11 replies to this topic

[lcc014]

Last night, on the way to drop off my daughter's prom date at 1 am in the morning, my car, all of a sudden, idling very rough in front of the traffic light. Idle speed dropped down to about 500 rpm and engine tried to get the idle speed back up to about 800 rpm. Then it kind of back to normal. That happened 2 times last night (this morning). In the second time, I had to shut down the engine and waited for a short time then restart. Check engine light came on. This morning, the rough idle had not happened yet. I pulled the codes: A1: 1-1-1, A2: 1-2-1, A3: 1-1-1.

I looked up A2: 1-2-1 from this forum and it pointed to MAF sensor signal. Could it be a dying MAF sensor ? My car's MAF is the original. It serves for about 14 years, 209k miles.

Any suggestion is appreciated.

Ching-Ho Cheng

[magicaljake]

sounds like a MAF to me...


and more then 200k....you got your use out of it.

[Cal3thousand]

Sounds like you found your own answer already.

here's confirmation: MAFs go bad, if it is original and lasted that long, you should consider yourself lucky.

[lcc014]

Thanks for all to reply my question. I just ordered a MAF from dealer - $203, not cheap !!! Hopefully, this will give me another 200k miles

Ching-Ho Cheng

[Mete Goktepe]

hello,

if your car is a non turbo 850 you may want to check your airbox thermostat.because it gets stuck in hot position, first the idle behaves weird,second the car lack power.. third it causes a check engine light and throws the code 1-2-1 mass airflow sensor absent or faulty. this is because the flap getting stuck in the hot position and the ecu doesnt receive the maf signal because the cold air inlet is closed by the flap... but if your flap is in cold position and still getting the code the time for replacing the maf sensor is up..

[lcc014]

Mete Goktepe, on 02 June 2009 - 05:22 PM, said:

hello,

if your car is a non turbo 850 you may want to check your airbox thermostat.because it gets stuck in hot position, first the idle behaves weird,second the car lack power.. third it causes a check engine light and throws the code 1-2-1 mass airflow sensor absent or faulty. this is because the flap getting stuck in the hot position and the ecu doesnt receive the maf signal because the cold air inlet is closed by the flap... but if your flap is in cold position and still getting the code the time for replacing the maf sensor is up..

How can I tell the flap is in hot or cold position ?

Thanks,

Ching-Ho Cheng

[Mete Goktepe]

hello again,


below is the link for the thread about the airbox thermostat failure.I think you have this problem because when the same thing happened to me I bought a new maf sensor and the same problem continued and the check engine light and code 1-2-1 came back.read the whole thread, there are pictures of the airbox thermostat and guide how to correct the problem.


if you check the airbox and see your flap is in cold position then your maf might be bad.but first check the airbox thermostat.. here is the link:

http://www.matthewsv...&st=0&sk=t&sd=a

[lcc014]

Mete Goktepe, on 02 June 2009 - 07:39 PM, said:

hello again,


below is the link for the thread about the airbox thermostat failure.I think you have this problem because when the same thing happened to me I bought a new maf sensor and the same problem continued and the check engine light and code 1-2-1 came back.read the whole thread, there are pictures of the airbox thermostat and guide how to correct the problem.


if you check the airbox and see your flap is in cold position then your maf might be bad.but first check the airbox thermostat.. here is the link:

http://www.matthewsv...&st=0&sk=t&sd=a

So, if I check the airbox now (car is shut off) and find that the flap is in cold position then I can be pretty sure that the MAF sensor is bad. Otherwise, thermostat is bad. Is this a TRUE statement ?

Thanks,

Ching-Ho Cheng

[Mete Goktepe]

hello,


this thermostat was designed to provide hot air in temperatures less then 15Celcius, at temperatures over 15Celcius the flap should be in cold position.. the best way to find out if its working properly is drive the car until it reaches normal operating temperature.. 3'o clock position... stop the car and open the box if you see it in cold position the thermostat is good, however if the thermostat is in hot position the thermostat is bad.


and yes after driving the car for half an hour and after stopping it if you open the box and see the flap is in cold position you can be sure that the maf is bad...


let us know what happens...

[lcc014]

Mete Goktepe, on 02 June 2009 - 08:11 PM, said:

hello,


this thermostat was designed to provide hot air in temperatures less then 15Celcius, at temperatures over 15Celcius the flap should be in cold position.. the best way to find out if its working properly is drive the car until it reaches normal operating temperature.. 3'o clock position... stop the car and open the box if you see it in cold position the thermostat is good, however if the thermostat is in hot position the thermostat is bad.


and yes after driving the car for half an hour and after stopping it if you open the box and see the flap is in cold position you can be sure that the maf is bad...


let us know what happens...

Thanks, I will update the finding.

Ching-Ho Cheng

[lcc014]

Just got home from about 45 minutes of driving, outside temperature was at about 25 C. Opened up the airbox and used my finger to feel the flap in which position. It was at "cold position" - flap closed the cold air from the front air tube. Hot air from the exhaust manifold constantly came into the airbox. I ordered the thermostat from FCP Groton. When I receive it, I will replace the thermostat. Another interesting point is that my mileage is always around 22 - 23 mpg. My car does not suffer from the drop of mileage. However, the MAF sensor has been suffering from hot air for a long time. :-(

Thanks for all the help from this forum.

Ching-Ho Cheng