellc Helix Ultra Fully Synthetic), plus filter and sump washer.
New fuel filter.
New air filter element.
Throttle body cleaned.
Cooling system drained, check hoses, and refilled with coolent.
New spark plugs - NGK BCPR7ES-11 gapped to 1.1mm.
New DI Cassette and DI Cassette wiring harness.

When I was bedding in the brakes on one of the acceleration runs I selected 3 instead of D on the Auto box and closed the throttle, as the car accelerated the Turbo boost gauge showed boost all the way into the middle of the red zone and then the car kinda 'sneezed' and pushed the boost back into middle of the yellow.

I tried it again in 3, and the car did the same thing again.

In D it would boost to where it should - the beginning of the broken line on the gauge.

My question - What happened there? The car, engine wise is standard, the TCS system did not engage, and I wasn't at REV limiter because I was only at around 5000 rpm when it happened.

Also, when on my last braking runs the big speed full-on stops.. just as the car nearly stops, the oil light blinks on.. considering that the oil is new and at the correct level.. is this normal ? Never seen this before on my 9-3 when braking hard.
 

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Originally posted by Mark_A:
[qb]Also, when on my last braking runs the big speed full-on stops.. just as the car nearly stops, the oil light blinks on.. considering that the oil is new and at the correct level.. is this normal ?[/qb][/b]
I've seen this on my Aero when testing my brakes after bedding them in, but I assumed I must have underfilled the oil slightly (hard to find a level surface to check the oil level on). However, I don't really know whether it is normal. I haven't seen it since I last changed the oil, although I don't think I've done the same type of braking either.

When you think about it, the oil must really slosh around in there and I think it has quite a lot of room to do it in. It wouldn't surprise me to find that you can briefly slosh all the oil away from the pickup pipe.
 

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Discussion Starter · #3 ·
to clarify..

I only ever drive in 'Drive' and before the work the car boosted to the broken yellow/red line, after the work it still does (which I think is correct and normal).

The sneeze I describe is like a 'big hiccup' as the car dramatically cuts the boost. It only happened on two runs, and then everything settled down and only when the car was locked into '3' (it was a rolling start to get up to a suitable speed for '3').

Now obviously, there were a lot of new parts fitted, and these parts may have replaced parts that were worn out and ineffective - could it have just been that the ECU had not, as yet, corrected for the sudden increase in efficiency that these parts may have brought? i.e. new DI cassette, new plugs - gapped correctly (so bigger - more accurate spark), new fuel filter (better fuel flow), new air filter (better airflow into engine). Hence the reason why everything has settled down and it boosts normally now. P.S. I also run 98 unleaded (euro) octane fuel.
 

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The oil pick up should be at the rear centre of the sump (don't know if it is on a Saab), so that the engine always has a supply of oil under hard acceleration and/or cornering. (A car I have owned previously had the pick up in the front, and would pick up air in flat out corners at 7000 rpm!!! I won't name the manufacturer, but I ended up with a sump with swinging baffles - a small help - and the running with oil 0.5 litre over the max mark which was a big help).

The amount of oil in various parts of the engine varies dramatically with operating conditions. When idling hot, there is little oil being pumped around, and it drains back quickly so most is in the sump. When charging hard near the red line, huge quantities are being pumped around, and so there is a lot in the head at any given moment. Also, there is a large vortex around the crankshaft at these speeds, a phenomenon which caused the designers of large capacity American Vee 8's to use a device known as a windage tray. This is basically a plate with holes/slots that fitted as closely as possible below the crank. Oil flying around or off the crank would hit the tray and drain down, and the vortex effect was prevented from reaching the surface of the oil in the sump. The use of a windage tray increased the power output significantly, as the oily vortex drained a large amount of power. I remember some years ago reading the results from the testing of the 440 cubic inch Chrysler engine used by Jensen (7.2 litres if you prefer). I think the windage tray was worth about 30 bhp.

Anyway, the conditions you describe are ideal for oil delivery problems, i.e. you accelerate hard, pumping most of the oil into the head and the drain paths, and hold a lot as a vortex around the high speed crank. You then brake hard, and cause what little oil remains in the sump to move forward, presumably away from the oil pick up, which then sucks up a bit of air. Although this is to be avoided, a small oil supply pressure drop with the throttle shut is infinitely preferable to any sort of oil supply problem under load. Just don't step on it until the light goes out. Please also check the oil level and make sure you keep it at max.

You may also consider whether the presure switch is entirely accurate.
 

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One of the earlist things I picked up when looking around the Saab sites was a recommendation on either the Quasimotors or Townsend sites to keep the oil at the X mark. 'MAX'

Whoever wrote this said that it helped to increase timing chain life, however it may assist with surge problems. Mark B is entirely correct about windage trays. The benefits sound too good to be true. I have one on my MGV8.
 

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With reference to your boost problem Mark, I've just replaced my DI and the car cut at the broken red line for the first couple of hundred miles, it is now getting back to normal. Wasn't very good for overtaking though as I couldn't put my foot hard down at all.

Neil
 
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