Boost felt great... till I got hydraulic lock.

AlHounos · Post by **AlHounos** » Sun Jul 23, 2006 8:29 am

Finally got my car up and boosting around, felt awesome. Came home to give some rides, and shut it off, waited about 30seconds and then held the key on the on position while waiting for passenger to get in. Wouldn't start. AFter fooling around, pulled a plug and saw that all 4 cyls were full of gas. I have read about MS leaving injectors open, but I have both MS and injector power off the same wire coming from the main relay. I really don't have any clues right now. I still can't get the car to start, I'm assuming it's fouled plugs.

Any ideas? I really thought I could start enjoying my car.

Keithg · Post by **Keithg** » Sun Jul 23, 2006 9:11 am

is your fuel pump relay coil powered from +12 continuous (not switched)? if so, you may have burned out your fet driver. search the archives. i have a solution on my page for the v2.2 board that i have used for well over a year.

KeithG

http://www.wideopenwest.com/~kgrider/saab/

Posted by email.

AlHounos · Post by **AlHounos** » Sun Jul 23, 2006 5:43 pm

Yes, I have jumpered the fuel pump with a paper clip in my diagnostics box, so my fuel pump is always on when the key is on.

I'm sorry, I forgot to mention I am using a V3 board with 029q2. Does your post still apply? Thanks for your help.

Keithg · Post by **Keithg** » Sun Jul 23, 2006 6:41 pm

I do not mean the 'load' contacts, I am referring to the coil side of the relay. If the coil side has continuous 12V (even on when the key is off), you can damage your fet driver unless you make other accomodations. If, on the stim, the injector output leds are on solid, the fet driver chip is a likely culprit and the above scenario is a possible cause.

KeithG

Posted by email.

AlHounos · Post by **AlHounos** » Mon Jul 24, 2006 4:02 pm

Did a little reading... The coil side does not have continuous 12V. The stock ECU supplies 12v to the fuel pump and the circuit is completed by the opening of the flapper door in the AFM.

I don't have a stim, because I bought my MS prebuilt. Also, my leds are disabled due to spark mods.

Just checked my injector harness, no faults. 12v on one pin, zero continuity to block on the other.
Checked my injectors as well, all still read 3ohms. (running 7ohm resistors PWM at 100% and 25.4ms)
Took out the MS and U4 looks to be in good shape. I am having difficulty figuring out how to actually test it without a stim.
All fuses are ok.

Can I use the LED tester (led w/330 ohm resistor on pos. leg) to test the inj1 and inj2 holes in my board while cranking? I assume that If the LED is on no matter what, my FETs are definately fried.

AlHounos · Post by **AlHounos** » Mon Jul 24, 2006 5:55 pm

So, for a course of action:

Connect a 12v led to the injector connectors to check for flashing while cranking. Constantly lit would mean burned FET.
Fix if necessary.
Get new plugs and see if it starts.
Wire up MS to control fuel pump.

But I still don't understand what caused the injectors to stay open in the first place, if my fuel pump does not seem to be the culprit.

spag · Post by **spag** » Tue Jul 25, 2006 12:49 am

If the injector driver goes, then the injectors just stay open, so any pump activity will tip fuel in (supprisingly fast !!!).

Also, any residual pressure in the line from the fuel pump will get dumped in too. With long fuel lines @3 bar it can be a reasonably messy amount of fuel, if you erm, happen to undo a union etc, so would make a decent puddle in the cylinders ???

AlHounos · Post by **AlHounos** » Tue Jul 25, 2006 8:41 am

Yes, I understand that somehow the injectors were held open, but how could the injector drivers fail? That seems like a pretty huge problem with the MS system. I have both injector and MS power coming from the same source!

AlHounos · Post by **AlHounos** » Tue Jul 25, 2006 2:53 pm

Ok, I hooked up a 12v LED (actually my motorcycle taillight) to the Injector connectors and got a steady flashing while cranking, and no lights with the key on but not cranking.

So this means my fet drivers are ok?

Edit: They must be ok because I just got back from a 5 min. drive. Everything seems the same as before the lock. Luckily no bent rods or burned injectors.

Now how the hell do I keep it from happening again?