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Discussion Starter #1
Hi all,

my 9-5 suddenly, from one day to the next, dropped to about 1/3 of full power. no misfires, no popping or banging, just no urge. Immediate suspicion was the turbo or associated plumbing, so I started a series of checks as follows, in the order given:
Turbo rotor- spins freely. Took off the exhaust connection and gave a little gas, you can hear it spin up. No weird noises like out-of balance, shot bearings etc.
Wastegate shaft rotates freely, wastegate in good condition and seals tightly.
Disconnected both wastegate actuator air supply hose and disabled dump valve to keep it shut (the connection between the cobra and turbo inlet - ) - no effect,
swapped air mass flowmeter for a known good one. No change.
Checked sparkplugs - no misfires but all of them have white-coloured central electrode. 2 months ago when I checked they were light coffee-coloured. So I suspect lack of fuel.
Checked fuel rail pressure - 35psi with just pump running (and not engine), 37psi with engine running. Should be ideally about 45psi, but I don't think this is the cause of all the power loss - unless you good people can tell me different....but read on..
Swapped fuel pump for a known good one. No change. And no apparent blockage in the inlet filter.
Got hold of a diagnostic meter, no fault codes. But the lambda sensor reading was 0.176V, which is weak. Stoichiometric ratio is 0.45V, rich limit is about 0.9V. Don't know if this was so weak just because it was at idle, will give it a run this weekend with the diagnostic meter connected.
finally, exhaust gas temperature at idle is very high. normally you can hold your hand in the exhaust stream from the tailpipe, it's normally just warm, now its uncomfortably hot. Another symptom of weak mixture.
I still suspect lack of fuelling, and all I can think of is that the fuel supply line (is there another inline filter apart from the pump inlet filter?) has become kinked or blocked.
I haven't looked at the injectors, I think its unlikely that all 4 of them would play up.
Electrics ok, chargng voltage 14.4V

Anyone else had this? All suggestions gratefully received.
 

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How do you know there are no misfires, do you have a TECH2?



Would a restricted CAT cause higher heat at the exhaust end at idle?

I'd swap out the DIC for a quick elimination.
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It could if the flow is restricted enough since there'd be no physical force pushing out the heat.
When my cat was dying, the exhaust end was unbelievably hot.

Think of it this way.... If it can't extract the heat by pushing it out, it will just continue to rise in temperature since it has nowhere to go, super heating the pipes and everything.
 

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Discussion Starter #6
Thanks guys. I'll try separating the exhaust upstream of the cat, see if that gets things moving. The DIC is new. But I'll swap it out first for one that is known to be good, it's an easy check.
 

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As a thought, when my car was in last week for a stumbling idle they found the wire that runs around the right (US Passenger) side of the engine. to go to the valve on the top of the COBRA to have an open. The car ran pretty well above idle but now it runs like a scalded dog. WAY more power.

The point is that the wiring harnesses in these cars are getting old and cracks are bound to happen. having a Tech 2 and knowing how to use to to chase stuff like this is a real benefit (I have one and don't really know how to use it for this kind of stuff).

Still didn't figure out the stumbling idle, but this was a pleasant surprise.
 

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Discussion Starter #8
Yes, sadly these cars will just become more and more difficult to diagnose. It would not surprise me if despite having no fault codes, my ecu turns out to be faulty. But haven't reached that point yet in the process.
 

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Discussion Starter #9
OK.
I'm on the point of admitting defeat and taking it to the hated fat man in the Saab garage. But in a last bid to see if anyone can come up with something that I've not thought of, heres a summary:

symptoms
only about 1/2 normal power. Up to 2500rpm it behaves perfectly normal.
diagnostic tool tells me that at full throttle and 3500rpm it's only making 1.12 bar in the inlet manifold. which says that the turbo is operating, but not generating enough boost -I believe because its' not getting enough exhaust energy to generate any more. At the same time its making 1.12 bar, the absolute throttle position was at 90% (also from the diagnostic tool)
No leaks in exhaust manifold. Exhaust system not blocked.

As advised above in previous posts I have changed the fuel pump and fuel pressure regulator. Pressure now ok and fuel pump sounds normal so I believe the fuel filter is OK too. (if that was blocked the pump would struggle to send fuel around the recirculation loop via the fuel pressure regulator, and that seems not to be the case.)

I wanted to swap the ECU from an identical model but I guess the VIN number has to correspond - anyway it didn;t start, and that ecu works fine in its own car. No fault codes on the original ECU
Air mass flow meter has been swapped for a known good one, no change.
Wastegate actuator has been disconnected to force wastegate shut, no change. Wastegate is in good condition and shuts tightly.
Air bleed valve from Cobra to turbo inlet has been disconnected so that it cant bleed air back, no change.
compression good on all cylinders.
Spark good on all cylinders.
All air/vacuum lines in position and not leaking.
No leaks in intercooler or hoses

WTF is going on? anyone have any further ideas? I have the distinct impression that for some reason the ECU is not wanting to send more fuel.








