Car stalled when I first turned on the car after uncorking the borla for open. It idled fine, I let it come down to 700rpm and I just blipped the throttle. The car was at about 120 degrees, still in open loop. Anyways, the darn thing choked and died. I have no idea why, maybe it was too much or not enough pump shot, or was it timing?!?! Anybody have any ideas. BTW, the car runs great, no problems other that what just happed last night.

 

Well, when you 'blipped' the throttle, you told it to throw a bunch of fuel in there. Then you cut off all its air. I think it drowned.

 

That's what I'm thinking.
It sucks that the 8746 ecm only has TPS position pump shot table with resolution from 0 to 12.5%. The 7747 ecm has the table from 0 to 25%. I'm going to have to correct this with some source code.
It must be too much pumpshot because when I blip it usually the idle will hang for a split second even with the IAC fully seated and unplugged. Should I keep the TPS table near stock and just modify the MAP pressure pumpshot or what?
Thanks madmax for the quick reply.

 

What kind of intake are you running? I was tuning on my friends T/A and he has a Sportsman II intake along with the heads. The intake has a HUGE plenum and I found that it took a heinous amount of AE vs. MAP to keep it happy.

Have you thought of switching to the 7747? Just a thought...

 

Is your IAC still disconnected?

Anyway, either it needs less fuel (which I would assume isnt a route you want to take, if its right in all other situations) or you need to let it get more air. You can open up the throttle plates more and reset your idle and all that, or you could steal a part off a carbed car and use that. Many came with a 'dashpot', some mechanical some electric. Basically it stops the throttle plates from slamming all the way shut when you let off, and slowly closes them. I'm sure you could rig one up on your TBI somehow. Could cause what you might perceive as a driveability problem, then again maybe not. You'll have to get your hands dirty though.

 

RPM dual plane intake along with the 1" adaptor/spacer = enough plenum volume.
The IAC was still connected when it stalled. It hasn't done is since I put the block-off plate on and routed all exhaust through the muffler. This makes me want to believe that it was running too lean. Less pressure in the exhaust and more/better scavaging would draw out the air better, or wouldn't it? Keep in mind this is with engine speeds below 1200.
So you really don't think it could be something with the timing?
The reason I don't want to go to the 7747 ecm is for the IAT and because the 8746 was designed for a car, not a truck. I've noticed a difference when I put in a resistor in place of the IAT sensor. I had it set at 180 degrees and I even tried a lower 140 and a higher 200, it was the same thing. It just didn't feel right.
that dashpot is a good idea. I'll look into it for a very obvious reason...IAC's SUCK with TBI. At low engine speed and idle, the IAC is a vacuum leak around the throttle blades. All of a suden a lot of air is bypassing the throttle blades and fuel starts to puddle and drip off the blades. I actually noticed a very stable idle when the IAC was disconnected and that's my only proof so far. I plugged the IAC back in and ever since it's been idling around 700. I've got the settings in the bin for a 550 idle but it never gets down that low unless it's 110 degrees out, 100% humidity, a friday, and the 13th of the month!!!
I'm going to try a few things but I like the dashpot idea. This is the one instance I wish I had dryflow. None of this IAC and pumpshot to tune.

 

HAH! Something else I can pick on TBI about

You could try messing with the timing at idle. It might help a little but stalling the car sounds pretty drastic to me. My results from doing that screwed up the idle, tip-in, etc. I finally gave up where I was at and put the timing back where I had it before. Maybe you'll have better luck than I did.