[Oyabun]

hey all

i got a 96 900SE and ever since i got it it has had a problem with gas mileage.

i replaced both o2 sensors, put in new ngk plugs, even tested the ignition cassette by the walkthrough on thesaabsite.com. The sparks all fired fine and the discharge in the end was fine too. i turned the cassette upside down and ran it that way too and it was fine that way also.

So right now the plugs are as black as they get after 200 miles, although i can easily wipe the carbon off, then its nice brown below it.

Anyone got any idea what i should check next? my exhaust smells... could a bad cat cause this?

TIA
DJ

 

[earthworm]

The MAF should be cleaned and checked, the fuel pressure regulator must be checked for leaks and the vacuum supply..

PMI may well have the answer.

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The excess unburned gas will cause a CEL and even ruin the cat-conv.

A cat-conv with collapsed internals can cause the engine not to run..
The car would be very hard to start and it would overheat..I'd say this is a rare occurrence..

 

[FlyPenFly]

is it possible to have cel codes without the cel light coming on? Do I just go to Autozone and ask to get it read? Do they know where to hook up to?

 

[Oyabun]

flypenfly: ok, the cel light i think always comes on if theres some error in the engine that is programmed to trigger it. and yes, autozone reads it for free, as long as its obd2(96>)

earthworm: i dont think my car has a maf sensor, because there isnt one before the turbo. there is though this:

this is routed into the intake manifold and just loops from it back into it. also why is there electrical tape on the line.. i took it off there doesnt appear to be any cracks in it

then another question while i was looking is this bosch sensor, i assume this is the MAP sensor?

and also theres a nipple without anything on it on the front side of the intake manifold inlet

i dont have a serivce manual yet, but im ordering it tonight

also, where is the fuel pressure regulator on this ;oops:

TIA
dJ

 

[Slaab4life]

In your first photo, the device you have circled is the Idle Air Control Valve (worth cleaning). Device on throttle body that you have circled in the second photo is the throttle position sensor.
FPR is located on the end of the fuel rail on the opposite side from the timing chain (the little silver thing wrapped in the red box):

 

[Oyabun]

Alright so I'll be cleaning the IACV, but i still need to know where the MAP or MAF is so I can clean it too, whichever it has..

Also, if thats the idle air control valve then whats the screw thats in the metal pipe at the bend right before the turbo? at first i thought that was the IACV..

Thanks for the help guys.

 

[Oyabun]

bump, wheres the MAP sensor!

 

[PMI]

bump, wheres the MAP sensor!

Don't try to clean it, just make sure the hose leading from the throtle body to the MAP sensor is intact.

 

[Oyabun]

So I cleaned the IACV and the MAP sensor is in tact..Not sure what else i can do. Could it be the cat? Exaust smell is rather strong...

 

[Slaab4life]

Do you have any codes showing for either of the oxygen sensors?

Did you ever figure out what vacuum line goes to that nipple with nothing on it?

This nipple could be something important to look into. It thats open to the atmosphere then you basically have a massive vacuum or boost leak going on. That nipple on my N/A engine goes to the PCV nipple on the valvecover. Where does that vacuum line that is passing just under the throttle body coolant nipple (the one just to the right of the circled vacuum nipple) go to? Then again, I could just be crying wolf, I have a few blank nipples on my throttle body that just have some plugs over them since they are not in use.

 

[Marks900SE]

You have the circled the left of the 2 that are right there correct?

The left one is for the Oil Check Valve coming from the valve cover, and shouldn't have any effect on gas mileage. At the top of the valve cover there is a grey plastic "Y" and one will have a little vacuum hose with the check valve on it leading to that nipple that you have with nothing attached.

 

[earthworm]

Oyabun, check out that 1" or so hose connecting the IACV unit to the throttle control valve. It appears to be swollen or just too large at one end.

Maybe it is a wrong replacement, these hoses must not leak...
There is also a unused vacuum port below the IACV.....

 

[Oyabun]

Thanks for the help guys, I really appreciate it.

 

[PMI]

Did you ever figure out what vacuum line goes to that nipple with nothing on it?

PCV port, same as on the n/a model. Air leaks out when on boost, and in when running on vacuum. This should be connected or capped. Boost leak is not a big problem, just lowers the power, but it leaks IN when on vacuum, which is most of the time. O2 sensor reads excess air as lean, ecu adds fuel, the amount of fuel being burned in the engine goes up - poor gas mileage, and fouled plugs (maybe). TB heating line looks to be bypassed in the pic, so who knows what else has been done to this engine... If the crankcase ventilation is messed up, there could be other problems. I would try to put it back the way it was supposed to be, get the engine running right before starting to modify it.