JDenhamCLK320

First off. I notice about Lil over a month ago in traffic when coming to a stop my idling was very jerky the rpms were up and down ( 200-500rpm) and the car would stutter as to almost wanting to turn off. I would hold my foot on the brake to give it gas and it would idle fine afterwards. Would only occur occasionally after that. But now lately it does it everyday. No codes would pop up. No check engine light ether. Dirty mass air sensor ? Air filters ? What gives. I'm having my dad take it in too his shop and see what's going on. Seems now to be getting a lot worse. He mentioned battery going out ?? Almost feels as bad gas or a glogged fuel filter ?

Second thing I notice the other day my shifter felt really unusually lose when going from Park down to Drive. I also hear almost like a loose metal sound from under the car when shifting down into Drive. Almost like a loose linkage ?? Any ideas ?? Thanks guys

Rudeney

It could be many things. Maybe a bad fuel pump, fuel filter, air filter, MAF, etc. The M112 engine did have some stalling problems, but that was usually only in hot/humid weather and didn't happen all the time (speculation is that it is related to a bad tuning of the variable-length intake manifold system). I doubt this is a CPS problem, as that usually just causes the engine to die or not start when it fails. See if there are any stored codes, even if the MIL is not illuminated.

JDenhamCLK320

Ya I can't remember when the last time the fuel filter or air filter was replaced. Could be a dirty MAF ?

Rudeney

Cleaning the MAF is easy and inexpensive enough to try.

Shifter

The clunky noise is your shifter bushing/s missing prob just the rear one missing.

JDenhamCLK320

My dad replaced the airfilters and notice they were really dirty and packed with sand n stuff. What happens if small partials get pass the filters ??




Thanks man

clydem

I'd expect the CEL lights to come on for a dirty MAF so, skip that. As asked above, when was the last service w air, fuel filters? if within 20K, I'd look elsewhere too. Put an ODB on it & see if any codes are showing.

Rudeney

A bad MAF sensor won't necessarily trigger an MIL. If it totally fails, or the heater filament breaks, it will throw a DTC, but a dirty MAF can just be giving "erroneous but in range" readings, which will then fool the ECU into giving the wrong mixture. The air filter are good, but you will still get some very small particulate past them, and this can affect the MAF sensor performance. Cleaning it is easy and unless you do something stupid, a safe thing to do.

clydem

Sorry about getting a little off topic,
and I'm not anything but a garage mechanic but...

If the engine is going to run rough enough to be noticeable and it's due to a MAF, then I'd think a code would be thrown somehwere as the A/F would be out-of-spec.
I thought a MAF heated it's sensor wire at every start to "Burn off" any contaminents. I know there's MAF cleaner, but I've also read that if that stuff gets upstream of the wire, it can foul sensors up. Lastly, replacing a MAF isn't cheap so I'm not inclined to mess with mine & risk breaking it.

Rudeney

A bad MAF won't always throw an error. If the wire is broken, the system will detect that, but dirt or just "lifespan limitations" can cause it to give slightly erroneous readings. The way the ECU works is that it accepts inputs from dozens of sensors, then it uses them all as "vectors" in a multi-dimensional table to lookup the proper fuel/air ratio to provide. If some sensor gives a reading that is out of bounds, you get an error. Or, if one sensor is giving a valid reading, but combined with reading from other sensors, there is no resulting "answer" to the vector lookup, then you get an error. But it's possible for sensors to give slightly wrong readings that throw things off a bit. This often happens with a dirty MAF sensor. Cleaning it with CRC MAF spray is easy, but I really recommend removing it to get the best results. Removing the MAF sensor is easy, but on an older engine, you can have brittle rubber hoses and plastic clips that tend to break. They probably need to be replaced anyhow, but that's just an extra cost.

JDenhamCLK320

Well it did it again. Replaced the air filters. This time it stumbled pretty good at a stop where all the dash lights lit up as if it shutdown for a split second. Could a on the way out battery do this ? Who knows how old the battery is

Rudeney

It could be a voltage problem - that can cause all sorts of gremlins. But it would probably be a bad alternator - not a bad battery.

JDenhamCLK320

U think if it was a voltage issue it would throw on a CELL LIGHT. That's what sucks cause when it does it no CELL LIGHT pops on