04 Monte keeps stalling
 

My 2004 monte carlo 3.4 keeps stalling. It will start right up but stall a second later. Replaced the gas in the tank, fuel pump and filter, pressure regulator, and cleaned the injectors. Also replaced the spark plugs and wires, battery, Ignition lock cylinder and ignition switch. The car runs if I spray starting fluid into the intake, but as soon as I stop spraying it, the car stalls... Thinking the MAF is bad... any suggestions of things I could try? Thanks!

Well, try unplugging the MAF.. If problem goes away, its the MAF..

Try the MAF, but also try the IAC Valve.

Click > https://itstillruns.com/clean-gm-iac-valve-5883650.html

Update:
 

Went out and first cleaned the IAC using carb cleaner. Tried firing it up, no go. Tried unplugging the MAF, still nothing. The car is now at the point where it will only crank unless I constantly spray starter fluid into the intake. I should also note that the pigtail going to the MAF got chewed through by a rabbit after the last time I'd driven the car. replaced the half going to the MAF. Not sure I wired it correctly because the pigtail I put on had all white wires (so there was no way to know what wire went to what). Could this be the problem? Thanks.

If the new plug was the issue, it would temporarily be fixed by unplugging it.. Unless this could have caused some other issue which I cant think it did..

Uhmm, clogged cat possibly?? Anyone??

Vacuum leak?? Like something you may have forgot to hook back up..

Was thinking clogged CAT as well since the car does have 123k, but would the car still be running on the starting fluid if that was the issue? As for the vacuum leak, I'm not sure how to check that; but will look into it when I get home from work. Also, could there be some type of computer malfunction causing the air/fuel ratios to be messed up? Thanks.

it wouldn't run on Sunoco racing fuel if it was the cat. Has to be an air/fuel supply issue, which you're bypassing with the starting fluid. That's all I got.

Could Passlock be the issue? Was reading through the owners manual and it says that if the light is on and flashing, it'll prevent fuel from going into the motor. The security light is on in my Monte, but not flashing. I have tried the relearn/reset procedure, but it does nothing. Don't know what this means. (I've already replaced the ignition lock cylinder and ignition switch). Thanks.

I would say yes, the Passlock is most likely an issue. A steady red security light is an indicator of a fault in the security system. The fuel pump could still be disabled by it, you should hear in hum when the ignition is turned to the "on" position. The ignition switch and/or the lock cylinder are the most common failures, you say you've already replaced those, but defects do happen. Also the security re-learn can be stubborn, sometimes takes several tries. Could also be a bad wire or connector. You should have a code stored directing you to the problem if you scan for them.

Okay Thanks. I'm going to go to Auto zone Later today and pick up a code reader and I'll let you know what I find.

UPDATE:Rented a code scanner today and hooked it up to the car... Absolutely nothing. Scanned several times and there wasn't a single code. I'm stumped. Considering bypassing the system entirely with a resistor... Would doing this trick the computer into allowing the car to start and idle? Thanks.

Has anyone attempted bypassing the passlock system in their Monte? If so, are there any drawbacks in doing so?

The resistor doesn't really bypass the passlock system, it just replaces the resistor in the lock cylinder that you already replaced, so unless that resistor is defective you'll still need to find the real problem. There's videos on Youtube that explain how to do it if you insist. Personally, I would fix the real problem. Seems like hacking up the harness just causes problems later down the road.
The steady security light is a indicator of a breach in the class 2 serial data circuit causing a "fail" to set for the CTD (content theft deterrent) system. The circuit needs to be complete in order for the PCM and BCM to enable the fuel pump and crank relay.
There should be a code. Either the scanner you're using is not smart enough to communicate with the serial data link or there's a problem with the DLC, specifically terminals 2, 5 of the DLC or terminal " A" of the splice pack, any of which would not set a DTC. You might need to get scanned with a Tech 2 which is capable of bi-directional communication and can test individual modules in the circuit as commanded by the scan tool.

So, how should I go about this? Should I tow the car to a shop to have them check for codes with a better scanner? Also, what would need to be done to "fix" the class 2 serial circuit? Thanks.

Unless you find someone willing to come to you to scan I guess you'll have to get a tow. Make sure it's a Tech 2, or one like a Snap-on that can emulate a Tech 2. If you do have to get it towed, I would take it to a chevy dealer or auto-electric shop with the right scanner.
As for the fix, that depends on what the scan reveals and points you in the right direction. Could be a short, bad ground, bad connection or module.
BTW...does the car happen to have a aftermarket stereo? They can be a problem too.

Thinking that the Chevy dealer 2 miles from my house will probably be my best bet... The car does have another stock stereo in it from an impala... Although, the car was already having this issue before I swapped the stereo...

Given what I know about the data system in these cars, it's very simple. Literally it is just wires from each computer in the car getting "spliced" together. There may be a better way to do this, but what I would try is disconnect the battery, remove the PCM, set your volt meter to do an ohms test (which can be a simple continuity test). See if you can get continuity from the data pin in the diagnostic port to any of the data lines on the PCM connector. One or more should have continuity. If none of them do, it is a mission to find the break.

With everything connected, I would also validate the 12v power connector and the ground connections on the diagnostic port function. Below are the pin outs for the data connector.
https://cimg0.ibsrv.net/gimg/monteca...523fecc351.jpg

The diagram below explains how to build an "Off board harness" (used to power and program a PCM without it being in the car). Ignore how it shows connecting the PCM for a DLC, focus on the pins on the PCM and what they are labeled as. By no means is this all the power/ground/data pins, but this was a quick find for me. I know these pins are used (as I built one of these harnesses and I have used it a few times). Validate the grounds and 12v are good on this connector. Also, going back to the continuity testing, this gives you some definite data pins to check out between the PCM and diag port (as I said, no guarantee these pins connect without further checking of the shop manual, BUT, I would guess at least one connects between this PCM connector and the diag port).
https://cimg3.ibsrv.net/gimg/monteca...38c64eebaf.jpg

I hope I did not confuse things......

Thanks for visuals Jason, a picture is worth a thousand words:thumbsup:

Huge Update!!

Ended up borrowing my buddy's tech 2 scanner... Plugged it in and it said it couldn't connect with the PCM... thought this was weird and popped the hood to check if there was potentially a break in the harness somewhere that I'd overlooked... Turns out when the rabbit chewed through my MAF wires, it also chewed up my harness for the PCM... A few butt connectors later, the car runs and drives without any issues. I want to thank everyone who has posted on this thread in an attempt to help me!

Congratulations, what a relief eh?

Blasted wabbits...lol

LOL How in the world..?:rotfl:

Good find. I had a feeling it was a wiring issue.
If you plan to have this Monte for a while, I would swap out those butt/barrel crimp on connectors and use heat shrink tubing and solder the connections. The soldered connection will hold much better and the use of heat shrink tubing will insulate the connection. Otherwise, those connections will eventually corrode and cause you big headaches down the road.

Thanks for the advice! will be busting out the soldering iron this weekend... lol