99 Monte Carlo MAF sensor problems

[cabledawg]

It has the 3.8l with 145k on the ticker. Last fall it threw a code for the MAF sensor but since I wasnt going to drive the car over winter I let it sit. Fast forward to last month and I'm driving the car around. It stalled just about everytime I came to a stop in gear (AT). So this past weekend I changed out the MAF sensor, spark plugs and coolant. The battery was disconnected for the few hours all this was happening.

Here's the new problem: the car still stalls occasionally, but now its random and there is no check engine light. Its hard to restart unless I sit there for a few minutes. Looking around the internet, it seems there might be a "relearn" process with a new MAF or that the aftermarket one sucks and a OEM one should have installed instead.

Can anyone verify any of this? Thanks in advance!

 

[black dawg]

I have seen the throttle plate and iac get very dirtly on a few of those, might want to check it out.

 

[Carcinogen]

x2 on the IAC being dirty and not closing all the way.

 

[cabledawg]

I'm a moron......whats the IAC?

Edit: Nevermind, google helped me out with this one. What's a good cleaner to use?

 

[89k5350]

castle actually makes a cleaner specifically for IACs. or use carb n choke cleaner

 

[cabledawg]

Update: Cleaned the MAF (again), new IAC valve, cleaned all the crap out of the intake where the IAC valve sits and reset the ECM. Ran like a champ. For a few miles

After I got to the gym, i shut the car off and went inside. Hour later I come out and the car wont start. When it finally did fire and run, it was stumbling and the CEL came on again. Smoothed out enough for me to get to work. Had to go somewhere and now the car wont start at all. Fortunately, I carried my code reader with me and its the damn MAF again. After trying for several minutes to start the car it finally fires but its dumping fuel into the cylinders. Black smoke and the whole car reeks. I shut it off and out of frustration, I unplug the MAF. I tried again and the car fires right up and I was able to drive it around with no problems. CEL is still on, but the car is running.

Been doing some reading and it seems there was an issue with aftermarket MAF's not working right or for very long. Called the local dealership and they want $300 for a factory MAF sensor. I cant imagine this is really a $300 part, but the guy wouldnt give me a part number.

Anyways, I'm going to try NAPA (last MAF came from AZ) and see if thier quality is good enough for my car. I dont feel like giving a blowjob to a GM parts manager just to afford a small plastic piece that probably cost $10 to make.........

 

[Blue85]

Get a used factory MAF from a junkyard, eBay or some message forum classifieds.

I was going to suggest unplugging it when the car won't run, but you already figured that out. You won't get as much MPG in speed density, but it's drive-able and much better then working with crap MAF data. Try pressing on different parts of the sensor, wiggling the connector, etc. It seems like some connection breaks inside and becomes intermittent. Sometimes putting pressure on the right place gets is running again for a day or two.

 

[diesel4me]

Sounds like the "flooding" symptoms are like what happens when a fuel pressure regulator diaphram ruptures--raw gas gets sucked into the intake thru the vacuum hose that connects to the regulator,and it doesn't always set a code....not sure if that engine has one though..

Seeing your scanner says its the MAF sensor it could be the new one is faulty..or the wiring to it has an intermittent break somewhere..a lot of cars around here that show codes end up needing wires fixed,after a new sensor didn't fix them...my friend sees a lot of rodent damage to wiring harneses,its like they make the insulation out of something mice love eating..his shop seems to be about the only one willing to chase down wiring problems--all the others give up if a new part dont "fix" it,and they tell the customer to go see him..

 

[cabledawg]

Hopefully a final update on my problem. Bought an AC Delco sensor and wiring harness. Overpriced if you ask me. I tried Napa but the store closes early in the day and when I finally got there during hours, they had closed shop anyways with no sign stating why. Check the internet and find a list of bad reviews for the same thing.

Anyways, I bought the new sensor and wiring harness from the Chevy dealership down the street from my shop. Got home that night and checked the car one last time, still showing the MAF issue. I went to work splicing in the new harness and swapped out the sensor and reset the computer. I had my laptop hooked up while I fired up the car. It stumbled for a second then took right off with a smooth idle. Didnt see any codes or flags show up on the screen. Drove it to work this morning with the same initial stumble then fine the rest of the drive.