Starts then dies, any ideas?

[sekse]

Ok, well I have had an ongoing problem with my grand am, 3100 v6, 1996 year. At first it was every once in a while, now it is every time I go to start it. The engine turns over, fires up, then dies. Out of pure rage one day I realized that if I turn the starter and leave it engaged while the engine fires up then dies, then still yet about another 15 seconds, the engine will start and run fine if it has been sitting for a few hours, if it has been driven a shot of starting fluid and it fires up (still after the start and die). I have found the problem to be a lack of injector pulse. The injectors get the initial start up pulse then nothing more beyond that. Also worth noting is that the engine will run fine after the funky start up procedure with NONE of the intake sensors (MAP, MAF, IAT, TPS, etc.) connected, as if the ECU is in some kind of odd limp home mode. That and the tach and temp gauges do not indicate anything except on occasion they flash to show a reading then go back down, and ALL dash idiot lights are lit up while car is running as if it was sitting with the key in the run position. And it idles very high, not sure how high due to no tach, but at least 2500 RPM. So naturally I was sure the problem had to be the ECU, but I replaced it and still have the same problem. True that the new ECU is a used unit, but the odds of both having this problem are very remote. I doubt it would be the crank sensor as the car wouldn't run at all and if it did it would die while driving it which it has never done once. And before anybody says it, this has nothing to do with my messed up head swap from earlier as this problem existed before the new heads were installed. I am about to throw my hands up at it, so if anyone has an idea or has been in this situation before I would appreciate the help. What could cause no injector pulse besides ECU, Crank and Cam sensors, and MAF sensor?

[91parkave]

the vats module will cause that, im not certain if your car can have a CASE learn performed or not. but that would be my first stab, then id go after the security key module (VATS) when they go bad it prevents the injectors from opening up. hope this helps

[sekse]

Actually I don't think mine has the VATS system, the key doesn't have the resistor in it, although somebody could have screwed with it I suppose, but I don't see how it would start after turning over for 30 seconds if the VATS was shutting the injectors down. I looked around for any hint of a VATS the first time this happened and didn't find anything so I dunno for sure about that. I will check around some more tomorrow though, thanks for the insight!

[davida1_hiwaay_net]

Have you hooked up a scan tool to the ECM to see what it is getting from its sensors during the malfunction?

The gauges showing garbled readings and lights on makes me think of a power or grounding issue.

If you have a scan program (such as EASE) this would be the first step.

I remember your head replacement, and you say this problem predates that. You would have found any bad grounds on the engine when you had the heads off so I doubt that is the problem.

Have you measured voltage on the ECM's power pins and ground pins when the malfunction is happening?

I think this is a "basic" problem with the car's wiring because it affects both gauges and engine management system.

If the ECM program is "locked up" it will go into an "analog" backup mode. I don't know for sure that is what is happening but sounds like it. If the power supply is very dirty or noisy it could lock up the CPU.

If you can't scan the ECM and the scan proram acts like the ECM is not responding, this would also point to a power/ ground problem.

I bet this is a simple problem once you find it!!

[crazyhorse]

If there's a black "chip" in the key, the you have the PassKeyII system, you've likely had a problem with it. When they act up, they can be INFURIATING! The start/die is the VATS cutting power to the injectors. It cranks, fires normally, then dies immediately after releasing the key. (sometimes accompanied by a pop in the exhaust)


Here's how to "go around" the system. 1st off, this really won't work to steal the car, as there are 15 different resistor combos, and you STILL need the key to start the car. BTW this only works with the version that you can see the resistor in the key.

Tools/supplies: Resistor(s) of the proper OHM rating, Small buttsplices, wire cutters, crimping tool, Heat shrink tubing.

1. Take your OEM key to Radio Shack. Have them measure the resistance across the "chip"

2. Pick up a pack of resistors that matches the reading you got earlier. This may require 2, or 3 resistors in series to make the exact resistance you need.
+-5% Mine required 2. While you're grabbing parts, get a pack of the smallest buttsplices they have. All told you'll get out of there for under $10

3. Under the dash, on the steering column, you'll find a harness in an orange cover. There will be 2 small white wires in it. Trace this to the connector in the dash harness. Unplug the connector. NOTE: DO NOT ATTEMPT TO START THE CAR WITH THIS UNPLUGGED! This will strand you for approximately 30 mins while you do the relearn procedure.

4. Here's where it gets scary. Cut the wires that go back up the column leaving approximately 2" attached to the plug.

5. Open the resistors, and buttsplices. Trim the leads on the resistors until they fit into the metal of the splice, but don't leave any lead showing. If neccessary connect all your resistors together first. Then strip back the wire on the plug. Connect one end of the resistor pack to one wire. Slide the heat shrink on, then connect the other end to the other wire. There isn't a right, or wrong way to connect this. It just reads the resistance. Slide the heat shrink up over your connections, and shrink it with your favorite method. I like to use my lighter.

6. Plug the connector back into the dash harness, then start your car. If your resistance is right, enjoy knowing that you can now go to Wal-Mart & get your keys, instead of the stealership, or a locksmith.

7. Finally button up your repair by securing the wires under the dash with a zip-tie.

This may help someone else out there with luck like mine.

[sekse]

lol thank you crazyhorse for the very in depth instrustions on bypassing the VATS, but as I said earlier my car is not equipped with it. Did not know it could leave you stranded for a half hour if you try and start it though, lol. I think I MIGHT have found the problem. The first two times it happened the vaccum lines to the EVAP solenoid under the coils had fallen off, but lately this was not the case. I put some silicone on the vaccum line that goes to it and T's right behind the throttle body where it goes into the TB. and let it sit over night, the next day it fired right up every time, although I never drove it anywhere because I broke the O-RIng on the FPR and now ahve to get a new set of rings for it before it will go anywhere. Will have to see if that is the problem.