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Turbo issues

3K views 25 replies 9 participants last post by  jawax30 
#1 ·
I have a 2000 mt running a rebuilt saab 9-3 Garret t25 turbo, stock ecu, cartech fmu, stock injectors, full catless 2 inch exhaust, it spools great running 5 lbs.
My problem is she runs super Lean some times other times it's 9;1 or so,
I can't figure out what's going on with it. Usually happens at wot
 
#2 ·
This would be in the tuning arena. A place i dont think the Insight community has as good a grasp on as it does electronics. If youre using stock injectors with stock ecu and youre running lean at full load then you need to look into why your fuel delivery isnt up to par. Could be the pump not producing, injectors reaching their flow limit, or the FMU not getting proper input to give proper output. Spooling is only a causality of exhaust flow. You can spool a turbo all day but managing fuel delivery and spark knock is key in forced induction. I can't imagine a scenario where going forced induction on stock components is wise unless you have done the math for fuel delivery and flow.
 
#4 ·
In my travels, and slapping a turbo on 3 of these cars, I can tell you the ecu is an absolute pain in the *** to deal with. The STFT is not limited to -25/+25 fuel, and it WILL pull everything you are trying to add with that FMU. This is the primary reason I went with an AEM FI/C-6. I know Sam(RainSux on the forums) is running an FMU, but I'm not sure if he is running an O2 fooler to trick the ECU into not seeing the extra fuel he is adding.

Also, why no pics? I would love to see pics of your setup!
 
#5 ·
In my travels, and slapping a turbo on 3 of these cars, I can tell you the ecu is an absolute pain in the *** to deal with. The STFT is not limited to -25/+25 fuel, and it WILL pull everything you are trying to add with that FMU. This is the primary reason I went with an AEM FI/C-6. I know Sam(RainSux on the forums) is running an FMU, but I'm not sure if he is running an O2 fooler to trick the ECU into not seeing the extra fuel he is adding.

Also, why no pics? I would love to see pics of your setup!

I have a fouler in the downstream sensor. Should I do one in the upstream be done to. I wonder if running bigger injectors would help as well
 
#6 ·
No absolutely do not put one in the upstream. As for injectors, unless you are going with a piggyback ECU like the aem fic 6, then no, there would be no way to control the extra fuel.
 
#8 ·
What are you using to monitor the AFR?
Maybe the turbo is too big?
 
#12 ·
Try changing your driving style and see if that makes a difference.

Instead of trying to get max. boost all at once, gradually go into the max. boost mode.
 
#24 ·
Long term fuel trims should not be resetting every time you start the car, your short term trims do though. If long term trims are resetting every time you power off your car is wired wrong.

From my memory, when I had the stock ecu and an FMU my AFR was terribly inconsistent all the time. I also remember my car not going into open loop when it should have as well though, often targeting 14.7 while in boost. In hind sight there may have been some other issues at play with all of that though.

As to just dropping in the Camry injectors and sending it, you're going to get a CEL after a little while. The ECU will get mad that you're short term fuel trims are maxed out. I don't remember if that really affects anything though. I do remember that my AFR's were pretty spot on when in boost though.

I'd love to be able to have a stock car to play with now days with how much more I know now days...
 
#25 ·
Just something to add. Right now I am running with an FMU and have decent control of the AFRs. From my fuel system testing the problem isn't the computer taking fuel away (as it actually tries to maintain a 12.5 AFR under WOT) but actually the inability of the stock fuel system to deliver fuel pressure in excess of 50 psi. I tested this on my car by connecting a fuel pressure gauge to the rail then kinking the return line. To get around this I have a second fuel pump in series with the fuel feed that kicks in under boost. With this setup I can get up to 140 psi in my fuel rail with the FMU, so it's able to provide adequate fuel enrichment for up to 8psi of boost. All this has been observed from the OBD C&C, but I'm not sure I trust that anymore (I had an incident where the line to my FMU was disconnected and I remember reading ok AFRs even though it seemed to be leaning out bad) I'll be putting an additional wideband in soon so I'll report back on this.

The setup looks super janky with the fuel pump from a 90s volvo sitting over the valve cover but it has been working for me. Although right now I'm working on modifying a Speeduino to take over control of fuel and spark while retaining IMA, as I'd like to be able to retard the ignition timing and have full control of my injectors to get the most out of my setup, maybe even run E85 flex fuel!

90633


- Jack
 
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