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Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, Tech Trainer
Category: Saab
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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My 1999 Saab is acting like it is starving and misfiring.

Customer Question

My 1999 Saab is acting like it is starving for fuel and misfiring. What am I missing ?
Submitted: 1 year ago.
Category: Saab
Expert:  Lou P. replied 1 year ago.

Hello,

can you elaborate on your issue? and what you may have tested and replaced or if you are doing the work or not?

Customer: replied 1 year ago.
I have replaced and checked the following:1. New OEM Swedish fuel pump less than a year ago - tested for 43PSI with key on and 38PSI at the rail at idle, new fuel filter
2. New Bosch FPR
3. New OEM DIC
4. New correct resistor type NGK plugs )previous new set 1-month old was showing lots of soot so i though DIC was toast)
5. New OEM intercooler to charge pipe hose, checked and cleaned the charge pipe
6. OEM Throttle body from a low miles donor with new gasket and charge pipe oring
7. Saab PCV revision kit and all rubber pcv lines replaced along with the check valves
8. Previous owner replaced the turbo
9. Compression is ~210 across the cylinder, does not burn oil, does not overheat
10. Pulleys and drive belt replaced
11. New battery, fresh fluidsKey ON - Check OKAfter the car has a chance to idle for a while or go for a short drive it acts like it is fuel cutting and not responding the the accelerator. This happens at moderate boost and the car hesitates then jerks into motion. It is not related to a change of gears, if pushed further the car will throw P0300 and P1300 ( hence again I thought it was the DIC). After it starts the the erratic acceleration pattern the Idle does the same and the car will eventually stall in idle with no codes.
Customer: replied 1 year ago.
oh and sorry this is a 1999 9-5 2.3T
Customer: replied 1 year ago.
113k on it
Expert:  Lou P. replied 1 year ago.

ok that is a lot, let me go over it and see what i can do to assist.

Customer: replied 1 year ago.
I know :/ the car drove just fine for about 2 months after the fuel pump replacement then started the current behavior. Also the speedo stopped working at about the same time.
Expert:  Lou P. replied 1 year ago.

ok gotcha

Customer: replied 1 year ago.
Any ideas ?
Expert:  Lou P. replied 1 year ago.

man i went over all of it and even called a saab tech i used to work with and he said that without being near the car and seeing the values this will be a hard one for us. so i will have to opt out maybe there is another expert that has had a similar issue that can assist , i wish you luck Lou.

Expert:  Juan Crespo replied 1 year ago.

Hello. Different expert here.

Any chance of plugging in a scan tool capable of reading engine PIDs at different engine conditions and sharing that data? Waveforms from the DIC?

Customer: replied 1 year ago.
I can get to some PIDs with my Actron, I did have a friend plug-in Tech2 and look at the knock/misfire count and there was nothing out of norm. Which PID's do you want me to read ?
Expert:  Juan Crespo replied 1 year ago.

With the Tech-II, I'd like to get any codes and their accompanying freeze-frame data; also would like to get crank sensor data at the various driving/load conditions; as well as fuel trim percentages, plus injector-on times, and O2 sensor voltages and switching times in response to the different driving/load conditions.

Also very important would be those waveforms from the DIC that could show us the different burn times and how the ignition system is behaving in general under different load conditions.

To give you just a random example of what I'm taking about: a long injector-on time at the same time fuel trim goes lean, and crank sensor slows down, and burn time gets longer, and O2 voltage goes down, and O2 switching frequency slows down would point to an under fueling condition.

That's why those tools are so necessary for this kind of driveability diagnosis. Without information we get from them, all we can do is throw parts at the problem and then hope that whatever it was we threw at it fixes the problem.

Customer: replied 1 year ago.
Got some runtime data captured with the Tech2 - waiting for the data to be sent to me. I did go ahead and replace the MAF (mine looked very rough) and put on a new air element. Re-examined all connections from the bottom to the throttle body and did not find any problems. Checked the CPS and got correct resistance. Replaced the DIC with yet another fully functional - no luck.
Expert:  Juan Crespo replied 1 year ago.

We'll wait for that data. Also, I hope you didn't misunderstand my request to see waveforms from the DIC for anything more than just that. I wasn't implying the DIC was bad. Just need to see those burn times.

Customer: replied 1 year ago.
I got what you meant, just not very versed with Tech 2 to get it to generate a waveform for me
Expert:  Juan Crespo replied 1 year ago.

Tech-II can't generate waveforms; those you get on a scope screen. I was just telling you that I need to see the waveforms. Never said they had to come from the Tech-II.

In view of our latest exchange, I don't think I'll be able to help you. I'll opt out so others may try. Do not reply until another expert responds or the site will cycle your request back to me.

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