'93 300e idle surging - fault code 009...advice needed - Page 2 - PeachParts Mercedes-Benz Forum

est · #16 12-12-2002, 06:44 PM

Finally the amm arrived and after installing everything started working like it suppose to. Conclusion: hfm air mass meter does not break- it wears out and with time, the measurment of this device becomes inaccurate wich leads to richer mixture, which in case leads to the clog up of Lambda sensor and catalytic converter.
The new Lambda sensor (which was installed before the aam) caused even greater fluctuation of idle speed, trying to correct the mixture.
This is my humble opinion, so please correct me if i am wrong, because i really wanna understand how the newer injection systems think.

blackmercedes · #17 12-13-2002, 03:38 AM

Onthe OBDII cars, the MAS is set to trigger a CE light pretty quick, as running with a defective MAS not only causes driveability problems, but it can break other emissions bits.

Think the MB MAS is $$? Our Mazda 626 needed one, and the Mazda OEM part was $1300. We got a used one for free...

est · #18 12-13-2002, 11:12 AM

Amen to that! The price is definately not liked by customers. The thing is that european cars do not have the mil light. This amm fault can cause malfunction of lambda sensor and catalytic converter.

onrails · #19 10-03-2003, 11:52 AM

I am having the same surging problem on my 1993 300e with a 3.2 engine.

So far we (the mechanics that is) have replace the O2 sensor after getting a flat line reading intermittantly. No help. They cleaned the idle control valve out which was mentioned in another thread, no help.

My symptoms are, slightly rough idle when cold, about 20 minutes into my commute the idle starts to surge and the exhaust stinks like the cat is bad. A friend said that might be the car leaning out and the cat "cooking"

There are no apparent vac leaks, and the harness recall was done on the car in the past.

The mechanics had a 1994 320E at the shop that runs fine, so they swapped in the known good Mass Air meter, and there was still an intermittant surge when warmed up.

No check engine light.....

Need more suggestions?

suginami · #20 10-03-2003, 07:16 PM

Your engine does not have an idle control valve. M103 and M102 engines have idle control valves.

M104 engines have a throttle actuator, which electronically controls three functions: Idle speed control, electronic accelerator, and cruise control. I don't believe it can be cleaned to fix the problem.

I don't know if the problem is your throttle actuator or not, but if replacing the Mass Air Meter didn't fix the problem, and if you don't have a vacum leak, then I would point the blame at the throttle actuator.

They usually fail for two reasons:

1. they have potentiometers that wear out over time.
2. they have a wire harness that has bad insualtion which flakes off, which cause the actuator itself to malfunction.

onrails · #21 10-06-2003, 08:43 AM

I understand that one test for this throttle actuator is to try the cruise control. I will check it today and post results.

Would the Throttle Actuator on a 1994 E320 be the same?

If so my shop has one that they possibly swap the part onto my car for testing. Is this thing a b!+ch to R&R?

Thanks for all your help, I think I need to find someone a little more competent with MB. I am using my BMW mechanic for my Benz and he just doesn't have the technical savvy.

onrails · #22 10-06-2003, 08:47 AM

Quote:

Originally posted by suginami
I have a 1993 300E and had a surging idle similar to what you are describing.

Common causes of this sympton usually are:

1. mass air flow meter
2. vacuum leak
3. throttle actuator

My problem in the end turned out to be a vacuum leak at the intake manifold. My crack mechanic figured this out after changing a $961 actuator and a $250 mass air meter.

Did you keep the old, now known good actuator? If it turns out to be the part I need I will buy your old one.

suginami · #23 10-06-2003, 11:05 AM

I ended up installing the new actuator because I couldn't return it, and selling the old one.

suginami · #24 10-06-2003, 11:06 AM

Quote:

Originally posted by onrails

Would the Throttle Actuator on a 1994 E320 be the same?

Yes, 1993 300E (3.2)'s and 1994-1997 E320's use the same actuator.

In fact I think S320's until 1999 used the same actuator as they have the same engine.

onrails · #25 10-06-2003, 02:14 PM

Quote:

Originally posted by onrails
I understand that one test for this throttle actuator is to try the cruise control. I will check it today and post results.

The cruise control works, so would that totally rule out the actuator as the problem?

I am currently looking for a Benz shop to diagnose this problem in the Nassau/Suffolk border area of Long Island. Any Suggestions?

suginami · #26 10-06-2003, 02:40 PM

Well, your cruise control can still work fine, and the actuator could still be bad.

The point is that if any of the three functions the actuator controls fails, then you have to replace the whole part.

I agree with you in that you need a mechanic who specializes in Mercedes to diagnose the car, whether at a dealer or an independent.

Two Mercedes independent shops that tried to fix my car couldn't find the vacum leak. They suspected it, but determined that there wasn't one.

The dealer took less than an hour to determine that there was a vacum leak, and that it was coming from the intake manifold seal.

In any event, the throttle actuators are a known failure item on our car, especially because the early ones (like ours) had bad harnesses.

onrails · #27 10-07-2003, 08:33 AM

I guess it is off to my local stealer....um.....dealer.

Thanks for the help.