Saab 9000 Boost loss

[Twinsen]

Do the spark plugs look alike?

A leaking booster won't cause engine problems for a speed density system. The IAC valve will compensate and if it can't, you'll get a high idle code. Your O2 sensor output is normal. Do you have brake assist a minute or so after the engine shuts off?

A clogged fuel filter is possible.

So is a clogged injector. If your dad's buddy has a known good injector around, you can swap it in for yours one at a time and look for any change in STFT at idle. A single, partially clogged injector will raise your trims.

[MrMuffin667]

Well The booster does need replaced, its a shame that wont affect the lean condition though.

As far as the plugs go, all of them look identical, so whats happening to one is happening to all. I know the o2 sensor looks normal, butt the short term fuel trim is reflecting that the ecu is conpensatying wayy more than it normally should for a lean condition. It was hanging around 8-10%, when it should have been 0-2%

[MrMuffin667]

**Update**

I replaced the Fuel filter this weekend. Made a huge difference. The Filter that was in there had a date written on it in sharpie that said 12/15/05. So it was definantley time for it. When i blew through it, i had to use every ounce of my being to force air through the filter, so it was clearly clogged.

Performance and acceleration increased, starting is easier, and the engine runs cooler. BUT, my concern is that now, it never knocks during boost, but on the highway, 65-80mph, 2700-3200rpm, if i use small throttle for a slight acceleration, it knocks like a madman. 2-7 flashes from my knock light. these knock only occur when the car is cruising in vaccumm. Is this an issue or no biggie?

[Twinsen]

Disconnect your battery to reset your ECU. The fuel table and trims have probably been trashed by driving with a clogged filter.

[MrMuffin667]

Already did so, short term fuel trim ranges from -0.76 to 4.32%

[rawill]

Originally Posted by MrMuffin667

**Update**

I replaced the Fuel filter this weekend. Made a huge difference.

Good you got that fixed, even if you have a new issue. But as said above.

An ECU reset and some adaption runs may fix the issue,
After all the ECU has been trying to compensate for low fuel pressure and volume.

[MrMuffin667]

I will work on getting an adaptation taken care of.

on the other side, it is nice i got my knock resovled, but i still have the first issue we discussed. I still have a boost surging issue when hitting full or close to full boost. i took off my aftermarket BOV and put the stock back on and it didnt fix anything.

[Twinsen]

Is it going into fuel cut? If so, the adaptation should take care of it.

[MrMuffin667]

No, is definantley not fuel cut. Its just a boost surge. I hit full boost, (10-12psi) and then the boost surges (between 8-10), the car surges, and I can hear the engine surging.

[MrMuffin667]

Update:
Curious if anybody can clarify if this is normal or not. Tested my map sensor today. Voltage values were a little off, so I hooked up the scan tool. When the car was idling, it registered 46kPa (6.67 psi). When under full boost (10psi) it measured 117kPa, which if my math is right that equals 17psi, which is way off...so im curious if there is an issue or if it's normal computer behavior?

[Twinsen]

The reported PSI numbers are absolute. Be careful not to mix them up with boost PSI, which is relative to atmospheric pressure (14.7). Are you checking the actual boost with a numbered gauge? 117kPa corresponds to about 2 PSI of boost.

[MrMuffin667]

Yes. I have a glow shift elite electronic boost gauge.

[MrMuffin667]

I'm just trying to eliminate every possible cause of this knock issue. I have lost all leads as to what could cause it

[chengny]

Not pretty but you should be able to see the voltage values:



The ECM supplies 5VDC at pin 3, the variable voltage generated by the pressure sensor comes out on pin 2 and pin 1 is to ground.

Hard to monitor without a BOB.

Here is a pin out diagram:

[Twinsen]

Don't rule out preignition. Carbon deposits have been known to cause these issues.

[rawill]

Have you read this thread:

http://forum.ecuproject.com/showthre...st-oscillation

[sp53]

Direct Ignition

[MrMuffin667]

The problem the whole time has been a detonation/preignition issue. Direct Ignition coil was replaced, all sensors were tested, engine was seafoamed, vacuum lines replaced, and plugs replaced. And the problem still persisted.

Alas, last night i figured it out. The whole time its been the engine temp. Earlier in this thread I mentioned that the engine temp gets close to 225 sometimes, but i was told not to pay mind to it as long as the fan functioned properly. I found the reason for my overheating was a crack in the top of the reserviour, so i had a pressure leak. and when the coolant wasnt pressurized, it began to heat up easily. I bought a new tank and put it in, and the engine temp has been holding a steady 195 with zero knocks for the past 25 miles.

The boost surge though (original point of the thread is still unresolved Though the link that Rawill just posted is the exact same thing thats happened to my car, so im gunna look deeper into that.

[Twinsen]

Glad you got it sorted. It's strange that you weren't rapidly losing coolant with a crack in the system.

I see 220F sometimes during prolonged idling, then the fan kicks on. When moving again, it quickly drops to 195F.

I've had some oscillation along with overboosting. I fixed it with an inline valve meant for an aquarium installed on the BPC line which vents to the plastic tube on the compressor inlet. By restricting the flow of air out of the valve, it broke the feedback loop that was causing the oscillation.

[MrMuffin667]

The crack was in the dead center on the top of the tank. Coolant came out slightly, but it was mostly bubbles and air that escaped.

I do see 220 during idling, but the other night i stopped at Mcdonalds, and went through the drive through. I ordered my food, and as I drove around I noticed that my temp gauge said 240, and I had only been sitting still for at the most 2 minutes. Thats when I knew i needed to do something. Driving on the highway i would hold a steady 205.

As for the boost problem, I will try that. Was it just a restrictor valve that you used?