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Discussion Starter #1 (Edited)
So, here's the next little conundrum our sleek Swedish lady has thrown at me.

Today is a public holiday, I am in the middle of nowhere and tomorrow I need to drive 700km. The car is a 2009 9-5 2.0t Biopower Griffin without any power enhancements. I mostly drive on E85.

Current mileage: 210ktm. I bought it with 187ktm on the clock last October.

Since I've had the car, it has been making a noise when accelerating under load at around 2000 RPM. I've had the feeling that it's got slightly louder, but you know how it is when it's your car and the changes are incremental... In any case, it stops at 2300 RPM or so, so isn't constant, even if it is consistent...

The noise is sort of like a rattle, as if something is loose - but nothing obvious is. It's always around 2000 RPM, definitely from the engine area, louder under load, and can't be replicated just by opening the throttle when stationary.

I've had the chain tensioner out a couple of times (see my posts about oil leakage underneath the tensioner) and the chain was close to, if not at, the wear limit.

Anyway, yesterday, WOT in 2nd for a manœuvre, and I noticed the CEL flashing briefly, just as the noise became apparent as I pulled through 2000 RPM. The CEL had never lit or flashed before. I tried a similar manœuvre - same result, CEL flashed and then went off.

Then, today, the same thing happened a couple of times (yes, I was provoking it intentionally) and the CEL stayed on. Codes read were the usual suspects - 0300 and 1300. Reset and carried on.

There was no loss in power, no increased consumption. I changed the DIC - identical symptoms with a known good DIC. I reduced the spark plug gap to 1.0mm - exactly the same symptoms. All vacuum hoses are fresh silicone tubing.

So I am starting to think that the timing chain is sufficiently stretched now that it is beginning to affect the timing under load conditions.

Can anyone with more experience tell me what they think? I know that the chain will need to be done soon in any case, but I'd like to know if there's anything more substantial going on before I invest lots of effort and cash in the old(er) girl...

Cheers!
 

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Discussion Starter #2
Well, I covered the 700km without consequence, but I could make the CEL flash at will.

However, I've changed my theory: I don't believe the chain could be so badly worn that it would cause misfires, without much more serious stuff going on.

A week ago, I changed the water pump. To do this, I had to take off the MAF sensor, the cobra pipe, the bypass pipe. I did not replace any o-rings. My suspicion is that there is now a leak somewhere in the intake tubing after the MAF sensor. This would also explain the white spark plug tips - the engine is taking in more air that the ECU thinks it is, and is therefore running lean all the time. Under load, this causes misfires. The (louder) noise I'm hearing is no chain rattle, it's pinking.

That sounds far more reasonable (and less worrying). I can now look forward to replacing the timing chain on my terms, not on the car's!

Now how to search for a tiny hole somewhere among all that tubing?

Happy Saabing!
 

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Discussion Starter #4 (Edited)
OK, I took everything on the intake side apart between the MAF sensor and the TB, the only issue was the upper TB o-ring, which was completely flattened. Replaced it, put everything back together, symptoms were the same although idle was smoother I think.

So I took out the Tech II which I have access to here, P0300 and P1300 as expected. But then I ran the IDM (DIC) test, and the IDM failed - failure status 225 and check code 59183. I then replaced the IDM with what I thought had been a functional unit and got exactly the same codes on it (after clearing DTCs).

The second IDM was bought used, but I had tested it after buying and it worked fine. Also, what is the probability of both IDMs failing independently in exactly the same way? This makes me suspect that something else is going on. The relevant connectors (IDM and bulkhead) have all been cleaned and reseated.

Any ideas anyone?
 

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Discussion Starter #6
I'll do it this morning. The IDM failure on the Tech II test is intermittent this morning, and no more flashing CEL...

I hate intermittent faults - such a waste of time...
 

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The O ring between Cobra and compressor housing might have fallen off during installation as there is no groove where it could be fixed. This might be a critical section for sucking in addtional air as this area just before the compressor creates the highest vacuum. Under higher load condition everything downstream compressor has higher air pressure than ambient and would blow off air, resulting in running richer.
 

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Discussion Starter #8
Thanks Thaistatos, I checked the o-ring yesterday, it's all fine. The white tips of my spark plugs indicate lean running, and this morning the CEL stopped coming on under acceleration, so something has obviously improved...
 

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Discussion Starter #10
Call it a miracle. I call it a dastardly time wasting intermittent fault...
I sanded down the thermostat housing earth connection point and eyelet, although they looked fairly clean...
 

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If Tech II or openSID is available you should check if O2S1 and O2S2 show rich mixture during full load acceleration to exclude further MAF related errors. Or at least check if spark plug tip color will change over time.
 
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