[Fluteguy]

My 01 E320 (120,000 miles) started having low fuel mileage and a little bit of an errant miss about three months ago. I scanned the car but no codes. I went ahead and replaced the MAF sensor (it was the original) and that seemed to help with the mpg but the miss was still there so I took the car to my mechanic. He checked the cats and they were ok but he gave me a list that was more than I could afford. Start with spark plugs (I bought the car at 107,000 miles so I don't know if the plugs were ever replaced), plug wires, engine mounts (which he claimed couldn't be checked unless the engine was lifted off of them and he said by that point I might as well replace them because the labor was the biggest part and he said that they would have to lift the engine up to get to the back plugs anyway) and if that didn't cure the problem he suggested new oxygen sensors. The total was over $2250.

I've just retired and I have a limited budget. Like I said, there were no codes so the computer is not seeing anything wrong but it's just got an errant miss that is driving me crazy.

Where would you start?

 

[Fluteguy]

It happens only at idle

 

[G-AMG]

If it were me? I would Unplug/Re-Plug in all of the Spark Plug leads. Or... In your case... take the car back to the operating mechanic, and have HIM do it on his dime.

If the Lead is not "Clicked" onto the Plug? you can get Funky, irregularly Irregular "Blips" of subtle mis-fire.

 

[hamada128]

The first thing you should do is to replace that mechanic. I just replaced the plugs on my car myself and didn't need to lift the engine at all, the plugs are all accessible from above.
The engine mounts could also be checked without needing to lift the engine, an experienced mechanic should be able to check it by putting the car on D while holding the brakes and looking at the engine movement when he pushes the gas pedal.

 

[fabbrisd1]

Let me describe a symptom - when coming to a braked stop - engine RPM drops down to idel, then seems to miss/choke and drop down below idel - where it seems to catch itself before cking and dying - is this what you are encountering ?

please describe.

 

[Fluteguy]

No, it never runs REALLY badly. My roommate drove it last night and said he thought it felt like more of a shudder. The tach needle stays steady and there is no loss of power, acceleration is great and it never feels like it's going to stall out. He said he thought it felt more like motor mounts were bad, said it was like I said, more of a shudder and vibration than a miss.

 

[Check Codes]

Can you DIY any of this stuff?

If you don't know whether the plugs have been replaced, pull one and check the P/N (or the resistance). If it's a NR plug, they've never been changed. (You may also be able to tell simply by the wear).

If the plugs have been done, then I would replace the engine mounts. Particularly since you only notice the issue at idle; that is classic for failed mounts and your car is of the age for that to be an issue.

And contrary to hamada's note, the old "load the engine and check for movement" doesn't really work with these hydraulic mounts; indeed, some have noted MORE movement from a new mount than a collapsed one. Given that the mounts are supposed to hydraulically suspend the engine, that makes sense, too.

Now if the plugs haven't been done, I would do both them AND the mounts at the same time, and check the wires for resistance while you are doing that job. Or shotgun it and change the wires at the same time, the Bosch are fairly inexpensive at Amazon (and if you're paying a shop to do it, just buy the set, their time to test them is more than the wire cost).

If I lived closer I'd come give you a hand, but KY is a bit out of the area.

Good luck.

 

[fabbrisd1]

The most common diagnosis for "failed" engine mount(s) - at a braked stop - with tranny in D - "shudder" will dimished if tranny moved to Nuetral or Park.

The best value are the Lemfoerder/Sach-Boge genuine mounts around $130 from reputable internet sellers - China made mounts can be advertised much more cheaply... but rightfully you are headed towards mounts..

Keep the beat !

 

[hamada128]

In my case, the mounts were completely shot and the rubber separated at the middle so the movement was much noticeable compared to the new mounts.

 

[Fluteguy]

Well, I made an appointment with a recommended new and improved mechanic to have the motor mounts and transmission mounts replaced and he's going to pull a couple of the spark plugs to see if they have been replaced. He did drive the car and said the motor mounts had "typical symptoms" that indicated that they were shot. Vibrating at standstill while the transmission in gear, etc. He also recommended doing the transmission mounts at the same time.

I'll keep you posted!

 

[fabbrisd1]

You need to make sure the new mechnical quotes you using either MB or Lemfoerder/Sach-Boge OE mounts - the non-brand or quasi-brand mounts are all China which for this part are "sh*t".

My expereince the tranny mount is non-consequential in "brand" as long as same style tranny mount is replaced.

 

[eric242340]

Well, I made an appointment with a recommended new and improved mechanic to have the motor mounts and transmission mounts replaced and he's going to pull a couple of the spark plugs to see if they have been replaced. He did drive the car and said the motor mounts had "typical symptoms" that indicated that they were shot. Vibrating at standstill while the transmission in gear, etc. He also recommended doing the transmission mounts at the same time.

I'll keep you posted!

Seems to me you did the right thing and got yourself a decent mechanic, when changing the engine mounts it is always best to do the transmission mounts at the same time.:thumbsup:

Lift the engine to change rear plugs???? I would run a mile from that guy.

 

[Fluteguy]

Got the spark plugs and motor and transmission mounts and now the car runs smooth as silk! I did find out from the new and improved mechanic about the raising the engine to change the plugs bit. He said that raising one side DOES make it easier to change the lower side but it's not essential.

Anyway Scheller Automotive in Lexington is awesome!

 

[e-420]

can your code reader display "pending codes" codes that have been stored but not trigger the CEL??? good chance that you have pending codes related to the miss, but it doesn't happen enough to store a code. E.g hasn't triggered a failure.

 

[Fluteguy]

Once the plugs were replaced the miss went away

 

[Check Codes]

Good to hear. Enjoy the smooth ride!

 

[G-AMG]

I will bet you the problem was incompletely "Snapped-In" Plug wires.

 

[eric242340]

I will bet you the problem was incompletely "Snapped-In" Plug wires.

LOL yes it does happen, fortunately not too often.

 

[Fluteguy]

Well the thing is that the plugs were the original ones from the factory. I'm surprised that after 120,000 miles and 14 years that it ran as well as it did

 

[eric242340]

Well the thing is that the plugs were the original ones from the factory. I'm surprised that after 120,000 miles and 14 years that it ran as well as it did

Blimey you were lucky, 100k is the expected life span.