Hello All,

I bought a used 01 Monte Carlo SS on Monday, and am currently having some stalling issues.
I have been searching and trying to troubleshoot online and keep running across threads in these forums, so this seems like a good community to ask these questions to. I thank you in advance to anyone who can help as I am pretty stumped. Sorry about the wall of text, I am just trying to be as detailed as possible.

First off some basic details about the car.

• 2001 Monte Carlo SS
• 3.8L 3800 engine
• Automatic Tansmission
• ~148,200 Miles
• Appears to have been regularly maintained

The story...

When I bought the car everything seemed to check out nicely. Took it for a short test drive around that area of the city, everything seemed to run nice and smoothly, no hesitations, no sputtering, no stalling, no strange noises. checked under the hood, everything seemed to look nice and didn't look like anything was leaking. The seller informed me that the MAF Sensor had been acting up, and he had cleaned it recently and hadn't had any problems with the sensor in a while. Very Little rust. Surprised how little rust was on bottom. He said he used something called fluid film on the bottom and the couple minor rust areas about twice a year. The body was in good condition except for the door popping the fender. (fender was bent towards door a little bit, and the door was catching on it. Said it got packed with snow and that's what bent it.) I decided to buy it anyway because it seemed like a good buy, and I really liked the car.


Issues so far...
When I got it home I noticed a squeak/squeal under the hood and it seems to be coming from the belt. smooth side of the belt looks shiny, and belt looks pretty worn in general. I have already bought a new belt but haven't had chance to replace it yet. Squeal went away. Figured I would try to replace belt when I had spare time as it stopped squealing and being a nuisence for now.


On my way home from work around 1AM Wednesday morning I started noticing some jerkiness, and high rpms at low speeds and in park. Shot Up to about 2500 - 3000 rpm when I shifted into Park. It also turned on the CEL. I disconnected the MAF sensor and took it for a test drive problem didn't change.



Wednesday afternoon I took it to Advance Auto Parts and had them run the codes. It threw a code for MAF sensor fail, MAF bad wiring(assuming this was thrown because I unplugged it), and Throttle Pedal Sensor Fail. I Purchased a Throttle Pedal Sensor and a MAF sensor and replaced the Throttle Pedal Sensor on the spot in their parking lot. Issues went away, CEL turned off. As of now all of my high RPM and High idle issues are gone, it now idles at ~800 - 900 RPM which seems normal.



Wednesday evening on my way to work the car had stalled twice while I was driving. Both stalls occured while driving at low speeds ~25 and ~35 MPH while foot off acceleration attempting to come to a stop. CEL came back on for MAF Fail. I installed the new MAF Sensor Before work in their parking lot (Decided to Put the new sensor in because current sensor appeared to be OEM sensor and it was 14 years old, I figured It would be ok to just replace it). On my way home from work ~1am Thursday everything seemed great CEL turned off.



~1AM Friday morning when I was on my way home from work It stalled out again at about 10 MPH while attempting to turn. CEL came back on. Again code was for MAF sensor Fail (While brand new sensor was installed). Was told it was probably a wiring issue. I Decided to buy a new sensor plug, and was planning to cut the old off and solder a new plug on since everything seems to be fine when I First plug the sensor in. I came home from work a few hours ago and disconnected the - terminal of the battery and was getting ready to chop the old plug off and I thought maybe I should just wait 15-20 mins and give the computer a reset and take it for a test drive before I chop the plug off and solder a new one on.



I waited and took it for several test drives over the last few hours and have stalled several times. Always at low speeds, while foot is off of the acceleration pedal. Usually when slowing to make a turn. However now my CEL has not turned back on yet so I am unsure of what is making my monte stall. I can see on the RPM gauge when its about to stall, it'll flutter between ~500 rpm and ~1000 rpm a few times, then battery light comes on and engine cuts. I have always been able to shift to neutral and restart, then shift to drive and continue without much problem. and if I tap the gas while its fluttering the RPM it usually continues for a little bit before it tries to stall again.



I am truly stumped as to why my car is stalling. I really don't think it is caused by the MAF at this point. I have also been able to rule out a vacuum leak.


Again sorry about my wall of text I was trying to be as detailed as possible. Any and all help is greatly appreciated.

 

Hello and Welcome to the forum.

Sorry to see your having issues with your Monte Carlo, nothing is more frustrating than getting a new car and having it start glitching out on you.

Here is a link to an earlier MCF thread, don't know if you have read it or not. Hope it helps.


https://montecarloforum.com/forum/ne...problem-36664/

 

Hello Zippy02. Thanks for your response. I read through that thread and it sounds like it may possibly be my IAC, air filter, or gummed up throttle body. If it was my IAC will it eventually turn on my CEL and throw a code? I'll go get replacements and see if that solves my stalling problem. I'll post an update when I get back.

