Thread: 2000 GT 3.8 N/A, starts, then shuts off??

Would the key be the Culprit, even if the Security light never lit up?? And, its the original key from 2000 for the car, plus, would it just go just like that?? And, would it just all of a sudden work after 10 tries, and then the engine idle kinda rough??? That is kinda what has me wondering. It never really did that before (well, it never really did ANY of this before). I can certainly try the Spare key, which I know works. Thanks for the suggestions, they are ALL welcomed!!

Well, it DID start and stay running on about the 10th try, but just didn't seem to be Idling right. I could even Rev it up. I have not messed with it since. Like I said, I DO know the Ignition Module is going (or its highly suspect) because of my Cylinder 4 Misfire on a Hot Re-start, but that has been happening for like 6 months. I know when the Modules completely fail, these cars will not start at all. And like you said, I would not have a code for the MAF. I think I will take out the MAF and inspect it, and buy a can of MAF Cleaner. It has been suggested to attempt to clean it before I drop $150+ on a new one and see if it makes a difference. Or, maybe I will take a gamble on a used one, for my budget is sort of limited at the moment.

Well, I went out yesterday to mess with the car again. It started right up after sitting for 2 days again out in the cold. I let it run for awhile, doing "snap" throttle hits to trigger the MAF. Once warm, it still idled kind of funny, the RPM's would fluctuate from 1,000 to down below 500, then back up again, but it kept running. Then, after about 15 minutes or so, it finally happened, the idle dropped, it hesitated, and it stalled, just out of nowhere. I hit the key, and it started back up as if nothing happened, but the idle still was off. I waited another few minutes, and it did it again. So, I turned off the key, and went and unplugged the MAF. I restarted the car, and let it run. The idle actually seemed a LITTLE better (I know it won't run perfect on Speed Density), but it did not stall. I left it this way for quite awhile, and no stalling. I shut it off, restarted, shut off, restarted, and no stalling. I plugged the MAF back in, started it back up, and the fluctuating idle returned, but I could not get it to stall again. I tapped the MAF with the butt of a screwdriver while it was running, and noticed when I did this, the car's idle would change, or sort of stumble a bit, but it would not stall during this last period. I also noticed the MAF has been changed before, there is a white label on it that read "REMFG", so I know someone in the past has changed it, it is not an orig. GM MAF, or, if it is, it was a Reman.

I also checked the Fuel Pressure Regulator as suggested by some, and the vacuum line was dry and had no fuel in it, or any smell. I ran the car with, and without the line hooked up, started it, and shut it off, and it seemed to make no difference, so I do not think it is a suspect, however, I DID find a tiny crack in the boot of the vacuum line going to it, so I taped it up for now, even though it was not sucking any air, I will get new lines from the junkyard when I get there next.

It seems to me that the MAF appears to be my prime suspect, but I still want to rent a fuel pressure gauge to rule out my fuel pump. What should the correct pressure be for these cars, N/A with no supercharger?? 40PSI?? Also, does anyone else have any other ideas on what I should be checking?? BTW, when I go to the boneyard and pick up a MAF, I'll pick up an ICM to help solve by hot-start misfire, and while I'm at it, might as well replace the IAC as Keko suggested. As I explained, at the moment I'm on a tight budget and cannot afford brand new parts, at least right now. This car is a secondary car anyway, but I would like it to at least run and know it will get me where I want to go when I want to use it. Thanks!

I will do that Scotty, but it looks like it might be an aftermarket Reman unit, the numbers did not look like Delco numbers on the MAF. Thanks for the info, and for the fuel pressure specs!

Ok...so I finally had time today so go out and mess with the car again. I borrowed a nice Snap On Scanner from a friend that monitors sensors (including the MAF) in live time. I ran the car for about 30 min, snapping the throttle, stopping it, re-starting it, etc. I could not get it to stall. Now, here comes the good part; according to the Scan Tool....my MAF is putting out NOTHING....0.00Hz and 0.00 (whatever the other reading is, gs's I think). I tried wiggling the wires, unplugging it, plugging it back in, no change. It's like it is not even there at all. Sure explains the P0103 Code of MAF Low voltage! But, WHY did the car run, or seem to run better when I unplugged it BEFORE?? Maybe it was still throwing out numbers before?? I don't know. I'm at a loss. I'm going to get another MAF and scan the readings again and see if drivability improves. I also did not get to check the fuel pressure yet, but I am going to do that as an added precaution just because it is simple enough to do.
Just keeping ya'll updated. Thanks!

