stalling out

[GreddySpyder]

Sometimes when I accelerate quickly then come to a pretty quick stop (such as when coming to a stop sign or stop light), my car will stall out. I am figuring this has something to do with too much or too little fuel since this has only happened since installing all of my fuel and other upgrades. I have tried leaning and richening the hi and lo throttle settings on the SAFC but it doesn't seem to really help, any ideas what the prob could be?

 

[4g63tc]

Does the car shudder, or shake when it is in the process of stalling? do the rpms drop really low? if you start the car does it start right up?

 

[GreddySpyder]

I guess it does kind of seem to shudder just a second before shutting off. It normally cranks right back up, but one time it did take a minute to crank back up, but that time i also noticed that i had blown the boost line off of my boost gauge, so I don't know if that had anything to do with it. It also seems to be more of a problem with the hot weather lately.

 

[4g63tc]

most of the time when this type of problem occurs the engine cannot maintain the amount of vacuum required by the power brake booster, putting the car into a rich/lean state (jumping rpms from 200-500 rpms) usually this is caused by a vac leak in the brake booster line coming from the intake manifold. If there isn't a leak in the line the next step is a faulty vechicle speed sensor located behind the gauge cluster (looks like a cross), and last but not least dirty maf plug, or faulty maf.

look for the leaks first, then clean the plug with a little rubbing alcohol, and a q-tip.

t.c.

 

[GreddySpyder]

I bet you are right on that, now that I think of it, I heard a hissing noise from around the intake manifold the other day but I didn't see any unplugged lines or anything so I thought the noise must be coming from elsewhere. Where exactly does this line for the brake booster plug into the intake manifold, is it underneath or something?

 

[4g63tc]

look on the brake booster, it's a faily large line about 1/2 " and it should go to the backside of the intake manifold.

t.c.

 

[jasteel13]

i had the same problem i would be at like 4 to 5 grand and push the clutch in and it would want to stall i found out that my blow off valve wasnt closing fast enough and it would let too much air out so i had to adjust it

 

[GreddySpyder]

Originally posted by jasteel13
i had the same problem i would be at like 4 to 5 grand and push the clutch in and it would want to stall i found out that my blow off valve wasnt closing fast enough and it would let too much air out so i had to adjust it

Thanks, I tightened the BOV and it seems to have fixed the problem.

 

[GreddySpyder]

NM The problem still seems to be there. I have pretty much concluded that it only happens if i accelerate to about 4k rpms or higher and press the clutch in, the rpms just drop all the way to 0 and the car stalls out. I have tried adjusting the BOV and the fuel settings. I am still wondering if there is something in the area of the intake manifold that is leaking because i hear a "hissing" noise from that area. I checked all of the hoses running to the intake manifold and there doesn't seem to be a leak from there. Maybe it is the throttle body gasket? Adjusting the BIS screw doesn't seem to affect much of anything. My boost gauge shows 20hg of vaccuum at idle, which seems to be pretty healthy. I'm stumped for now?

 

[GreddySpyder]

Just for an update, to those who may be having the same stalling problem I was having, I finally figured it out! I hooked up my pocketlogger and purposely did what I knew would make the car stall (rev up to over 4,000rpms and hold the clutch in and let the rpms drop). I noticed on the logger that i was running 1.00 volts on the o2 sensor when the car would try to stall, so I leaned out the lo-throttle settings A LOT! I pulled the 1,000rpm setting all the way back to -45%, 2,000rpm to about -37%, and 3,000rpm to about -35% and now stalling is no more! After applying these settings the car doesn't try to stall and the o2 sensor reads a more reasonable .96 volts (indicating that I could actually afford to lean it out a little more). Of course your settings will vary according to your setup, but I hope this helps one of the many other people who were having stalling problems.