 

I had a similar issue it turned out to be the maf. Sometimes just cleaning the maf won't do it needs to be replaced before it goes completely and you have to be careful on a replacement these cars with the maf do best with an ac delco one

 

Thanks for the reply owens91. I replaced the MAF sensor with a brand new one from the parts store, they tried to sell me a remanufactured one but i Insisted on buying brand new as I usually do when buying parts. I figured it probably needed replaced instead of cleaned again because it was the original MAF that came in the car. I had asked for ac delco but all Advance auto seems to sell for this car is Dorman/Cardone. Also it came with a lifetime warrenty so I can always exchange it at the store if it goes bad again.

Also I just got back from Advance Auto again, I got a new Idle Air Control, A new Air filter, and a can of SeaFoam. The car didnt stall at all on the way to the store and back home, So I'm ganna wait to install the new IAC, but I'm going to replace the Air filter. I have about a half tank of gas so later when Im back around that area I'll stop at a gas station and put the can of seafoam in and throw a couple extra gallons of gas in to mix everything up. If after that I continue to have issues, I'll install the replacement IAC, otherwise if everything seems to go go good I'll just return it.

On a side note, my squeak is coming back so I should probably get that new serpentine belt on pretty soon.

 

*Update*

I'm ganna have to wait until early next week to get the belt put on. I'm having some difficulty getting the old belt off and don't have a 15mm long enough to get enough leverage.

I Put a can of seafoam in the tank, added some gas to mix it up. Haven't noticed much of a difference yet so it may or may not be cause by clogged injectors.

I replaced the air filter and noticed a pretty big difference. It sounds and feels like its running a lot smoother. The old filter had some dust and dirt in it, but overall didn't look to bad, felt like a chinsey filter though. I put in a Purolator PureONE filter because it was the best quality filter that didnt have an oil film. the post I was linked to said not to use the K&N filter because it had an oil film that can gum up the Throttle body, So I avoided that and the Spectre filter for that reason.

I noticed that the old air filter I pulled out had about a 5 inch tear in the seal at the bottom. Could this have been causing stalling issues?

I havent installed the new IAC yet because It hasn't stalled yet since I put the new air filter in. If it continues to stall again Ill install it.

 

That's good to hear. I hope that the stalling issue is fixed.

 

I'm reading this and may have missed a few things, but, I am really thinking you need to review this thread:
https://montecarloforum.com/forum/fw...0-miles-46078/
One item in specific I'd recommend reviewing is the part of about spark plugs. If the plugs are still factory or if the plugs are BOSCH, change'em. Go AC Delco or NGK Platinums. Plugs can sometimes be the source of low RPM stalling (and dirty air filters too, as it sounds like you hit that one).

As for your wiring to the MAF, do NOT cut connectors until you diagnose the wiring. It would take digging through a shop book, but a wiring problem is not necessarily a connector, you could have a damaged wire somewhere in the harness.

The belt squeal, a common cause is the bearings in the tensioner pulley failing. But, good way to check, turn the car off, remove the belt, by hand spin the pulleys. Listen for noise and feel for issues in the pulley travel. Also, if the PCV valve is missing it's O-rings, this has been known to generate a sound that sounds like a noisy alternator pulley.

Review that maintenance thread, it has a LOT of stuff that is common and could be the blame for some random issues your having or may be coming up.

 

Thank you for your response The_Maniac. That thread has a lot of useful information. I'm actually not sure about the brand or age of the plugs. I'll try replacing them today with the plugs you recommended. Looks like I'm going to have to go with the ac delco as the ngk platinums are not in stock at the store.

I have not yet cut and replaced the connector for the MAF yet as it stopped throwing codes for the MAF after the reset. I originally thought the connector was the issue because it continued to throw codes for the MAF with a brand new sensor installed. And where the three wires go into the connector they are at pretty sharp angles and act a little bit loose going into the connector. The sensor wires were also at a sharp angle coming out of the harness. I will return the unused connector today when I go to get the spark plugs in a little bit.

Also I will check the tensioner pulley when I'm finally able to get the old belt off. I know I need to replace the belt though. the current belt's smooth side is really shiny and it is worn and cracked a bit. I already have the replacement belt, I just don't have a long enough 15mm wrench.

Edit: I will replace the plugs before trying to install the replacement IAC I had bought, as it has still not yet thrown a code for the IAC.

 

First time I replaced my belt was in the Auto Zone parking lot, they loan a tool just for that, came in an orange case, worked great, and just had to walk it back in the store when I was finished. Made it easy. Hope that helps. My Tensioner pulley was bad and broke my new gatorback from RockAuto so had to replace it with the Auto Zone belt and pulley.