Well, I think I fixed it today. I replaced the MAF sensor AFTER testing that there was 12 volts at the MAF plug with the key on, which there was, so thank you for reminding me to check for power there fivefinger. I replaced it, fired her up, and there was an INSTANT difference. It actually had a fast idle for being cold (never really did since I bought it)...then slowly came down after about 1-2 minutes. When I brought it up on the scan tool, boom...I had readings....all within spec...G/S and HZ wise...at Idle and snapping the throttle. I even graphed both and made sure they stayed within spec until the engine came up to Temp. Took her for a ride, and it even seemed to shift better (smoother) (weird huh) and when I came to a stop, it idled better than it ever did. It purrs like a kitten now. I am still in shock that a MAF would just "go" one day like that causing my car to stall out...restart..run for 3 min...stall...restart...then maybe run for an hour before stalling...etc. That was messed up! I STILL am going to test my Fuel Pressure, I am waiting for the right adapter for the tester, I, like an idiot, dropped it down the front fascia, and the car "swallowed" it, can't find it ANYWHERE, dropped the lower splash shield and everything, and spent 30 minutes in my yard and driveway looking for it. Oh well, guess the car was hungry. Least it APPEARS to be fixed. Cleared the codes before taking it for a ride...nothing so far...and ran scanner again....everything still within specs. Hot started it after the ride, and she started right back up, no usual stumble or "misfire" I was getting. Maybe it wasn't my ICM after all?? Time will tell. Thanks everyone for your help, and I hope this can help anyone else out there!

Just a quick update, I FINALLY got to test the fuel pressure, and all seems to be well there. I got a constant 41 PSI at idle. When disconnecting the vacuum line to the Regulator, it spiked up to 50PSI. Putting the hose back on, it came back down to 40-41PSI and hovered there. When revving up the engine, the pressure would instantly rise to 45-50PSI with the snapping of the throttle, then go back to 40-41PSI as it came back down.....telling me my Regulator is also pretty much good. I think I am about 95% sure now that the culprit was that stupid $%&%^&^^& MAF sensor. Thanks again for everyones help. Any comments are still also always welcomed!

UPDATE to this thread: Now that the weather here in PA is getting warmer....I drove the car to work the other day, drove it to my hair cut appt. after work, ran the A/C the whole way, everything was fine. It sat at the barber shop for about 20 min hot....went to start it...it started, sputtered, and stalled. Then, did not want to re-start right away, and when it did, she had a terrible bucking and misfiring, and I had to rev it a few times and keep it stabilized for a bit until it settled down to drive it. After that, then it drove home fine with the A/C on again like nothing happened. I suspected my ICM finally was starting to crap out since the weather was getting warmer, and engine was running a bit warmer, and it was misfiring, plus I have replaced and moved the coil pack that the misfire was coming from and it did not follow the pack. Figured I had better replace the ICM before it left me stranded. I bit the bullet and got a genuine Ac-Delco ICM and replaced the unit. Sure enough, someone else had been in there at some point, and replaced it with an aftermarket unit. I drove it to work today, and it seems MUCH better, much smoother idle, better starts, and better throttle response. So I think my issue was two-fold....MAF and the ICM. Just FYI for everyone as an update. Thanks!!!

Ok...ANOTHER Update: I went to start the car again...on a HOT start after coming out of the store...and it did the same thing...started...sputtered...and stalled. Then, started right back up, idled a little funny for about 5 seconds, and then everything was peachy fine. The new Delco ICM DEFINITELY has helped, and I had diagnosed the MAF as being bad, so that is new as well. My question is, could my IAC valve be bad as well?? For only $30....Im willing to try it at this point. Would that cause this issue?? Car starts fine when its cold. Also, this is a very intermittent problem. Could do it 2 times in a row, may not do it on a hot re-start for a week. Weird issue guys. Thanks!!

Couldn't hurt. One other thought came to mind: have you removed and cleaned the entire throttle body? As in, clean the backside of the butterfly, the IAC bore, etc.

If you keep having issues, shotgun a crank sensor on it. Or take yours off.. clean all the stuff stuck to it's magnetic surface off and put it back on. With enough mileage that bit of junk can cause some odd behaviors.

Will try cleaning the T/B Fordman, not a bad idea. If I keep having issues, I was thinking the Crank sensor, but hoping that was not it Billboost, b/c I understand that is not a fun project due to having to pull the crank pulley to change it, BUT, we all do what we need we need to keep them running. Btw, Bill, it has 126k on it, just b/c you had inquired about mileage. Thanks all!!

Have not yet gotten to clean out the T/B yet or messed with anything yet....but the new ICM has been in more than 2 weeks now...and after 1-2 incidents of the same "hot start" stall issue....now, it seems to have mystically disappeared. Its weird guys, I have no idea. I'm still going to grab an IAC from the junkyard for good measure....but, maybe the PCM had to adjust to the new ICM??? I have no idea. It starts and runs like a dream now....even on a hot start....and runs great and idles great at stop lights....even with the A/C on. I am kind of at a loss now. **shrug** I hate Ghost problems....lol.