idle

[c5vetteman]

I have a problem with my 96 c280. At startup or when i come to a stop my car idles uncontrollably. The rpms bounce around from 800rpm to 1500rpm even up to 2000 rpms sometimes. Can anyone tell me what the problem might be. I have had this problem for a while and since the check engine light has recently came on it seems to have gotten worse.

[C280Rookie]

had a similar problem more than a month ago. in fact, my car stalled a few times and had to get it towed to my indy mechanic.
i ended up replacing my maf and ovp relay. actually, my check engine light didn't come on, because the ovp relay went out before the maf. cost me $600. it had been driving great until yesterday.
now my check engine light is on, and my car sounds 'unhealthy' and the engine idles a bit roughly.
i will take it to my mechanic this week, and i will post what the problem is this time.
hope this helps. good luck.

[J Irwan]

That does sound like a MAF/MAS (Air Mass Sensor) failing.


You should change it quickly, and the car will feel stronger and have smoother idle.


Never buy a used MAS ever..!!

Buy new, and new MAS can be purchased less than $300 USD new.

There are a lot place carry these part , do a search on the internet and you'll be fine.


Regardz,

[C280Rookie]

Originally posted by J Irwan
That does sound like a MAF/MAS (Air Mass Sensor) failing.


You should change it quickly, and the car will feel stronger and have smoother idle.


Never buy a used MAS ever..!!

Buy new, and new MAS can be purchased less than $300 USD new.

There are a lot place carry these part , do a search on the internet and you'll be fine.


Regardz,

Hi J

But I bought a new MAF/MAS? Maybe it's a dud huh? I will ask my mechanic to check the MAF/MAS once again.
I have read other posts, and some mention oxygen sensors may need replacing when you get these problems?
Have you had your oxygen sensors replaced?
Thanks for your advice.

[J Irwan]

Originally posted by C280Rookie
Hi J

But I bought a new MAF/MAS? Maybe it's a dud huh? I will ask my mechanic to check the MAF/MAS once again.
I have read other posts, and some mention oxygen sensors may need replacing when you get these problems?
Have you had your oxygen sensors replaced?
Thanks for your advice.

Where did you purchaed the MAS from..?

IF you have another buddy who also have C280. You could try swapping their MAS into your car and see if that fix it.

Other wise your 02 sensor might be the next on the list.



Regardz,

[slugger]

I've been advocating this a lot here these days, but even before going to the mechanic, go to an Autozone and have them pull the code for the check engine light. It takes them only a few seconds and they are happy to do it. It specifically tells you the exact problem, that way you will go to the mechanic with the correct information. Also, many times, even in the case of the MAS, you can do it yourself and save hundreds.

Good luck!

[C280Rookie]

J, thanks for the suggestion. unfortunately i don't know anyone who has a c280 close by.

Slugger, thanks for the tip. The nearest autozone from my place doesn't have an obd 1 scanner. My car (96 C280) uses an obd 1 right?

Anyway, I will leave the car with my mechanic tomorrow and hopefully he finds the problem soon and I will let you guys know.

I will mention to him about the possibility of a faulty MAS or the sensors.

Thanks again guys for your help.

[Rocky]

Originally posted by c5vetteman
I have a problem with my 96 c280. At startup or when i come to a stop my car idles uncontrollably. The rpms bounce around from 800rpm to 1500rpm even up to 2000 rpms sometimes. Can anyone tell me what the problem might be. I have had this problem for a while and since the check engine light has recently came on it seems to have gotten worse.

Your in 'LIMP' mode. without pulling the codes it's tuff to tell.

[slugger]

I might be wrong, but I thought it was OBD II that's used.

Definitely keep us posted.

[stox]

1996 is an OBDII car, the port will be right above your right knee when sitting in the drivers seat.

[C280Rookie]

stox

thanks for clarifying this obd stuff. i try to find that port tonight.

[speedybenz]

Your problem could be a Crank Position Sensor. My C43 would fire up and idle up to like 2000 rpm and then slow down and then started to idle fine. I also had some rough idle and startup problems.

Jeff

[97Brabus]

Originally posted by c5vetteman
I have a problem with my 96 c280. At startup or when i come to a stop my car idles uncontrollably. The rpms bounce around from 800rpm to 1500rpm even up to 2000 rpms sometimes. Can anyone tell me what the problem might be. I have had this problem for a while and since the check engine light has recently came on it seems to have gotten worse.

I recently replaced the MAF in my 97 C280. I had MB do a diagnostic and found that the code was something to the effct of "program outside of adaptation limits" This is usually the MAF, so I decided to replace. Luckily I knew a mechanic with MB and we rolled it in the shop and did the work under the table. The tech told me the most important thing when replacing MAF is to reset the adaptation which can only be done with MB machines. Car runs like a dream now. I would check to see if adaptation was reset if you have had the problem only since the replacement. One other very very easy fix to check first is the vaccum lines. Under the hood next to the oil filter there is a soft vaccum line that gets knocked loose on occasion. Check that line. If it's loose, that definitely causes a fluctuation in idle.

Good luck!

[jstrat85]

its the slide valve. i just had mine replaced. its like around $700!

[Rocky]

It's the Flux Capacitor!

[97Brabus]

Originally posted by Rocky
It's the Flux Capacitor!

Naw, it's the muffler bearing! The elite, the mysterious, the muffler bearing!

In all seriousness...first things first when it comes to a fluctuating idle. If there's anything I have learned about DIY mechanic work, it's to check the simple things first. Vaccum lines and get the computer reset. Saves you lots of $$$ on parts you may not need.

[CKlasse]

Originally posted by 97Brabus
The tech told me the most important thing when replacing MAF is to reset the adaptation which can only be done with MB machines.

... or by unplugin' the battery ground cable for few minutes.

[97Brabus]

Guess even the tech's know how to sell things around there. At least he got me the parts for cost and I paid for half the normal MB labor charge. Now I know the secret trick for the next time!