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Just a very slight possibility - I didn't see whether you have checked for cracked or leaking intercooler hoses or a leak from the intercooler itself. This could mimic a leaking waste gate.
 

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How much boost are you getting below 2500 RPM?

If you can get proper full boost below your critical RPM, then I would think that the turbo and intake plumbing is all okay.

Just reading the symptoms, I would think "exhaust plugged", but you have checked that.

A Tech II would help you get a fuller picture of what the ECU is seeing and doing. That would also require the knowledge to interpret the readings properly.

Hopefully the fat man got fat through his knowledge and ability to diagnose and fix obscure Saab problems.
 

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Discussion Starter #14
Nocturne, I have to thank you, and admit that for a month (after you initial suggestion) I've been on a wild goose chase, believing that fuel pressure was the problem. There was some flow through the exhaust, (of course) and I WAS on the point of running it up the road with the nuts on the exhaust studs on the turbo wound back to allow a gap. But I got diverted, and only did this check this morning after your reminder. It ran normally. So a new cat required. thanks again.
For future reference if anyone else suspects they have this problem, my wife reported that there was a hot, burning smell coming into the car for a few days before it really dropped to its knees. I thought that was down to an exhaust leak. Wrong.
 

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Nocturne, I have to thank you, and admit that for a month (after you initial suggestion) I've been on a wild goose chase, believing that fuel pressure was the problem. There was some flow through the exhaust, (of course) and I WAS on the point of running it up the road with the nuts on the exhaust studs on the turbo wound back to allow a gap. But I got diverted, and only did this check this morning after your reminder. It ran normally. So a new cat required. thanks again.
For future reference if anyone else suspects they have this problem, my wife reported that there was a hot, burning smell coming into the car for a few days before it really dropped to its knees. I thought that was down to an exhaust leak. Wrong.
No problem! I've been through 2 blocked cats and 3 DIC's so I'm pretty familiar with the symptoms and I'm a firm believer in starting diagnostics with the cheapest avenue being the first step lol.
We're all here to help and I'm glad you got down to the root of the issue.
 

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It's not like how it sounds lol. When I first bought the car the cat was already plugged (I just knew it was only getting 3 psi of boost max) but the dealers mechanic refused to believe that it was the cat so I couldn't pick the car up right away. After a month, I told them I had no choice now since I sold my current car. I have to pick it up but I'll bring it back when I have time so they can continue working on it. They replaced the turbo, vacuum lines, boost solenoid, boost controller, MAF sensor, DIC and some other things I can't recall right now. Anyway, I picked up the car and drove it for the week taking it easy even though it squealed, screeched and screamed constantly. I had my wife hit the gas one day while I listened with the hood open and that's when I realized what was happening. The next day I got the P0420 or whatever Cat efficiency code. Called the dealers mechanic, told him what happened, he didn't believe me. Took the car there and he removed the upstream 02 sensor. Car took off like a Space-X rocket. Replaced the cat and it was fine.
However, since everything had become super heated, my muffler internally melted down and I had 20 ft trails of fiber glass spewing out of the tail pipe now that there was actual pressure coming out.
At the time it was a Pro Parts Sweden DIC that was in the car, they replaced it with another Pro Parts DIC. Eventually that DIC began to die (random misfire blinking CEL). I didn't have the money for an original so I got some other aftermarket DIC which ran solid for just under a year.
When it went, it was catastrophic. The car was fine one second, then the next, it just started violently shaking, then lurching, then surging and then.... Nothing, Engine shut off at 80 km/h. I coasted to a stop. Swapped in my dying Pro Parts DIC, got the car home. Ordered the NGK and put it in right away. Noticed the car had no power. Just like when I first bought it. Checked the heat at the tail pipe and it was boiling hot. You could hear the metal popping and snapping. Took the car in to a muffler shop, when he took the cat off and looked inside, he was shocked. The whole cat looked like cream coloured concrete inside. He couldn't believe at first that this happened that quickly. But then he thought about it and said if the fuel either was or wasn't getting there because the ignition wasn't right and all the wrong signals were getting sent, the cat would either melt away, or melt and solidify depending on what was happening in the engine (extremely rich or extremely lean condition).
Only twice did I get a CEL during this entire thing.
 

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Discussion Starter #20
Hmmm. Had to change the DIC on this car about 6months ago, and noticed that the previous DIC was also aftermarket. I'm wondering if this was the thing that started the collapse of the cat. And what happened recently would have happened anyway, the rot maybe having already been established. One thing perhaps positive, the spark plugs fitted along with the DIC that came with the car, were wrong. Correct ones now fitted so I hope when I fit a new cat it won't be taken down again in no time........????
 
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