My engine has been acting up again lately... First it started with a surging idle for a month. And once in a while, the car idle would surge so far down the car would stall. But as of today, it surged down and the engine wouldn't start. The starter cranks perfectly and the smell of gas fumes fills the air. So I try putting the ECM into clear flood mode (TPS > 80%) and still no combustion. 5min later it starts to almost start. You know, the *put put vroom.. DIE*. It kept doing this so i decided to go inside and try later thinking the problem is fouled spark plugs. 8 hours later, I attempted to start it again and nothing, not even close. But after playing with it for a few minutes, it started up. So I go driving for about 25min and at certain rpm's, the engine would just die for a split second followed by a MIL which went away immediately. This problem repeated itself about 10 times and then the MIL stayed on steady and the RPM's were pinned around 2200RPM's. Funny thing is it felt really smooth and wouldn't cut out while the MIL was on. When I finally stopped (was on the highway for 25minutes) the RPM's gradually dropped down to a stall over about 45seconds. I come back out a few minutes later to try and retrieve a DTC using a paperclip (Jumper pins A&B on ALDL) and all i get is code 12 which is normal. But guess what? The car will not start. Starter still engages and works perfectly.

I guess my question is where should I start to look tomorrow? Could this be a VATS problem somehow? A faulty IAC which somehow freaked out the PCM? Or perhaps a bad ECM? Please put in some feedback. I'de appreciate it.

 

Mine is doing the same thing, bro. Put it in flood mode, surge, sputter quit. Changed the plugs, the coil the TPS, IAC, CTS, cap, rotor, even ther starter (which incidentally was bad, it seems). Same thing. Strangely, it throws codes 15, 22and 42, and the next time I try to start it, then test it, it doesn't. Not hijacking your thread, but I thought I would chime in on the mayday.

 

First, don't assume that a '12' means "everything is normal." A '12' is defined as missing distributor reference pulses. Of course, that is always the case when the ignition is ON but the engine is not running. It can also be a code set while the engine is running, caused by a failing pickup coil/reluctor assembly, ignition module, or wiring. The fact that the "engine would just die for a split second followed by a MIL" might indicate a reference pulse problem.

You might also want to check the main ECM power fuse and harness supply, and ECM connections.
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interfac9,

You probably should have your own thread for your car's problem, but the combination of the '15' and '22' could indicate an intermittent connection or fault in the power supply circuit to the CTS and TPS, or their ground. The '42' might also be related to a connection problem with the distributor, including connections at the ECM end.

 

UPDATE:

I woke up this morning. Grabbed my spark tester. Hooked it up to the coil secondary wire, and cranked it over. I got swpark after about 3 seconds of cranking. I guess the ecm was figuring out the #1 cylinder pulse. So I plug the wire back onto the cap and it starts right up and runs fine. Not even a MIL.

So I guess you are on the right track vader. There must be a loose connection somewhere in the harness. Now to go about testing this using the old wiggle test lol.

 

There should have been spark immediately. It is not a sequential system, and has a distributor, so the ECM doesn't have to determine #1 TDC (it can't without at least a CKP sensor). The fact that the spark was not present right away is a sign.

Have you checked the pickup coil and reluctor?

 

You are right Vader... Matter of fact, gonna paste this to a new thread, because this car is driving me nuts. Can I PM you when I do? I'd like you to read what I've done, and what happened, so maybe you could shed some light on where I should go next

 

Got it! Since I have an msd box and it splices in between the distributer and coil, I used insulated connectors and heat shrinked them. But some how, water got inside them. I eptied the water out and I had spark immediately. Guess I have to run some new wires. Thanks for the help vader. Problem was that the switching ground for primary coil was getting excess resistance from the water.