Sudden stall, rich, no vac, no idle. HELP!

[USAF 98 GSX]

So here's the deal. I was in 2nd gear at about 6K RPM with about 11 psi when the car stumbled once and completely stalled. While coasting I tried to restart it and it jumped to around 4K then stalled and wouldn't start again.

To start it off the only mods I have on the car regarding engine performance mods is Intake, test pipe on full stock exhaust and DSMLink v3lite.

I was able to find an area to pull over and investigate wtf had happened. No fluid leaks, no burning smell or weird smells, nor did I notice any noticeable damage or missing parts. Prior to the car stalling on me there was also no knocking, no ticking, no hissing of any sort, no smells or leaks of any find. HOWEVER, I do have a shitty alternator and possible bad battery. Not sure if this helps any.

I had the car towed back to the house and didn't touch it until about an hour ago. I went out there, wouldn't start, dead battery. Hooked it up to my wife's car and left it hooked for about 30 mins. While charging I attempted to start it. Got about 15 seconds of idle with -2 vacuum, 15 psi oil, and an AFR of around 12.1 - 12.5. It would then stall out. I would try again after a minute, this time I gave it some throttle and was able to get it to run for about 30 seconds and it died again even with constant 50% TPS. However, within those 30 seconds, AFR was around 12.5-13.0, vacuum at -18 and oil pressure around 60.

I let it sit again for a few minutes and tried again, this time I hit launch control limit which I believe is 4.5K for me and I would only get 0 vac instead of my typical 6-7psi for launch control, oil 55 psi, and AFRs around 10.0-10.5. Weirdly enough I was able to keep the car on as long as I had the car around 3K it would stay on, but here's the weird thing when I let off, the car idled fine. Fine in the fact that it idled at the target 900 RPM, AFR was still rich around 13.5, vacuum around -16 and oil still at 15 psi. But as soon as I gave it a little gave it revved to 2K then bogged down and died.

I then tried to figure out what other components would affect air input or the vacuum in any way. So I tried something, I disconnected my MAF. I started it up and it did its initial high rev for a second, then idled great around the target 900 RPM, AFR steady at 13.1 (because of open loop right??), and oil press at 15 psi. I let it run for about 30 seconds with no extra throttle at idle and it did fine. I reconnected the MAF with the car running still and it stumbled instantly. The AFRs went nuts and the vacuum went to -2 again before it took a shit on me.

I'm not sure if having the MAF disconnected helped temporarily cure a boost/vacuum leak and gave it life to idle. But I don have a log attached for you all to see. Yes my front 02 is taking a shit on me too (front 02 heater circuit malf.). But before yesterdays problem the AFRs at idle and cruise have been a perfect 14.6-14.7. WOT is at 10.1-10.2 (haven't tuned it to 11.1 yet).

If anyone has ANY suggestions, I don't care if they are weird sounding or out of the blue suggestions, I need something to go off of. No major or noticeable boost leaks. Besides piping coupler and throttle body gasket. But that's been there for over 3 months now. Yes I keep forgetting to fix them.

After looking at the log again, I noticed that my Combined FT is at -16%!!

Thank you for reading my crazy story and essay.

 

[PotatoFlakeSTi]

I'd get a volt-meter out and check the MAF, followed by the alternator, then do a boost leak test.

 

[USAF 98 GSX]

I'd get a volt-meter out and check the MAF, followed by the alternator, then do a boost leak test.

Do you think its possible for a MAF to give out or die in mid pull in 2nd gear? At first I thought maybe I popped a vacuum line and maybe I still do have one popped, but this MAF thing is weird too.

Coincidence maybe?

 

[PotatoFlakeSTi]

Do you think its possible for a MAF to give out or die in mid pull in 2nd gear? At first I thought maybe I popped a vacuum line and maybe I still do have one popped, but this MAF thing is weird too.

Coincidence maybe?

I suppose anything is plausible, which is why you should test it if you've got the chance.

 

[gophishy10]

I would do a boost leak test. It ALMOST sounds like it could be one. Check all pipes for the fmic. My car was doing this same thing right after I installed my fmic and it turned out one of my pipes was loose. My log looked the about the same as yours too. Also make sure no vacuum lines blew off either. Your log is showing no/barely any airflow so I'm guess a boost leak.

 

[USAF 98 GSX]

I would do a boost leak test. It ALMOST sounds like it could be one. Check all pipes for the fmic. My car was doing this same thing right after I installed my fmic and it turned out one of my pipes was loose. My log looked the about the same as yours too. Also make sure no vacuum lines blew off either. Your log is showing no/barely any airflow so I'm guess a boost leak.

Awesome thank you, you are probably right because I installed a rebuilt 14b last week, but then reinstalled my T25 because the 14b had a slight bend in the shaft and it tore the new seals apart. So I could have possibly ####ed up my IC piping during the install

I would do a boost leak test. It ALMOST sounds like it could be one. Check all pipes for the fmic. My car was doing this same thing right after I installed my fmic and it turned out one of my pipes was loose. My log looked the about the same as yours too. Also make sure no vacuum lines blew off either. Your log is showing no/barely any airflow so I'm guess a boost leak.

With a boost leak of this size, would the MAF actually help it out when its not connected??

 

[gophishy10]

To be honest, I'm not entirely sure about that whole MAF thing. It is possible that it helped out when you unplugged it because all it does is measure the amount of air coming in and sends that to the ecu for fuel trims and such. By unplugging it, it no longer was reading the amount of air entering so it wasn't trying to give you perfect fuel trims or correct the amount of air. But this is just my guess. Just trying to throw a possibility out there.