Slight hesitation at 2100-2300 rpm?

[jianelli]

Hi,
My 2000 9-5 2.3 lpt with 208k runs great except around 2200rpm where it sputters slightly.... I just replaced the water pump and had a few things loosened up around the throttle body. Could I have messed up something? any ideas what to look for? should I try some Fuel system cleaner and a prayer? No CEL or anything else, just this slight hesitation....
Thanks for any help...  John

[sgould]

Might be worth getting the codes read by a good code reader or a Saab Tech2.  You may have some "Pending Codes" stored in the ECU.  There are some faults that need to occur several times before an engine light comes on.

I had pending codes on my DI failure misfire.  The DI was broken but it didn't misfire badly enough or often enough to throw a light, but the codes were "waiting" when I checked with the code reader.

I have an Autop D900 code reader, bought from eBay.  There are similar readers out there.

[jianelli]

Thanks. It does seem like it may be the DI... Last time I replaced it was 70k ago... The misfire will show up on an OBD II? Thanks much

[sgould]

There are lots of codes but the common ones that you see with a DI failure are P1312 & p1334.  Possibly P1300 & P0344 (maybe it's P0334...). I'm not by my laptop at the moment so I can't check.

[phoenix]

DI misfire related issues mainly start with P13--



P1300- Random misfire, often accompanied by P1312 & P1334
P1301-1304 Cylinder specific misfire
P1310- no power to DI
P1312, 1334 Combustion detection problem on cyls 1/2 or 3/4
P1390- Random misfire, fuel level low
P1391-1394 Cylinder specific misfire, fuel level low

I can't see any P0334 but there are

P0300- Random misfire
P0301- P0304 Cylinder specific misfire (often with P1312, P1334)

[sgould]

P0334 came up on my code reader last autumn in Italy.  It's a generic "Camshaft sensor failure" that isn't listed by Saab.  Don't know quite what software Saab use to collect failure codes, but it was on the code reader at at top of the Stelvio pass, along with P1312 & P1334. That was more codes than I had seen up to then. I only did a run downhill from there to the hotel where I changed the DI.

The whole saga was "blogged" here... http://www.saabtechtalk.com/forum/index.php?topic=2333.0

[phoenix]

I suspect that may be the generic reader not reading the correct code

Trionic derives an equivalent of a cam shaft position detection via the combustion detection in the cylinders, which would be P1312 or P1334.

[jianelli]

Well the MY00 2.3. LPT now has 212k. I put a new DI cassette and a new fuel pump (the whole assembly, not just the motor) and I still get a a cough when I downshift and accelerate to pass. Yesterday it coughed twice and then caught and accelerated like it should. Is this a PCV issue? Throttle body? Thanks for any help...
John

[Steve440]

Have you checked the fuel pressure?

There is a pressure regulator on the fuel rail.

Steve

[nine-fiver]

Jianelli,

How did you replace just the fuel pump motor? Since doing mine the same way I have had ongoing issues with the section of pipe to the pickup, being submersed in fuel. It rots out pretty quickly. If there is a kink in the line you will lose pressure too, so the length of it is important. How well does the car start too? If it is a bit grumpy that is a clue too.

[jianelli]

I have not checked the fuel pressure. It starts fine and is running better than it did before these new parts, just not perfect.
I replaced the entire unit, plastic and motor preassmbled, so I don't have to worry about hose lengths or kinks. The pump went in ok with a bit of jiggling and turning it this way and that. I did mark a reference point so the new one is pretty close to where the old one was. The car really just coughs once when I floor it, then takes off... It starts fine and runs well otherwise.
Maybe I'll try a pressure regulator...
Thanks!

[nine-fiver]

Sounds good from the fuel delivery side then. It may be as simple as an air leak upsetting the air-fuel mix. Check all clamps with a 7mm spanner, not a screw driver. Check the hood clamp onto the throttle body, that one is critical.
How old is the fuel filter and air filter?

[jianelli]

Fuel filter 1 year, air filter 7 months... I drive about 22k a year...